Even Criminals Avoid Contact with that Chemical!

Her eyes looked at me sadly, as if trying to say something for the last time, but I understood that it was all over. It's sad to realize, but I did everything I could. I hope I can finish what I started and end up where I've always dreamed of being. Signature photographer. A strange note, of course. It was recently found by the police in one of the apartments along with other evidence. At first glance, nothing special. Apparently, the suspect was the photographer and also kept a strange diary with blank pages. I wonder if chemistry can help find out what happened there and identify the suspect. Well, let's figure it out.

First, let's see what evidence has been collected and what information can be extracted from it using chemical and physical methods. On top of the box with evidence, there is a camera flash as well as some kind of stand apparently also for filming. There is also a charger and an old notebook with some stains. Most of the pages, by the way, are empty, which is quite strange. But apparently, it was from this notebook that the page was torn out on which that strange note was left. Next, there are various cameras with rather greasy fingerprints. Or maybe it's not grease at all. To find out what traces might have been left on all these items, I first turned off the light and turned on a rather strong ultraviolet flashlight. The fact is that many substances as well as biological fluids can glow under ultraviolet light. For example, under such conditions, many fats like sunflower or peanut oil glow well. And in ultraviolet light, soap, sugar pieces, blood, and other dried biological fluids are also clearly visible. So far, at first glance at the evidence, I don't see any bright glowing spots as the same dust also glows well. Although here on one of the cameras, there is something glowing. And on this stand, I indeed discovered some glowing traces. Often such bright traces can either be dried biological fluids or some cleaning agent. Soap, for example, can be easily distinguished using a pH indicator, while biological fluids can be identified by smell or color. But judging by the stains on the cameras, it can be assumed that some intimate filming took place at the crime scene, as no obvious traces of red liquid have been found on these items so far. It's possible that the blood remained on other objects or was attempted to be washed away. For example, there are some stains on this notebook as there might be on other pieces of evidence. Fortunately, there are several quite accurate chemical methods for detecting blood residues which are fairly easy to conduct even at home. For the first method, you will need one unusual substance, luminol, which can emit light in chemical reactions. I still have this jar of luminol from my old supplies, which is about 10 years old. However, as far as I remember from chemist stories, when this th when this substance is stored for a long time, it can easily oxidize, making it unsuitable for sensitive experiments to detect blood traces. Therefore, just in case, I bought another jar of fresh luminol, which even differs in color from the old one. Meanwhile, before checking the evidence, I became curious to find out how much my old luminol had oxidized after being stored for 10 years. And maybe I shouldn't have spent money on a rather expensive reagent. After all, such a jar with 10 g of luminol cost more than €60. To test my different samples of luminol, I first prepared their solution so to conduct an unusual chemoluminescence reaction. To start, I weighed out 0. 22 g of the old yellow luminol and the fresh gray one into each of the beers. After that, to create the necessary environment in the solution, I add 6. 5 g of baking soda and approximately 0. 27 g of copper sulfate as a catalyst for the reaction. Then I pour 250 ml of water over all of this and mix it well on a magnetic stirer because the baking soda in both solutions did not create a sufficiently alkaline environment. I added a bit of ammonia solution to ammonium hydroxide to the solution after which the luminal dissolved well. As you can see, so far the differences between the old and fresh luminol are only in the color of the solution since all the other components were the same in identical proportions. However, that's not all. To conduct the reactions, another solution needs to be made consisting of 20 ml of 3% hydrogen peroxide and 250 ml of water. Well, now we can check how the old and new luminal glow under the influence of hydrogen peroxide. For this, first in the dark, I pour the hydrogen peroxide solution into the old luminal solution. Yes, it glows very beautifully as this substance when oxidized by hydrogen peroxide in the presence of copper salts emits a quantum of light which looks quite mesmerizing. But will there be a difference with the fresher luminol? At first glance, everything looks the same. Perhaps it's better to compare these reactions side by side and see how the glow looks. In principle, I don't see a significant difference as I had the camera settings on manual for both experiments. Perhaps if you look closely, the solution with the fresh luminol glows slightly brighter. So, in principle, over 10 years of storage, luminol hasn't significantly lost its properties. So, there was no need to spend on a new one. Nevertheless, besides copper salts, the glow of luminol in a hydrogen peroxide environment or can also be triggered by compounds of other metals. For example, iron, even trace amounts of which can cause a glow. And as you understand, in blood or even its remnants, there will be enough iron to cause luminol to glow. For another experiment, I prepared a larger solution of fresh luminol. But this time, instead of copper sulfate as a catalyst, I used red blood salt, which releases iron ions when dissolved. Yes, the glow here looks no less bright and quite beautiful. Perhaps after I figured out my lumininal, I can try to find possible

