Application of dopamine as an electroactive ligand for the determination of aluminum in biological fluids

Dopamine (3,4-dihydroxyphenylethylamine, DA) is applied as an electroactive chelant for indirect determination of aluminum (Al) in biological fluids. It is observed that the decrease of the differential pulse voltammetric (DPV) anodic peak current of DA is linear with the increase of Al concentration. Under optimum experimental conditions (pH 8.6, 2.0 x 10(-4) M DA, and 0.03 M NH4Ac-NH3 x H2O buffer solution), two linear ranges, 5.0 x 10(-8) - 4.0 x 10(-7) M and 4.0 x 10(-7) - 7.2 x 10(-6) M Al(III), are obtained. The detection limit of Al is 1.9 x 10(-8) M and the relative standard deviation for 4 x 10(-6) M Al(III) is 3.1% (N = 8). Many biologically active foreign species have been selected for interference. Excellent recoveries and accuracy have been obtained in the measurements of Al in biological samples such as synthetic renal dialysate, Ringer's solution, human whole blood, cerebrospinal fluid of demented patient, and urine of diabetic patient. The methodological principle that Al complexes with DA on the electroactive position result in the depression of electrochemical activities of DA has been verified by comparing both the electrochemical behaviors and the spectroscopic responses like UV-vis and Raman of DA in the presence and in the absence of Al.

Neurotransmitter dopamine applied in electrochemical determination of aluminum in drinking waters and biological samples

It was demonstrated that the decrease of the differential pulse voltammetric (DPV) anodic peak current of dopamine (3,4-dihydroxyphenylethylamine, DA) was linear with the increase of aluminum (Al) concentration. Under optimum experimental conditions (pH 4.6, 1.2 x 10(-3) M DA, and 0.04 M NaAc-HAc buffer solution), the linear range is 4.0 x 10(-7)-8.0 x 10(-5) M, the detection limit is 1.4 x 10(-7) M, and the relative standard deviation for 4 x 10(-5) M Al(III) is 3.5% (n=8). Many foreign species, especially some low-molecule-weight biological molecules, were chosen for interference testing. The proposed method was applied to the determination of Al in biological samples such as synthetic renal dialysate, Ringer's solution, human blood, cerebrospinal fluid of a patient, and urine of a diabetic patient. The corresponding recoveries were generally between 95 and 105%. The basic principle of the method was determined by examining Al complexed with DA. This results in the blockage of the electroactive sites on DA, followed eventually by the reduction of the electrochemical response of DA. This result was verified by examining the behavior of DA, both in the presence and absence of Al, using electrochemical, UV-Vis, Raman, and (13)C NMR spectroscopic methods.

Biochemical and hematological changes in low-level aluminum intoxication

The aim of this study was to investigate the biochemical and hematological changes in patients on routine hemodialysis treatment when they were accidentally exposed to moderately high serum aluminum concentrations during a period of time of less than four months. We studied the changes in biochemical and hematological measurements in 33 patients on dialysis in our hospital before and during the exposure to about 0.85 pmol/l of aluminum in dialysis water due to a malfunction of the reverse osmosis system of water purification. Patients showed a decrease in the hemoglobin concentration from 115+/-12.4 g/l to 108+/-12.2 g/l (p=0.026) and in the mean corpuscular hemoglobin concentration from 5.15+/-0.22 to 5.02+/-0.30 mmol/l (p=0.014). Ferritin was decreased from 243+/-192 microg/l to 196+/-163 microg/l (p=0.047) and transferrin saturation from 0.20+/-0.06 to 0.15+/-0.07 (p=0.004). Biochemical measurements related to calcium-phosphate metabolism did not change. Otherwise, all patients showed an increase in serum aluminum from 0.56+/-0.44 to 1.63+/-0.52 micromol/l (p<0.001). No differences were detected in serum aluminum between patients receiving and not receiving oral aluminum salts. Even moderately high aluminum concentrations maintained during a short period of time could produce significant hematological alterations and a depletion of body iron stores before clinical manifestations were evident.

Trace element status of hemodialyzed patients

The trace elements Ba, Bi, Cd, Co, Cs, Cu, Hg, La, Mn, Mo, Pb, Rb, Sb, Sn, Sr, Tl, and Zn were determined by inductively coupled plasma mass spectrometry in plasma samples of 68 hemodialysis patients. The same elements (with exception of La and Mn) were also determined in whole blood after mineralization with high-purity nitric acid/hydrogen peroxide in a closed-pressurized microwave system. The accuracy and precision was checked by analyzing two Seronorm "whole blood" reference materials. All samples were contaminated with barium (heparinized tubes) and the plasma samples with tin (collection tubes). The concentrations for Bi, Hg, Pb, Rb, Sb, and Sr in whole blood were within the literature ranges for healthy adults. All of the concentrations for Co, and some of the concentrations for Cd, Cs, Tl, and Zn were higher than the high limits of the normal ranges. Approximately 14% of the Cu concentrations were lower than the low limit of the normal range. The Mo and Sn concentrations are difficult to evaluate, because the normal ranges appears to be unreliable. All concentrations for Cd, Co, Mo, Pb, Sn, and Sr and some of the concentrations for Cu (15%) and Mn (75%) in the plasma samples were higher than the high limits of the normal ranges. The concentrations for Rb tended to be lower than the normal range. To establish unequivocally the causes for elevated and reduced concentrations of trace elements in whole blood and plasma of dialysis patients, all fluids in the dialysis process must be investigated.