Farahani Hadi, Ganjali Mohammad Reza, Dinarvand Rassoul, Norouzi Parviz
Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, P.O. Box 14155-6455, Tehran, Iran.
J Agric Food Chem. 2009 Apr 8;57(7):2633-9. doi: 10.1021/jf802981z.
A simple, efficient and virtually solventless headspace liquid-phase microextraction (HS-LPME) technique, combined with gas chromatography-mass spectrometry (GC-MS), was developed for the analysis of sorbic acid (SA) and benzoic acid (BA) in soft drinks and environmental water samples. A microdrop of organic solvent was suspended from the tip of a microsyringe needle over the headspace of the stirred sample solution, containing the analytes for a desired time. The microdrop was then retracted into the microsyringe and directly injected into the GC-MS, without any further pretreatment. Initially, microextraction efficiency factors were optimized, and the optimum experimental conditions found were as follows: 2.5 microL toluene microdrop exposed for 20 min over the headspace of a 6.5 mL aqueous sample (45 degrees C), containing 3 M of NaCl with pH of 1.5 and stirred at 1000 rpm. Under the optimized extraction conditions, preconcentration factors of 154 and 198, limits of detection of 0.3 and 0.1 microg L(-1) (S/N=3) with dynamic linear ranges of 1-500 and 0.5-500 microg L(-1), were obtained for SA and BA respectively. A good repeatability (RSD<10.3%, n=8) and satisfactory linearity (r(2) >or= 0.99) of results were achieved. The accuracy of the method was tested by the relative recovery experiments on spiked samples, with results ranging from 90 to 113%. The method proved to be rapid and cost-effective and is a green procedure for screening purposes.
本文开发了一种简单、高效且几乎无溶剂的顶空液相微萃取（HS-LPME）技术，并将其与气相色谱-质谱联用（GC-MS），用于分析软饮料和环境水样中的山梨酸（SA）和苯甲酸（BA）。将一小滴有机溶剂悬挂在微量注射器针头尖端，置于搅拌的样品溶液顶空上方，使分析物在其中保持所需时间。然后将微滴抽回微量注射器，无需进一步预处理，直接注入GC-MS。首先，对微萃取效率因素进行了优化，得到的最佳实验条件如下：在6.5 mL水样（45℃）的顶空上方，暴露2.5 μL甲苯微滴20分钟，该水样含有3 M NaCl，pH为1.5，搅拌速度为1000 rpm。在优化的萃取条件下，SA和BA的预富集因子分别为154和198，检测限分别为0.3和0.1 μg L⁻¹（S/N = 3），动态线性范围分别为1 - 500和0.5 - 500 μg L⁻¹。结果具有良好的重复性（RSD < 10.3%，n = 8）和令人满意的线性（r²≥0.99）。通过对加标样品的相对回收率实验测试了该方法的准确性，结果在90%至113%之间。该方法被证明快速且经济高效，是一种用于筛选目的的绿色方法。
