电感耦合等离子体质谱法测定食用植物油中的磷和硅

建立了电感耦合等离子体串联质谱(ICP-MS/MS)准确测定食用植物油中的P和Si的方法.以HNO3+H2O2混合酸经密闭微波消解系统处理植物油样品,向碰撞反应池(CRC)中分别通入O2和H2,P与O2反应,利用O2质量转移,通过测定子离子31P16O+测定P,而Si不与H2发生反应,利用H2原位质量反应消除质谱干扰,显著改善了分析结果的准确度.分别考察了不同O2和H2流速对31P16O+和28Si+信号强度和背景等效浓度(BEC)的影响,确定了最佳O2和H2流速.在优化的条件下,测得31P16O+和28Si+的检出限分别为0.043和0.66 μg/L.采用本方法分析美国国家标准与技术研究院提供的标准参考物质润滑油(SRM 1848),结果表明,测定值与验证值无显著性差异.采用本方法分析来自中国不同产地的5种植物油(分别为油菜籽油、葵花籽油、花生油、玉米油和大豆油),结果表明,5种植物油中花生油的P含量最高,大豆油的Si含量最高.

Determination of Phosphorus and Silicon in Edible Vegetable Oil by Inductively Coupled Plasma-Tandem Mass Spectrometry

An analytical method was developed for determination of P and Si in edible vegetable oil using inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS).The microwave-assisted acid digestion of vegetable oil using HNO3 + H2O2 was carried out in closed vessels.The mass spectral interferences were eliminated by O2 mass shift when promoting reaction with O2 inside the collision reaction cell (CRC), and the monitoring of P as 31P16O+ product ion significantly improved the accuracy of the analysis.H2 was added into the CRC for H2 on-mass reaction.The interferences were eliminated by the quadrupole analyzer to accurately identify 28Si+.The effects of the flow rate of O2 and H2 in ORS3 on the signal intensities and BECs of 31P16O+ and 28Si+ were investigated.The optimum O2 and H2 flow rate was determined.Under the optimized conditions, the limits of detection were 0.043 and 0.66 μg/L for 31P16O+ and 28Si+, respectively.The accuracy of the analytical method was assessed by the analysis of the standard reference materials lubricant oil (SRM 1848) from the National Institute of Standard and Technology.No significant differences were observed between the certified values and measured values.This method was used to analyze 5 kinds of edible vegetable oils (rapeseed oil, sunflower oil, peanut oil, corn oil and soybean oil) from different regions of China, and it was found that the content of P was the highest in peanut oil, and Si showed the highest content in soybean oil.