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This study aimed to optimize and validate methods for the analysis of thiamin and folic acid in fortified rice, pure and mixed to the milled rice (raw and cooked). The analysis was performed by high-performance liquid chromatography coupled to a diode array detector (HPLC—DAD). Different mobile phases were tested. Different ratios of organic modifier, pH ranges, triethylamine concentrations, and flow rates were used. For the validation, tests of recovery, repeatability, linearity, limit of detection (LOD), and limit of quantification (LOQ) were performed. The optimized methods showed good resolution of vitamins’ peaks, excellent recovery (82.6 to 104%), repeatability with relative standard deviation of peak areas, and retention times less than 10% and high coefficients of determination (0.9998 for thiamin and 0.9997 for folic acid). The LOD and LOQ were 0.00193 μg and 0.0193 μg for thiamin and 0.000934 μg and 0.00934 μg for folic acid. The optimized methods demonstrated reliability and sensitivity in the detection and quantification of these vitamins in fortified rice, pure and mixed to milled rice (raw and cooked). Furthermore, the methods were performed in isocratic mode, with short run time (<13 min), reflecting positively on the economy of reagents and analysis times.

Open access
European Journal of Microbiology and Immunology
Authors: Ingrid E. Pereira, Kyssia P. Silva, Laura M. Menegati, Aimara C. Pinheiro, Elaine A. O. Assunção, Maria De Lourdes P. Araújo, Elfadil Abass, Malcolm S. Duthie, Ulrich Steinhoff, and Henrique C. Teixeira

Abstract

Control of canine visceral leishmaniasis (CVL), a major zoonotic disease in Brazil and many other tropical and subtropical countries, remains difficult as an accurate and reliable diagnosis is still missing. In endemic regions, infected dogs are the main parasitic reservoir host of human Visceral leishmaniasis (VL) infection. Vaccination of dogs against Leishmania infection constitutes an important strategy to prevent or to better control CVL, thus, a serological test that can discriminate between antibodies induced by immunization versus infection is highly desirable in order to improve and simplify diagnosis. Here, four recombinant proteins were evaluated for their ability to detect and differentiate between dogs that are infected with Leishmania or have been immunized with the anti-Leishmania vaccine Leish-Tec®. Receiver operating characteristic (ROC) curve analysis of the four Leishmania-specific IgG ELISA revealed superior performance of rK28, followed by rKLO8, rK39 and rLb6H. The rK28-based ELISA revealed not only the best accuracy against CVL, but also the lowest cross-reactivity with sera from Leish-Tec® immunized dogs. Our data show that the rK28-based ELISA is highly suitable for CVL screening as it shows high sensitivity with simultaneous low cross-reactivity. Further, the high specificity of the rKLO8 indicates its suitability for the confirmation of CVL diagnosis.

Open access