Proceedings Article | 31 December 2020
KEYWORDS: Lead, Blood, Absorption, Lamps, Absorbance, Ultraviolet radiation, Spectroscopy, Calibration, Statistical analysis
Lead levels monitoring in humans is of great interest because of its high toxicity1. In order to detect lead in whole blood, the authors developed a methode using GF-AAS, for quantifing blood lead level2. Absorption spectrometry is the analytical method for determining the amount of metals or metalloids in a sample, based on the amount of light absorbed by atoms, from a characteristic light beam line given by the respective atoms brought into the excitation state. The aims of this study is to show the importance of reducing background noise with the use of a deuterium lamp in a determination method for lead in blood using graphite furnace atomic absorption spectrometry (GFAAS). Lead analysis was performed using a Graphite Furnace Atomic Absorption Spectrophotometer (GF- AAS), Varian SpectraAA-880 with a hollow cathode lamp and a deuterium lamp for background correction, coupled to GTA-100 atomizer and a programmable sample dispenser (Varian, Australia), with monochromator Czerny-Tuner, focal length 0.33 mm. The automatic sample dispenser PSD Varian had 54 positions for samples, standards, modifiers, quality control and buffer, maximum injected quantity 100 μl, injection accuracy 0.2 μl, automatic dilution and mixing, automatic re-injection of samples. Blood samples were collected from patients admitted to the Emergency Clinical Hospital of Bucharest, in ICU II Toxicology. The application of the optimized temperature program and the deuterium lamp background correction made possible to eliminate the whole matrix of the sample before the atomization step, as confirmed by the low background signals observed in the measurement of lead. The atomization temperature was established by varying the atomization temperature between 1600 and 2100°C. As expected, the lead signal increased with the increase in the atomization temperature up to 2000°C. For temperatures higher than 2100°C, the signals remained almost constant, indicating that maximum atomization efficiency can be achieved in this range. The application of the optimized temperature program made possible to eliminate the whole matrix of the sample before the atomization step, as confirmed by the low background signals observed in the measurement of lead. A linear relationship was found between the absorbance at 283,3 nm and the concentration of lead in the range of 10.0 to 100 μg/L. The representative linear equation was y = 0.0054 x + 0.0219 where: y is the absorbance, x is lead concentration (μg/L), calculated by the least squares method. The regression coefficient (r) standard curve was 0.9993 (fig. 1) indicating good linearity (r < 0.999). Determination of lead levels in blood gives very useful information to the therapist. The absorbance signals obtained for lead at 283.3 nm in the optimizing conditions presented a well-defined profile and a low background. The reported method shows a high precision and accuracy all so a wide aplicability in rutine lead determination and research assays. This method was applied for determination of lead levels in blood by GF-AAS technique, in order to establish the correct diagnosis and to monitoring EDTA chelation therapy for patients with lead poisoning.
