GBZ/T 306-2018Determination of chromium in urine -- Graphite furnace atomic absorption spectrometric method (English PDF)

Foreword

This standard is formulated in accordance with the Law of the People's Republic this standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This standard replaces WS/T 37-1996 "Method for the determination of chromium in urine by graphite furnace atomic absorption spectrometry".

Compared with WS/T 37-1996, the main changes are as follows.

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

-- Improved standard formulation and sample handling methods;

-- Increased use of matrix modifiers.

This standard was drafted. Jiangsu Provincial Center for Disease Control and Prevention, China Center for Disease Control and Prevention, Occupational Health and Poison Control Institute, Guangdong Provincial Occupational Disease Prevention and Control Institute, Wuxi Municipal Center for Disease Control and Prevention, Nanjing Occupational Disease Prevention and Control Institute.

1 Scope

This standard specifies the determination of chrome graphite furnace atomic absorption spectrometry in urine.

This standard applies to the determination of urinary chromium in occupational contact 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

3 Principle

A urine sample (hereinafter referred to as a urine sample) is diluted with a mixed solution of magnesium nitrate and nitric acid, and then a graphite furnace atom is used at a wavelength of 357.9 nm.

Determined by absorption spectroscopy.

4 Instruments

4.1 Covered plastic bottle, 100 mL.

4.2 Volumetric flasks, 10 mL, 100 mL, 500 mL, 1000 mL.

4.3 Pipettes, 50 µL,.200 µL, 1000 µL.

4.4 Covered plastic centrifuge tube, 1.5 mL.

4.5 Balance with a sensitivity of 0.1 mg.

4.6 Atomic absorption spectrometer with graphite furnace atomizer, Zeeman calibration device, chrome hollow cathode lamp.

5 Reagent

5.1 Experimental water, deionized water or quartz glass sub-boiling distilled water.

5.2 Nitric acid, high purity.

5.3 Magnesium nitrate hexahydrate, excellent grade.

5.4 Preservation solution. Weigh 0.865 g of magnesium nitrate hexahydrate dissolved in an appropriate amount of water, add 50.0 mL of nitric acid, and dilute to 100 mL.

5.5 Matrix modifier. Weigh 0.865 g of magnesium nitrate hexahydrate dissolved in an appropriate amount of water, add 50.0 mL of nitric acid, and dilute to 1000 mL.

5.6 Chromium standard stock solution. Accurately weigh the reference material potassium dichromate (110 °C, baking 2 h) 1.4315 g (accurate to 0.0001 g), After dissolving with a small amount of water, transfer the whole amount to a 500 mL volumetric flask, add 5.0 mL of nitric acid, dilute to volume with water, and mix. This solution per ml Contains 1.0 mg of chromium. Or purchase a standard stock of chromium monoliths certified by the state and awarded a certificate of reference material.

5.7 Chromium standard intermediate solution [rho(Cr) = 5.0 µg/mL]. Dilute the standard stock solution of chromium monolith to a concentration of 5.0 µg/mL with a preservation solution.

Standard intermediate solution.

5.8 Chromium standard series solution. respectively absorb chromium standard intermediate solution (5.0 µg/mL) 0.0 µL, 30.0 µL, 50.0 µL, 100.0 µL, 200.0 µL, 400.0 µL, and 800.0 µL in a 10 mL volumetric flask, dilute to the mark with a preservation solution, and mix. Per liter in each volumetric flask Containing 0.0 µg, 15.0 µg, 25.0 µg, 50.0 µg, 100.0 µg,.200.0 µg, and 400.0 µg of chromium, respectively. Available now.

6 Sample collection, transportation and storage

Collect chrome-contact workers for more than 50 mL of urine samples at the end of the working week. After measuring creatinine as soon as possible, take 9.0 mL of urine sample at 10 mL with stopper plastic.

Add 1.0 mL of preservation solution to the tube, mix and refrigerate. The sample can be stored for two weeks at 4 °C and for two months at -20 °C.

7 Analysis steps

8 Calculation

8.1 Calculate the concentration of chromium in the urine sample according to formula (1).

cFc xx= ...(1)

In the formula.

c -- the concentration of chromium in the urine sample, in micrograms per liter (µg/L);

10/9 -- dilution factor of urine sample treated with preservation solution;

F -- the matrix modifier reduces the multiple of the urine sample when the absorbance of the sample exceeds the linear range; 1 when not diluted with the matrix modifier;

C1 -- The concentration of chromium in the urine sample calculated by the regression equation in micrograms per liter (µg/L).

8.2 In order to correct the dilution of urine, the concentration of chromium in the urine sample is corrected by the concentration of creatinine in the urine sample. The correction formula is shown in equation (2).

c =2 ...(2)

In the formula.

C2 - the concentration of chromium in the urine sample after creatinine correction, in micrograms per gram of creatinine (µg/g creatinine);

c -- the concentration of chromium in the urine sample, in micrograms per liter (µg/L);

Cr - creatinine concentration in urine samples in grams per liter (g/L).

9 Description

9.1 The detection limit of this method is 0.21 µg/L; the lower limit of quantification is 0.71 µg/L; the method range is 0.71 µg/L to 44.44 µg/L, in this range, the correlation coefficient is >0.9990; the precision within the method batch range is 0.8% to 5.1% (the urinary chromium concentration is 1.7 µg/L to 36.6).

Gg/L, n=6); the inter-assay precision range is from 1.1% to 8.3% (urinary chromium concentration is 1.7 µg/L to 36.3 µg/L, n=6);

The recovery of urine samples was 91.9%~104.8% (the urinary chromium background concentration was 0.0 µg/L~18.2 µg/L, and the spiked concentration was 2.0 µg/L~ 30.0 µg/L, n=6).

9.2 This method is used for the determination of urinary chromium. The minimum sample size of urine sample is 100.0 µL.

9.3 Commercially available nitric acid often contains a considerable amount of chromium. It should be inspected according to the sample measurement conditions before use and distilled if necessary.

9.4 All the utensils used in the experiment should be soaked in nitric acid solution overnight, rinsed repeatedly with water, and finally rinsed with deionized water.

9.5 When this method is used for the determination of urinary chromium, the graphite furnace atomic absorption spectrometer of the xenon lamp calibration device should not be used for analysis, otherwise the accuracy is better.

difference.

9.6 1000.0 µg/mL Na, K, 500.0 µg/mL Mg2, 100.0 µg/mL Ca2, Zn2, Cu2, 50.0 µg/mL Fe3 and 10.0 µg/mL Co2, Li, Si, Ba2, Be2, Al3, Ni2, Mn2, and Pb2 do not interfere with the measurement.

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