Speciation of the immediately mobilisable As(III), As(V), MMA and DMA in river sediments by high performance liquid chromatography–hydride generation–atomic fluorescence spectrometry following ultrasonic extraction
Speciation of the immediately mobilisable As(III), As(V), MMA and DMA in river sediments by high performance liquid chromatography–hydride generation–atomic fluorescence spectrometry following ultrasonic extraction
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DOI：
10.1016/j.aca.2004.11.025
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发表时间：
2005-04
影响因子：
6.2
通讯作者：
A. Huerga;I. Lavilla;C. Bendicho
中科院分区：
文献类型：
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作者：
A. Huerga;I. Lavilla;C. Bendicho
建立了聚焦超声萃取-氢化物发生-原子荧光检测法快速测定河流沉积物中As(III)、As(V)、MMA和DMA形态的方法。研究了流动相中甲醇用量、离子对试剂浓度、pH、流速等相关参数对等度洗脱后离子对色谱柱分离的影响。从超声探头发射的聚焦超声提供了与常规提取相同的可提取内容物，而不改变物种分布。考察了干燥步骤对砷形态提取的影响。比较了冷冻干燥、烘箱干燥、微波干燥和空气干燥四种干燥方法。干燥操作对水浸出物的影响不大。然而，与烘箱和微波炉相比，冷冻和风干产生的可提取磷酸盐的As(III)和As(V)量显著高于烘箱和微波。水溶态砷的检出限为1.3~4.1 ng/g，磷酸盐可交换态的检出限为1.6~4.8 ng/g。该方法被应用于沿Louro河(西班牙加利西亚南部)河床采集的11个沉积物样品中立即可移动As(III)、As(V)、DMA和MMA的形态分析。
In this work, a fast method is developed for the speciation of As(III), As(V), MMA and DMA in the immediately mobilisable fraction of river sediments (i.e. water-soluble and phosphate-exchangeable) by high performance liquid chromatography–hydride generation–atomic fluorescence detection (HPLC–HG–AFD) after extraction using focused ultrasound. The influence of relevant parameters influencing an ion-pairing chromatographic separation following isocratic elution (i.e. amount of MeOH in the mobile phase, ion pair reagent concentration, pH, flow rate) was studied. Focused ultrasound transmitted from an ultrasonic probe provided the same extractable contents as conventional extraction with no changes in the species distribution. The effect of the drying step over extraction of As species was investigated. The following drying procedures were compared: freeze-, oven-, microwave- and air-drying. No influence of the drying operation on the water-extractable fraction was observed. However, freeze- and air-drying yielded significantly higher phosphate-extractable amounts of As(III) and As(V) as compared to oven and microwaves. Detection limits for the As species were in the range 1.3–4.1ng/g for the water-soluble fraction and 1.6–4.8ng/g for the phosphate buffer exchangeable fraction. The method was applied to the speciation of immediately mobilisable As(III), As(V), DMA and MMA in 11 sediment samples collected along the beds of the Louro River (southern Galicia, Spain).