title: A candidate reference method for serum potassium measurement by inductively coupled plasma mass spectrometry.
abstract: BACKGROUND
  Potassium is an important serum ion that is frequently assayed in clinical laboratories. Quality assurance requires reference methods; thus, the establishment of a candidate reference method for serum potassium measurements is important.
  
  
  METHODS
  An inductively coupled plasma mass spectrometry (ICP-MS) method was developed. Serum samples were gravimetrically spiked with an aluminum internal standard, digested with 69% ultrapure nitric acid, and diluted to the required concentration. The 39K/27Al ratios were measured by ICP-MS in hydrogen mode. The method was calibrated using 5% nitric acid matrix calibrators, and the calibration function was established using the bracketing method.
  
  
  RESULTS
  The correlation coefficients between the measured 39K/27Al ratios and the analyte concentration ratios were >0.9999. The coefficients of variation were 0.40%, 0.68%, and 0.22% for the three serum samples, and the analytical recovery was 99.8%. The accuracy of the measurement was also verified by measuring certified reference materials, SRM909b and SRM956b. Comparison with the ion selective electrode routine method and international inter-laboratory comparisons gave satisfied results.
  
  
  CONCLUSIONS
  The new ICP-MS method is specific, precise, simple, and low-cost, and it may be used as a candidate reference method for standardizing serum potassium measurements.
authors.affiliation: .
authors.forename: Ying
authors.initials: Y
authors.lastname: Yan
authors.affiliation: .
authors.forename: Bingqing
authors.initials: B
authors.lastname: Han
authors.affiliation: .
authors.forename: Jie
authors.initials: J
authors.lastname: Zeng
authors.affiliation: .
authors.forename: Weiyan
authors.initials: W
authors.lastname: Zhou
authors.affiliation: .
authors.forename: Tianjiao
authors.initials: T
authors.lastname: Zhang
authors.affiliation: .
authors.forename: Jiangtao
authors.initials: J
authors.lastname: Zhang
authors.affiliation: .
authors.forename: Wenxiang
authors.initials: W
authors.lastname: Chen
authors.affiliation: .
authors.forename: Chuanbao
authors.initials: C
authors.lastname: Zhang
mesh_terms: D006801:Humans; D007753:Laboratories / Q000592:standards; D013058:Mass Spectrometry / Q000379:methods* / Q000592:standards; D011188:Potassium / Q000097:blood* / Q000592:standards; D012015:Reference Standards; D015203:Reproducibility of Results
chemical_list: D011188:Potassium
keywords: aluminum; inductively coupled plasma mass spectrometry; potassium; reference method; serum