Flame atomic absorption spectrometric determination of serum zinc: collaborative study

A method for determining serum zinc concentrations was collaboratively studied by 9 laboratories. Serum samples in polypropylene tubes are directly diluted with 0.03% Brij 35, and zinc is determined by flame atomic absorption spectrophotometry (AAS). A certified standard reference material serves as an external control. Repeatability relative standard deviations (RSDr) were 1.2 and 11.4% and reproducibility relative standard deviations (RSDR) were 6.1 and 12.9% for serum zinc concentrations of 6.36 and 0.63 micrograms/mL, respectively. The method has been approved interim official first action by AOAC.