Study of enrichment factors for six ß-blockers in aliphatic alcohols by hollow-fiber liquid-phase microextraction.

The selectivity of a suitable organic solvent is key for extraction in liquid-phase microextraction experiments. Nevertheless, the screening process remains a daunting task. Our research aimed to study the relationship between extraction efficiency and extraction solvents, analytes, and finally select the appropriate extraction solvent. In the present article, ß-blockers and six extraction solvents were chosen as the models and hollow-fiber liquid-phase microextraction was conducted. The relationship was built by statistical analysis on the data. Factors affecting extraction efficiency including the logarithms of the octanol/water partition coefficient (logPo/w ) of analytes, acid dissociation constants, the logarithms of the octanol/water partition coefficient of solvents and pH of the sample solution were investigated. The results showed that a low water solubility of extraction solvent is the foundation to ensure higher extraction efficiency. Moreover, when ΔlogPo/w > 0, a higher extraction efficiency is observed at lower ΔlogPo/w , on the contrary, when ΔlogPo/w < 0, extraction efficiency is higher as the absolute value of ΔlogPo/w becomes greater. Finally, the relationship between enrichment factor and extraction solvents, analytes was established and a helpful guidance was provided for the selection of an optimal solvent to obtain the best extraction efficiency by liquid-phase microextraction.

[Determination of aflatoxin B1, B2, G1, G2 in Ben Lamge granules by HPLC-FLD after multi-pretreatment clean-up].

To establish a multi-pretreatment method for the determination of aflatoxin B1, B2, G1, G2 in Chinese patent medicines, aflatoxins were analyzed by high performance liquid chromatography-fluorescence detector with post-column derivatization, after the multi-pretreatment of samples. The results showed that after the samples extracted with MeOH-H2O, dehydrated by anhydrous magnesium sulphate and sodium chloride, and finally purified by neutral alumina, the impurity interference of different sources in Chinese patent medicines matrix can be effectively removed, and the main peak can be nicely separated from the impurity peak. The detection limits were 0.25, 0.25, 0.50, 0.25 µg x L(-1) for AFB1, AFB2, AFG1, AFG2, respectively. The quantification limits were 1.00, 0.50, 1.00, 0.50 µg x L(-1), respectively. Aflatoxin B1, G1 showed a good linear relationship at a range of 1.0-50 µg x L(-1), aflatoxin B2, G2 at a range of 0.5-12.5 µg x L(-1) (R2 > 0.99). The average recovery was 80.40% - 108.6%. The present method is simple, reproducible with the reasonable recoveries and can be applied for the determination of aflatoxins in Chinese patent medicines.

[Determination of residual aluminium Ion in Huoxiang Zhengqi pellets by GFAAS with EDTA complexation extraction].

To establish an EDTA complexation extraction pretreatment combining with GFAAS method for the determination of residual aluminium ion in Huoxiang zhengqi pellets without digestive treatment, systematical investigation was made on sample preparation, and EDTA was used for the complexation extraction of residual aluminium ion in samples. The pH, concentration and volume of extraction solution, the temperature and time of microwave extraction, and graphite furnace temperature program were investigated. The results were compared with the microwave digestion. It was showed that, 0.1 g of sample weight was added in 20 mL 0.05 mol x L(-1) EDTA solution (pH 3.5), followed by heating at 150 degrees C for 10 min in the microwave extraction device. The determination of GFAAS was performed at optimized detection wavelength (257.4 nm) as well as graphite furnace temperature program, the detection limits and quantification limits were 2.37 µg x L(-1) and 7.89 µg x L(-1), respectively. The precision (RSD) was less than 2.3%. The average recovery was 96.9% -101%. The present method is easy, rapid and accurate for the determination of residual aluminium ion in Huoxiang zhengqi pellets.