Gibbs, Gibbs, Gibbs, Or How Forensics Detects Blood

Gibbs, Gibbs, Gibbs, or How Forensics Detects Blood

Joseph Parish

Introduction

“Gibbs, Gibbs, Gibbs.” We have all heard these famous lines uttered by Abby in NCIS as she waves her hands hysterically in the air attempting to gain Special Agent Gibbs attention. But now you too can be an NCIS Forensics lab tech as well. Here is a simple experiment that you can perform for your own satisfaction or in conjunction with your children to teach them the value of chemistry. With these simple instructions you can demonstrate how meat-blood, left to dry on a kitchen knife can reveal that it just sliced a piece of beef and contains samples of blood.

Background

Few people realize it, but within my storage area are several boxes packed with enough equipment to stock a complete high school or college chemistry lab for one person. Hidden within the contents of these containers is an assortment of both basic, and specialized equipment to make any chemistry enthusiast break a smile on their face. In addition to the usual selection of glass beakers and test tubes with stands, can be seen various size graduated cylinders used to measure liquids, multiple Erlenmeyer flasks, alcohol lamps with stands, thermometers for all occasions, rubber stoppers and supplies such as burette clamps, etc., Necessary to set up and perform a variety of chemical experiments and tests. Complimenting the usual lab gear needed to perform normal chemistry activities there are a host of specialty items needed to clone plants, and do the DNA genetic analysis and experiments. The equipment, even includes a professional grade microscope, centrifuge, cell injectors and cell incubators.

Science has always been one of my enjoyments in life. Many years ago, before it was popular, I built a small robot that wandered around the room endlessly with no purpose in life but to nip annoyingly at the ankles of an unsuspecting visitor. Additionally, at one time in Nebraska, I built a minicomputer (before you could buy them) which took up a complete corner of our living room. Guess it wasn’t a mini by today’s standards. It is not unusual that if I am conducting an experiment that I will use myself as the guinea pig. I suppose in the long run, I could perhaps become the first of the zombies from completing such experiments on myself, LOL. So as can be seen science has held a valued place in my life.

Many of you may be wondering why a normal person would have a need for a full-fledged chemistry laboratory. Well, according to my wife, I am not a normal person, but putting that aside, I had developed a fascination with cloning plants which are referred to as micropropagation. In my lifetime, I have even purchased a dental x-ray machine to use in my varied plant experiments. At one time in my life, I had seriously considered majoring in Chemistry or perhaps biotechnology, but decided that it would have consumed a large portion of my life if I followed through so that idea was placed on the back burner. From there I discovered that I could make better use of my hobby by assembling a chemistry lab to assist with my experiments. Thus, the chemistry lab was developed. After a short period of time and the necessary funds shriveled up, so did the lab and into storage it went. At about this point in time, I was teaching math and science to 7th and 8th graders in the Vineland New Jersey school district. It was a pleasure instructing children who wanted to excel in the AP Chemistry classes, however, all good things must come to an end and I eventually ended up having to instruct the emotionally disturbed children, so much for my enthusiasm in teaching. It got old fast having a child pick up a desk and threaten to toss it across the room, especially after you specifically tell him to choose his victim very carefully before acting on his impulses.

My Lab Glassware in the Bathroom

My lab supplies may have been placed in storage but never fear as my wife rummaged through my boxes and made good use of some of my glassware in our home’s bathroom. Pam in her decorating theme had taken my chemical supplies of glassware and included it in her bathroom décor. Upon entering the bathroom, one would think they had slipped into a laboratory environment by error. On her bathroom cabinets can be seen an assortment of small vials and bottles complimented with various sizes of beakers, flasks and even several Erlenmeyer flasks out in the open for public view.

Before going too far into my wife's decorative adventure, let's talk for a bit on beakers. Anyone familiar with chemistry knows that the lab is not complete unless there is an assortment of different beakers scattered around the lab bench. They come in various sizes and are frequently used to measure volumes of liquid. Although they may not be especially precise in their calibration scale you will find them with markings which indicate volume measurements. Beakers are generally only accurate to a mere 10 percent, so therefore, a 250-ml beaker will contain 250-ml with an error of plus or minus 25 ml. With larger beakers the error of measurement will greatly increase. Since these items of glassware are flat on the bottom, they are easily placed upon flat surfaces such as the lab bench or perhaps a hot plate. They generally have a spout which makes it very easy when pouring liquids. In the case of my wife's decorations, these items are shown in plentiful supply in our bathroom.

Although this may be an entertaining article, I still try to bring some chemical education to the reader, and with that in mind, I will briefly describe the benefits of using beakers. Its wide mouth makes it easy to add various materials to the glassware. As mentioned above, they consist of a flat bottom and contain a pour spout for transferring liquids.

Various flasks are frequently employed in a laboratory and come in not just a variety of names but shapes and purposes as well. Popular among the flasks are the Florence flask which is a thick-walled flask intended for withstanding direct flames while used for heating products within. The neck of the flask allows a clamp to be installed securely, making it able to be easily moved. There are also the volumetric flasks which accurately permit the measurements of any solution. This is the generally accepted flask for preparing chemical solutions while in the lab. This glassware is also not intended to be heated, but merely used to mix the various chemicals. Thanks to my wife we readily find all these types of flasks sitting appropriately within the confines of our bathroom.

Another popular piece of my lab glassware which my wife freely incorporated into her bathroom decor is the Erlenmeyer Flasks. Flasks in general cover a vast array of glassware, but in this case, we are speaking of one special type of flask. The most common of flasks found in the modern laboratory is the Erlenmeyer flask. This flask has a narrow neck and of course a flat bottom to allow it to sit on the lab bench. These flasks are excellent for swirling liquids around and for heating liquids inside of them. As can be seen there are several similar uses for both the beaker and the flask, however, in the event that you need to seal the contents or to save them for a period of time then the logical choice would be the Erlenmeyer flask. It is usually much easier to place a stopper in the Erlenmeyer flask than it would be with a common beaker.

