Measurement of cations, anions, and acetate in serum, urine, cerebrospinal fluid, and tissue by ion chromatography

Accurate quantification of cations and anions remains a major diagnostic tool in understanding diseased states. The current technologies used for these analyses are either unable to quantify all ions due to sample size/volume, instrument setup/method, or are only able to measure ion concentrations from one physiological sample (liquid or solid). Herein, we adapted a common analytical chemistry technique, ion chromatography and applied it to measure the concentration of cations; sodium, potassium, calcium, and magnesium (Na+, K+, Ca2+, and Mg2+) and anions; chloride, and acetate (Cl-, -OAc) from physiological samples. Specifically, cations and anions were measured in liquid samples: serum, urine, and cerebrospinal fluid, as well as tissue samples: liver, cortex, hypothalamus, and amygdala. Serum concentrations of Na+, K+, Ca2+, Mg2+, Cl (-), and -OAc (mmol/L): 138.8 +/- 4.56, 4.05 +/- 0.21, 4.07 +/- 0.26, 0.98 +/- 0.05, 97.7 +/- 3.42, and 0.23 +/- 0.04, respectively. Cerebrospinal fluid concentrations of Na+, K+, Ca2+, Mg2+, Cl-, and -OAc (mmol/L): 145.1 +/- 2.81, 2.41 +/- 0.26, 2.18 +/- 0.38, 1.04 +/- 0.11, 120.2 +/- 3.75, 0.21 +/- 0.05, respectively. Tissue Na+, K+, Ca2+, Mg2+, Cl-, and -OAc were also measured. Validation of the ion chromatography method was established by comparing chloride concentration between ion chromatography with a known method using an ion selective chloride electrode. These results indicate that ion chromatography is a suitable method for the measurement of cations and anions, including acetate from various physiological samples.