二维离子色谱法测定海水中的铵离子

Determination of Ammonium in Seawater by Two-Dimensional Ion Chromatography

研究了二维离子色谱测定海水中铵离子的方法.海水样品经10 倍稀释,-维色谱采用高容量的CS–165mm 柱,以30 mmol/L 甲磺酸溶液等度淋洗,流量为1mL/min,进样25μL,CSRS–3004mm 抑制电导分离Na＋,NH4＋ ;二维色谱采用CS–12A4mm 柱,以8mmol/L 甲磺酸溶液等度淋洗,流量为1mL/min,以1300μL 定量环进样,SC–CSRS–300 盐转换器抑制电导检测NH4＋.结果表明色谱峰面积与NH4＋ 质量浓度线性相关,相关系数为0.999 9.10μg/L 标准溶液测定结果的相对标准偏差为2.7%（n=7）,NH4＋ 的方法检出限和仪器检出限分别为0.42,0.05μg/L,海水中NH4＋ 加标回收率为80.8%～105.8%.

A two-dimensional ion chromatography was developed for determination of ammonium in seawater samples.Seawater samples was injected using 25 μL sample loop after being diluted 10 times,the first-dimensional approach utilizingwas a CS–165mm column and a CSRS–3004mm suppressor,30mmol/L MSA soloution isocratic eluent was selectedfor the separation of Na＋,NH4＋ with 1 mL/min flow rate. The second-dimensional approach utilizing was a CS–12A 4mmand a SC–CSRS–300salt converter,8 mmol/L MSA solution for the isocratic eluent with 1 mL/min,using 1 300 μL loop,determination of NH4＋ by conductivity detector. The results showed that the peak area was linearly correlated with the massconcentration of NH4＋ and the correlation coefficient was 0.999 9. The relative standard deviation of 10 μg/L standard solutionwas 2.7% （n=7）. The method detection limit （MDL） was 0.42 μg/L and limit of detection （LOD,S/N =3） was 0.05 μg/L.The recoveries of seawater samples were 80.8%–105.8%.