Method for determination of sodium, potassium, calcium, magnesium, chloride, and phosphate in the rat choroid plexus by flame atomic absorption and visible spectroscopy.

A rapid simple technique for the measurement of Na+, K+, Mg2+, Ca2+, PO4(3-), and Cl- was developed to analyze ion contents in the choroid plexus of the rat. The technique involves digestion in piperidine, precipitation of proteins with HClO4, and analysis of Na+, K+, Ca2+, and Mg2+ by atomic absorption spectroscopy and Cl- and PO4(3-) by visible spectroscopy. The coefficient of variation for the measurement of eight replicates was 1-3% for all ions. Analysis of choroid plexuses from eight rats yielded coefficients of variation of about 6% and the values for Na+, K+, and Cl- compared favorably to previous works. The analytical procedure described in this paper allows the determination of six major physiologic ions in rat choroid plexus (4 mg wet wt).