In the criminal sphere, it is extremely important to identify perpetrators of crimes based on latent fingerprints (invisible to the naked eye) revealed at crime scenes and their corresponding objects. The present work aimed to evaluate four synthetic analogues of curcumin as possible IDL developers, and to compare their results with those of carbon black developer, as well as to reach the most adequate parameters in the use of the LTQ and FT-ICR mass spectrometers with the paper spray ionization (PS) source to study the chemical composition of the endogenous substances contained in the IDL. For this, a 24-1 factorial design was developed, where it was verified that the distance and voltage factors were the most influential for the increase in the response of signals, in the analysis of latent fingerprints by PS. Among the detected substances we can mention around 20 fatty acids, and squalene. Finally, four potential developers, synthetic analogues of curcumin, were compared with carbon black developer. The revelation of latent fingerprints occurred efficiently, allowing the visualization of minutiae, such as bifurcation and end of line, making it possible to classify them, according to the Vucetich Fingerprint Classification System.

O potencial da técnica de espectroscopia de infravermelho com transformada de Fourier e acessório de reflexão total atenuada (FTIR-ATR) foi avaliado para o monitoramento da degradação da poliamida 11 (PA-11) usada em dutos flexíveis. As amostras foram submetidas a envelhecimento em reatores com pressão controlada e atmosfera inerte. Os corpos de prova foram imersos em água deionizada (pH 7), nas temperaturas de 110, 120 e 140 ºC por um período de até 50 dias. A técnica recomendada para monitoramento da degradação da PA-11 é a viscosimetria, através de medidas da viscosidade inerente corrigida (VIC) e a análise termogravimétrica (TGA). O comportamento observado para a VIC e TGA durante o envelhecimento possibilitou a construção de modelos que correlacionam com a técnica de FTIR-ATR. A partir dos resultados de FTIR-ATR, a variação na intensidade da banda atribuída à fase amorfa, 1161 cm-1, possibilitou o monitoramento do envelhecimento quando associamos a técnica a modelos quimiométricos como o de regressão dos mínimos quadrados parciais, PLS. Portanto, a técnica FTIR-ATR pode ser uma nova alternativa no monitoramento da degradação hidrolítica da PA-11, eliminando assim o uso de solventes orgânicos tóxicos e reduzindo, consequentemente, o tempo de análise.

The potential of the infrared spectroscopy with the attenuated total reflection technique (FTIR-ATR) was evaluated to monitor degradation of polyamide 11, PA-11, applied in flexible pipes. The samples were subjected to aging on reactors with controlled pressure and atmosphere. The samples were immersed in deionized water, pH 7, at temperatures of 110, 120 and 140 ºC over a period of up to 50 days. The typical technique recommended for monitoring PA-11 degradation is viscometry from inherent viscosity corrected (VIC) and thermogravimetric (TGA) measurements. TGA and VIC results allowed the use of chemometric models that can be related to FTIR-ATR spectra, with assignment of a band to the amorphous phase (1161 cm-1) of PA-11. The chemometric model generated from PLS data was satisfactory in predicting the aging of PA-11. Therefore, FTIR-ATR can be used as a new analytical methodology to monitor PA-11 degradation, thus eliminating the use of toxic organic solvents and reducing the time required for the analysis.