Hello,
I was just wondering if anybody can tell me why n-butanol is not used as a solvent in ninhydrin formulae for fingerprint development? It's quite extensively used in the analytical chemistry field as a colorimetric test for amino acids. I have been doing some testing in solution recently and I am finding that fluorinated solvents such as HFE7100 appear to be quenching the reaction between analogues and amino acids.
Your thoughts would be much appreciated.
Kind regards,
Shaheen
Ninhydrin Formulae
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Shaheen
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clpexco
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Concern
Shaheen,
Thank you for your post. I hope someone can offer specific insight into your question, although it's very specific.
However, it raises an issue of greater concern to me, as I am currently involved in a project that involves the recommendation of using HFE7100. Would you be willing to share your research results with the CLPEX membership? If so, I would encourage you to contact me off-line from this forum and we can prepare the information for circulation. If not, I have a few additional follow-up questions for this thread...
-Kasey Wertheim
Thank you for your post. I hope someone can offer specific insight into your question, although it's very specific.
However, it raises an issue of greater concern to me, as I am currently involved in a project that involves the recommendation of using HFE7100. Would you be willing to share your research results with the CLPEX membership? If so, I would encourage you to contact me off-line from this forum and we can prepare the information for circulation. If not, I have a few additional follow-up questions for this thread...
-Kasey Wertheim
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Kasey Wertheim
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From a sideline e-mail
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Reference Shaheen on HFE7100. I found that using DFO with HFE7100 develops excellent latents although there is a strong reddish background. I have also found that following with Ninh. HFE7100 formula, it does not enhance development. It also seems to dimish constrast somewhat on DFO developed latents. My DFO photographs actually produce better contrast than those following Ninh. application.
As a result I hesitate using Ninh after DFO with the HFE formulation.
However, using Ninh. as a first reagent application produces excellent results with the HFE7100 formualtionl. It is my primary Ninh. formula.
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Reference Shaheen on HFE7100. I found that using DFO with HFE7100 develops excellent latents although there is a strong reddish background. I have also found that following with Ninh. HFE7100 formula, it does not enhance development. It also seems to dimish constrast somewhat on DFO developed latents. My DFO photographs actually produce better contrast than those following Ninh. application.
As a result I hesitate using Ninh after DFO with the HFE formulation.
However, using Ninh. as a first reagent application produces excellent results with the HFE7100 formualtionl. It is my primary Ninh. formula.
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Shaheen
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- Location: Sydney, Australia
A new question on ninhyrin formulae
Thank you Ernie for the email regarding ninhydrin formulae.
Butanol is undesirable as it is flammable and runs inks.
The problem with formulae is thus having a solvent that is polar enough for maximum reaction with amino acids but non-polar enough so that the amino acids are not washed away, and the inks do not run.
My next question is tangential to my initial question - how important is it to have a formula that incorporates non-flammable solvents? Is this mainly a storage issue or an OH&S issue given that the fingerprint technicians are non-chemists?
Your thoughts would again be appreciated.
Kind regards,
Shaheen
Butanol is undesirable as it is flammable and runs inks.
The problem with formulae is thus having a solvent that is polar enough for maximum reaction with amino acids but non-polar enough so that the amino acids are not washed away, and the inks do not run.
My next question is tangential to my initial question - how important is it to have a formula that incorporates non-flammable solvents? Is this mainly a storage issue or an OH&S issue given that the fingerprint technicians are non-chemists?
Your thoughts would again be appreciated.
Kind regards,
Shaheen
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mdavis
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As a late reply to this thread, I am still using the older petroleum ether formulation for ninhydrin with a very small amount of methanol and 2-propanol. Rather than dipping in open trays, I spray the surface to "dampness" on both sides, then develop with heat and humidity between sheets of "blotter paper". This avoids the cost of the HFE7100, minimizes the amount of reagent consumed, and nearly completely avoids ink solubility problems.