Forensic science experiments to do at home

illustrated guide to home forensic science experiments and also explain forensic science home study courses
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Published Date:15-07-2017
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Laboratory 1 Safety First things first. This is a short chapter, but a very important one. Many of the lab sessions described in this book use chemicals, such as strong acids and bases, that are dangerous if handled improperly. Some lab sessions use open flame or other heat sources, and many use glassware. To state the obvious, you can get hurt working in a lab. Fortunately, there are steps you can take to minimize or eliminate hazards. If you remember one thing from this chapter, remember this: If there is even the slightest chance that you will be exposed to any hazardous chemical, always wear chemical splash goggles, gloves, and protective clothing. We follow this advice ourselves, without exception. Most injuries that occur in student labs are minor and easily DENNIS HILLIARD COMMENTS avoidable. Among the most common are nicks from broken or Whenever you are working with any chemicals, glassware, chipped glassware and minor burns. Serious injuries are very and/or biological material, always wear chemical splash rare. When they do occur, it’s nearly always because someone goggles, gloves, and protective clothing. Protective did something incredibly stupid, such as using a flammable clothing works two ways: it protects the analyst from solvent near an open flame or absentmindedly taking a swig chemical, sharps, and biological hazards associated with from a beaker full of a toxic liquid. (That’s why one of the rules of evidence collection and processing; and it protects from laboratory safety is never to smoke, drink, or eat in the lab.) contamination of the evidence by the collector/analyst. The primary goal of laboratory safety rules is to prevent injuries. Knowing and following the rules minimizes the likelihood of Although working in any lab has its dangers, so does driving a accidents and helps to ensure that any accidents that do occur car. And, just as you must remain constantly alert while driving, will be minor ones. you must remain constantly alert while working in a lab. But it’s also important to keep things in perspective. More serious The following are the laboratory safety rules we recommend: injuries occur every year among a few hundred thousand high school football players than have ever occurred in total Prepare properly among millions upon millions of student scientists in the 200- year history of student labs. Statistically, students are much, • All laboratory activities must be supervised by a much safer working in a home or school lab than they are out responsible adult. skateboarding or riding bicycles. Chapter 1 : Laboratory Safety 1Direct adult supervision is mandatory for all of the activities The MSDS is a concise document that lists the specific in this book. This adult must review each activity before characteristics and hazards of a chemical. Always read the it is started, understand the potential dangers of that MSDS for every chemical that is to be used in a lab session. activity and the steps required to minimize or eliminate If an MSDS was not supplied with the chemical, locate one those dangers, and be present during the activity from on the Internet. For example, before you use lead nitrate in start to finish. Although the adult is ultimately responsible an experiment, do a Google search using the search terms for safety, students must also understand the potential “lead nitrate” and “MSDS”. dangers and the procedures that should be used to minimize risk. • Organize your work area. • Familiarize yourself with safety procedures and equipment. Keep your lab bench and other work areas clean and uncluttered, before, during, and after laboratory sessions. Think about how to respond to accidents before they Every laboratory session should begin and end with your happen. Have a fire extinguisher and first-aid kit readily glassware, chemicals, and laboratory equipment clean and available and a telephone nearby in case you need stored properly. to summon assistance. Know and practice first-aid procedures, particularly those required to deal with burns Dress properly and cuts. If you have a cell phone, keep it with you while you’re working in the lab. • Wear approved eye protection at all times. One of the most important safety items in any lab is Everyone present in the lab must at all times wear splash the cold water faucet. If you burn yourself, immediately goggles that comply with the ANSI Z87.1 standard. (seconds count) flood the burned area with cold tap water Standard eyeglasses or shop goggles do not provide for several minutes to minimize the damage done by the adequate protection, because they are not designed to burn. If you spill a chemical on yourself, immediately rinse prevent splashed liquids from getting into your eyes. the chemical off with cold tap water, and keep rinsing for Eyeglasses may be worn under the goggles, but contact several minutes. Ideally, every lab should have an eyewash lenses are not permitted in the lab. (Corrosive chemicals station, but most home labs do not. If you do not have an can be trapped between a contact lens and your eye, eyewash station and you get any chemical in your eyes, making it difficult to flush the corrosive chemical away.) immediately turn the cold tap on full and flood your eyes until help arrives. • Wear protective gloves and clothing. Never allow laboratory chemicals to contact your bare skin. When you handle chemicals, particularly corrosive WARNING or toxic chemicals or those that can be absorbed through Everyone rightly treats strong acids with great respect, but the skin, wear gloves of latex, nitrile, vinyl, or another many students handle strong bases casually. That’s a very chemical-resistant material. We recommend disposable dangerous practice. Strong bases, such as solutions of nitrile gloves, which you can purchase at Costco, Walmart, sodium hydroxide, can blind you in literally seconds. Treat or any drugstore. We are comfortable using disposable every chemical as potentially hazardous, and always wear nitrile gloves for handling any of the chemicals used in splash goggles. this book. If you want to be extra cautious when handling corrosive and/or toxic chemicals, either double-glove with disposable nitrile gloves or wear heavier gloves, such as the Keep a large container of baking soda (sodium thick “rubber” gloves sold by lab supply vendors and in the bicarbonate) on hand to deal with acid or base spills. supermarket for household use. Baking soda neutralizes either type of spill. We keep a 12-pound bag from Costco on hand for this purpose. Wear long pants, a long-sleeve shirt, and leather shoes or boots that fully cover your feet (NO sandals). Avoid loose • Always read the Material Safety Data Sheet (MSDS) for sleeves. To protect yourself and your clothing, wear a every chemical you will use in a laboratory session. lab coat or a lab apron made of vinyl or another resistant material. Wear a disposable respirator mask if you handle chemicals that are toxic by inhalation. 