改进QuEChERS法结合超高效液相色谱-串联质谱法同时测定冷冻食品中7种季铵盐化合物

Simultaneous determination of seven quaternary ammonium compounds in frozen food by ultra performance liquid chromatography-tandem mass spectrometry combined with modified QuEChERS method

近年来,季铵盐类消毒剂的广泛使用,导致其残留在食品或环境中,并经食物链进入人体,引起呼吸系统和生殖系统的不良反应,威胁人类身体健康。为此,建立了QuEChERS-超高效液相色谱-串联质谱(QuEChERS-UPLC-MS/MS)同时测定冷冻食品中6种常规季铵盐化合物和1种新型季铵盐化合物残留的分析方法。对样品前处理方法进行改良,色谱条件进行优化,样品经20 mL 90%甲醇水溶液(含0.5%甲酸)涡旋提取20 min后,超声10 min,10000 r/min离心10 min,取1 mL上清液放入装有100 mg PSA净化剂的15 mL离心管中净化,涡旋1 min后,10000 r/min离心5 min,取上清液直接上机测定。以甲醇与5 mmol/L乙酸铵溶液作为流动相进行梯度洗脱,采用ACQUITY UPLC BEH C_(8)色谱柱(50 mm×2.1 mm,1.7μm)分离,在ESI+模式,多反应监测(MRM)方式下采集数据,基质匹配曲线外标法定量。结果表明,7种待测物在C_(8)色谱柱上完全基线分离,在0.1~100.0μg/L的范围内线性关系良好,相关系数(r^(2))为0.9971~0.9983,该方法的检出限(LOD)为0.5~1.0μg/kg,定量限(LOQ)为1.5~3.0μg/kg。以阴性三文鱼、鸡肉为基质样品,在低、中、高3个水平(3.0、10.0、100.0μg/kg)下进行加标回收试验,各待测物的平均回收率为65.4%~101%,相对标准偏差(RSD)为0.64%~16.8%。该检测方法灵敏度高,选择性强,稳定性好,结果准确可靠,适用于冷冻食品中7种季铵盐化合物的批量快速测定,同时,弥补了新型季铵盐化合物检测方法的空白。

Quaternary ammonium compounds(QACs)are a class of cationic surfactants that can be used as the main active ingredient of disinfectants.The increased use of QACs is concerning as exposure from inhalation or ingestion to these compounds that has been associated with adverse effects on the reproductive and respiratory systems.Humans are exposed to QACs primarily by food consumption and inhalation of air.QAC residues pose significant threats to public health.Given the importance of assessing potential residue levels for QACs in food,therefore,a method was developed for the simultaneous detection of six common QACs and one emerging QAC(Ephemora)in frozen food by ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS)coupled with the modified QuEChERS method.The main factors governing the response,recovery,and sensitivity of the method,including extraction solvents,types and dosages of adsorbents,apparatus conditions,and mobile phases,were optimized in the course of sample pretreatment and instrument analysis.QAC residues in frozen food were extracted using 20 mL methanol-water(90∶10,containing 0.5%formic acid)for 20 min by the vortex shock method.The mixture was ultrasonicated for 10 min and centrifuged at 10000 r/min for 10 min.A 1-mL aliquot of the supernatant was transferred to a new tube and purified using 100 mg of PSA adsorbents.After mixing and centrifugation at 10000 r/min for 5 min,the purified solution was analyzed.Target analytes were separated on an ACQUITY UPLC BEH C_(8)chromatographic column(50 mm×2.1 mm,1.7μm)at a column temperature of 40℃and a flow rate of 0.3 mL/min.The injection volume was 1μL.Gradient elution was performed using methanol and 5 mmol/L ammonium acetate solution as the mobile phases.Multiple reaction monitoring(MRM)was conducted in the positive electrospray ionization(ESI+)mode.The matrix-matched external standard method was used to quantify seven QACs.The optimized chromatography-based method completely separated the seven analytes.Good linear relationships were obtained for the seven QACs in the range of 0.1-100.0 ng/mL.The correlation coefficient(r^(2))ranged from 0.9971 to 0.9983.The limits of detection and limits of quantification ranged from 0.5 to 1.0μg/kg and 1.5 to 3.0μg/kg,respectively.Accuracy and precision were determined by spiking salmon and chicken samples with 3.0,10.0,and 100.0μg/kg of analytes,in compliance with the current legislation,with six replicates per determination.The average recoveries of the seven QACs ranged from 65.4%to 101%.The relative standard deviations(RSDs)were between 0.64%and 16.8%.Matrix effects of the analytes were between-27.5%and 33.4%in salmon and chicken samples after purifying using PSA.The developed method was applied to the determination of seven QACs in rural samples.QACs were detected in only one sample;the level did not exceed European Food Safety Authority specified residue limit standards.The detection method has high sensitivity,good selectivity and stability,and the results are accurate and reliable.It is suitable for the simultaneous rapid determination of seven QAC residues in frozen food.The results provide valuable information for future risk assessment studies targeting this class of compounds.