Detection of trace metal ions in high-purity boric acid by online two-dimensional valve switching coupled with ion chromatography-inductively coupled plasma mass spectrometry

In this paper, a two-dimensional valve switching technique was established to detect 10 trace metal ions in high-purity boric acid by ion chromatography-inductively coupled plasma mass spectrometry (IC-ICPMS). The system consisted of a quantitative loop, a matrix capture column, an iminodiacetic acid cationic chelating column, an ion chromatography column, two sample valves and an inductively coupled plasma mass spectrometer. The iminodiacetic acid cationic chelating column coupled the metal ions in the sample with its carboxyl functional groups to separate them from the matrix boric acid solution, and then eluted the chelated metal ions into the ion chromatographic column and inductively coupled plasma mass spectrometer. The proposed method feasibly achieved an online, rapid and efficient detection of 10 trace ions in high-purity boric acid with the optimized experimental conditions (1.0 mol/L HNO3), such as loading solution, loading flow rate, type of eluent, concentration of the eluent, sample matrix, etc. The experimental data showed that this method had good linearity in the range of 0.01-2.0 mu g/L for 10 metal ions, such as Cr, Fe, Ni, Co, V, Mn, Cu, Zn, Cd and Pb in high-purity boric acid samples, with a correlation coefficient greater than 0.998. The limit of detection (LOD, S/N = 3) and the limit of quantitation (LOQ, S/N = 10) were 0.001-0.023 mu g/L and 0.003-0.077 mu g/L, respectively. The relative standard deviation (RSD) of each element was less than 3.0% (n = 6) and the spiked recoveries ranged between 83% and 110%. This method could be proposed to be suitable for determination of trace metal ions in real samples.