2 DIY Science: Illustrated Guide to Home Forensic Science ExperimentsAvoid laboratory hazards Don’t Do Stupid Things • Avoid chemical hazards. • Never eat, drink, or smoke in the laboratory. Never taste any laboratory chemical or sniff it directly. All laboratory chemicals should be considered toxic by (Use your hand to waft the odor toward your nose.) Never ingestion, and the best way to avoid ingesting chemicals is use your mouth to fill a pipette. When you heat a test tube to keep your mouth closed. Eating or drinking (even water) or flask, make sure the mouth points in a safe direction. in the lab is very risky behavior. A moment’s inattention can Always use a boiling chip or stirring rod to prevent liquids have tragic results. Smoking violates two major lab safety from boiling over and being ejected from the container. rules: putting anything in your mouth is a major no-no, as is Never carry open containers of chemicals around the carrying an open flame around the lab. lab. Always dilute strong acids and bases by adding the concentrated solution or solid chemical to water slowly • Never work alone in the laboratory. and with stirring. Doing the converse can cause the liquid to boil violently and be ejected from the container. Use the No one—adult or student—should ever work alone in the smallest quantities of chemicals that will accomplish your laboratory. Even if the experimenter is adult, there must at goal. In particular, the first time you run a reaction, do so least be another adult within earshot who is able to respond on a small scale. If a reaction is unexpectedly vigorous, it’s quickly in an emergency. better if it happens with 1 mL of chemicals in a spot plate than 500 mL in a large beaker. • Never horse around. • Avoid fire hazards. A lab isn’t the place for practical jokes or acting out, nor for that matter for catching up on gossip or talking about last Never handle flammable liquids or gases in an area where night’s ball game. When you’re in the lab, you should have an open flame or sparks might ignite them. Extinguish your mind on lab work, period. burners as soon as you finish using them. Do not refuel a burner until it has cooled completely. If you have long hair, • Never combine chemicals arbitrarily. tie it back or tuck it up under a cap, particularly if you are working near an open flame. Combining chemicals arbitrarily is among the most frequent causes of serious accidents in home labs. Some • Avoid glassware hazards. people seem compelled to mix chemicals more or less randomly, just to see what happens. Sometimes they get Assume all glassware is hot until you are certain otherwise. more than they bargained for. Examine all glassware before you use it, and particularly before you heat it. Discard any glassware that is cracked, Laboratory safety is mainly a matter of common sense. Think chipped, or otherwise damaged. Learn the proper about what you’re about to do before you do it. Work carefully. technique for cutting and shaping glass tubing, and make Deal with minor problems before they become major problems. sure to fire-polish all sharp ends. Keep safety constantly in mind, and chances are any problems you have will be very minor ones. Chapter 1 : Laboratory Safety 3Equipping Your Forensics 2 Laboratory To do a serious study of forensic science lab work, you’ll need some specialized equipment and chemicals. Fortunately, it needn’t be expensive to acquire the items you need. You may already have some of those items, such as a microscope purchased for a biology course or a balance and other lab equipment purchased for a chemistry course. To make matters as easy and inexpensive as possible, as we wrote this book we designed a custom lab kit to go with it (http// .html). With the exception of readily available materials, major items (such as a microscope and balance), and some optional items, this kit includes the specialized equipment and chemicals you need to complete the lab sessions in this book. Of course, you don’t have to buy the kit to use this book. We provide full details of what’s needed for each lab session, and all of those materials can be obtained locally or purchased individually from numerous online lab supply vendors and law-enforcement forensic supply vendors. Optical EquipmEnt The iconic image of Sherlock Holmes has him smoking a pipe, wearing a deerstalker cap, and examining evidence with his magnifying glass. The pipe and cap are optional but, as Holmes knew well, optical equipment is essential for successful forensic investigations. Like Holmes, we’ll use a variety of optical aids in our investigations, all of which are described in the following sections. the crime scene as it was first encountered, with both overall IMAGING EqUIPMENT images to show the crime scene in context and close-up images One of the fundamental principles of crime scene management to show details of objects of particular evidentiary value. is that everything possible should be recorded in situ photographically. Once an object has been moved, the scene Photography is also used extensively for recording specimens is permanently altered. The primary goal of crime scene that have been recovered from the crime scene and transported photography is therefore to preserve a permanent record of to the forensics laboratory. Such images provide a permanent record of specimens as they appeared when they were received Chapter 2 : Equipping Your Forensics Laboratory 5by the lab, and are particularly useful for situations in which Digital cameras soon achieved resolution nearly as good as the subsequent testing may alter the appearance of the evidence, best available film cameras—and in some cases, better—which perhaps permanently. answered the first objection. And, as it turned out, sophisticated digital image analysis algorithms can detect changes to digital images, answering the second objection, as well. CAMERA (OPTIONAL) Forensic technicians have routinely photographed crime scenes since the last quarter of the 19th century. At that time, the DENNIS HILLIARD COMMENTS best cameras available were large, bulky, and used glass plate Despite their relatively low image quality, camcorders emulsions that for anything other than full daylight required were formerly widely used to record crime scene video. long exposure times or flash exposures that scattered unburned With the use of digital still cameras, crime scene video has flash powder and ashes all over crime scenes. As camera fallen out of favor. The digital camera is used to document technology improved, so too did the quality and quantity of the entire scene and photos can be stitched together in crime scene images. Today, most crime scene photographers a computer program such as Adobe Photoshop to give panoramic views. use both standard digital SLRs—film cameras are seldom used any longer, other than in special situations—and specialized cameras that capture images in the infrared