GB/T 7363-2021Test method for polynuclear aromatics in petroleum wax (English PDF)

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for Standardization Work Part 1. Structure and Drafting Rules of Standardization Documents" drafted.

This document replaces GB/T 7363-1987 "Test Method for Condensed Aromatic Hydrocarbons in Paraffin". Compared with GB/T 7363-1987, except for structural adjustment In addition to editorial changes, the main technical changes are as follows:

--- Added "scope", and the scope of application has added microcrystalline wax, fully refined paraffin wax and special packaging wax for food (see Chapter 1);

--- Added "normative references" (see Chapter 2);

--- Added "Terms and Definitions" (see Chapter 3);

--- Change the reagent purity to analytical grade (see Chapter 5, 3.2, 3.3, 3.8~3.13 of the 1987 edition);

--- Added reagent safety warning instructions (see Chapter 5);

--- Changed the control pressure of nitrogen (see 5.4, 2.12 of the 1987 edition);

--- Increased the initial amount of purified dimethyl sulfoxide (see 5.6);

--- Added chromatography silica gel reagents (see 5.16);

--- Quartz absorption cell optical path changed from 4cm to 5cm (see 6.2, 2.10 of the 1987 edition);

--- Increase the 24/40 interface of the glass container, adsorption column and condenser (see 6.4, 6.5 and 6.9);

--- Added provisions for the use of tetrafluoroethylene polymer sleeves and grease for vacuum distillation units (see 6.11);

--- Added pipettes, acid-resistant funnels, constant temperature ovens, standard sieves and water bath equipment (see 6.13~6.17);

--- Added the note for the analysis of the unqualified absorbance of dimethyl sulfoxide and the treatment method (see 7.3.3);

--- Changed the particle size of magnesium oxide (see 7.4.4, 4.4.4 of the 1987 edition);

--- Added "Sampling" (see Chapter 8);

--- Delete the description of the dripping of the displacement agent in the adsorption separation stage of the test procedure (see 9.2.3, 5.2.3 of the 1987 edition).

1 Scope

This document specifies the equipment, reagent materials, test preparation, sampling, test procedures and result report for the determination of fused-ring aromatic hydrocarbons in petroleum wax and so on.

This document applies to products such as food paraffin wax, food microcrystalline wax, fully refined paraffin wax and special packaging wax.

2 Normative references

The contents of the following documents constitute essential provisions of this document through normative references in the text. Among them, dated citations documents, only the version corresponding to that date applies to this document; for undated references, the latest edition (including all amendments) applies to this document.

GB/T 4756 Petroleum liquid manual sampling method

SH/T 0229 Sampling method for solid and semi-solid petroleum products

3 Terms and Definitions

The following terms and definitions apply to this document.

4 Method overview

Use dimethyl sulfoxide as solvent to extract aromatic hydrocarbons in petroleum wax, and then use isooctane to reverse extract aromatic hydrocarbons dissolved in dimethyl sulfoxide. Concentrate to the concentration equivalent to 1g of sample per milliliter of isooctane, measure its UV absorbance. If the absorbance value exceeds the specified limit value, then use Treated with sodium borohydride, adsorbed by magnesia-diatomaceous earth to separate the fused ring aromatic hydrocarbons, and then measure the UV absorbance. If the absorbance value is still greater than the specified the limit value, the report fails. The first or second absorbance measurement value is not greater than the specified limit value, and the report is passed.

5 Reagents and materials

Warning: Phosphoric acid is corrosive, isooctane, n-hexadecane, acetone, benzene and methanol are flammable, acetone and benzene are toxic, benzene is a carcinogen, sodium borohydride is a strong irritant, and the above reagents are harmful to health; be careful with nitrogen compressed gas under high pressure.

5.1 Distilled water: should meet the inspection index of 7.3.4. If necessary, it needs to be purified by ion exchange resin or by other suitable methods.

5.2 Phosphoric acid: analytically pure.