Indanedione Zinc Chloride mix?

[amydorsey]

Hello! Does anyone know of a new mixture of indanedione and zinc chloride? Or is it just using zinc chloride after the paper has been processed with indanedione? Can it be mixed or is it sequential. Thanks!

[Pat]

To the best of my knowledge, ZnCl has never been used for anything except following up after ninhydrin to make the nin print fluorescent. Since both DFO and Indanedione are fluorescent anyway, I don't think there is any additional benefit to following them with ZnCl. At least, I've never heard of it.

[cchampod]

The best formulation is a mix: indanedione with ZN in a single formulation. Hence it is a one-step process. Compared to Indanedione alone, the addition of Zn provides a much higher sensibility.

The comparison against DFO: Our laboratory has obtained better results with Indanedione-Zn compared with DFO. We have switched to DFO. Similar to the results in Australia: Stoilovic, M., Lennard, C., Wallace-Kunkel, C., and Roux, C., "Evaluation of a 1,2-Indanedione Formulation Containing Zinc Chloride for Improved Fingermark Detection on Paper", Journal of Forensic Identification, vol. 57 (1), pp. 4-18, 2007.

Note that in the UK DFO is still recommended by CAST: Sears, V., Batham, R., and Bleay, S., "The Effectiveness of 1,2-Indanedione-Zinc Formulations and Comparison with HFE-Based 1,8-Diazafluoren-9-One for Fingerprint Development", Journal of Forensic Identification, vol. 59 (6), pp. 654-678, 2009.

To understand the role of Zn on the process, see the excellent:
Spindler, X., Shimmon, R., Roux, C., and Lennard, C., "The Effect of Zinc Chloride, Humidity and the Substrate on the Reaction of 1,2-Indanedione-Zinc with Amino Acids in Latent Fingermark Secretions", Forensic Science International, vol. 212 (1-3), pp. 150-157, 2011.


Kind regards

Christophe

[g.]

Definitely have to agree with Christophe here. We use IND-ZnCl exclusively now over DFO. At first when we started using IND it had variable results, but the Zn-Cl addition to the formula stabilized it significantly. Like the papers Christophe cited indicate, humidity and moisture (both ambient and in the substrate) had HUGE effects on our results. The Zn-Cl helped a lot with that.

Now we routinely get some of the best prints with IND ZnCl, and sometimes in lesser property crimes/forgery/check fraud have no need to even go to ninhydrin.
What we observed was the sensitivity of IND-ZnCl was comparable or "slightly better than" DFO, but the real advantage was less background noise. So the IND- ZnCl showed up better and with higher contrast against the background when photographed.

Happy to share our SOP with anyone if they are interested.

g.

[David Grady]

.8 g 1,2-Indandione, dissolved in
90 ml Ethyl Acetate, then add
10 ml Acetic Acid
900 ml Petroleum Ether
4 ml Zinc Chloride Solution

Zinc Chloride Solution
8 g Zinc Chloride
200 ml Absolute Ethanol

Works Great - especially with Coherent Tracer Laser

[JBK]

What range of light wavelengths are optimal for the mix, if no laser available?

[David Grady]

Our laser is 532nm. Most Forensic Light Sources have a 530nm bandpass filter.

[JBK]

Hello, g-

Is your formula/procedure the same as David Grady's? If not, would you please post yours, as well?

Thanks to both of you!

JBK