or ultraviolet portions of the spectrum. Although you won’t be photographing any crime scenes for the lab sessions in this book, a camera is also useful for Because any camera inherently distorts reality by representing recording images of specimens for your lab notebook, shooting three-dimensional scenes in two dimensions and by rendering photomicrographs (images through the microscope), and so colors and contrasts imperfectly, crime scene photographers on. If you don’t have a suitable camera, you can make sketches, take great care to minimize any such effects their equipment instead. may impose on the final images and to record the pertinent data about each image. For example, because the focal length of a lens affects perspective, back when film cameras were DENNIS HILLIARD COMMENTS in common use, many crime scene photographers used Sketches are often a part of the analyst’s notes and are only fixed-focal length lenses or, alternatively, recorded the required in accredited laboratories, because notes are focal length used for each image. That’s seldom a problem subject to review and photos are not always able to be nowadays, because nearly all digital cameras record such data taken of some evidence or are difficult to take through a microscope. automatically and store it with the image file. Crime scene photographers also use grids to show the distances and angular relationships among objects in the image. Similarly, where image scale is not obvious, crime scene photographers take If possible, use a digital camera with a macro feature, ideally one great care to make image scale clear within the image itself, for that permits imaging to at least a 1:3 scale (1:3 means the image example, by including a section of a ruler next to an object in an on the sensor is a third the size of the actual object), and 1:2 or image. 1:1 is better. A point-and-shoot digital camera is acceptable; a digital SLR is preferable. Although some standard “kit” zoom In the last few years, digital cameras have come to dominate lenses supplied with digital SLRs allow focusing down to a 1:3 or crime scene photography. Digital images are immediately closer ratio, these lenses do not provide the best image quality accessible, much less expensive than film images, and much for extreme close-ups. A macro lens—one optimized for best easier to store, copy, search, and transfer. The main early image quality at very short distances—is the best choice for impediments to widespread adoption of digital imaging for macro shots. We use Pentax K100D Super and K-r digital SLRs forensics were the relatively low resolution of early digital with a Pentax 50mm macro lens. cameras and the perception that digital images could be altered easily and undetectably, making them useless as evidence. 6 DIY Science: Illustrated Guide to Home Forensic Science ExperimentsBecause an on-camera flash unit provides flat lighting other than at very close focusing distances, it’s also helpful to have a A camera records an image from a fixed sensor (lens) small slave flash unit to provide low-angle or cross lighting for position, which means that different objects within the contrast when photographing small specimens. We use a 25 field of view are imaged at slightly different angles and distances, even if the object is flat. For example, if you use Vivitar DF120, which is triggered by the main flash. a camera to shoot an image of a document, the camera lens is slightly closer to the center of the document than SCANNER (OPTIONAL) to the corners, introducing some distortion. We think nothing of this, because that’s also how our eyes work. One relatively recent development has been the use of ordinary A scanner, conversely, images objects with a moving PC flat-bed scanners for recording high-resolution images of flat sensor. Each tiny part of the image is made with the specimens, usually in the lab but sometimes at the crime scene. sensor effectively in contact with the subject, so there One major advantage of using a scanner is that the images are is essentially no distortion of flat objects, such as automatically calibrated, with the resolution stored in the image documents, surfaces, or clothing specimens. It is because file header. You can open an image file with Photoshop or a scanner images have nearly zero distortion that accurate similar graphics program and perform direct measurements on direct measurements may be made from them. the image. Alternately, you can count pixels and simply convert pixels to millimeters or inches using a spreadsheet. Because typical scanners record images at 2,400 to 9,600 dpi (dots per MAGNIFIER (REquIRED ) inch) or higher, such measurements are accurate and precise. Figure 2-1 shows a small fabric tear imaged at 3,200 dpi using One of the most useful items in any forensic kit is a magnifier an inexpensive Epson scanner. that provides moderate magnification, something in the range of 5X to 15X. A magnifier provides a close-up view of small Figure 2-1: A fabric tear imaged at 3,200 dpi using a scanner objects, fingerprints, and other small but significant evidence. The FK01 Forensic Science Kit includes an inexpensive folding magnifier, but if you have a better magnifier or loupe, by all means use it. Sherlock Holmes used a simple magnifying glass, but there are better tools available today. The best choice is a photographer’s loupe with a transparent base, such as the 5X Viewcraft Lupe shown in Figure 2-2. With some scanners, you can remove the lid, invert the scanner over (for example) a stain on the floor, and record an image directly. Results are often better than camera images because the scanner provides a flat, even light, eliminating the problems with hot spots and reflections that are common with an on- camera flash. Chapter 2 : Equipping Your Forensics Laboratory 7Figure 2-2: A 5X Viewcraft Lupe A stand magnifier, preferably illuminated, is useful for examining objects while keeping both hands free. The model shown in Figure 2-4 provides 2X magnification overall and has a smaller embedded lens that provides 4X magnification of small parts of the object. Magnifiers like this one are available from stores and catalogs that serve the needs of the elderly. Figure 2-4: A stand magnifier allows you to work with both hands free A loupe with a built-in scale or reticle allows you to determine the size of objects directly, as shown in Figure 2-3. (A scale appears alongside the object in the field of view, while a reticle is superimposed optically on the image.) A basic loupe costs 5 to 15 and can be purchased from any vendor of photography supplies. High-quality loupes from German and Japanese makers are considerably more expensive. Some loupes have built-in illuminators, but most do not. Even if your loupe is illuminated, but particularly if it is not, add a small flashlight to MICROSCOPE (REqUIRED ) your portable forensics kit. We use a two-AA model with a white LED bulb, although many forensics technicians prefer to use a Microscopes take over where magnifiers leave off. Typical flashlight with an incandescent bulb because