Ion chromatography as candidate reference method for the determination of chloride in human serum

We developed an ion chromatography (IC) method for measurement of chloride in human serum which was regarded as a simple, rapid, accurate, and sensitive technique. The method will be hopefully selected as a candidate reference method.

Serum aliquots of 0.1 mL were diluted 500 times with Milli-Q water, and chloride in serum samples was measured by IC with a gradient elution procedure using a KOH eluent generator.

Based on the data, chloride in human serum was well detected by IC. The calibration curve for chloride was linear in the concentration range from 0 to 0.42 mmol/L with a correlation coefficient of .99995 under the optimum experimental conditions. The chloride concentration had a good linear relationship with the peak areas of chloride. This method was sensitive because of the low limit of detection (LOD) and the low limit of quantification (LOQ) 9.87 × 10^-5  mmol/L and 3.27 × 10^-4  mmol/L, respectively. Besides, the method was highly precise with the within-run coefficient of variations (CVs) for the measurement of low, medium, and high concentration level samples 0.32%, 0.73%, and 0.50%. As for the evaluation of accuracy, the biases were less than ±1% and 2% by comparing with National Institute of Science and Technology (NIST) standard material SRM 956d and 2013-2018 IFCC-RELA samples, respectively. Finally, the biases between IC method and the inductively coupled plasma mass spectrometry (ICP-MS) method were less than 1% which showed good agreement.

Ion chromatography is a simple sample treatment procedure for the determination of chloride in human serum with high sensitivity and specificity. The proposed method could be recommended as a candidate reference method for the determination of serum chloride in human serum.