traces of blood on some evidence with strange stains. For this test, I have already made a stronger solution consisting of half a gram of luminol and sodium hydroxide to completely dissolve all substances. After that, I poured all of it into a small spray bottle to which I added an equal amount of 3% hydrogen peroxide. All that's left is to turn off the lights and sprayed the resulting solution on the evidence I selected. As you can see, those suspicious stains immediately began to glow with a bluish tint, which means that there was once blood or its remnants at this spot. In fact, this method is very sensitive and can detect even trace amounts of blood that someone tried to clean thoroughly. If the glow is not strong enough initially, then you will need to set the camera to a long exposure to better see that very blue luminescence of luminol. Forensic experts have been using this method of blood detection to since 1942 because it is incredibly sensitive and at that time it revolutionized police work. In chemistry there are reactions that occur instantly but sometimes there is a chance that suspicious traces are found in a place where it's not possible to turn off the light. For example, during the polar day or for instance there is a risk of damaging the evidence by spraying it with an aqueous solution. In such a case, there is another unusual chemical method for detecting blood

traces. To conduct this test, you need to prepare the so-called castle reagent for which I used the indicator phenofin. I think many have seen how this substance turns crimson when alkali is added to it during chemistry lessons. However, today I will be using it in forensics. In addition to phenolin, zinc powder and potassium hydroxide will also be needed. To prepare the reagent, I add 12 g of potassium hydroxide to a flask with 30 ml of water. Then mix everything on a magnetic stirer until fully dissolved. Now I add about 1 g of phenolthaline to the flask which immediately colors the solution a dark crimson and over time it begins to lighten due to the further reaction of phenolthaline with the concentrated alkali. Next I add 3 g of zinc powder to the flask after which I continue to heat the mixture. Over time, the zinc slowly begins to react with the potassium hydroxide, forming hydrogen bubbles, which in turn reduce the final back to its colorless form. The formula, if you need it, is now on your screen. It takes about an hour for the finthal to completely decolorize with the help of hydrogen, during which I gradually added a bit of distilled water to the mixture to replenish the losses from evaporation. After an hour of reduction by hydrogen, the alkaline solution of phenolin is almost completely decolorized and it is now ready to be used as a reagent for detecting traces of blood when examining evidence. Now we just need to wait for it to cool down a

bit. For the test, I took this camera, which initially had some strange greasy spots on it. Perhaps they might also contain traces of blood. Upon the first examination of this device as well as the rest of the video equipment, I did not find any files. Therefore, it is necessary to chemically test whether this camera was involved in the disappearance of that woman. For this, I first dipped a cotton swab in the Castle Meer reagent, then thoroughly wiped the areas of interest on the camera where traces of blood might have remained. To be absolutely sure that it is indeed the red liquid, I also add a drop of hydrogen peroxide to the cotton swab I used for wiping everything. If there were traces of blood in the samples, over time, the iron ions from it will accelerate the oxidation of the colorless form of phenylthalen with the help of peroxide and the color of the cotton on the swab should turn pink. And yes, I think something is starting to appear. Indeed, the cotton swab turned pink, which means that there were actually traces of blood on the camera, which I previously completely mistook for

for grease. I wonder what the notebook will tell us about this. Perhaps the suspect also used it while carrying out their nefarious intentions. At first glance, there are some suspicious stains on both sides, which did not glow under ultraviolet light. I'll try to examine them as well using my reagent and a cotton swab. Yes, initially there's an issue with the material itself. Oh, as the green paint from the cardboard smudges easily, which might interfere with the blood test. However, since this test is quite sensitive, it also shows us the presence of blood on the cover of this notebook, but uh with its purple color. If the initial test indeed showed the presence of blood either from the suspect or someone else at the scene, then it is possible with very high accuracy to determine to whom this red substance actually belonged. And perhaps the note in that apartment was not written by the suspect at all, but by the missing person, woman to, for example, lead investigators on a false trail. For this, a DNA analysis can be done, which initially requires extracting the genetic code of the person from this stain. Often the area with the stain is simply cut out, then immersed in a special solution, and then it is transported to the laboratory where an extremely complex and rather tedious process of DNA extraction and analysis is conducted. In short, since red blood

