采用离子色谱法分析了3种浸提液对芥菜和葱中硝酸盐和草酸盐的提取效果.结果表明:用离子色谱法同时测定蔬菜中硝酸盐和水溶性草酸盐时,可直接用水提取;同时测定硝酸盐和总草酸盐含量时,选择含0.5 mol·L-1盐酸溶液2 mL的浸提液效果较好;采用IonPac AS11阴离子分析柱,抑制电导检测器,淋洗液为8 mmol·L-1氢氧化钠溶液,流速为1.0 mL·min-1,进样量为25 μL时,可有效分离和定量测定蔬菜中硝酸盐和草酸盐的含量,NO-3和C2O2-4的线性范围在20 mg·L-1以内,检出限分别为0.02,0.05 mg·L-1,相对标准偏差分别为1.8%,2.3%,硝酸盐和草酸盐的加标回收率在95.1%~103.2%,95.5%~103.6%之间.

In the extraction of nitrate and oxalate from samples of vegetables (i.e.,leaf mustard and shallot),pure water containg 2 mL of 0.5 mol ·L-1 HCl was found to be the most effective among the 3 extractants tested. In the ion chromatographic determination,the IonPac AS11 column was used as stationary phase,and 8 mmol·L-1 NaOH solution was used as mobile phase to elute the anions (NO-3 and C2O2-4) from the column in succession. Range of linearity was found within 20 mg·L-1 for both the anions,using 25 μL as the amount of sample introduced. Detection limits (3S/N) of the method found were 0.02 mg·L-1 (for NO-3) and 0.05 mg·L-1 (for oxalate). Precision was tested with mixed standard solutions of NO-3 and C2O2-4 at different concentrations by 10 replicate sample introductions,giving values of RSD′s of 1.8% for NO-3 and 2.3% for C2O2-4. Recovery of the method was tested,and the values of recovery found were ranged over 95.1%-103.2% for NO-3,and 95.5%-103.6% for C2O2-4.