Segura Marta, Muñoz Juan, Madrid Yolanda, Cámara Carmen
Departamento de Química Analítica, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid, Spain.
Anal Bioanal Chem. 2002 Oct;374(3):513-9. doi: 10.1007/s00216-002-1492-7. Epub 2002 Sep 10.
The stability of arsenic species (arsenate [As(V)], monomethylarsonate [MMA], dimethylarsinate [DMA] and arsenite [As(III)]) in two types of urban wastewater samples (raw and treated) was evaluated. Water samples containing a mixture of the different arsenic species were stored in the absence of light at three different temperatures: +4 degrees C, +20 degrees C and +40 degrees C. At regular time intervals, arsenic species were determined by high performance liquid chromatography (HPLC)-hydride generation (HG)-atomic fluorescence spectrometry (AFS). The experimental conditions for the separation of arsenic species by HPLC and their determination by AFS were directly optimised from wastewater samples. As(III), As(V), MMA and DMA were separated on an anion exchange column using phosphate buffer (pH 6.0) as the mobile phase. Under these conditions the four arsenic species were separated in less than 10 min. The detection limits were 0.6, 0.9, 0.9 and 1.8 micro g L(-1) for As(III), DMA, MMA and As(V), respectively. As(V), MMA and DMA were found stable in the two types of urban wastewater samples over the 4-month period at the three different temperatures tested, while the concentration of As(III) in raw wastewater sample decreased after 2 weeks of storage. A greater stability of As(III) was found in the treated urban wastewater sample. As(III) remained unaltered in this matrix at pH 7.27 over the period studied, while at lower pH (1.6) losses of As(III) were detected after 1 month of storage. The results show that the decrease in As(III) concentration with time was accompanied by an increase in As(V) concentration.
评估了两种城市废水样本（原水和处理后水）中砷形态（砷酸盐[As(V)]、一甲基砷酸盐[MMA]、二甲基砷酸盐[DMA]和亚砷酸盐[As(III)]）的稳定性。将含有不同砷形态混合物的水样在无光条件下于三种不同温度（+4℃、+20℃和+40℃）下储存。定期通过高效液相色谱（HPLC）-氢化物发生（HG）-原子荧光光谱法（AFS）测定砷形态。直接从废水样本中优化了通过HPLC分离砷形态及其通过AFS测定的实验条件。使用磷酸盐缓冲液（pH 6.0）作为流动相，在阴离子交换柱上分离As(III)、As(V)、MMA和DMA。在这些条件下，四种砷形态在不到10分钟内分离。As(III)、DMA、MMA和As(V)的检测限分别为0.6、0.9、0.9和1.8μg L⁻¹。在测试的三种不同温度下，经过4个月，As(V)、MMA和DMA在两种城市废水样本中均保持稳定，而原废水样本中As(III)的浓度在储存2周后下降。在处理后的城市废水样本中发现As(III)具有更高的稳定性。在所研究的时间段内，在该基质中pH 7.27时As(III)保持不变，而在较低pH（1.6）下，储存1个月后检测到As(III)有损失。结果表明，As(III)浓度随时间的降低伴随着As(V)浓度的增加。