cells lack a nucleus which contains the DNA, it is necessary to extract the human genome from the white blood cells. For this, a sugar syrup is added to the blood samples, after which the red blood cells are separated using a centrifuge. Next, the white blood cells are broken down using a simple soap solution and this mixture is separated from the remnants of the cells using chloroform in which DNA does not dissolve while all other debris from the broken cells can dissolve. After this, the samples are placed in a centrifuge again where the lower layer containing the DNA is separated to eventually precipitate. The DNA molecules from the solution ethanol is added causing the ready to analyze DNA molecule to precipitate to the bottom appearing as these white strands. This molecule is then sent for sequencing where high precision machines can decode either the entire genome of a person or its segments. After such analysis, it is possible to identify a person with very high accuracy if their DNA is in the database. But if for example they are not present, it will be

easier to identify the person by fingerprints. Many people today submit fingerprints when applying for a biometric passport. To find fingerprints on pieces of evidence, there are several methods. One of them uses regular superglue based on cenoacrylate. Such glue is now sold in almost any store. For demonstrating this method, initially under ideal conditions, I took a petri dish and dropped a drop of water on one side and a drop of superlue on the other. As a sample fingerprint, I left my fingerprint on the plastic lid of the petry dish. Then covered the dish itself with this lid. Over time, uh, the vapors of the superlue begin to react with the water vapors, causing them to gradually polymerize. The residues of amino acids on the fingerprint in the form of keratinized skin activate the polymerization of the superglue, causing the fingerprint to be the first to be covered with a layer of superglue, which is easily indistinguishable against a dark background. In the end, of course, under ideal conditions, I managed to reveal the fingerprint. Y. But will it be possible to do this at home on complex objects like video cameras? To achieve this, I placed the evidence in a regular Ziploc bag, then dropped into it the little super glue and water and left it like that for about 30 minutes. After this time, I carefully opened the bag to avoid smearing the evidence with superglue residue. And look at the resulting outcome. Yeah, it looks pretty good. In many places, the fingerprints have indeed come out well. Now, they can be, for example, photographed and given to specialists for analysis. Yes, this method will work well on dark objects where the white developed fingerprints will be clearly visible. But what about light colored objects or those made of paper? For

this, there is another interesting method for detecting fingerprints. For it, I will need a reagent called ninhydrine. which has a pinkish tint due to rather long storage. I pour 50 ml of acetone into it and mix well until completely dissolved. After that, I poured the resulting solution into a spray bottle. This way, the substance will be much easier to apply to the object under investigation. As the piece of evidence, I took that very notebook on which there must be someone's fingerprints. Here on the first page is some kind of strange drawing. I think we can start with it. After applying nine hydrin, I cover the page with a napkin. Then place a hot pan on top to heat the page and speed up the reaction. After about 5 minutes, I remove the pan and the napkin. And what do we see? Indeed, in some places, quite distinguishable purple prints have appeared. This happens because ninhydrron reacts with the proteins left in the print, coloring them purple. By the way, on the next page of the notebook, the prints appeared even better than on the first. Here, apparently, it also depends on how sweaty the hands were when they came into contact with the paper. As with superlue, these prints can be photographed and then sent for examination. But besides the rather rare ninhydrron, ordinary iodine can also be used to reveal prints on paper. Pure iodine itself consists of these black crystals which gradually sublimate in the air, meaning they transition from a solid state directly to a gaseous state, bypassing the liquid phase. This is even more noticeable when heated. However, since pure iodine is quite difficult to find, I will obtain it from regular iodine alcohol tincture. In a small glass and press, I measure out the iodine tincture along with citric acid. After which I add about a tablespoon of 3% hydrogen peroxide to the glass. In this form, the solution needs to be left for a few minutes so that elemental iodine precipitates out of it. It is noticeable that due to the warmth in the room, some of the iodine even settled on the top paper, which I used to cover the glass. After I poured out the excess solution from the glass, a black residue of pure iodine remained at the bottom, which sublimates very easily at room temperature. I will use this property to reveal a fingerprint on this paper. You just need to turn the glass over and let the iodine vapors settle on the tiny traces of grease from the fingerprint left on this paper. The whole process takes about 10 minutes. And voila, the fingerprint also becomes clearly visible against the white paper background. All that's left is to photograph it before the iodine evaporates. By the way, this method can also be used to reveal fingerprints on other light surfaces or on glass. This experiment, by the way, was briefly shown in the movie National Treasure, which is quite fascinating. It's working. Unbelievable. Yes, it's all certainly interesting. But to find out what really happened in the apartment from which I got those pieces of evidence, we need to wait for the results of the fingerprint analysis and DNA testing. In the meantime, you've learned how modern forensics works. And if you like this video, as always, don't forget to give it a like and subscribe to the channel say to learn many more new and interesting things.