Determination of cadmium in urine by graphite-furnace atomic absorption spectroscopy

A simple procedure for graphite-furnace atomic absorption analysis of cadmium in urine, based on the use of a temperature-controlled heating unit, is described. The temperature of the carbon rod is measured by resistance and controlled by electronic feedback. We studied the influence of various heating times and temperatures of ashing and atomization, as well as suitable diluents. Urine samples were diluted with an equal volume of 0.3 mol/liter HNO3, and 1 to 5 microliter of the mixture was analyzed, with background correction. Signals were evaluated electronically, giving values for integrated peaks as well as for peak heights. The detection limit was 1.2 nmol/liter. The method appears to be accurate and reproducible. The CV averaged 8% for concentrations in the range 20 to 100 nmol/liter. Correlations with a chelation-extraction method was 0.994.

Blood lead determination by flameless atomic absorption spectroscopy

A simple procedure for flameless atomic absorption analysis of lead in blood is described. It is based on the use of a temperature-controlled heating unit, which, with a photodiode, measures and, by electronic feedback, controls the temperature of the carbon rod. Examination of the influence of various heating has been made. Blood samples with heparin were diluted with Triton X-100, HNO3 added, and 2 microliter of the mixture analysed. Automatic background correction was used. Signals were evaluated by an electronic facility which gives integrated as well as peak height values. The method appears to be accurate and reproducible. The C.V. was, on average, 4%.

High-speed automated atomic absorption spectrophotometry

We describe an integrated automated system for the atomic absorption spectrophotometer. The system makes use of a light-dependent resistor to detect the presence of a marker ion which is present along with the sample ion in the flame. An electronic circuit has been developed which enables the marker ion to trigger the read signal of the spectrophotometer. The system has been tested by determining magnesium and calcium in serum. Alternative modes of operation and different potential applications are discussed.

A study of methods for the determination of lead and cadmium

This paper describes laboratory comparisons of precision and accuracy of some widely used methods for the determination of lead in blood and for lead and cadmium on filters. With the exception of the tantalum boat atomic absorption technique, the methods studied were found to be rugged for a variety of minor procedural changes. Recovery of cadmium from spiked filters was quantitative over a wide range of dilutions and for a variety of instrumental readout and calculation combinations.

Comparison of serum calcium measurements with respect to five models of atomic absorption spectrometers using NBS-AACC calcium reference method and isotope-dilution mass spectrometry as the definitive method

Utilizing the recently described reference method for calcium (NBS-AACC) and the recently developed definitive (referee) NBS method for serum calcium measurement by isotopedilution mass spectrometry (IDMS), an evaluation of five recent-model atomic absorption spectrometers was carried out. Under optimal conditions of instrument operation using aqueous standards, significant differences were found during the comparative analyses of three lyophilized pool samples and one liquid serum pool sample. Use of the NBS-AACC serum calcium protocol did not guarantee analytic results within +/- 2% of the IDMS value. In four of eight comparisons, differences from IDMS greater than 2% were observed. Several variables were studied to account for these differences. It was shown that a serum matrix, when present in standards used to bracket the unknown sample, reduced differences between instruments in four of four instances and improved the accuracy of the results from a range of -1.1 to +3.5% to +0.1 to +1.0%. It is concluded that a serum sample with a verified IDMS calcium value is a valuable tool that establishes an accurate and stable reference point for serum calcium measurement. The use of transfer-of-NBS-technology multipliers is suggested. Regional quality control serum pools and clinical chemistry survey sample materials that have been analyzed for calcium concentration by the NBS-IDMS definitive method are examples of these multipliers.