Of course, the flasks come in an assortment of sizes similar to the beakers and once again they too have volume marked off and with a similar accuracy of only ten percent as well. If one goes into our home’s bathroom you will see an assortment of various size Erlenmeyer flasks sitting neatly on the countertops and on various shelves.

Lastly, we will talk briefly about test tubes. Their usual use in the lab is to hold small samples. You would not use a test tube for measurements involving precise volumes. Of all lab equipment, the test tube is generally the least expensive and in the case of my wife's decorating ideas it has a prominent place in her scheme of lab related bathroom design. Although some types of test tubes are intended to be heated with a Bunsen burner flame, fortunately my wife does not include this characteristic in her decorating plans. In keeping with the educational philosophy of this article we can state that test tubes are nothing more than thin glass cylinders with a round bottom rather than flat ones. In short, their purpose is primarily for the collection and storage of specimens and samples and rarely has any sort of measurement scale on them.

As a last-minute note, it is possible to see a few small pipettes in the bathroom from my lab supplies. Pipettes are used when measuring and transferring small volumes of liquid. Like most lab equipment there are different types of pipettes for different purposes. Generally, a lab will use the plastic, disposable types of Pipette. A word of advice is in order here since pipettes are not intended to be exposed to flames even if using the glass versions. It is highly possible that they will become deformed by the heat which would make their measurement ability greatly inaccurate. In concluding this section, I would suggest that all bubbling chemists should accurately know their lab glassware after all - my wife does! The proof is a walk into our bathroom. Who knows, I might at some time remove my lab from mothballs and in the future resurrect my chemistry lab once again?

On with the show

But enough about me this is about you and the experiments you can perform to detect the presence of blood. I relate all the above information to you so that you can get an idea of what makes me tick, and prepared to have some fun today. I am about to explain to you how they can play the role of an NCIS forensics investigator and perform a simple forensic blood test. This is an inexpensive way to instruct students in appreciating the value of modern forensic science in resolving deadly criminal activities. The usual method of conducting these tests is via the Kastle-Meyer test which is easy, inexpensive and extremely reliable. By following the enclosed instructions, you can detect the presence of blood in your own home.

Kastle-Meyers Solution

The only item out of the list of materials needed to detect blood that you will have to spend some time making or purchasing is the Kastle-Meyer Solution. To create this solution, you will need the following items:

0.1 grams of phenolphthalein powder

25% aqueous sodium hydroxide solution

0.1 grams of mossy zinc

Distilled water which should be readily available in any respectable chemistry lab

70% ethanol

In a test tube you will need to dissolve 0.1 grams of phenolphthalein in 10.0 ml of 25% sodium hydroxide solution. Next, add 0.1 grams of mossy zinc to the solution in the tube. To verify it is properly dissolved the solution should be a bright pink color. Gently boil the solution until it begins to take on a colorless or pale-yellow tint. Add the water as needed to maintain the suggested volume. Finally, allow the solution to cool to room temperature. Dilute the final quantity of liquid to 100 ml with the 70 percent ethanol.

You may be saying, “this is all well and good if you have the necessary ingredients at hand.” Granted, the above process seems like a lot of work thus you can readily purchase this reagent online already made for $7.85 in a 30 ml bottle from Carolina Biological Supply. It is item # 871300. One thing to remember about this reagent is that it is corrosive and should be stored appropriately. I have dealt with this company for a number of years and find them to be reliable, honest, offer quality products and quick to deliver your order. They are an excellent source of biological materials if that is your passion.

Detecting the blood

Reverting now back to the topic of detecting the dried blood, let’s first review the materials and supplies necessary to conduct these tests. Prior to conducting the blood tests, you will need to assemble the following items:

Materials for Test

Kastle-Meyer solution as described above either homemade or purchased

70% ethanol

Distilled water

3% hydrogen peroxide

Assortment of cotton swabs

Eye dropper

Sample of dried blood

Procedure

Begin by moistening a cotton swab with water and lightly touching a dried blood sample. There is no need to rub the sample too hard or to coat the swab with the blood. Only a small amount is necessary.

Add several drops of 70% ethanol to the sample on the cotton swab. Again, you do not need to soak the cotton swab. The alcohol serves to reveal the hemoglobin within the blood, encouraging the chemical react.

Next, add several drops of the Kastle-Meyer solution. It should be colorless or a shade of pale yellow. If instead of clear it turns yellow it cannot be used for the test as it is old and will not work properly. The color on the swab should be clear or pale yellow only.

Now, add several drops of hydrogen peroxide solution and note the color. If the color of the cotton swab should turn pink, it is a positive indication that blood is present, if there is no change in color, then no blood is detected. After about 30 seconds, the swab will turn pink even though there is no blood detected. This is a normal reaction from the hydrogen peroxide and phenolphthalein combination.

There are several other methods used to detect blood at crime scenes, but this is one of the simplest. Of interest in this test is that it is very sensitive, and able to detect blood dilutions at such levels as 1:107. Now that you know how to detect blood why not gather your children together, and show them how they too can be Junior NCIS lab technicians. In this lesson, I attempted to educate and entertain. If you enjoyed this short lesson and would like to have more please let me know. I might be inclined to open its own Facebook page featuring experiments in chemistry, biology and cloning of plants. Getting your children to appreciate the value and fun in science can result in a lifelong pursuit of knowledge.

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