Hey guys I did the Kastle Meyer test on a sample of my own dried blood and did not work. I swabed the blood with a moist swab, added a drop of a solution of phenolpthalein, ethanol, and methanol, then added one drop of Hydrogen peroxide. Nothing happened, just lots of bubbling. Can anyone tell me what I need to fix?
Is your solution of phenolpthalein properly prepared? Was it refluxed under basic conditions with zinc until the solution turned clear? Also your steps listed above while probably not the cause of your problem can be simplified as such: Moisten a swab with ethanol (if needed) Swab the area (a very little bit is needed) Add one drop of your prepared pheno. soln. Add one drop of your 3% hydrogen peroxide solution (concentration is somewhat important, do not use "concentrated" hydrogen peroxide. The type of solution avaliable at grocery stores for first aid purposes is perfect.) If you need any additional information, I can try and post a recipe for KM solution.
My phenolphthalein solution is actually a pre-mixed combo. of phenolphthalein, ethyl, methyl, and Isopropyl alcohol. Is that not the proper solution to use? It also says on the bottle that its composition is "1% in ethanol". I'm actually new at this kind of stuff so any information is appreciated. Thanks
The concentration of my hydrogen peroxide is 3%. I added that separate. I just can't seem to get the test to work. My process(In detail)went like so: I collected a sample of my own blood on a cotton pad, let it dry, after it had dried I put two drops of distilled water on the end of my cotton swab, rubbed it onto the dried blood stain until I could see that a trasfer had taken place, put one drop of the phenolpthalein solution (1% in ethanol), then I added one drop of 3% hydrogen peroxide to the end of the swab, the color stayed the same and the only reaction that I could see was the bubbing reaction between the blood and the hydrogen peroxide. Im stumped...
I am stumped as well. That should work as described. Your phenolpthalein solution is colorless correct?
Yeah, its been boiled already. Do you think I should test the phenolpthalein solution on another basic compound to see if it changes color? On the bottle it says that it is supposed to change to pink at a ph of about 10. I could test it just to see if it works for sure. Any other suggestions?
make sure you are only testing a small amount of blood. don't overload your swab and give it another go.
Does it matter if my phenolpthalein solution is refridgerated or not because I read somewhere online that it should be refridgerated. Also, here is the link to the phenolpthalein solution that I bought on-line: http://secure.sciencecompany.com/Phenolphthalein-125ml-4-oz-P6482C0.aspx
OOOHHH. You are using a indicator solution for titration - same chemical, but different chemistry being used for the two types of solutions. What you have isn't going to work. The KM solution starts out already basic, you have to reflux the basic solution with zinc to remove the pink color.
So I need to order or somehow get another phenolphthalein solution that has been refluxed with zinc? The solution I have right now isn't pink, but your saying that it wasnt refluxed with zinc yet?
I suggest you purchase a prepared Kastle Meyer solution, not a phenolphthalein pH indicator solution - they are two different beasts. Something like this (note I am not recommending any particular brand, this is just the first one I found on Google): http://www.evidentcrimescene.com/cata/blood/blood.html #3658 Phenolphthalein Blood Test Kit $30.00