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利用离子色谱仪,对柠檬酸、柠檬酸钠中的痕量F~-、Cl~-、SO_4~(2-)、C_2O_4~(2-)等进行测定,采用DIONEX ION PAC ASll-HC分离柱,以电导检测器检测,对淋洗分离条件进行了试验。选择NaOH作淋洗液,0.025～0.050mol/L NaOH做梯度淋洗,可使F~-、Cl~-、SO_4~(2-)、C_2O_4~(2-)等很好地分离,其中Cl~-在0.01～200mg/L,F~-在0.05～200mg/L,SO_4~(2-)在0.05～200mg/L,C~2O_4~(2-)在0.1～200mg/L范围内,浓度和响应值有良好的线性关系,检出限分别为F~-0.01mg/L、Cl~-0.01mg/L、SO_4~(2-)0.03mg/L、C_2O_4~(2-)0.03mg/L,回收率为90％～110％。该方法无需前处理,无基体干扰,可用于柠檬酸、柠檬酸钠中F~-、Cl~-、SO_4~(2-)、C_2O_4~(2-)的测定。
The contents of trace F ~ -, Cl ~ -, SO_4 ~ (2 -) and C_2O_4 ~ (2-) in citric acid and sodium citrate were determined by ion chromatography. The separation was performed on a DIONEX ION PAC AS11-HC column , With conductivity detector detection, the conditions of the eluent separation were tested. When NaOH is selected as the eluent and gradient elution is carried out with 0.025-0.050 mol / L NaOH, F ~ -, Cl ~ -, SO_4 ~ (2 -) and C_2O_4 ~ ~ - in the range of 0.01 ~ 200mg / L, F ~ - 0.05 ~ 200mg / L, SO_4 ~ (2-) in the range of 0.05 ~ 200mg / L and C ~ 2O_4 ~ (2-) in the range of 0.1 ~ 200mg / The detection limits were respectively F ~ -0.01mg / L, Cl ~ -0.01mg / L, SO_4 ~ (2-) 0.03mg / L, C_2O_4 ~ (2-) 0.03mg / L, the recovery rate of 90% to 110%. The method can be used for the determination of F ~ -, Cl ~ -, SO_4 ~ (2 -) and C_2O_4 ~ (2) in citric acid and sodium citrate without any pretreatment or matrix interference.