Measurement of trace potassium hexachloroplatinate concentrations in carboplatin by HPLC-ICP-MS with valve switching
High performance liquid chromatography (HPLC) coupled to an inductively coupled plasma mass spectrometry (ICP-MS) method with a valve switching modality was developed for determination of trace potassium hexachloroplatinate concentrations in carboplatin. Standard samples of carboplatin and potassium hexachloroplatinate were used to determine the retention time in the detector after separation in a PRP-X100 chromatography column and elution following an isogradient elution procedure with a moving phase of 50 mmol·L-1 dihydrogen phosphate and pH 5.5. For determining the concentration of potassium hexachloroplatinate by HPLC-ICP-MS, high concentration carboplatin was eluted via a four-way valve switching modality which was installed in series with HPLC and ICP-MS. The results showed that the linear range of potassium hexachloroplatinate was 1.0 ~ 100 µg·L-1, the detection limit (3S/N) was 0.1 µg·L-1, the recovery rate was 90.0 ~ 98.8%, and the relative standard deviations (n=6) were 2.7 ~ 3.4%. Overall, we found that the four-way valve switching system was practical for the determination of trace potassium hexachloroplatinate in carboplatin.