State-of-the-Art on Ultra-Trace Analysis of Ultrapure Water

Ultrapure water is used in various areas such as pharmaceutical manufacturing, electric power generation, and the electronic industry. The types of noticeable impurities and required purity vary, too. Especially, purity for ultrapure water used in the semiconductor sector is so demanding as to be required to remove almost all impurities to the utmost limit. To evaluate the water quality of such ultrapure water, the sensitivity of online measuring equipment is not enough, and off-line analysis using more sensitive analysis equipment is necessary. Preconcentration techniques to increase the sensitivity and various contamination controls including from sampling to analysis are necessary in off-line analysis. Examples of measuring metal components and nonmetal components in ultrapure water for semiconductor at the ng L−1 to pg L−1 level by using these water-quality evaluation techniques are introduced.