ICP-MS method development and validation for determination of trace elemental impurities in caustic potash

Abstract

ICP-MS method is developed and validated for quantification of trace elemental impurities in caustic potash. Employment of suitable system configuration and optimization of operational parameters was done. Argon Gas Dilution (AGD) kit was employed in this method and metal ions analyzed by employing this method include 208Pb, 111Cd, 107Ag, 88Sr, 64Zn, 63Cu, 59Co, 58Ni, 57Fe, 55Mn and 52Cr. Under normal/routine configuration (without AGD kit), ICP-MS instrument can handle solution having dissolved solids up to 0.2% and is susceptible to compromise with low detection limits. In this work, 1% KOH solution is aspirated post its neutralization by high pure grade HNO3 using AGD kit. It addresses issues of high dissolved solids and high alkalinity. External calibration with internal standards (Sc, Y, Gd) is performed with the matrix of KNO3 since neutralization of KOH by HNO3 forms KNO3. A detailed study of the key features related to the method development such as matrix-matching, accuracy and precision was done.