Ultrapure water blank for boron trace analysis

Weakly charged elements, or elements that are not well dissociated in water, are not removed ef®ciently by conventional water-puri®cation technologies. In the production of high-purity water, silica and boron are generally the ®rst ions to breakthrough into puri®ed water when the ion-exchange resin approaches depletion. In this study, the behavior of these two elements was studied through various steps in a water-puri®cation chain. An optimized system con®guration is proposed that combines reverse osmosis and electrodeionization technologies in the pre-treatment phase, and results in the ef®cient removal of boron. These initial puri®cation steps produce high-resistivity water, presenting a low ionic challenge to ultrapure polishing resins. In addition, a speci®c chelating adsorbent enhances the retention capacity of boron. Typical values achieved for the most important parameters assessed while producing ultrapure water are described.