直接进样测定车用尿素溶液中微量钾

DIRECT INJECTION DETERMINATION OF THE TRACE K^+ IN AUTOMOBILE UREA SOLUTION BY ION CHROMATOGRAPHY

采用离子色谱法直接进样分析了车用尿素溶液中微量钾离子,常规色谱柱不能满足要求,选用Metrosep C3-250色谱柱,5mmol/L硝酸为淋洗液,非抑制电导模式和选择IonPacCS17色谱柱,甲烷磺酸为淋洗液,梯度淋洗,外接水抑制电导模式,均可以直接进样分析车用尿素溶液中的K^+。抑制测定方法和非抑制测定方法检出限分别为0.0025 mg/L和0.0073 mg/L,定量限分别为0.004 2 mg/L和0.012 mg/L,满足ISO22241标准中K^+分析要求,具有无试剂干扰,操作简便的特点。

A confirmative method was developed with the help of ion chromatography direct injection to determine traces of potassium ion in automobile urea. The common chromatographic column could not meet the need of direct analysis in this case. Instead there are two other choices, namely Metrosep C3-250 chromatographic column with 5 mmol/L nitric acid as elution in the ＂non-suppressed conductance detection mode＂ and IonPac CS17 chromatographic column with gradient elution of methanesulfonic acid in the ＂external water-regeneration suppressed conductance detection mode＂. Both allows direct injection analysis of traces of potassium ion in the automobile urea. When it is applied to actual samples, this direct injection method using non-suppressed mode or suppressed mode could completely satisfy the demands regarding potassium analysis of ISO 22241, with the detection limits of O. 002 5 mg/L and O. 007 3 mg/L, while the limits of the quantification could be O. 004 2 mg/L and O. 012 mg/ L, respectively, avoiding the reagent interference and complex operations at the same time.