高效液相色谱-电感耦合等离子体质谱法测定水中砷形态

Determination of Arsenic Species in Water by High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry

基于自研高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)仪,建立了测定地表水与废水中4种砷形态,包括三价砷[As(Ⅲ)]、二甲基砷(DMA)、一甲基砷(MMA)和五价砷[As(Ⅴ)]含量的方法。水样经0.45μm滤膜过滤后,用Agilent G3154-65001色谱柱为固定相进行吸附,以NaH_(2)PO_(3)-Na2EDTA溶液(pH 6)为流动相进行等度洗脱,分离后的目标物用ICP-MS测定,用碰撞反应模式来消除75ArCl+对75As的干扰。结果表明:三价砷、二甲基砷、一甲基砷和五价砷等4种砷形态可在7 min内完成出峰,其质量浓度均在0.1-10.0μg·L^(-1)内与其对应的信号值呈线性关系,检出限(3.143s)分别为0.34,0.18,0.11,0.17μg·L^(-1)。对实际样品进行加标回收试验,回收率为91.8%-110%,测定值的相对标准偏差(n=6)小于6.0%。在2种水样中检出了五价砷,其均低于GB 3838-2002规定的限值(50μg·L^(-1))。将本方法同相关文献方法进行比对,方法验证结果基本处于同一水平。

A method for determination of 4 arsenic species, including, As(Ⅲ), DMA, MMA and As(Ⅴ), in surface water and sewage was developed based on self-developed combined instrument of high performance liquid chromatography(HPLC)-inductively coupled plasma mass spectrometry(ICP-MS). Sample of water was filtered by 0.45 μm filter membrane, and the 4 arsenic species were adsorbed with Agilent G3154-65001 chromatographic column as stationary phase, and eluted isocratically by a mixture solution(pH 6) composed of NaH_(2)PO_(3) and Na2EDTA as mobile phase. Targets obtained were detected by ICP-MS, and the collision reaction mode was used to eliminate the interference of 75ArCl+ to 75As. The results showed that As(Ⅲ), DMA, MMA and As(Ⅴ) could be separated within 7 min, and linearity ralationships between mass concentrations of 4 arsenic species response values were kept in the same range of 0.1-10.0 μg·L^(-1), with detection limits(3.143s) of 0.34, 0.18, 0.11, 0.17 μg·L^(-1), respectively. Test for recovery was made by standard addition method on actual samples, giving values of recovery in the range of 91.8%-110% and RSDs of the determined values less than 6.0%. As(Ⅴ) was detected in 2 water samples, and its content was lower than the limit(50 μg·L^(-1)) of GB 3838-2002. The proposed method was compared with related reference methods, and results of mtehod verification were basically at the same level.