Zinc Determined in 1O-/2L Serum or Urine Samples by Flameless Atomic Absorption Spectrometry

spectrometricmethod requiring only 10 tL ofsample, which thus permits repeated measurements in the neo-nate. Standard curves covering the range of 0 to 30 mg of zinc per liter, with standards in various matrixes (albumin, glycerol, serum, or nitric acid) hadslopesrangingfrom 0.49 to1.17, relativetothatforaqueousstandards.We prepared low-zinc matrixes, which had slopes similar to that of serum, by dialyzing serum or a 50 gIL solution of albumin vs a buffered zinc-free dialysis fluid containing appropriate inorganic constituents. Use of thoroughly de-ionized water, reagent-grade chemicals, “ultrapure” nitric acid, specified disposable plastic ware, and appro-priate pipet tip-rinsing techniques minimized extraneous contaminationwith zinc. Concentrations of zinc in serum calculated froma “rational-method”calibrationalgorithm fit tothestandardcurveagreedwellwith independent determinations by flame atomic absorption spectrom-etry. AddItIonal Keyphrases: albumin, glycerol, serum, and nitric acid matrixes compared neonatal chemsstiy. variation, source of. nutritional status. trace elements. ref-erence intervals Information concerning the concentration of zinc in body fluids has become increasingly important because the role of zinc in both normal and abnormal growth and development is better recognized. In addition, oral and parenteral dietary supplements that include zinc are being used more frequently in sick and undernourished patients, including premature infants. In the case of newborns, the current sample volumes required for analysis may produce hematological problems for the patient, which discourages measurements at appro-priately frequent intervals to monitor mineral status and nutritional adequacy. The high sensitivity and specificity of flameless atomic absorption spectrometry permitted us to develop a convenient and reliable technique for measuring zinc in 10 sL of sample