Wagner F. Pacheco

Determination of cocaine in Real banknotes circulating at the State of Rio de Janeiro, Brazil

This paper shows the result of a study on the extent of cocaine contamination in Real banknotes in circulation in the state of Rio de Janeiro (Brazil). A study of the percentage of contaminated banknotes was made, as well as a study on the contamination of banknotes based on different values, and a study of contamination depending on the region where the banknote was collected. The idea of this last study was to verify if the peculiar characteristics of the region of study (in particular, the city of Rio de Janeiro) influence the amount of cocaine in the banknotes. Some regions have higher consumption/drug trafficking of cocaine than others. Also, some contaminated banknotes confiscated directly from drug dealers and users were analyzed. Also, is showed in this paper all the optimization of the available analytical techniques for making the measurements possible.

Direct determination of sitagliptin in pharmaceutical formulations and its determination in urine after solid‐phase extraction by spectrofluorimetry

The fluorescence characteristics of sitagliptin phosphate were used to develop a methodology that allowed its determination in pharmaceutical formulations and urine samples; under the studied conditions, limits of determination and quantification of 0.25 and, respectively, 0.85 mg/L were achieved. Linear correlation between fluorescence analytical signal and sitagliptin concentration was achieved up to 10.0 mg/L. The method was considered selective for sitagliptin determination in pharmaceutical formulations because no interferences due to excipients present in considered matrix were observed (as demonstrated by recovery tests comparing analytical and addition curves). When the method was applied to urine samples, Interferences related to the matrix were observed, which made a solid-phase extraction system necessary. The use of calibration was possible only by applying the standard addition method.

Iodine determination in table salts by digital images analysis

For human health reasons the World Health Organization (WHO) stated in 2014 that the amount of iodine present on table salts should lie within the range of 15 to 65 mg per kilogram of salt, depending on the salt intake levels presented in each population. This means that booth industrial laboratories (for quality control) and governmental agencies (for external quality control) should perform iodide quantification in table salts. The main method for this determination is based on volumetric analyses or WYD iodine checker. This work proposes an alternative approach for the quantification of iodine in table salt samples, that combine the good accuracy and precision obtained by titrimetric methods with the convenience of using a spectrophotometer, using just a polyurethane foam and a scanner, trough digital image analysis. The results here obtained indicate that the proposed method offers satisfactory precision and accuracy as well as sufficient sensitivity to address the resolutions provided by the WHO and the Brazilian legislation relating to iodine content in table salts. The limit of detection (LOD) was calculated as 3.94 mg kg−1 and the limit of quantification (LOQ) as 13.2 mg kg−1. When compared to the standard iodometric method, the developed method presented no statistical difference at 95% confidence level.

Development of an analytical method for the determination of N-nitrosamines in tobacco by GC-NCD after solid phase extraction

In this paper an analytical method was developed for the determination of some tobacco specific N-nitrosamines (TSNAs) in cigarettes, and applied to cigarettes purchased in the city of Rio de Janeiro/RJ (Brazil). The analyte detection is based on the gas chromatography technique with a chemiluminescence detector (GC-NCD), while the extraction is based on two stages, the first is a cigarette leaching step, and the other is solid phase extraction of TSNAs from this leaching. The method presented an accuracy of 92 ± 18%; the precision was calculated using the coefficient of variation of a standard TSNA mix solution measured on 3 successive days and was in the range from 4.7 to 6.8%. The working range of all TSNAs was 50–700 ng mL−1, allowing the method to have LOQ values from 198.3 to 623.7.1 ng per cig. The method developed allowed determination of NNN, NAT, NNK and NAB in commercial cigarette samples.

Development of a flow‐injection analysis system with fluorescence detection for gatifloxacin determination in organized medium

This work reports the development and optimization of a flow injection analysis system with fluorescence detection (FIA-FLUO) for gatifloxacin (GFX) determination in organized medium. The analytical system was based on the enhanced fluorescence of gatifloxacin in micellar medium containing sodium dodecyl sulfate (SDS) at pH 6.0. The influence of physical (carrier flow rate, sample volume and volume of reaction coil) and chemical (pH, concentration of buffer and concentration of SDS) parameters that could affect the performance of the FIA system was evaluated in order to reach optimum conditions in terms of sensitivity and analytical throughput. Under optimized conditions, the FIA-FLUO system allowed the injection of 40 samples per hour with a limit of quantification of 72 µg/L and a RSD of 3.5% at 0.20 mg/L. Real samples of commercial pharmaceutical formulations containing GFX were analyzed, and no statistical difference was observed between the results obtained using the developed system and those obtained using the reference method based on high-performance liquid chromatography with UV detection.