Development of a Simple Monitoring Device for Ultra-Trace Silicate lon in Quality Control High-Purity Water Used in Semiconductor Production.

本计画的目的是发展一种简易的流动预浓缩-分光光度法检测装置，以定量测定高纯水中的超痕量（亚ppb至ppb）硅酸根离子。其基本思想和基本化学过程是：1.硅酸根离子被转化为蓝硅酸根，蓝硅酸根在830 nm处的近红外区有最大吸收。因此，可以设计出一种基于光半导体（如LED和光电二极管（PD））的廉价检测器。2.阴离子型硅酸盐蓝作为离子对吸附在纤维素类材料上，与大的有机阳离子形成离子对，该阳离子很容易被某些有机溶剂解吸（洗脱）。优化后的系统由两个分别用于进样和洗脱的泵单元和一个填充无灰矿浆的短柱（4cm）组成。将30 ml钼硅蓝溶液与辛基三甲基铵离子形成离子对，经无灰矿浆柱富集后，用80wt%的乙腈-水溶液洗脱至波长为830 nm的LED-PD检测器。

The aim of this project is to develop a simple monitoring device for quantitation of ultra-trace (sub-ppb to ppb) silicate ion in high-purity water using flow preconcentration-spectrophotometric detection system. The basic ideas and the underlying chemistry are :1.Silicate ion is converted to molybdosilicate blue which has the absorption maximum in near infrared region, at 830nm. Thus, one can devise a cheap detector based on the optosemiconductors, such as LEDs and photodiodes (PD).2.Anionic molybdosilicate blue is adsorbed on cellulose-type materials as the ion-pair with a large organic cation which is very readily desorbed (eluted) with certain organic solvents. These leads the high-performance flow preconcentration systems.The optimized system consists of two pump units for sampling and elution, respectively, and a short column (4 cm) packed with ashless pulp. Molybdosilicate blue in 30 ml is concentrated on the ashless pulp column as an ion-pair with octyltrimethyl ammonium ion and the ion-pair is eluted with 80 wt% acetonitrile-water mixture down to the LED-PD detector operated at 830nm.In order to ensure the practical capability, the prototype equipment is now under field testing in some semiconductor production manufacturers and electric power plants.