氧弹燃烧-离子色谱法测定一次性食品接触用生物基塑料中氟含量

Determination of Fluorine in Disposable Food-contact Bio-based Plastics by Oxygen Bomb Combustion-ion Chromatography

目的建立并优化氧弹燃烧-离子色谱法测定一次性食品接触用生物基塑料(下文简称生物基塑料)中氟含量的检测方法,分析市售生物基塑料产品中氟含量情况。方法生物基塑料经氧弹燃烧发生高温氧化分解,氟化物转化为游离态氟离子,被吸收或溶解在吸收液中,以5.0 mmol/L碳酸氢钠和1.0 mmol/L无水碳酸钠溶液作为流动相进行等度洗脱,进样量为20μL,流速为0.8 mL/min;采用Metrosep A Supp 7色谱柱(250 mm×4.0 mm,5.0μm)和Metrosep A Supp 5 Guard保护柱(50 mm×4.0 mm,5.0μm),柱温为45℃;以电导检测器进行测定,外标法定量。结果氧弹燃烧-离子色谱法测定生物基塑料中氟含量的相关系数R2>0.995,检出限为5.0 mg/kg,定量限为10 mg/kg,线性关系良好,加标回收率为93.8%~98.4%,精密度为2.9%~6.8%(n=6)。通过对119款实际样品中氟含量进行定量分析,总体检出率为94.11%,总体不合格率为15.94%;PLA吸管、PLA+PBAT吸管和PLA+PBS吸管的检出率均为100%,不合格率分别为45.16%、30.77%和5.88%。结论该方法可靠、方便、灵敏,分离效果好,适用于生物基塑料中氟含量的检测。

The work aims to establish and optimize a method for the determination of fluorine in disposable food-contact bio-based plastics(hereinafter referred to as bio-based plastics)by oxygen bomb combustion-ion chromatography,and analyze the fluorine content of commercially available bio-based plastic products.The oxidative decomposition of bio-based plastics occurred at high temperature by oxygen bomb combustion,and the fluoride was converted into free fluoride ions,which were absorbed or dissolved in the absorbent solution,and then eluted with 5.0 mmol/L sodium bicarbonate and 1.0 mmol/L anhydrous sodium carbonate solution as the mobile phases,with an injection volume of 20μL and a flow rate of 0.8 mL/min.The determination was carried out on a Metrosep A Supp 7 column(250 mm×4.0 mm,5.0μm)and Metrosep A Supp 5 Guard column(50 mm×4.0 mm,5.0μm)at a column temperature of 45℃with a conductivity detector,and was quantified by external standard method.The correlation coefficient for the determination of fluorine content in bio-based plastics by oxygen bomb combustion-ion chromatography R2>0.995,the limit of detection(LOD)was 5.0 mg/kg,and the limit of quantification(LOQ)was 10 mg/kg,with good linearity,the spiked recoveries were in the range of 93.8%-98.4%,and the precision ranged from 2.9 to 6.8%(n=6).By quantitatively analyzing the fluorine content in 119 actual samples,the overall detection rate was 94.11%,and the overall failure rate was 15.94%.The detection rate in PLA straws,PLA+PBAT straws and PLA+PBS straws was 100%,and the failure rate was 45.16%,30.77%and 5.88%,respectively.The method is reliable,convenient,sensitive,with good separation effect,and suitable for the determination of fluorine content in bio-based plastics.