高级检索

    离子色谱法测定硝酸钠晶体中微量亚硝酸根的方法研究

    Study on the Determination of Traces of Nitrite Ion in Single Crystals of Sodium Nitrate by Ion Chromatography

    • 摘要: 为保持大尺寸硝酸钠单晶的优良性能,要求控制其微量杂质NO2-的含量在极低的浓度水平。因此亟需提供具有高实用性和强操作性的NO2-的测定方法。研究并提出了梯度淋洗-离子色谱法(A法)和阀切换-离子色谱法(B法)两种分离模式。取样品0.200 0 g溶于水中,定容至100.0 mL,经0.22 μm滤膜过滤,取滤液进行离子色谱分析。梯度淋洗中,在9 min以内用8 mmol·L-1 KOH溶液将NO2-从AS11-HC阴离子交换柱上洗脱,并用电导检测。随后用30 mmol·L-1 KOH溶液将交换柱上由样品而来的大量NO3-在较短时间内洗脱,从而避免其对下一样品分析的干扰。在阀切换中,利用仪器的六通阀与加装的十通阀之间的切换实现NO2-与其基体的高浓度NO3-之间的分离。方法采用峰面积积分方式计算测试结果。上述两种方法的线性范围均在0.10~2.00 mg·L-1之间,检出限(3S/N)为8×10-4%(A法)和5×10-4%(B法)。另取同一样品分别按两种方法进行6次平行测定,测定值的相对标准偏差(n=6)依次为4.2%,3.2%。另分别在6份样品的基础上加入NO2-标准溶液,按上述两种方法操作进行回收试验,测得回收率分别为92.5%~108%(A法)和95.5%~104%(B法),结果表明两种方法各有优缺点。

       

      Abstract: For keeping good optical property and its service life, it is necessary to restrict the content of NO2- in large sized single crystal of NaNO3 to a very low concentration, and hence it is of urgent importance to offer methods with high practicability and good serviceability for determination of trace amounts of NO2- in single crystals of sodium nitrate. Two ion chromatographic methods with different ways of separation of traces of NO2- and the matrix of NO3-, by gradient elution (mode A) and by value switching (mode B) were proposed. A portion of 0.200 0 g of the sample was taken and dissolved in water, and its volume was made up to 100.0 mL with water. After filtering through 0.22 μm filtering membrane, the filtrate was used for IC-analysis by either of the 2 modes. In mode A, 25 μL of the sample solution was passed through AS11-HC anion exchange column. The column was rinsed with 8 mmol·L-1 KOH solution at a flow-rate of 1.0 mL·min-1 within an interval of 9 min to elute NO3- from the column and the eluate was used for determination of NO2- with conductivity detector. Afterwards, the column was eluted with 30 mmol·L-1 KOH solution to remove macro amounts of NO3- as matrix of the sample from the column, thus to avoid interference of NO3- to NO2- in the next determination. In mode B, by switching of a 6-way valve of the instrument with an extra-10-way valve at definite time intervals, the separation of NO2- from NO3- of the matrix was attained. Method of integration of peak area was adopted in calculation of results of determination. Linear relationships between values of integration of peak areas and mass concentration of NO2- were found in the same range of 0.10-2.00 mg·L-1, and values of detection limits (3S/N) found were 8×10-4% for mode A and 5×10-4% for mode B. Tests for precision was carried out by 6 paralle determinations of a same sample for its NO2- contents, results of RSDs (n=6) found were 4.2% (for mode A) and 3.2% (for mode B). Recovery was tested by addition of standard solution of NO2- to 6 NaNO3 single crystal samples and their contents of NO2- were determined by the proposed methods, giving values of recovery in the ranges of 92.5%-108% (for mode A) and 95.5%-104% (for mode B). It was shown that 2 modes in the method of IC determination of NO2- proposed in this paper have their own virtues and defects.

       

    /

    返回文章
    返回