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    中空纤维膜液相微萃取-高效液相色谱法测定酱油、食醋及碳酸饮料中苯甲酸和山梨酸的含量

    Determination of Benzoic Acid and Sorbic Acid in Soy Sauce, Vinegar and Carbonated Beverage by High Performance Liquid Chromatography Combined with Hollow Fiber Membrane Liquid Phase Microextraction

    • 摘要: 建立了中空纤维膜液相微萃取-高效液相色谱法(HPLC)测定酱油、食醋及碳酸饮料中苯甲酸和山梨酸含量的方法。称取酱油、食醋或超声脱气后的碳酸饮料样品0.100 0 g,加入500 mg·L-1内标(肉桂酸)溶液0.1 mL,用水稀释至50 mL。移取10 mL上述样品溶液于萃取小瓶中,用1 mol·L-1盐酸溶液调节溶液pH至2.5,加入0.50 g氯化钠。用丙酮超声洗涤聚偏氟乙烯中空纤维膜小段(6.0 cm)并置于磷酸三丁酯中超声浸润3 min。向中空纤维膜腔体注入50 μL氢氧化钠溶液(pH 13.0),封口后浸入萃取小瓶中,以转速1 000 r·min-1萃取25 min。按照仪器工作条件,吸取中空纤维膜内的溶液用于HPLC分析,内标法定量。结果显示:苯甲酸和山梨酸的质量浓度均在0.01~10.00 mg·L-1内与其对应的目标物与内标峰面积比值呈线性关系,检出限(3S/N)分别为0.001,0.003 mg·L-1;对酱油样品进行测定,日内精密度(n=6)和日间精密度(n=6)均小于3.0%;对酱油样品进行3个浓度水平的加标回收试验,回收率为95.5%~106%。方法用于实际样品分析,苯甲酸和山梨酸均被不同程度地检出。

       

      Abstract: A method for determination of benzoic acid and sorbic acid in soy sauce, vinegar and carbonated beverage by high performance liquid chromatography (HPLC) combined with hollow fiber membrane liquid phase microextraction was established. 0.100 0 g of soy sauce, vinegar or ultrasonic degassed carbonated beverage sample was taken and 0.1 mL of internal standard (cinnamic acid) solution (500 mg·L-1) was added, and made its volume up to 50 mL with water. The above sample solution of 10 mL was removed into extraction vial for adjusting pH to 2.5 with 1 mol·L-1 hydrochloric acid solution, and 0.50 g of sodium chloride was added. The small segment (6.0 cm) of polyvinylidene fluoride hollow fiber membrane was washed with acetone and soaked in tributyl phosphate for 3 min by ultrasonic. The hollow fiber membrane cavity was injected with 50 μL of sodium hydroxide solution (pH 13.0), and immersed into the extraction vial after sealing to extract for 25 min at 1 000 r·min-1. According to the working conditions of the instrument, the solution in the hollow fiber membrane was absorbed for HPLC analysis, and internal standard method was used for quantitative analysis. As shown by the results, linear relationships between mass concentrations of benzoic acid and sorbic acid and their peak area ratios of analytes to internal standard were kept in the range of 0.01-10.00 mg·L-1, with detection limits (3S/N) of 0.001 mg·L-1 and 0.003 mg·L-1, respectively. Soy sauce sample was determined, and intra-day precision (n=6) and inter-day precision (n=6) were less than 3.0%. Recovery test was made on soy sauce samples at 3 concentration levels by standard addition method, giving results in the range of 95.5%-106%. This method has been applied for analysis of substantial samples, and benzoic acid and sorbic acid were detected in varying degrees.

       

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