it renders colors magnifiers enlarge an object by 5X to 15X, while microscopes more accurately. enlarge objects from about 10X to 1000X or more. Modern forensics labs use many different kinds of microscopes, including electron microscopes, microscopes designed to Figure 2-3: A loupe with a scale or reticle allows you to measure work with polarized or UV light, and comparison microscopes objects directly that allow viewing two samples side by side in the same field of view. Such specialized microscopes are much too expensive for a basic forensics lab, but all of the lab sessions in this book that require a microscope can be completed with a standard compound microscope. A 40/100/400X model will suffice for all but the lab sessions that require observing diatoms and pollen; for those, a 40/100/400/1000X model is a better choice. If at all possible, use a microscope with a mechanical stage. Many microscopes include an ocular micrometer/reticle as a standard or optional feature. This is worth having, because it allows you to determine the actual sizes of objects you’re viewing through the microscope. 8 DIY Science: Illustrated Guide to Home Forensic Science Experimentspermanently, you’ll need mounting fluid. You can buy special permanent mounting fluids such as Permount or For detailed information about choosing and buying a microscope, see Illustrated Guide to Home Biology Melt-Mount, but a drop of colorless nail polish (we use Experiments. Sally Hansen Hard as Nails) works about as well. The FK01 Forensic Science Kit includes glycerol and olive oil, both of which are suitable for temporary wet mounts. MICROSCOPE ACCESSORIES Slide storage In addition to the compound microscope itself, you’ll need a Most science supply vendors carry a variety of slide modest selection of supplies and accessories. Most laboratory storage boxes in plastic and wood as well as slide folders. If supply vendors offer starter kits that contain many of these you intend to permanently mount specimens, buy boxes or items. folders as necessary to store your slides. Slides Immersion oil You’ll need a reasonable number of standard (25×75 mm or If your compound microscope has an oil-immersion 1×3") microscope slides. Buy a box of 72; you’ll use a lot of objective (usually the 100X objective), you’ll need slides. Avoid the cheapest slides, which may be fragile and immersion oil. If your microscope doesn’t have an oil- have sharp edges. You’ll also need a few concavity slides immersion objective or if you don’t plan to use high (also called well slides). These are useful for containing magnification, you can do without immersion oil. small specimens and performing micro-procedures on them. Buy deep-cavity slides, which are about three times Cleaning kit the thickness of standard slides (3 mm versus 1 mm). The You’ll need to clean the ocular and objective lenses of your deep-cavity models are harder to find and more expensive microscope periodically. If you use immersion oil, you than standard well slides, but they’re also much more should clean the immersion objective each time you use it. useful. The FK01 Forensic Science Kit includes a box of 72 Science supply vendors carry cleaning kits that include a flat slides and a box of 12 deep-cavity slides. blower, brush, lens-cleaning tissue and fluid, and so on. Coverslips Dust cover or storage case Buy a half-ounce or one-ounce box of standard 18×18 mm One of the most important and frequently overlooked to 24×24 mm square glass coverslips. 1.5 coverslips are accessories is a dust cover or storage case for the the ideal thickness for most standard microscopes, but microscope. Always keep your microscope covered when they’re relatively difficult to find. 2 coverslips are suitable you are not using it to protect it from dust and damage. If for most microscopes. Buy the very thin 1 coverslips you don’t have a cover or case, a kitchen trash bag makes only if your microscope requires them. The FK01 Forensic an adequate substitute Science Kit includes a box of standard coverslips. PHOTOMICROGRAPHY EquIPMENT (OPTIONAL) Photomicrography is the process of recording images through Avoid all plastic slides and coverslips, which are grossly a microscope. (Microphotography, conversely, is the process of inferior optically to glass models. The one exception is the lab session on doing cross sections of fibers, for which making very tiny photographs, such as the microdots formerly you’ll need at least one plastic slide. used by spies.) Using a camera to record the specimens you observe with your microscope is a very useful adjunct to narrative descriptions of your observations. Expert forensic Mounting fluids witnesses often use photomicrographs in court to supplement For routine use, you can simply make a temporary wet their verbal testimony. mount by placing a drop of water, glycerol, or vegetable oil on the specimen and then placing a coverslip on top of the specimen, but if you want to mount specimens Chapter 2 : Equipping Your Forensics Laboratory 9The ideal setup for photomicrography in a basic forensics lab SPECTROMETER (OPTIONAL) is a dual-head microscope with a digital SLR mounted to the vertical head by means of a T-ring and microscope adapter (see Professional forensics labs use a variety of spectrometers Figure 2-5). Such adapters are available from camera stores, and spectrophotometers to analyze unknown substances by Edmund Optics (http//, and other examining the light they emit or absorb at specific wavelengths. vendors. We used the Edmund Microscope Adapter (41100) Technically, a spectrometer may cover any range of wave- and Pentax K100D Super and K-r digital SLRs with a K-mount lengths, visible and/or invisible, while a spectrophotometer T-ring adapter to shoot many of the photomicrographs in this is limited to visible wavelengths, but spectrophotometers are book. Similar microscope adapters are available for specific often referred to by the more inclusive (and shorter) term as point-and-shoot digital camera models. spectrometers. Broadly speaking, there are two classes of spectrometers. Figure 2-5: A DSLR coupled to a microscope with a T-ring and microscope adapter An absorption spectrometer measures how much light at specific wavelengths is absorbed by a sample in liquid or gaseous form. For example, a copper sulfate solution appears blue because it selectively absorbs yellow wavelengths strongly but is nearly transparent to blue wavelengths. Observing the absorption spectrogram allows a scientist to identify the compound as copper sulfate and determine its concentration. Similarly, an atomic absorption spectrometer can be used to identify the specific chemical elements present in an unknown gaseous sample because each element absorbs light at specific wavelengths characteristic to that element. An emission spectrometer measures the light emitted by an unknown sample that has been vaporized and heated to incandescence. Just as each element when in an unexcited state absorbs light at specific wavelengths, each chemical element when in an excited state emits light at those same wavelengths. For example, Figure 2-6 shows the line emission spectrum of a compact fluorescent lamp, showing strong emission lines for mercury. Figure 2-6: The spectrum of a compact fluorescent lamp, showing Even if you don’t have a dual-head microscope or a camera strong mercury lines (image courtesy Rob Brown) adapter, it’s possible with patience and trial-and-error to shoot usable photomicrographs merely by setting a point-and- shoot digital camera to macro mode and holding it up to the microscope eyepiece. If you attempt this method, you may get better results if you use a short length of cardboard or plastic tube between the eyepiece and the camera lens to block extraneous light and make alignment easier. 