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A rapid, accurate and precise method for the determination of sudan I-IV in chili products using on-line solid phase extraction and LC-MS has been developed. Chili products were extracted with acetone and the analytes were cleaned up and enriched on an SPE column (C18, 15–40 µm) through on-line SPE. Chromatographic separation was performed on a C18analytical column (2.1 × 150 mm, 3 µm) with gradient elution programming of 0.1% formic acid in water and 0.1% formic acid in acetonitrile. All four sudan dyes were separated in less than 8 min. Using in-house validation data, linearity coefficients of determination (R2) of more than 0.9997 were obtained. The limits of detection (LOD) and limits of quantitation (LOQ) for sudan I, II and IV were 0.03 and 0.05 mg kg−1, respectively, and 0.04 and 0.1 mg kg−1for sudan III. The intra- and inter-day recoveries of the four sudan dyes in chili powder were between 90.1–101.6% and 90.2–102.0%, respectively, with relative standard deviation (RSD) between 0.014–0.164% and 0.011–0.202%, respectively. Therefore, this proposed method could be an alternative assay for the determination of sudan I-IV in chili products due to its rapidness, sensitivity, less sample and solvent consumption. [ABSTRACT FROM AUTHOR]

Coenzyme Q10 (CoQ10) is a cofactor in the respiratory chain and a potent endogenous antioxidant. Abnormally low levels of CoQ10 in the circulatory system are often involved with pathological states such as heart failure, mitochondrial and muscular diseases, and cancer. The development of simple, rapid, and highly sensitive methods capable of quantifying low CoQ10 levels in plasma is, therefore, increasingly required. In this work, we developed a miniaturized HPLC-UV system for the determination CoQ10 in human plasma using an XTerra microcolumn (50 mm × 2.1 mm i.d., 3.5 µm particle size), methanol:water (98:2, v/v) as mobile phase, 275 nm, flow rate of 0.3 mL/min, 30 °C column temperature, and 2 µL injection volume. The extraction procedure consists of a plasma precipitation with 1-propanol and evaporation under nitrogen to allow a 1.5-fold enrichment. The chromatographic analysis was accomplished in 7 min. As a result, it was possible to quantitate CoQ10 in small sample volumes down to 0.07 µM and detect as low as 0.02 µM in real plasma, with good accuracy and precision, even in pathological conditions. The proposed method was found to be suitable for routine CoQ10 determination in clinical laboratories. [ABSTRACT FROM PUBLISHER]