WS/T 107.2-2016Determination Part 2: inductively coupled of iodine in urine-plasma mass spectrometry method (English PDF)

Foreword

WS/T 107 "Determination of Iodine in Urine" to be released in sections , Divided into the following two parts.

--- Part 1. arsenic-cerium catalytic spectrophotometry;

--- Part 2. Inductively coupled plasma mass spectrometry.

This part is the second part of WS/T 107.

This section is drafted in accordance with the rules given in GB/T 1.1-2009.

This section was drafted. Beijing Centers for Disease Control and Prevention, Fujian Province Center for Disease Control and Prevention, Shandong Province Center for Disease Control and Prevention, Shenzhen Center for Disease Control and Prevention, Peking University School of Medicine, Beijing Shijingshan District Center for Disease Control and Prevention.

1 Scope

This part of WS/T 107 specifies the method for the determination of iodine in urine by inductively coupled plasma mass spectrometry.

This section applies to the determination of total iodine concentration in urine.

2 Principle

After the sample solution is treated with tetramethylammonium hydroxide, the carrier gas (argon) is sent into the inductively coupled plasma torch flame by atomization, and the sample solution the processes of ionization, dissociation, atomization, ionization, etc. are mostly converted into positively charged positive ions, which enter the mass spectrometer through the ion collection system.

It is separated according to its mass-to-charge ratio and detected by the detector. The ion counting rate is directly proportional to the content of the analyte in the sample.

Eliminate matrix effects and achieve quantitative analysis of iodine content in samples.

3 Instrument

3.1 Inductively coupled plasma mass spectrometer.

3.2 Electronic balance (sensitivity 0.1mg).

4 Reagents

4.1 Pure water (H2O, Mr = 18.0), resistivity greater than 18.0 Mohm · cm or deionized water (in accordance with GB/T 6682 level 1 water regulations).

4.2 Tetramethylammonium hydroxide [(CH3) 4NOH, 25% by mass], electronic grade.

4.3 Triton X-100 (C34H62O11, Mr = 647.0), reagent grade.

4.4 Potassium iodate (KIO3, Mr = 214.0), reference reagent or standard reagent.

5 Solution preparation

6 Collection, transportation and storage of urine samples

Collect no less than 5mL of urine and place it in a polyethylene plastic or glass test tube with a tightly sealed mouth to prevent evaporation. Urine samples are collected and shipped on site There is no need to consider special storage conditions during the transfer process, it can be stored for 2 weeks at room temperature; the sample can be stored for 2 months at 4 ° C; polyethylene plastic Store the sample, and it can be stored for 4 months at -20 ° C after being sealed.

7 Analysis steps

7.1 Main reference conditions of the instrument. radio frequency (RF) power is 1320W; carrier gas flow rate is 1.10L/min; sampling depth is 7mm; atomization the room temperature is 2 ° C; the sampling cone and interception cone are nickel cones; the atomizer is a high-salt or concentric atomizer.

7.2 Take 1.0mL urine samples separately (mix urine before sampling to suspend all precipitates), add 1.0mL pure water (4.1) and 8.0mL Diluent (5.3), mix well.

7.3 Take 1.0mL of iodine standard use series solution (5.5) and iodine standard solution (5.4.3), add 1.0mL of background urine (5.6) and 8.0mL diluent (5.3), mix well, the iodine concentration of this standard working series solution is 0.0µg/L, 1.0µg/L, 5.0µg/L, 10.0µg/L, 15. 0 µg/L, 30.0 µg/L, 60.0 µg/L, 10.0 µg/L. 7.4 Start up, when the vacuum degree of the instrument reaches the requirements, use the tuning fluid (5.7) to adjust the various indicators of the instrument, so that the instrument sensitivity, oxide, double power WS/T 107.2-2016 After the various indicators such as charge and resolution meet the measurement requirements, edit the measurement method, select the measurement element iodine (127I) and the selected internal standard element, and cite Insert the internal standard solution (5.8), and then introduce the reagent blank, standard series, and sample solution into the instrument for measurement.

Note. If the iodine content in the sample exceeds the measurement range, dilute the sample with pure water at an appropriate ratio and measure it according to the method.

8 Calculation of analysis results

8.1 Regression equation method. According to the measurement results, draw the calibration curve of the standard addition method, and use the software that comes with the instrument to convert the standard addition method curve.

For the standard curve of the external standard method, calculate the regression equation = X + . Calculate the mass concentration of iodine content in the measured sample according to the regression equation (Mg/L). 8.2 The calculation of the mass concentration of iodine in urine is shown in formula (1).

rho (I) = · K (1)

In the formula.

rho (I) --- the mass concentration of iodine (I) in urine, the unit is micrograms per liter (µg/L); --- the measured sample calculated from the standard curve regression equation or checked from the standard curve Mass concentration of iodine in micro Grams per liter (µg/L); K --- dilution ratio of urine sample.

9 Method characteristics

10 Key points of quality assurance and control

10.1 Sampling process, sample transportation, experimental environment, utensils and reagents shall avoid iodine contamination.

10.2 A standard series shall be prepared and determined for each sample determination, and the absolute value of the correlation coefficient of the standard curve regression equation shall be >= 0.999.

10.3 It is advisable to use parallel samples, urinary iodine reference materials approved by the state and granted reference material certificates, and spiked recovery for quality control.

means.

WS/T 107.2-2016