勞工作業環境中三價砷及五價砷同步分析方法之開發

Simultaneous Determination of As(III) and As(V) with Reversed-Phase High-Perfromance Liquid Chromatography and Indirect UV Detection

本研究在於發展以高效率液相層析術搭配紫外光偵測器（HPLC-UV）同步分析水中砷物種的方法。研究中以Hexadecyltrimethylammonium （（C16H33（CH3）3）N+）流洗靜相使四級銨吸附在靜相表面，將靜相表面調整成帶正電的狀態，而砷物種（Arsenit, Arsenat, Phenyl arsenic acid, Aminophenylarsonic acid）以陰離子形式系統中，所以砷物種便能以類離子交換模式在管柱內進行滯留依不同之作用力而沖提分離；研究中因無機砷物種並無適當紫外光吸收峰，故以KHP（Potassium Hydrogen Phthalate）為光吸收劑，以間接偵測法對砷物種進行偵測，偵測波長設定為280 nm。本研究對層析分之最佳條件進行探討，包括偵測波長之選擇、光吸收劑濃度、TRIS buffer的濃度及有機修飾劑，結果顯示在進行分析時應配置含光吸收劑（KHP）1.0 mM及20 mM TRIS buffer的沖提液，將流速調整為1ml/min，對砷物種進行分離。為了提高系統的穩定性，分離時將管柱溫度維持於30.0度C。在此條件下，砷物種濃度約在1~100 ppm之間，積分面積與注入量有良好之線性關係，其線性相關係數（r）約可達0.9999，偵測極限則為2ng以下，相對標準偏差（R.S.D.）均小於3.3%。

Speciation analysis of trace elements is very important in the area of environment, clinic and biological researches because of the unique biochemical roles of these species. Some of species are considered to be essential elements in nutrition, and some were reported as carcinogen. Arsenic is one of the most widely measured trace metals because of its toxicity and possible carcinogenicity, it generally occurs in the oxidation states as As(III) and As(V). Biologically, As(III) is considered more toxic than As(V). In order to get a better understanding of the arsenic toxicity in working environment; analytical methods capable of measuring As(III) and As(V) are necessary for studying the chemistry of arsenic species. A liquid chromatographic method with UV detection for the simultaneous determination of As(III) and As(V) in work environment was developed. A reversed phase polymer (polystyrene-divinylbenzene) column codified with an eluent containing TRIS buffer. The separated species were monitored at 280 nm with the potassium hydrogen biphthalate as the probe added in the eluent for indirect detection. Factors affecting the chromatographic behavior and possible interferences as well as the recovery and stability of species were investigated. The proposed LC-UV detection method provides a simple procedure for the determination of arsenic speciation. The detection limits were 2.0 ng for both with a 20-μl injection. The relative standard deviations for As(III) and As(V) were below 3.30% (n=7).