10 DIY Science: Illustrated Guide to Home Forensic Science Experimentsnonetheless. We’ll use one of these spectrophotometers in toxicology and soil analysis labs to detect barium and other ABOuT FIGuRE 2-6 heavy metals. We had little luck in shooting our own images of emission spectra, so we asked Rob Brown (http// net/emcculloch-brown/astro/spectrostar.html), who MASS SPEC created the image shown, for permission to use one of his images, which he kindly granted. In fact, Rob shot a Despite its name, the mass spectrometer, another new image for us, and included these comments when he instrument used in forensics labs, is used to separate ions emailed the image to me. by mass, and so is not a spectrometer at all in the usual sense of the word. “The calibration is a little off. The strong green line should line up with 546 nm, but it’s a little short of 545 nm. The camera does not do the image justice. The colors are very compressed due to the color filters in the camera uLTRAvIOLET LIGHT SOuRCE ( OPTIONAL) detector. Notice the lack of yellow (575 nm), cyan (490 nm), Ultraviolet (UV) is electromagnetic radiation at wavelengths and violet (400 nm). Even the orange looks muddy. I can see visually lines at 710, 705, 685, 656, 645, and 400 too short to be visible to the human eye. UV wavelengths range nanometers. The camera can’t.” from 400 nanometers (nm), just beyond visible violet, down to 1 nm, beyond which lies the class of light called X-rays. Forensic scientists use UV light in the near UV range—400 nm down to Figure 2-6 was made by using the Project Star Spectrometer 200 nm—for many purposes, including detecting blood at crime shown in Figure 2-7. This assembled, calibrated plastic version scenes, revealing alterations in questioned documents, and sells for 40. examining chromatograms of colorless compounds such as drugs and poisons. Figure 2-7: The Project Star Spectrometer, an inexpensive spectrophotometer The near UV range is further divided into the UVA (400 nm to 320 nm), UVB (320 nm to 280 nm), and UVC (280 nm to 200 nm) ranges. UVA light, also called long-wave UV or blacklight, has relatively low energy and is therefore safe to work with. We’ll use UVA light in several lab sessions in this book. UVB and particularly UVC light has higher energy and is therefore dangerous to work with, requiring special protective goggles and clothing to prevent damage to eyes and skin. Because UVB and UVC light sources are also considerably more expensive than UVA light sources, we decided to limit the use of UV light in these lab sessions to UVA. UVA light sources are sold in toy and novelty shops as “black light” lamps. Battery-powered portable UVA lights, often described as “long-wave UV” lights, are sold by laboratory supply vendors for as little as 10. If you already have a portable Although they look like toys and are priced accordingly, fluorescent light such as a camping lantern, you can simply these inexpensive spectrophotometers are serious scientific replace the standard fluorescent tube with a BLB (blacklight instruments. Obviously, they are not as sensitive or as accurate blue) fluorescent tube of the correct size and wattage. Figure as professional models that sell for a thousand to ten thousand 2-8 shows a typical 10 battery-powered “black light” that is times the price, but they can be used to do real science suitable for the lab sessions in this book. Chapter 2 : Equipping Your Forensics Laboratory 11Figure 2-8: A typical 10 battery-powered UVA “black light” Another option is an ultraviolet LED flashlight. Typical pocket models use three AAA cells to drive an array of six to nine UV LEDs, providing bright illumination at 395 nm. These flashlights are widely available from online vendors for 5 to 10. We’ve come to prefer UV LED flashlights because they provide a relatively tight, intense beam of UV and because battery life is much better than the tube-based units. Although none of the lab sessions in this book requires a UV light source, having one available is useful for several lab sessions. Table 2-1 lists the optical equipment we recommend. Items flagged in the FK01 column are included in the FK01 Forensic Science Kit. Table 2-1: Recommended optical equipment Item FK01 Sources Camera with macro capability (optional)○ Local/on-line vendors Magnifier● Local/on-line vendors ○ Microscope (ocular micrometer/reticle recommended) Lab supply vendors ○ Microscope adapter for camera (optional) Camera/microscope vendors ○ Microscope cleaning kit Lab supply vendors ○ Microscope cover Microscope vendor ● Microscope coverslips, box Lab supply vendors ○ Microscope immersion oil (optional) Lab supply vendors ● Microscope slides, flat, box of 72 Lab supply vendors ● Microscope slides, deep-cavity, box of 12 Lab supply vendors ○ Mounting fluid for permanent mounts (optional) Lab supply vendors, drugstores ● Mounting fluids for temporary mounts drugstores, supermarkets ○ Scanner with software (optional) Local/online vendors ○ Spectrometer (optional) See text ○ Ultraviolet light source See text 12 DIY Science: Illustrated Guide to Home Forensic Science Experimentslaboratory Equipment In designing the lab sessions for this book, we made every effort to keep equipment requirements as modest as possible. With few exceptions—mainly optional items and expensive items such as a microscope—the FK01 Forensic Science Kit includes the specialty equipment and chemicals needed to do the lab sessions. Most of the lab sessions in this book use microscale techniques. teardown, cleanup, and storage faster and easier, and also These techniques are in accord with real forensic practices, minimizes disposal issues. which usually (not always) operate on very small samples, often as small as a single hair or a few milligrams of a questioned The following sections list and describe the equipment needed specimen. Microscale experiments also have the advantage to complete the laboratory sessions in this book. Many of the of using smaller and less expensive equipment and requiring items you’ll need are common household items or things that smaller quantities of expensive chemicals. That makes setup, are readily available locally, such as the following: Aluminum foil Ovens (standard and microwave) Bags, plastic zip (several quart/liter and one or two gallon) Paper (white copy and bond; black) Bottles, storage (250 and 500 mL, 1 