Trace elements in urine

Simultaneous Determination of Trace Elements in Urine by Inductively Coupled Plasma-Atomic Emission Spectrometry... 

Inductively coupled plasma-atomic emission spectrometry was investigated for simultaneous multielement determinations in human urine. Emission intensities of constant, added amounts of internal reference elements were used to compensate for variations in nebulization efficiency. Spectral background and stray-light contributions were measured, and their effects were eliminated with a minicomputer-con-trolled background correction scheme. Analyte concentrations were determined by the method of additions and by reference to analytical calibration curves. Internal reference and background correction techniques provided significant improvements in accuracy. However, with the simple sample preparation procedure that was used, lack of sufficient detecting power prevented quantitative determination of normal levels of many trace elements in urine. 

An important question in the development and application of any new analytical procedure is what is the state of the art One aspect of the state of the art with respect to the determination of trace elements in urine is illustrated in Table I. The table shows the range of reported analytical values and the model values for 24-hour urinary excretion of a number of trace elements, as compiled from the report of the Task Group on Reference Man (6). The main feature of the information in Table I is that the range of reported normal values covers two orders of magnitude for most of the elements listed. There may be considerable variation in the normal excretion of trace elements in urine, but the extent of the ranges shown in the table also may be signiflcantly and artificially enhanced by wide variations in the accuracy of the analytical results that were surveyed. The latter view is supported by the data... 

The state of the art with respect to the potential of ICP-AES for the determination of trace elements in urine can be assessed by comparing the model concentration and range of concentrations for each of the elements (computed from the data in Table I) to the corresponding experimental limit of quantitative determination (LQD) for that element in aqueous solutions with 1% (vol) nitric acid, as is done in Table II. If the trace element concentrations in urine are as shovm in the table, and if the LQDs which can be achieved for urine samples are not substantially different from those observed for 1% nitric acid solutions, then ICP-AES should be applicable for the quantitative determination of many of the trace elements occurring in urine. 

For certain sample types, both stray light and recombination eflFects on the analytical results can be largely eliminated by matrix matching. Such an approach is not practical for the determination of trace elements in urine because of the wide ranges of calcium and magnesium concentrations which occur in so-called normal samples. 

Table V summarizes the quantitative results obtained for 13 trace elements in urine. Both the results from the method of additions and those obtained from the 1% NaCl analytical cahbration curves are given. Concentrations were determined for dilute, normal, and concentrated urine solutions but, for ease of comparison, the results listed in the table are all reported in terms of the concentration of analyte present in the original composite urine sample. Background correction was performed for each sample and reference solution according to the wavelengthprofiling procedure outlined above. A 10-second photocurrent measure-...

Table V. Analytical Results for Trace Elements in Urine (ng/mL) ...

The principal conclusions of the present study are as follows. First, the ICP-AES technique is useful for the rapid, simultaneous determination of trace elements in urine. However, the limits of detection will have... 

CoENELis R, Speeke A and Hoste J (1975) Neutron activation analysis for bulk and trace elements in urine. Anal Chim Acta 78 317-327. 

Precondition for a voltammetric determination of trace elements in urine is a sample pretreatment. The problem of losses of mercury with classic mineralization methods is described above. To avoid this problem, the authors have developed an acid digestion method with the addition of thioacetamide. All mercury in the sample is converted by this to the extremely poorly soluble mercury sulfide (HgS), which is stable under the conditions chosen. Subsequently hydrogen peroxide is added to oxidize the HgS and liberate the Hg ion [113]. 

In a study that included 72 children and 87 adults in Germany, the concentration of 30 trace elements in urine was determined by ICPMS equipped with and octopole... 

Heitland, P. and Koster, H.D. (2006). Biomonitoring of 30 trace elements in urine of children and adults by ICP-MS, Clin. Anal. Acta 365, 310-318. 

Fujimori, E., Sawatari, H., Chiba, K., and Haraguchi, H. (1996). Determination of minor and trace elements in urine reference sample by a combined system of inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry. Anal. Sci. Int.J.Jpn. Soc.Anal. Chem. 12(3), 465. 

Krachler, M., Ahmonti, A., Petrucci, E, and Forastiere, F. (1998). Influence of sample pretreatment on the determination of trace elements in urine by quadrupole and magnetic sector field inductively coupled plasma mass spectrometry. J. Anal. At. Spectrom. 13(8),... 

An internal quality control should be performed with each analytical run. Control materials for internal quality control of cadmium analytical procedures are commercially available, e.g., certified reference material for trace elements in urine, plasma, serum, and whole blood [46,47]. 

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