Development and validation of an analytical method for determination of citrinin in red rice and red yeast rice-based food supplements by ultra-high performance liquid chromatography tandem mass spectrometry.

Citrinin is a hepato-nephrotoxic mycotoxin produced by fungal species. The Monascus purpureus fungus plays a crucial role in the fermentation of red rice to produce red yeast rice-based food supplements, which represent the primary source of human exposure to citrinin. In this study, a simple and sensitive analytical method was successfully developed and validated for the citrinin determination in these products. The extraction process involved a QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) step and citrinin determination by ultra high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). The proposed method provided satisfactory linearity, percentage of recovery from 82 to 104% with relative standard deviations (RSD) lower than 14%, and limits of detection and quantification of 0.07 µg/Kg and 0.24 µg/kg, respectively. Among the 14 samples analyzed, citrinin was found in two red rice samples (0.24 and 0.46 µg/kg) and in six food supplements (from 0.44 to 87 µg/kg).

Application of ultra performance liquid chromatography-tandem mass spectrometry to the analysis of priority pesticides in groundwater.

Ultra performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UPLC-MS/MS) has been applied for the accurate and rapid analysis of nine trace level priority pesticides in water. The UPLC technology, based on the use of columns packed with 1.7 microm porous particles combined with higher pressures than those conventionally applied in HPLC, enabled to improve in peak resolution, sensitivity and speed of analysis. UPLC chromatograms showed very sharp peaks with less than 2 s wide at the base, except for alachlor. This enhanced efficiency resulted in an increased separation speed of the whole UPLC-MS/MS procedure that required less than 5 min. Limits of detection, determined for 300 ml water samples after SPE preconcentration were in the range between 0.1 and 20 ng/L. The presence of matrix effects or ion suppression was checked by the obtaining of calibration curves in both pure solvent and matrix matched standards. Other performance characteristics of the method, such as linearity and precision were also satisfactory. Finally, the method was successfully applied to the analysis of two water samples from an inter-laboratory exercise.

Método de inclusión en parafina para diagnóstico rápido por medio de microondas / A paraffin inclusion method for fast diagnosis using microwaves

Se desarrolló un protocolo de impregnación rápida en parafina por medio de microondas, para muestras histológicas y de diagnóstico, con el propósito de que fueran observadas en microscopia de campo claro. Se procesaron muestras de hígado, papiloma, piel y pulmón de perro; cerebro y riñón de gato; ovario, cuerno uterino y arteria de rata. Se utilizó un horno de microondas casero (600 watts) a 75 por ciento de su potencia, con soluciones ascendentes de alcohol para deshidratar, mezclas de benceno-etanol para aclarar y parafina para embeber. Un grupo de especialistas revisó el material y fotografías de los diversos órganos procesados, con tres técnicas de inclusión distintas, con los resultados obtenidos a partir de las observaciones realizadas se concluye que no hay una diferencia significativa entre las muestras de histokinette (HK) y microondas (MO). Al comparar las técnicas de HK, MO con la de Robinson y Fayen (RF), se advierten diferencias morfológicas muy aparentes. Este método permite obtener diagnósticos patológicos y morfológicos 30 minutos después de que las muestras se reciben en el laboratorio. La morfología de las muestras procesadas por medio de microondas es mejor que las muestras procesadas por el método rápido de RF y no hay diferencias apreciables en comparación con el método de rutina por HK.