and 2 L soft drink bottles) Paper towels Butane lighter P en, permanent marking, ultra-fine point (Sharpie or similar) Cotton balls (real cotton) Pencil Cotton swabs Refrigerator/freezer Cups, foam, 500 mL/pint Scissors Hair dryer (optional) Tape, masking Hammer Tape, transparent, wide (packing tape or similar) Nickel (US coin) Toothpicks, plastic Newspapers or brown paper bags In addition, you’ll need the following items: WARNING Goggles Safety glasses or impact goggles are not sufficient to All lab sessions that involve handling chemicals require protect your eyes against chemical splashes. You need goggles that are designed to prevent liquids from chemical splash goggles, which are vented by cap vents penetrating the goggles and getting into your eyes. You rather than holes. Figure 2-9 shows a set of impact goggles on the left and proper chemical splash goggles on the right. can purchase chemical splash goggles from any lab supply vendor. Chapter 2 : Equipping Your Forensics Laboratory 13Figure 2-9: Impact goggles (left) and chemical splash goggles Centrifuge tubes, 1.5 mL, 15 mL, and 50 mL Polypropylene centrifuge tubes have numerous uses: everything from storing specimens to holding solutions to acting as small reaction vessels to developing chromatography strips. The FK01 Forensic Science Kit includes fifteen 1.5 mL tubes with snap caps and six each of the 15 mL and 50 mL tubes with screw-on caps. If you don’t have the kit, you can purchase these tubes from most lab supply vendors, or simply substitute suitable small glass or plastic containers. Chromatography paper Chromatography paper is used in several lab sessions. You can purchase chromatography paper from lab supply vendors in letter-size or larger sheets or as pre-cut strips. If you don’t have the FK01 kit, or if you need additional Balance chromatography paper, you can substitute strips cut from A balance is required for Lab Sessions I-2, Examine the filter paper or bleached white coffee filters. Physical Characteristics of Soil, and III-1, Determine Densities of Glass and Plastic Specimens, and optional Dissection tools but recommended for several other lab sessions. Suitable Some of the lab sessions involve manipulating tiny pocket electronic balances are available from lab supplies specimens such as a single hair or fiber. The FK01 Forensic vendors for as little as 25. Look for a model with Science Kit includes bent and straight dissecting needles centigram (0.01 gram) resolution and a capacity of 100 and forceps. If you don’t have the kit, you can buy these to 200 grams. Such a balance is also useful for the other items individually or as part of a dissecting kit from any lab sciences, including biology, chemistry, and physics. supply vendor, or you can substitute household tweezers and large sewing needles. Beakers, 100 mL and 250 mL Many lab sessions require making up solutions and other Digital voice recorder activities for which 100 mL and 250 mL polypropylene Although it is optional, a digital voice recorder is extremely beakers are useful. You can can purchase suitable beakers useful for taking voice notes hands-free during procedures. from any lab supplies vendor, or substitute measuring cups We use an old Olympus WS-100 digital voice recorder, or similar containers. which hangs around Robert’s neck on a lanyard, but you can substitute a cell phone, MP3 player, or other device Bottle, sprayer that has a digital voice recorder function. Some lab sessions require misting a surface with a particular reagent. The FK01 Forensic Science Kit includes Dishes, drying a suitable sprayer bottle. If you don’t have the kit, you can Two of the lab sessions in the soil analysis group require buy small “fingertip sprayer bottles” at most drugstores for drying soil specimens in the oven. You can use any oven- a dollar or so. safe flat containers—saucers, oven dishes, and so on—or even boats made from aluminum foil. Disposable aluminum Burner, gas pie plates, which are used in another lab session, are also Lab I-5, Examine the Spectroscopic Characteristics of an excellent choice. Soil, requires a gas burner of some sort. Hardware store propane torches are suitable, as are the small gas torches Filters, plane-polarizing sold for soldering and other hobby purposes. In a pinch, Two of the lab sessions involved examining specimens you can substitute a natural gas kitchen stove burner. by polarized light. For those sessions, you’ll need a pair of plane-polarizing filters, which are included in the FK01 14 DIY Science: Illustrated Guide to Home Forensic Science ExperimentsForensic Science Kit. If you don’t have the kit, you can the chemicals you’ll be using. It’s important to use gloves purchase these filters from most lab supply vendors, or that fit your hands properly. If the gloves are too small, you can substitute a pair of plane-polarizing camera filters. they stretch excessively and are more likely to develop (Although we haven’t tested it, you may also be able to pinholes or even tear. If they’re too large, it’s more difficult substitute polarizing sun glasses.) to manipulate small items while wearing them. Fingerprint brush The lab session on dusting for fingerprints requires a When you’re working with particularly corrosive suitable brush, which is included in the FK01 Forensic chemicals—such as diphenylamine reagent, Mandelin Science Kit. If you don’t have the kit, you can substitute reagent, and Marquis reagent—you may wish to use more a small artist’s paintbrush, a makeup brush, or a similar protection than a single thin layer of latex or nitrile. In soft-bristled brush, ideally camelhair. In a pinch, you that case, either double-glove with exam gloves or wear can substitute a feather. (Actually, a few professional heavier gloves, such as the heavy “rubber” gloves sold in supermarkets for household use. fingerprint technicians prefer a feather to any brush.) The size of the brush is a matter of personal preference. Some professional fingerprint technicians prefer a very small brush, while others prefer a brush with bristles 2 cm or Graduated cylinders, 10 mL and 100 mL more in diameter. Many lab sessions require measuring solutions accurately. You’ll need both 10 mL and 100 mL graduated Fuming chambers cylinders, either glass or polypropylene. Glass cylinders Two lab sessions in the fingerprinting group require fuming are transparent, but are easily broken. Polypropylene chambers, one for iodine and the other for superglue. cylinders are translucent, but are unbreakable and have The required sizes of both depend on the sizes of your no meniscus. Which you use is personal preference. The specimens. For the superglue fuming chamber, we FK01 Forensic Science Kit includes 10 mL and 100 mL used a disposable plastic one-quart Gladware kitchen polypropylene cylinders. If you don’t have the kit, you can container with a snap lid, which is also suitable for iodine- purchase graduated cylinders from any lab supply vendor. fuming small specimens. If you are iodine-fuming larger specimens, use a one-gallon zip lock plastic bag. Inoculating loop