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, mainly test for placenta and neurotropic poison, The presence of any traces of lead in the body can cause harm, such as reaching a certain concentration, and can cause irreversible damage to the child's brain. Blood lead values ​​reflect recent lead intake and are often used as an important indicator of exposure levels in the body. The World Health Organization (WHO) regulates blood lead biological thresholds for all types of people, with 100 ug/L for children. At present, the country has not recommended the method. In 1999, the Ministry of Health promulgated the acid deproteinization of blood lead with standard number WS/T174-1999, graphite furnace atomic absorption spectrometry. We refer to this method and use 10% (V/ V) Nitric acid removes blood protein, and then it is easy to splash according to the blood sample. The graphite furnace is programmed to heat up and dry in two steps to solve the problem that the blood sample is easy to splash. In order to evaluate the accuracy of the method, a busy sample was taken and the results were satisfactory. The recovery of the sample was 86%-103%, and the relative standard deviation was RSD=4.19%. 1 Experimental part 1.1 Principle of the whole blood After 10% HNO3 tolerate blood and deproteinize the blood, fully oscillate and centrifuge at high speed. The supernatant was taken for determination of lead content by graphite furnace atomic absorption spectrometry. 1.2 instruments and reagents 1.2.1AA-1800 atomic absorption spectrometer, lead hollow absorption lamp. 1.2.2 The concentration of blood lead standard stock solution is 38ug/L, 112ug/L, 284.2ug/L, 385.7ug/L, respectively (Chinese Academy of Preventive Medicine, Environmental Sanitation Institute). 1.2.3 1.5ml polyethylene tube with lid. 1.2.4 Liquid high speed mixer. 1.2.5 High speed benchtop centrifuge. 1.2.6 10% (V / V) nitric acid, take 10mL high purity nitric acid diluted to 100L with pure water. 1.2.7 25, 50, 1000ul adjustable micro sampler. 1.2.8 Instrument operating conditions pb measured wavelength 283.3nm, lamp current 3mA, spectral bandwidth 0.2nm, shielding gas: argon. The neon light deducts the background. 1.3 Standard curve preparation 50uL lead standard stock liquid pipe inner wall is ring-shaped into a 1.5-capped polyethylene tube which has been pre-loaded with 300uL 10% HNO3. At this time, the concentration is diluted 7 times, and the standard series concentration is: 0.0ug/ L5.43ug/L16.0ug/L40.6ug/L55.1ug/L. Immediately set high-speed liquid vortex mixer to mix 30/s, place for 30min, centrifuge at 1000rpm for 10min, take 20ml of supernatant, sample the absorbance, draw the concentration-absorbance standard curve, regression equation: y=3.394×10 -3X+0.0103r=0.9992, linear range 5ug/L-100ug/L 1.4 Sample determination Take 50uL anticoagulant and standard curve preparation, then take the supernatant liquid 20uL for graphite furnace analysis, find the corresponding concentration from the standard curve Multiply by the dilution factor to get the lead content in the blood. 2 Results and discussion 2.1 Temperature program Because the viscosity of the sample is large, it is easy to splash when dry. We divide it into two steps and extend the drying time of the second part to solve the problem of easy splashing. Table 1 Graphite furnace heating program program Starting temperature (°C) Termination temperature (°C) Time (s) Gas drying 60 120 25 Opening drying 120 130 20 Opening ashing 130 450 20 Opening ashing 450 450 10 Opening ashing 450 450 6 Close atomization 2000 2000 4 Close clear 2300 2300 3 Open 2.2 precision and recovery rate Take the blood sample repeatedly and measure it 6 times, and add the standard to determine the recovery rate. The results are shown in Table 2 and Table 3 Table 2 precision experiment results (n= 6) Blood sample value (μg / L) measured value (μg / L) S RSD (%) 10.8 11.2 11.3 0.45 4.1910.2 10.3 10.7 Table 3 recovery rate test results blood sample bottom plus scalar determination times recovery average recovery rate (μg /L)(μg/L) (n) (%) (%)20.4 20 5 86.2-103.5 92.42.3 Determination of blind samples We used this method to determine the quality control samples provided by the Chinese Academy of Medical Sciences Environmental Protection Institute. 4 and Table 5. The quality control samples of the two groups were statistically processed, and their quality assessment values ​​Q<[1], indicating that the overall operation has small errors and the test results are qualified. Table 4 Quality Control Experimental Results Quality Control Sample Code Test Value (μg/L) True Value (μg/L) p1 116.4 118 p2 148.5 147 p3 318.2 314 p4 182.2 191 p5 80.8 87 Sanitation Institute provides quality control results of Table 5 quality control samples Code test value (μg/L) True value (μg/L) 1 102.8 1102 194.4 2803 22.3 204 47.2 485 345.2 3626 162.5 157 Sanitation provided 2.4 Stability of the sample Through the experiment, the blood sheep is stable 2 hours after treatment, due to blood components It is more complicated. After more than two hours, the result is unstable, so the blood sample should be measured as soon as possible after treatment. 3 Summary In this paper, through the exploration of the method of measuring blood lead in deproteinized graphite furnace, the experimental conditions are improved according to the experimental conditions, which proves that this method has the characteristics of fast, accurate and high sensitivity, combined with less blood, finger blood or earlobe. It is easy for children to accept and is suitable for large-scale determination of blood lead levels in children.