一种使用透明膜和可见光谱法检测水中痕量磷酸盐和砷酸盐的无溶剂方法。

A solventless method for detecting trace level phosphate and arsenate in water using a transparent membrane and visible spectroscopy.

机构信息

Department of Chemistry, University of Maine, 154, Aubert Hall, Orono, ME, 04469, USA; Frontier Institute for Research in Sensor Technologies (FIRST), University of Maine, Engineering Science Research Building, 5708 ESRB-Barrows Hall, Orono, ME, 04469, USA.

出版信息

Talanta. 2021 Apr 1;225:122023. doi: 10.1016/j.talanta.2020.122023. Epub 2021 Jan 6.

DOI:10.1016/j.talanta.2020.122023

PMID:33592753

Abstract

The molybdenum blue method is the American Public Health Association (APHA) approved method for the detection and quantification of phosphate in water. The standard molybdenum blue method, APHA 4500 PE has a detection limit of 30 μgL phosphate (10 μgL phosphorus) in freshwater with a 5 cm cuvette. To further lower the detection limit to sub μgL levels, we have developed a simple, fast, and solventless method for conversion of phosphate present in solution to a solid for quantification by Visible spectroscopy. The process converts the anionic heteropolymolybdate ions into a solid colloidal precipitate by charge neutralization with the cationic surfactant cetyltrimethylammonium bromide (CTAB), and the precipitate is then captured on a Visible transparent membrane. A Visible spectrum is then recorded in transmission mode through the membrane and the concentration of the phosphate is determined from the intensity of a band cantered at 700 nm. Using this method, the detection limit for phosphate in water is lowered to 0.64 μgL. The approach has also been extended to detect arsenate in water with a detection limit of 4.8 μgL arsenate. . The method is also used to investigate real matrices with accuracy that matches the standard APHA method for detection of phosphate in water.

摘要

钼蓝法是美国公共卫生协会（APHA）认可的水中磷酸盐检测和定量方法。标准钼蓝法，APHA 4500 PE 在 5cm 比色皿中，淡水的检测限为 30μg/L 磷酸盐（10μg/L 磷）。为了进一步将检测限降低到亚μg/L 水平，我们开发了一种简单、快速且无溶剂的方法，用于将溶液中存在的磷酸盐转化为固体，以便通过可见光谱进行定量。该过程通过带正电荷的阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）的电荷中和作用，将阴离子杂多钼酸盐离子转化为胶体沉淀，然后将沉淀捕获在可见透明膜上。然后通过膜以透射模式记录可见光谱，并根据位于 700nm 处的带的强度来确定磷酸盐的浓度。使用这种方法，水中磷酸盐的检测限降低至 0.64μg/L。该方法还扩展到检测水中的砷酸盐，检测限为 4.8μg/L 砷酸盐。该方法还用于研究真实基质，其准确度与 APHA 标准方法检测水中磷酸盐的准确度相匹配。