The lab session on spectroscopic analysis of soil requires an inoculating loop, which the FK01 Forensic Science Kit includes. If you don’t have the kit, you can purchase an Any chamber you use for superglue fuming will have a inoculating loop from any lab supply vendor, or you can cloudy layer of superglue covering all its interior surfaces, substitute a large sewing needle with the tip embedded in so use something disposable. Iodine stains can be removed with a solution made by dissolving a vitamin C a wooden dowel or pencil. If you don’t intend to do that lab tablet in a few milliliters of tap water. session, you don’t need the loop. If you don’t have the kit, inoculating loops are available from any lab supply vendor. Gloves Leads, alligator clip Wear chemical-resistant gloves at all times while working In Lab Session XI-4, DNA Analysis by Gel Electrophoresis, with chemicals and/or specimens. The purpose of the we construct and use a DNA gel electrophoresis apparatus. gloves is two-fold: to protect you from chemicals, and To construct that apparatus, you’ll need a pair of alligator to protect the specimens from being contaminated by clip leads, which are included in the FK01 Forensic Science oils and other substances present on your skin. The best Kit. If you don’t have the kit, you can purchase these leads choice is disposable latex or nitrile exam gloves, which at a local Radio Shack or other electronics supply store. are inexpensive and sufficient to protect your hands from Chapter 2 : Equipping Your Forensics Laboratory 15Light sources convenient and inexpensive source is the disposable Several lab sessions require a bright light source, aluminum pie pans sold in supermarkets. Buy a pack. such as a small desk lamp. (If you have a work surface These can also be used as drying dishes. that is illuminated by bright natural light, the lamp is unnecessary.) Examining opaque objects under the Plastic sheet, transparent microscope requires a source of incident (top) illumination. Lab IV-5, Revealing Latent Fingerprints On Sticky Surfaces, We use a white LED book light with a flexible neck, which optionally uses a plastic sheet as a fingerprint transfer allows positioning the angle and distance of the light. You sheet. The transparent plastic sheets sold for overhead can also use a bright desk lamp or other light source. transparencies or as notebook sheet protectors are suitable. Mesh, fiberglass Lab Session I-2, Examine the Physical Characteristics of Pipettes, plastic graduated Soil, involves sifting soil specimens through a mesh to Plastic graduated pipettes are used for measuring and separate particles by size. The FK01 Forensic Science Kit transferring small amounts of liquids (see Figure 2-10). The includes a suitable piece of mesh, but you can substitute pipettes supplied with the FK01 Forensic Science Kit are any similar mesh, such as a piece of window screen or a graduated with four lines on the stem of the pipette at 0.25, kitchen flour sifter. 0.5, 0.75, and 1 mL. They can also be used to measure very small amounts of dilute aqueous solutions because Microscope slide, cross-sectioning they deliver about 36 drops per mL, which translates to A cross-sectioning slide is a standard plastic or metal about 27.8 microliters per drop. (This value may differ for microscope slide drilled with a small hole or holes. Fibers solutions that are more or less viscous than water.) If you are drawn through the hole and then cut flush with the don’t have the kit, these pipettes can be purchased from top and bottom of the slide using a scalpel or razor blade any lab supply vendor. to allow viewing the fibers in cross section through the microscope. The FK01 Forensic Science Kit includes a drilled plastic cross-sectioning slide. You can purchase Figure 2-10: Graduated plastic pipettes metal versions of these slides from forensic supply vendors or make your own by drilling a plastic slide or using a heated needle to melt a hole in it. Modeling clay Modeling clay is included in the FK01 Forensic Science Kit, but can also be purchased from toy, hobby, and craft stores. It’s used to mount small opaque specimens for viewing under the microscope. Paint chips Lab I-2, Examine the Physical Characteristics of Soil, requires a selection of soil-colored paint chips, which you can obtain at a hardware store or paint store. Pie pans, disposable aluminum Plates, reaction and spot Lab VI-1, Tool Mark Analysis, requires thin aluminum The FK01 Forensic Science Kit includes a 24-well sheets, thicker than foil, for making tool marks. One polystyrene deep-well reaction plate with a lid, shown in 16 DIY Science: Illustrated Guide to Home Forensic Science ExperimentsFigure 2-11. This reaction plate is used in many lab sessions piece of mesh, which allows separating the specimens into for running chemical tests, mixing or diluting solutions, and two fractions. Optionally, you can use other mesh sizes so on. The FK01 kit also includes a 12-well polypropylene to separate the specimens into three or more fractions. shallow-well spot plate. The 12-well plate is used for Household items such as a flour sifter or a fine mesh metal liquids—strong acids, solvents, and so on—that may coffee filter can be used to do this. damage the polystyrene plate. If you don’t have the kit, you can purchase these plates from any lab supply vendor. Small items The FK01 Forensic Science Kit includes a flat/spoon Figure 2-11: A reaction plate microspatula, a ruler, and a stirring rod. If you don’t have the kit, you can purchase these items from any lab supply vendor, or substitute similar household items. Steam iron (or oven) Lab session IV-3, Revealing Latent Fingerprints Using Ninhydrin, requires a steam iron (by preference) or a kitchen oven. Test tubes and accessories The FK01 Forensic Science Kit includes six test tubes, a test tube clamp, and a test tube rack. If you don’t have the kit, you can purchase these items from any lab supplies vendor. Timer Ruler Several lab sessions require timing with more or less The FK01 Forensic Science Kit includes a standard accuracy. Any watch or clock with a second hand is 6"/150 mm ruler. If you don’t have the kit, you can sufficient for these sessions. substitute any millimeter-graduated ruler. Transfer sheets Scalpel Lab session II-1, Gathering Hair Specimens, requires The FK01 Forensic Science Kit includes a standard transfer sheets to contain the hair specimens you obtain. disposable scalpel. If you don’t have the kit, you can You can use something as simple as index cards or even purchase a scalpel from any lab supplies vendor or sheets of paper. substitute a single-edge razor blade. Table 2-2 summarizes the laboratory equipment we Sieves recommend. Lab I-2, Examine the Physical Characteristics of Soil, involves separating soil specimens into fractions based on particle size. The FK01 Forensic Science Kit includes one Chapter 2 : Equipping Your Forensics Laboratory 17Table 2-2: Recommended laboratory equipment Item FK01 Sources ○ Balance (optional) Lab supply vendors Beaker, 100 mL (glass or polypropylene)● Lab