Determination of Na and K in the rat lens by atomic absorption spectrophotometry

A new procedure is described for determination of sodium and potassium in rat lenses with atomic absorption spectrophotometry. Samples were prepared by soaking of the ground or the intact lens in deionized water. For potassium determinations HNO3 dissolution was also tried. Deionized water or CsCl aqueous solution was adopted for dilution for measurement. At absorbances up to 1.0 absorbance unit only measurements on HNO3 dissolved lenses diluted in deionized water were compatible with a linear absorbance function. At absorbances below 0.2-0.3 absorbance units all combinations were in agreement with a linear absorbance function. Grinding of the lens was found to increase the variability but did not change the level. HNO3 dissolution did not increase the level. Dilution with CsCl increased the sensitivity and decreased the variability. A schedule is proposed for determination of sodium and potassium in which lens samples are obtained by soaking in deionized water. Aqueous solution of CsCl is suggested for dilution.