Search

A method based on high-performance liquid chromatography with a UV detector (HPLC-UV) was developed for the simultaneous determination of sorbic acid, benzoic acid, and natamycin in yogurt. The method does not require time-consuming, labor-intensive pre-treatment processes or complicated procedures. Using a C18 150 mm × 4.6 mm, 3.0 µm column (Roc) at 25°C, the target analytes were separated within 5 minutes with high sensitivity and selectivity. The mobile phase consisted of trifluoroacetic acid (0.1%) in water containing 100 mM sodium acetate, trifluoroacetic acid (0.1%) in acetonitrile, and trifluoroacetic acid (0.1%) in tetrahydrofuran, in a ratio of 70:20:10 (v/v). Using this mobile phase as an extraction mixture, recoveries ranged from 83.0% to 110.2% at spike levels between 2.5 µg/kg and 80.0 µg/kg. The relative standard deviations (RSDs) for these recoveries were below 10%. Intra-day precision and inter-day precision varied from 5.3% to 6.7% and 7.6% to 9.2%, respectively. Additionally, the limits of detection (LOD) were between 0.24 and 0.61 mg/L, and the limits of quantification (LOQ) ranged from 0.80 to 2.0 mg/L for sorbic acid, benzoic acid, and natamycin. Principal component analysis revealed that yogurt type had the greatest positive influence on preservative concentration, while the weight or volume of the yogurt package had the greatest negative influence. [ABSTRACT FROM AUTHOR]

A method was developed for the simultaneous determination and analysis of sildenafil, vardenafil, and tadalafil in honey-mixed herbal sachets using high-performance liquid chromatography with a UV detector (HPLC–UV). This method eliminates the employment of complex procedures and abolishes time-consuming and labour-intensive pre-treatment processes. In ten minutes, the separation process (at 25oC) of sildenafil, vardenafil, and tadalafil using a C18 150 mm × 4.6 mm x 5 μm column (Shim-pack GIST) was successful with high selectivity and sensitivity. The mobile phase was a 60:40 (v/v) mixture of 0.1 percent formic acid in water and 0.1 percent formic acid in acetonitrile. Using the mobile phase as an extraction mixture, it gave recoveries in the range of 93.0-103.3% at spike levels of 50–150 mg/kg with relative standard deviations (RSDs) lower than 10%. The intra-day and interday precision results were in the range of 0.4–0.8% and 1.0–1.7%. Furthermore, the retention times for sildenafil acid, vardenafil acid, and tadalafil were 1.93, 2.47, and 9.62 minutes, respectively, and the limits of detection (LOD) were 1.70, 2.16, and 1.03 mg/L, while the limits of quantification (LOQ) were 5.65, 7.21, and 3.42 mg/L. [ABSTRACT FROM AUTHOR]

Abstract: A new method for the determination and analysis of aflatoxins in noodles, based on the use of the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) procedure, enhanced with a high performance liquid chromatography–coupled to a fluorescence detector (HPLC–FLD) has been developed. The method excludes the use of dispersive solid-phase extraction (dSPE) extraction cleanup step to reduce time and cost of analysis. Separation of the four(4) aflatoxins with higher selectivity and sensitivity, and within reasonable limits of retention time, was performed by using an isocratic mobile phase of water/methanol/acetonitrile (65/25/10) at a column temperature of 30 °C. Optimization of sample preparation and analytical conditions gave recoveries in the range of 75%–107% at spike levels of 5.0–20.0 μg/kg, and relative standard deviations (RSDs) lower than 13% in all the cases. The repeatability and reproducibility results were in range of 2.0–12.3% and 3.4–16.5% respectively. Additionally, the limits of detection (LOD) (0.01–1.00 μg/kg) and the limits of quantification (LOQ) (0.05–1.80 μg/kg) of these aflatoxins are well within the legal limits set by the European Union (EU). [Copyright &y& Elsevier]

The application of antibiotics in animals for therapeutic and growth promotion purposes and to meet the need to increase meat production has been reported to cause the development of antibiotic resistance and other health risks due to the consumption of poultry products. Therefore, the need for rapid and accurate analytical methods for the determination of drug residues has become necessary. The Quick, Easy, Cheap, Effective Rugged and Safe (QuEChERS) technique involves liquidliquid extraction by partitioning with acetonitrile, followed by clean-up with a mixture of magnesium sulphate and a primary secondary amine. The extract obtained was then analyzed using high-performance liquid chromatography (HPLC). The figures of merit of the analytical methodology were determined using optimized parameters and the calibration curve was linear over the tested concentration range. The linearity ranged from 5 to 500 μg/kg for all the drug residues, and the correlation coefficients (r2) were greater than 0.99. The limit of detection (LOD) ranged within 1.45 - 5.02 μg/kg while the limit of quantification (LOQ) ranged within 4.68 - 6.72 μg/kg. The inter-day and intra-day precisions for beef samples had respective ranges of 1.94 - 19.03 % and 2.78 - 9.04%, and the average recoveries were from 79.48 to 107.48 %. The selectivity was determined by a blank matrix containing external standards and a sample spiked with target analyte and the results indicate a good selectivity with no interferences. [ABSTRACT FROM AUTHOR]