SN/T 0962-2010Determination of sodium tungstate content in sodium tungstate for import and export (English PDF)

Foreword

Instead of the standard SN/T 0962-2000 "Determination of sodium tungstate import and export of sodium tungstate content." the main difference compared with the standard SN/T 0962-2000 as follows.

--- Relative molecular mass of sodium tungstate changed from 329.82 to 329.86.

--- WO3 in terms of Na2WO4 · H2O coefficient changed from 1.4224 to 1.4228.

This standard is proposed and managed by the National Certification and Accreditation Administration Committee.

This standard by the Tianjin People's Republic of China Exit Inspection and Quarantine is responsible for drafting.

1 Scope

This standard specifies the method for determination of sodium tungstate content of sodium tungstate in import and export.

This standard applies to the determination of the content of sodium tungstate, sodium tungstate in the import and export.

Note. The relative molecular mass of sodium tungstate. 329.86 (according to 2007 international relative atomic mass).

2 Normative references

The following documents for the application of this document is essential. For dated references, only the dated version suitable for use herein Member. For undated references, the latest edition (including any amendments) applies to this document.

GB/T 603 chemical reagent in test methods - Preparations with GB/T 6678 General Principles for Sampling Chemical Products GB/T 6679 General rules for sampling solid chemicals

3 Method summary

Hydrochloric acid and nitric acid decomposition of the sample, so that acid precipitation, hydrochloric acid cinchonine tungsten acid precipitate completely isolated by filtration, sedimentation by burning into WO3 weighed. Calculations to Na2WO4 · H2O or in terms of sodium tungstate WO3 content.

4 Reagents and materials

Unless otherwise indicated in the analysis using only recognized as analytical grade reagents and distilled water or equivalent purity. Test preparation needed and products, in the absence of other provisions prepared according to GB/T 603's.

4.1 HCl. rho = 1.19g/mL.

Nitrate 4.2. rho = 1.40g/mL.

4.3 hydrochloric acid solution. 13.

4.4 cinchonine hydrochloride solution. 6g 7g cinchonine or cinchonine hydrochloride dissolved in 100mL of hydrochloric acid solution (4.3).

4.5 cinchonine hydrochloride lotion. cinchonine hydrochloride solution (4.4) 4mL added 200mL of water.

4.6 slow quantitative filter paper (203 type).

5 Apparatus

5.1 General laboratory instruments.

5.2 Furnace temperature. The temperature can be controlled at 750 °C ± 25 °C.

6 Sampling

The method according to GB/T 6678 and GB/T 6679 regulations. Batch sampling weight of not less than 500g. The product was sampled thoroughly mixed Uniform, into a clean and dry grinding mouth glass jar or double plastic bags. Label, indicating the sample name, date of sampling, sample number and the like.

7 Procedure

Weigh about 0.5g sample (accurate to 0.2mg), placed on a high type 400mL beaker, was added 10mL of water was dissolved (if insoluble materials should Filtered and washed), was added 20mL of hydrochloric acid (4.1), 10mL of nitric acid (4.2), the beaker was placed on a low-temperature heating furnace to maintain micro-boiling about 10min, remove the beaker was added 150mL of water and 10mL cinchonine hydrochloride solution (4.4), then into a beaker of boiling water bath for 30min