GB/T 6324.4-2008Test method of organic chemical products - Part 4: Determination of trace sulfur in organic liquid products - Microcoulometric method (English PDF)

Foreword

GB/T 6324 is divided into six sections.

--- Part 1. Liquid water-miscible organic chemical products test;

--- Part 2. Determination of the volatile organic liquid residue after evaporation of the water bath dry;

--- Part 3. Organic Chemical method for the determination of potassium permanganate reducing substance;

--- Part 4. Liquid organic products - Determination of trace sulfur Microcoulomb;

--- Part 5. Organic chemical products of carbonyl compounds content - Volumetric method;

--- Part 6. Organic chemical products Spectrophotomeric carbonyl compounds content.

This section GB/T 6324 Part of.

This Part replaces GB/T 6324.4-1986 "organic liquid products - Determination of trace sulfur Microcoulometry." This portion of the GB/T 6324.4-1986 compared to the main changes are as follows.

--- Expanding the scope of the standard (see Chapter 1);

--- Canceled instrument diagram (3.1, Chapter 5 of this edition 1986 edition);

--- Increased dibenzothiophene and dibutyl sulfide material and two standard iso-octane and cetane two solvents (see 4.5 and 4.6);

--- Increase the types of electrolyte (see 4.4);

--- Redefined the scope of the reaction conditions (1986 version 5.1.4, this version 6.2);

--- Redefined repetitive sample, increasing the reproducibility (1986 edition, Chapter 6, Section 8 of this edition).

1 Scope

GB/T 6324 This section specifies the test methods for trace sulfur in organic liquid product was determined by Microcoulometry.

GB/T 6324 This section applies to the sulfur content in organic liquid product sample in the 0.5mg/kg ~ 1000mg/kg range.

2 Normative references

The following documents contain provisions by GB/T 6324 this part of the reference in terms of this section. For dated reference documents Member, all subsequent amendments (not including errata content) or revisions do not apply to this section, however, encouraged to reach under this section Parties to research agreement to use the latest versions of these documents. For undated reference documents, the latest versions apply to this section.

GB/T 6682-1992 Analysis Laboratory use - Specification and test methods (neq ISO 3696:1987)

GB/T 8170-1987 numerical rounding rules

3 PRINCIPLE OF THE METHOD

Samples gasification stage gasification cracking tube and mixed with a carrier gas into the combustion zone is mixed with oxygen and burned, the sulfur is converted to sulfur dioxide, with a carrier gas Went into the titration cell, the electrolyte triiodide ion (I3-) the following reaction.

I3- + SO2 + H2 -> O SO3 + 3I- + 2H +

Titration cell triiodide ion (I3-) concentration decreased, indicating - an indication of the reference electrode and the change and given bias compared this Microcoulometry signal is input to the amplifier and amplified output voltage is applied to the electrodes for electrolysis, electrolysis at the anode the following reaction.

3I -> - I3- + 2e

Consumed triiodide ion (I3-) replenished, the consumption of electricity is the time integral of the electrolysis current, according to Faraday's law of electrolysis Calculate the sulfur content of the sample.

4 Reagents

Unless otherwise indicated in the analysis using only recognized as analytical reagents and GB/T 6682-1992 the provisions of secondary water.

4.1 Carrier gas. nitrogen, argon or helium, the volume fraction of not less than 99.5%.

4.2 Oxygen. volume fraction of not less than 99.5%.

4.3 electrolyte 1. 0.5g of potassium iodide, add a little water to dissolve, add 4mL acetic acid solution (1 + 9), diluted with water to 1000mL, Load brown bottle, stored in a cool dark place, the use of a period not exceeding one month. Suitable halogen content of less than 60µg/mL, the small total nitrogen content At 100µg/mL, heavy metals (nickel, vanadium, lead) content is less than 500mg/kg of the sample.

4.4 electrolytic solution 2. 0.5g of potassium iodide, 0.6 g of sodium azide, dissolved in 500mL of water, adding 5mL of glacial acetic acid, diluted with water to 1000mL, loaded brown bottle, stored in a cool dark place, the use of a period not exceeding one month. Suitable halogen content of the sulfur content of less than 10 times, the total nitrogen content of less than 1000 times the sulfur content of heavy metals (nickel, vanadium, lead) content is less than 500mg/kg of the sample.

4.5 Standard substance. dibenzothiophene (C6H4C6H4S), thiophene (C4H4S) or dibutyl disulfide (C4H9C4H9S2), etc., the mass fraction of Not less than 98%.

4.6 solvent. iso-octane, n-heptane or hexadecane and the like. Sulfur-free solvent integrated value displayed under test conditions.