气相色谱-质谱法测定乳制品中光引发剂异丙基硫杂蒽酮的残留量

建立了采用气相色谱（GC）-质谱(MS)检测由包装材料迁移到乳制品中的光引发剂异丙基硫杂蒽酮残留量的方法。使用氘代蒽为内标,样品经Carrez试剂除蛋白质后用丙酮-正己烷(体积比为1∶1)提取,上层提取液用氟罗里硅土固相萃取小柱净化。采用单四极杆质谱进行样品筛选和定量,选取的监测离子为m/z 184,m/z 224,m/z 239,m/z 254(异丙基硫杂蒽酮)和m/z 80,m/z 94,m/z 188,m/z 160(氘代蒽)。疑似样品采用离子阱串联质谱法进行确证,选取的母离子和子离子分别为m/z 254，m/z 239(异丙基硫杂蒽酮)和m/z 188，m/z 160(氘代蒽)。本方法的测定低限(LOQ)分别为7.0 μg/L(GC-MS)和5.0 μg/L(GC-MS/MS),回收率为74.9%~89.6%。采用该方法对11种不同类型的乳制品进行了检测,发现了两例阳性样品。

Determination of Isopropylthioxanthone Residue in Milk Migrated from Packaging Materials by Gas Chromatography-Mass Spectrometry

Isopropylthioxanthone (ITX) has been widely used as the photoinitiator in printing ink of packaging materials in modern food packaging industry. A method regarding the identification and qualification of ITX residue in milk migrated from food contact packaging materials was developed. The procedure was based on the gas chromatography-mass spectrometry (GC-MS) for screening and gas chromatography-tandem mass spectrometry (GC-MS/MS) for confirmation after a solid phase extraction (SPE) step using Florisil column with anthracene D10 (AD10) as the internal standard. Data was acquired in selective ion monitoring (SIM) mode with the following ions: m/z 184, m/z 224, m/z 239, m/z 254 for ITX and m/z 80, m/z 94, m/z 188, m/z 160 for AD10 in screening method of GC-MS. The m/z 254 was selected as the parent ion and m/z 239 as the daughter ion in the conformation method of GC-MS/MS. Data acquired employed the transition of m/z 254, m/z 239 for ITX and m/z 188, m/z 160 for AD10. The method gave limits of quantification (LOQ) of 7.0 microg/L (GC-MS) and 5.0 microg/L (GC-MS/MS) respectively as well as recoveries ranged from 74.9% to 89.6%. The analysis of real samples found two positives out of 11 different milk stuffs available using this method.