Determination of lead in whole blood by AA-1800 atomic absorption spectrometry - Master's thesis - Dissertation

Determination of Lead in Whole Blood by AA-1800 Atomic Absorption Spectrometry

Key words: atomic absorption spectrometer; lead; aesthetic instrument; AA-1800. Lead (Pb) is a multi-system, multi-affinity heavy metal poison that mainly affects the placenta and nervous system. Even trace amounts of lead in the body can cause harm, especially to children, as high concentrations can lead to irreversible brain damage. Blood lead levels reflect recent exposure and are an important indicator of lead intake. The World Health Organization (WHO) sets biological thresholds for blood lead levels, with a limit of 100 µg/L for children. In China, no official method has been recommended yet. However, the Ministry of Health issued standard WS/T174-1999 in 1999, which uses graphite furnace atomic absorption spectrometry for blood lead analysis. This method involves deproteinizing blood using 10% (V/V) nitric acid, followed by centrifugation and measurement. To improve accuracy, the method was adjusted by drying the sample in two steps to prevent splashing during evaporation. A spiked sample was used to evaluate the method, and the results were promising. Recovery rates ranged from 86% to 103%, with a relative standard deviation (RSD) of 4.19%. The experimental procedure involved deproteinizing blood samples with 10% HNO3, mixing, centrifuging, and measuring lead content using a graphite furnace atomic absorption spectrometer. The standard curve was prepared using lead standards at concentrations of 0.0–55.1 µg/L, with a regression equation of y = 3.394×10⁻³X + 0.0103, R² = 0.9992, and a linear range of 5–100 µg/L. Sample determination included taking 50 µL of anticoagulated blood, adding 300 µL of 10% HNO3, and analyzing the supernatant. The concentration was calculated based on the standard curve and multiplied by the dilution factor. The temperature program was optimized to reduce sample splashing, with two drying steps and controlled ashing. Precision and recovery tests showed good repeatability, with RSD values below 5%. Quality control samples from the Chinese Academy of Medical Sciences were tested, and the results met acceptable criteria. Stability tests revealed that blood samples remained stable for up to 2 hours after treatment, but beyond that, results became unreliable. Therefore, it's recommended to measure samples promptly after preparation. In conclusion, this method offers fast, accurate, and sensitive lead detection, suitable for pediatric testing due to its minimal sample volume requirements. It is ideal for large-scale screening of blood lead levels in children.