• Analytical Science and Technology
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• v.30 no.6
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• pp.312-318
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• 2017

The shelf life of 1,2-indandione/zinc (1,2-IND/Zn) solution and polyvinylpyrrolidone (PVP) solution, which are known as reagents for developing latent fingermarks deposited on the surface of thermal paper, was studied. The standard latent fingermarks used for comparisons were artificial latent fingermarks printed on thermally sensitive and non-sensitive surfaces with the same intensity. Upon treatment of standard latent fingermarks with the pre-mixed 1,2-IND/Zn and PVP solutions, the fingermarks could be successfully developed until 3 days after the preparation of the mixture. However, from the third day after mixing the reagents, blackening was observed on the surface of the thermal paper, indicating deterioration of the reagent performance. The 1,2-IND/Zn and PVP solutions separately stored without mixing in advance were mixed immediately before use, and the development efficiency of the latent fingermarks deposited on the surface of thermal paper was observed. The performance of the PVP solution decreased after 20 days from the preparation of the reagent. It was also found that the shelf life of 1,2-IND/Zn and PVP mixture was determined by the PVP solution. The effect of oxygen and moisture on the degradation of PVP was investigated. It was found that the performance of the PVP solution deteriorated because of the influence of moisture, though it was not affected by oxygen.

• Analytical Science and Technology
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• v.32 no.3
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• pp.105-112
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• 2019

Fingerprints may be contaminated with ethanol solutions. In order to solve the case, the law enforcement agency may need to visualize the fingerprint from these samples, but the development method has not been studied. The paper with latent fingerprint was contaminated with ethanol solution and then the blurring of ridge detail was observed. As a result, when the copy paper was contaminated with ethanol solutions of less than 75 % (v/v), the amino acid components of latent fingerprint residue blurred but lipid components of latent fingerprint residue didn't blurred. On the other hand, when the paper was contaminated with ethanol solution of more than 80 % (v/v), the amino acid components of latent fingerprint didn't blurred but the lipid components of latent fingerprint blurred. Therefore, it is found that the paper contaminated with ethanol solutions of less than 75 % (v/v) should be treated by oil red O (ORO) enhancing lipid components, and the paper contaminated with ethanol solutions of 80 % (v/v) or more should be treated by 1,2-indandione/zinc (1,2-IND/Zn) enhancing amino acid components. The blurring of ridge detail was not observed when the fingerprints were deposited with fingers contaminated with ethanol solution. This fingerprints were treated with 1,2-IND/Zn or ORO to compare the latent fingerprint development ability, and using 1,2-IND/Zn was able to visualize the latent fingerprint more clearly than using ORO.