Detection and Chemical Analysis of High Purity Water

To establish a database to determine whether selected chemicals, not included in the NCCLS standards, could be detected in point-of-use water treatment systems (POUs), we analyzed water samples collected from 50 POUs following service maintenance. These samples were first analyzed for compliance with NCCLS standards for reagent grade water. A spectrophotometer was then used to analyze product water samples for detectable levels of free and total Cl, ClO₂, Cr, Cu, Fe, Mn, NO₃, SO₄ and Si. The following percentages of water systems had detectable levels chemicals (according to water type). For Type I water, free Cl was found in 89%, total Cl, 50%; ClO₂, 11%; Cr, 28%; Cu, 78%; Fe, 33%; Mn, 22%; NO₃, 89%, Si, 83%; and SO₄, 17%. For Type II water, free Cl was found in 71 %, total Cl, 50%; ClO₂, 21%; Cr, 29%; Cu, 63%; Fe, 25%; Mn, 4%; NO₃, 54%; and Si, 75%. For Type III water; 63% of the product water samples analyzed had detectable levels of both free and total Cl; 88% Cr and Si; 38% Cu and NO₃; and 13%, Fe. These findings illustrate that in many cases selected chemicals are not completely retained during the purification process and that a portion may pass from source water to product water.