supply vendors Beaker, 250 mL (glass or polypropylene)● Lab supply vendors ● Bottle, sprayer Drugstores Burner, gas○ See text Centrifuge tubes, 1.5 mL● Lab supply vendors ● Centrifuge tubes, 15 mL Lab supply vendors Centrifuge tubes, 50 mL● Lab supply vendors Chromatography paper● Lab supply vendors ○ Digital voice recorder (optional) See text Dishes, drying○ See text ● Filters, plane-polarizing (2) Lab supply vendors ● Fingerprint brush Forensic supply vendors Forceps● Lab supply vendors ○ Fuming chambers See Text Gloves○ Drugstores, supermarkets Goggles, chemical splash● Lab supply vendors ● Graduated cylinder, 10 mL (glass or polypropylene) Lab supply vendors Graduated cylinder, 100 mL (glass or polypropylene)● Lab supply vendors Inoculating loop● Lab supply vendors ○ Lab notebook (bound composition book or similar) Office supply vendors Leads, alligator clip (2; red and black)● Electronics supply vendors ○ Light sources See text ● Mesh, fiberglass Hardware stores Modeling clay● Toy/hobby/craft stores ● Needle, dissecting (teasing), bent Lab supply vendors Needle, dissecting (teasing), straight● Lab supply vendors Paint chips○ See text 18 DIY Science: Illustrated Guide to Home Forensic Science ExperimentsItem FK01 Sources ○ Pie pans, disposable aluminum Supermarkets Pipettes, plastic, graduated● Lab supply vendors Plastic sheet, transparent (optional)○ See text ● Plate, reaction, 24-well polystyrene with lid Lab supply vendors Plate, spot, 12-well polypropylene● Lab supply vendors Ruler, millimeter scale● Office supply vendors ● Scalpel Lab supply vendors Sieves (optional)○ See text Slide, microscope, cross-sectioning● Forensic supply vendors ● Spatula Lab supply vendors Steam iron (or oven)○ See text ● Stirring rod Lab supply vendors ● Test tube clamp Lab supply vendors Test tube rack● Lab supply vendors ● Test tubes Lab supply vendors Timer (watch or clock with second hand)○ Obtain locally Toothpicks, plastic○ Supermarkets ○ Transfer sheets See text chemicals and Reagents In addition to the equipment described in the previous section, you’ll need an assortment of raw chemicals and reagents to complete the lab sessions. (Broadly speaking, raw chemicals are materials that are supplied and used as-is in pure form or as simple solutions, while reagents are specic m fi ixtures of chemicals, usually in liquid form.) The word reagent has two meanings in lab parlance: a reagent may be a mixture of chemicals, and often bears a person’s name. For example, Marquis reagent is a mixture of the raw chemicals sulfuric acid and formaldehyde. But “reagent” is also used to specify a purity grade for raw chemicals. Chemicals that are specified as “reagent,” “reagent grade,” or “ACS reagent grade” meet specific purity standards, are assayed to determine their exact contents, and are extremely pure. Reagent-grade chemicals are suitable for the lab sessions in this book but are often purer (and more expensive) than actually necessary. For most of the lab sessions in this book, laboratory-grade, USP-grade, or another relatively pure grade of chemicals is sufficient. Chapter 2 : Equipping Your Forensics Laboratory 19All of the lab sessions that require special reagents include Ammonia, household (clear, non-sudsy) instructions for preparation of those reagents from raw Two lab sessions require ammonia, which is not included chemicals. If you make up these reagents yourself, be sure in the FK01 Forensic Science Kit. Household ammonia is to follow all safety procedures, including reading the MSDSs generally a 5% to 10% concentration, which is fine for our (Material Safety Data Sheets) for the chemicals you use. Always purposes. Get the clear, non-sudsy version. wear goggles, gloves, and protective clothing while making up and using these reagents. Ascorbic acid (vitamin C) tablets, 500 mg The FK01 Forensic Science Kit includes 500 mg ascorbic Acetone acid (vitamin C) tablets. If you don’t have the kit or if you Several lab sessions require acetone, which is not included require additional tablets, simply use standard 500 mg in the FK01 Forensic Science Kit. You can purchase pure vitamin C tablets. acetone in pint (500 mL) or quart (1 L) containers at any hardware store or paint store. Baking soda (sodium bicarbonate) One lab session requires baking soda, which is not included Agar powder in the FK01 Forensic Science Kit. Use ordinary baking soda The FK01 Forensic Science Kit includes 10 grams of agar from the supermarket. powder, which is used in the DNA gel electrophoresis lab session. If you don’t have the kit, you can purchase Bleach, chlorine laundry agar from a lab supply vendor. You can also substitute Two lab sessions require chlorine laundry bleach, which is food-grade agar, which sells for a few dollars per ounce not included in the FK01 Forensic Science Kit. Use ordinary in some supermarkets and most stores that sell Chinese 5.25% sodium hypochlorite bleach. The cheap, no-name and Japanese specialty foods. The gelling quality of food- stuff is fine. grade agar is variable, so we recommend using twice the amounts specified in the lab session. Blood, synthetic The FK01 Forensic Science Kit includes synthetic blood, Alcohol, ethyl (ethanol), 95% which mimics the chemical behavior of actual blood. If you Several lab sessions require ethanol, which is not included don’t have the kit, you can purchase synthetic blood from in the FK01 Forensic Science Kit. You can purchase a forensic supply vendor, or simply substitute actual blood 95%/96% ethanol under that name or as ethyl alcohol in from raw meat or another source. (Note that there are hardware and paint stores. Most drugstores carry 70% several types of synthetic blood available. Theater blood ethanol, which is not ideal but is generally usable. is designed to look like real blood, but is unsuitable for our purposes. Synthetic blood designed for use in spatter- Alcohol, isopropyl (isopropanol), 99% pattern analysis is also unsuitable. If you buy synthetic Several lab sessions require isopropanol, which is not blood, you want the type used for training analysts on included in the FK01 Forensic Science Kit. You can blood detection activities.) purchase 99% isopropanol under that name or as isopropyl alcohol in some hardware stores. Most drugstores carry Buffers, DNA loading and running 70% isopropanol, which is not ideal but is generally usable. The FK01 Forensic Science Kit includes a 6X concentrate of Some drugstores also carry 91% isopropanol, which is DNA loading buffer and a 20X concentrate of DNA running superior to the 70% concentration for our purposes. buffer. If you don’t have the kit, you can make up these buffers yourself or purchase them from forensic supply vendors or general lab supply vendors. In general, ethanol and isopropanol can be used interchangeably for the lab sessions in this book. Sometimes one or the other yields superior results. If we specify one and you don’t have it, the other will almost certainly work. 20 DIY Science: Illustrated Guide to Home Forensic Science Experiments

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