GBZ/T 303-2018Determination of lead in urine -- Graphite furnace atomic absorption spectrometry method (English PDF)

Foreword

This standard is formulated in accordance with the Law of the People's Republic this standard replaces WS/T 18-1996 "Method for the determination of lead in urine by graphite furnace atomic absorption spectrometry".

Compared with WS/T 18-1996, the main changes are as follows.

----The operating conditions of the instrument are changed to the reference conditions for instrument operation;

---- Improved matrix modifier, standard preparation, and measurement range;

---- Added the requirement for sample dilution.

This standard is mainly drafted by. China Center for Disease Control and Prevention, Occupational Health and Poison Control Institute, Guangdong Provincial Occupational Disease Prevention and Treatment Institute, Shandong Provincial Institute of Labor Health and Occupational Diseases, Jiangsu Provincial Center for Disease Control and Prevention.

1 Scope

This standard specifies the graphite furnace atomic absorption method for the determination of lead in urine.

This standard applies to the determination of lead in urine in occupational exposure personnel.

2 Normative references

The following documents are indispensable for the application of this document. For dated references, only the dated version applies to this document.

For undated references, the latest edition (including all amendments) applies to this document.

General rules for biological monitoring of GBZ/T 295 occupational population GB/T 6682 Analytical laboratory water specifications and experimental methods

3 Principle

Urine sample (hereinafter referred to as urine sample) with palladium chloride matrix modifier, measured by graphite furnace atomic absorption spectrometry at 283.3 nm Determine the concentration of lead.

4 Instruments

4.1 Covered polyethylene plastic bottle, 100 mL.

4.2 stoppered polyethylene centrifuge tube, 1.5 mL.

4.3 Volumetric flask, 10 mL.

4.4 Microsampler,.200 µL, 1000 µL.

4.5 Atomic absorption spectrophotometer with graphite furnace, background correction and lead hollow cathode lamp. Refer to Table 1 for instrument operation reference conditions.

Table 1 Instrument operation reference conditions

step

temperature

Heating time

Residence time

Carrier gas flow

mL/min

Dry 90 1 30 250

Dry 120 15 30 250

Ashing 800 10 20 250 Atomic 1900 0 5 0 Clear 2100 1 3 250

5 Reagent

5.1 Experimental water. According to GB/T 6682.

5.2 Nitric acid, rho20=1.42 g/mL, excellent grade pure.

5.3 Nitric acid solution, 1% (volume fraction).

5.4 Matrix modifier. 0.33 g of palladium chloride (excellent grade) is slightly soluble in 10 mL of nitric acid, shake well, and diluted to 500.0 mL with water. Storage Stored in a brown reagent bottle and stored in the refrigerator for one year.

5.5 Normal human urine. normal human urine that does not touch lead.

5.6 Lead standard solution. The lead standard solution standard substance with the national standard substance certificate number is used.

5.7 Lead Standard Application Solution. Dilute the lead standard solution to 1.0 µg/mL lead standard application solution with 1% nitric acid.

6 Sample collection, transportation and storage

6.1 Sample collection. Collect about 50 mL of urine sample once in a polyethylene plastic bottle. After measuring the specific gravity as soon as possible, add in proportion to 1% Nitric acid, mix well.

6.2 Sample blank. Take 5 mL of 1% nitric acid in a plastic tube with a blank.

6.3 Samples and sample blanks should be placed in a clean container and shipped under refrigerated conditions. It can be stored in the refrigerator at -18 ° C for 1 month.

7 Analysis steps

8 Calculation

Calculate the lead concentration of the urine sample according to formula (1).

C = C0 × k (1)

In the formula.

C -- the concentration of lead in urine in micrograms per liter (µg/L);

C0 - the concentration of lead after subtracting the blank from the urine curve obtained by the working curve or the regression equation, in micrograms per liter (µg/L);

k -- The urine sample is converted to the concentration correction factor at the standard specific gravity (1.020).

9 Description

9.1 The minimum detectable concentration of this method is 1.0 µg/L; the lower limit of quantitation is 3.0 µg/L. The measurement range is from 3.0 µg/L to.200 µg/L; batch the relative standard deviation within the range is 1.0% to 2.6% (n=6), and the relative standard deviation between batches is 1.6% to 3.9% (n=6);

97% to 104.1%.

9.2 Palladium chloride in the matrix modifier used in this method forms a stable complex with lead, and lead is not easily lost during ashing, so ashing the temperature can be increased to 700 ° C ~ 900 ° C, at which temperature most of the interference components in the urine sample are removed.

9.3 All containers and laboratory supplies should be soaked in a 1.1 nitric acid solution overnight, rinsed with water and distilled water for later use.

9.4 The urine sample collection time is not limited. When the urine sample is taken, it is necessary to leave the site environment, replace the overalls, and do a good job of personal hygiene in a clean room.

Leave urine to prevent lead contamination in the environment.

9.5 When the lead concentration in the urine sample exceeds the measurement range, the working curve range can be increased to 400.0 µg/L, and diluted by 3 times (0.2 mL).

Urine sample, add 0.2 mL matrix modifier plus 0.2 mL 1% nitric acid to mix), 4 fold dilution (0.2 mL urine sample, add 0.2 mL matrix to improve) Add 0.4 mL of 1% nitric acid to mix) or 5 times to dilute (0.2 mL of urine sample, add 0.2 mL of matrix modifier plus 0.6 mL of 1% nitric acid to mix) the measurement was carried out. At the same time, the sample, blank and standard series of treatment methods should be consistent. The measurement results do not need to calculate the dilution factor.

9.6 The quality assurance of the entire inspection process shall be carried out in accordance with the requirements of GBZ/T 295.