Determination of lithium isotope ratio in aqueous solution—Multiple-collectors inductively coupled plasma mass spectrometry

This document specifies a multiple-collector inductively coupled plasma mass spectrometry method for determining lithium isotope ratios in aqueous solutions. It applies to surface water, groundwater, salt-lake brine, rainwater, and chemically treated solutions. Testing laboratories shall use cation-exchange resin to separate and purify samples; surface water, rainwater and groundwater require one purification, while seawater, salt-lake brine and chemically treated solutions require two. Instrumental fractionation shall be calibrated using standard-sample-standard bracketing, with simultaneous measurement of 6Li and 7Li ion currents and calculation of isotopic composition. Each batch shall include at least two certified reference materials and parallel samples representing no less than 10% of total samples. Blank signals, repeatability and trueness shall meet specified limits, and waste acids and hazardous reagent wastes shall be handled in accordance with relevant requirements.