稳定同位素稀释-离子色谱-三重四级杆质谱法测定茶叶中高氯酸盐

Determination of perchlorate in tea by stable isotopic dilution - ion chromatography - triple quadrupole mass spectrometry

目的 建立离子色谱-三重四极杆质谱联用技术测定茶叶中高氯酸盐的检测方法。方法 1.00 g样品经50 ml 0.2%(V/V)乙酸水溶液超声提取,提取液经过石墨碳黑固相萃取柱净化,以IonPac AS 19型阴离子色谱柱(2 mm×250 mm, 7.5μm)作为分离柱,自动在线产生的氢氧化钾进行梯度分离,色谱柱流出液经阴离子抑制器抑制后进入质谱系统,以电喷雾电离负离子多离子监测模式(MRM)进行检测,稳定同位素内标法定量茶叶中高氯酸盐的含量。结果 方法线性为0.02μg/L~100.0μg/L,检出限为0.3μg/kg,定量限为1.0μg/kg,平均加标回收率在95.9%~114.0%,相对标准偏差在2.1%~13.0%。检测了20份市售茶叶中高氯酸盐含量,所有样品中均检出高氯酸盐,含量为0.044 mg/kg~0.855 mg/kg,均未超出欧盟的参考限量。结论 本方法灵敏、准确,适合于茶叶中高氯酸盐的测定。

Objective This paper aims to develop a method for the determination of perchlorate in tea by ion chromatography-triple quadrupole mass spectrometry(IC-MS/MS).Methods A total of 1.00 g sample was conducted for ultrasonic extrac⁃tion with 50 ml 0.2%(V/V)acetic aqueous solution,and the extracting solution was cleaned up by graphite carbon black solid phase extraction column.IonPac AS 19 anion column(2 mm×250 mm,7.5μm)was used as the separation column.Potassi⁃um hydroxide generated automatically on line was used for gradient separation.The effluent of the column was inhibited by anion inhibitor and then entered the mass spectrometry system for detection by electrospray ionization anion multi-ion monitoring mode(MRM).Perchlorate in tea was determined by stable isotope internal standard method.Results The method showed good linear relationship in the range of 0.02μg/L-100.0μg/L.The limits of detection(LOD)and the limits of quantification(LOQ)were respectively 0.3μg/kg and 1.0μg/kg.The average recoveries ranged from 95.9%to 114.0%,and the relative standard deviations(RSDs)ranged from 2.1%to 13.0%.Perchlorate was detected in all of the 20 tea samples in Wenzhou.Its concentration ranged from 0.044 mg/kg to 0.855 mg/kg,all within the reference for maximum limit standard of the EU.Conclusion The method is sensitive,accurate and appropriate for the detection of perchlorate in tea.