土壤中典型人工甜味剂的前处理方法优化及高效液相色谱-串联质谱分析

Optimization of sample pretreatment method for the determination of typical artificial sweeteners in soil byhighperformance liquid chromatographytandem mass spectrometry

优化了同时提取土壤中4种典型人工甜味剂的前处理与净化方法,并结合高效液相色谱-串联质谱（HPLCMS/MS）技术,建立了一种快速高效的分析方法。样品采用25 mL0.01 mol/L醋酸-醋酸钠溶液（pH4）提取2次,每次提取20 min;萃取样品进一步采用CNW Poly-Sery PWAX固相萃取小柱净化浓缩;最后采用HPLC-MS/MS进行测定。在干燥土壤中添加1、10、100μg/kg标准品时,4种甜味剂的平均回收率为86.5%-105%,日内精密度（RSD）≤5.94%,日间精密度（RSD）≤6.53%;在1-100μg/kg范围内的线性关系良好（r2〉0.995）;方法的检出限为0.01-0.21μg/kg,定量限为0.03-0.70μg/kg。利用该方法对天津某污水灌溉的农田土壤进行了分析测定,结果表明该方法快捷可靠,可用于土壤中人工甜味剂的环境调查。

The sample pretreatment method for the determination of four typical artificial sweeteners （ASs） including sucralose, saccharin, cyclamate, and acesulfame in soil by high performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS） was optimized. Different conditions of extraction, including four extractants （ methanol, acetonitrile, acetone, deionized water）, three kinds of ionic strength of sodium acetate solution （0. 001, 0.01, 0. 1 mol/L）, four pH values （3, 4, 5 and 6） of 0.01 mol/L acetate-sodium acetate solution, four set durations of extraction （20, 40, 60, 120 min） and number of extraction times （ 1, 2, 3, 4 times） were compared. The optimal sample pretreatment method was finally set up. The samples were extracted twice with 25 mL 0.01 mol/L sodium acetate solution （pH 4） for 20 min per cycle. The extracts were combined and then purified and concentrated by CNW Poly-Sery PWAX cartridges with methanol containing I mmol/L tris （hydroxymethyl） amino methane （Tris） and 5% （v/v） ammonia hydroxide as eluent. The analytes were determined by HPLC- MS/MS. The recoveries were obtained by spiked soil with the four artificial sweeteners at 1, 10, 100 μg/kg （dry weight）, separately. The average recoveries of the analytes ranged from 86.5% to 105%. The intra-day and inter-day precisions expressed as relative standard deviations （RSDs） were in the range of 2.56%-5.94% and 3.99%-5.53%, respectively. Good linearities （ r^2〉0. 995） were observed between 1-100 μg/kg （dry weight） for all the compounds. The limits of detection were 0.01-0.21μg/kg and the limits of quantification were 0.03-0.70μg/kg for the analytes. The four artificial sweeteners were determined in soil samples from farmland contaminated by wastewater in Tianjin. This method is rapid, reliable, and suitable for the investigation of artificial sweeteners in soil.