Determination of copper in urine by graphite furnace atomic absorption spectrometry

Direct determination of copper in urine using a sol–gel optical sensor coupled to a multicommutated flow system

In this work, a multicommutated flow system incorporating a sol-gel optical sensor is proposed for direct spectrophotometric determination of Cu(II) in urine. The optical sensor was developed by physical entrapment of 4-(2-pyridylazo)resorcinol (PAR) in sol-gel thin films by means of a base-catalysed process. The immobilised PAR formed a red 2:1 complex with Cu(II) with maximum absorbance at 500 nm. Optical transduction was based on a dual-colour light-emitting diode (LED) (green/red) light source and a photodiode detector. The sensor had optimum response and good selectivity towards Cu(II) at pH 7.0 and its regeneration was accomplished with picolinic acid. Linear response was obtained for Cu(II) concentrations between 5.0 and 80.0 microg L(-1), with a detection limit of 3.0 microg L(-1) and sampling frequency of 14 samples h(-1). Interference from foreign ions was studied at a 10:1 ( w/ w) ion:Cu(II) ratio. Results obtained from analysis of urine samples were in very good agreement with those obtained by inductively coupled plasma mass spectrometry (ICP-MS); there was no significant differences at a confidence level of 95%.

Re-evaluation of the "week-end effect" data: possible role of urinary copper and phosphorus in the pathogenesis of renal calculi

Early morning urinary concentrations of 10 elements which had demonstrated a "week-end effect" in a previous study, were subjected to a normalization procedure thereby allowing a re-assessment of their potential role in urolithiasis. After transformation of each concentration to a weighted proportion of the total concentration on each day, only Cu and P values were significantly different for kidney stone formers and healthy controls on all three days indicating that these elements may play a role in the pathogenesis of renal calculi. The results obtained in this study demonstrate that a more meaningful picture of the possible differences in the urinary concentrations of stone formers and normal controls might emerge if "proportional" rather than "raw" concentrations are compared.

Measurement of copper, zinc and magnesium in serum and urine by DC plasma emission spectrometry

The application of a DC plasma emission spectrometer to the measurement of copper, zinc and magnesium in serum and urine is reported. Each assay requires only a simple dilution in 1% nitric acid. Comparisons with standard atomic absorption techniques showed good analytical agreement, especially for copper and magnesium. Analysis of quality control preparations for copper and zinc gave results ranging from -1.5% to +3.6% of the stated values for five copper and four zinc experiments, with an unexplained result of +7.6% for one zinc experiment. Reference ranges were compiled for serum zinc and urinary copper which agreed closely with those established by atomic absorption and neutron activation analysis. Assays by DC plasma emission are thus precise and reproducible, and simple enough to authenticate the method for use in a clinical laboratory.

Disturbed metabolism of copper and zinc in aspartylglycosaminuria: possible involvement with connective tissue changes

In aspartylglycosaminuria (AGU), a lysosomal storage disorder of glycoprotein degradation, there are some abnormalities in collagen and proteoglycan metabolism. Because of earlier observations suggesting a disturbance of copper balance, the metabolism of copper and zinc was studied in more detail to find out if possible trace metal disturbances could be correlated with connective tissue disorder. Highly elevated copper concentrations in the hair and significantly reduced zinc levels in serum and urine were detected in AGU patients indicating a disturbance of trace element balance. However, the patients had normal serum copper levels, and the concentrations of zinc and copper in cultured fibroblasts did not differ from those of control cells. Normal lysyl oxidase activities in cell culture indicate that collagen cross-link formation is not affected. The changes in copper and zinc balance are probably secondary to the basic enzyme deficiency, and may contribute to the development of the clinical signs and symptoms of AGU although the mechanisms involved are not yet understood.

Analytical approaches for biomedical elemental analysis

Several different analytical systems are available for biomedical elemental analysis related to human nutrition. The principle, detection limits, analytical artifacts, and applications are presented for the following analytical systems for elemental analysis classified by sample volume: macro volume systems--flame atomic absorption spectroscopy (FAAS) and inductively coupled plasma (ICP); micro volume systems--electrothermal atomization (graphite furnace) atomic absorption spectroscopy (ETA-AAS) and x-ray fluorescence (XRF); and ultramicro volume systems--electron probe x-ray microanalysis (EPX) and laser microprobe mass analysis (LAMMA).

Trace elements in human body fluids and tissues

Published figures for trace element concentrations in body fluids and tissues of apparently healthy subjects are widely divergent. For a considerable time, the apparent disparities were readily ascribed to biological sources of variation such as age, sex, dietary habits, physiological conditions, environmental exposure, geographical circumstances, or similar influences. Growing evidence, however, suggests that this interpretation may be seriously questioned in numerous instances. First, values obtained in reference materials leave no doubt that some previous studies must have been subject to gross analytical inaccuracies. Second, it has now been thoroughly documented that inadequate sample collection and manipulation may drastically distort the intrinsic trace element content of biological matrices. This review scrutinizes data reported by a number of investigators. In an effort to settle the currently flourishing confusion, critically selected reference values are set forth for trace element levels in human blood plasma or serum, packed blood cells, urine, lung, liver, kidney, and skeletal muscle tissue.