在线基体消除-离子色谱法测定甲醇汽油中的无机阴离子

建立一种在线消除基体、直接进样测定甲醇汽油中无机阴离子的离子色谱(IC)方法。样品经90%(V/V)甲醇溶解、稀释后直接进样,通过在线基体消除和预富集,采用IonPac AS23(250×4mm)分析柱分离,淋洗液为4.5mmol/L Na2CO3-0.8mmol/L NaHCO3,流速1.2 mL/min,采用Dionex DS6电导检测器检测,外标法定量。Cl-和SO42-的线性范围分别为0.05～5.0 mg/L,0.5～10 mg/L,相关系数分别为0.9998和0.9999,加标回收率为92.5%～96.7%,相对标准偏差RSD(n=8)<2.0%,检出限(以信噪比S/N=3计)分别为0.02 mg/L,0.08 mg/L。该方法用于甲醇汽油中无机阴离子的测定,结果令人满意。

On-line Removing Matrix- Determination of Anions in Biogasoline by Ion Chromatography

An on-line removing matrix method with valve-switching was developed for the simultaneous determination of trace impurity anions in bio-gasoline by ion chromatography(IC).The bio-gasoline sample was diluted with 90%(V/V) methanol,filtrated by 0.22 μm nylon filter membrane,and then injected to the IC system directly without further pretreatment.The analytical column was Dionex IonPac AS23(250×4 mm),carbonate was used as the eluent at a flow rate of 1.2 mL/min.The detection was performed by a Dionex DS6 conductive detector.The quantitive analysis of external standard calibration curves was used.The linear ranges of the method for Cl-and SO42-were 0.05~5.0 mg/L(r=0.9998),0.5~10 mg/L(r=0.9999) respectively.The average recoveries were 92.5%~96.7% with the relative standard deviations(RSD) less than 2.0%.The detection limits(S/N=3) were 0.02 mg/L and 0.08 mg/L for Cl-and SO42-,respectively.The method has been applied to determine the chloride and sulfate in methanol gasoline with satisfactory results.