离子色谱法测定地沟油和食用油中氯离子含量

Determination of Chlorine in Hogwash Oil and Edible Oil by Ion Chromatography

样品采用氧化钙为溶剂,在恒温马弗炉中550℃加热4h,冷却后用水超声浸提,过On Guard NaⅡSPE柱除去处理液中金属离子,用离子色谱法测定其氯离子含量。结果表明:地沟油中氯离子含量远高于食用油中氯离子含量。离子色谱条件:分析柱IonPac AS19(4mm×250mm),KOH淋洗液30.0mmol/L,流速1.0mL/min,进样体积500μL,外标峰面积定量。该方法对氯离子的检出限为0.004mg/L,在0.004～0.8mg/L范围内具有良好线性关系(r=0.9992),平均加标回收率为88%,相对标准偏差为(RSD)为3.1%。该法操作简便,快速灵敏、准确。

An ion chromatography method was presented to determine chlorine in hogwash oil and edible oil.Oil samples were ashed in muffle furnace at 550 ℃for 4 h with calcium oxide,cooled down,extracted with water in an ultrasonic field,and purified on an On Guard Na Ⅱ SPE column for eliminating metal ions before ion chromatographic analysis.The chromatographic separation was carried out on an IonPac AS19（4 mm× 250 mm） column using 30.0 mmol/L KOH as mobile phase at a flow rate of 1.0 mL /min.The injection volume was 500μL.The external standard method was used to quantify chlorine.The detection limit of the method was 0.004 mg/L and a good linear relationship was observed over the range from 0.004 to 0.8 mg/L（r = 0.9992）.The average recovery rate and RSD were 88% and 3.1%,respectively.This method proved easy to use,rapid,sensitive and accurate.