GB/T 33647-2017Determination of silicon content in motor gasoline—Inductively coupled plasma optical emission spectrometry (ICP-OES) (English PDF)

Foreword

This Standard was drafted as per the rules specified in GB/T 1.1-2009.

1 Scope

This Standard specifies the test method of adopting the inductively coupled plasma optical emission spectrometry (ICP-OES) to determine the silicon content in motor gasoline.

This Standard is applicable to determine the silicon content of 1.0mg/kg ~ 50.0mg/kg in the motor gasoline (the volume fraction of oxygen-containing compounds shall not exceed 15%), such as motor gasoline containing methyl tert-butyl ether, motor methanol gasoline (M15) and motor ethanol gasoline (E10). For the motor gasoline sample with silicon content higher than 50.0mg/kg, it can be diluted by the isooctane with higher proportion, then determine according to this Standard method; but its precision has not been statistics yet.

When testing according to this Standard, some elements in the motor gasoline like sulfur, lead, iron, manganese, phosphorus and chlorine shall not interfere the determination results of the silicon content.

2 Normative References

The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) are applicable to this document.

GB/T 4756 Method for Manual Sampling of Petroleum Liquids

GB/T 17476 Standard Test Method for Determination of Additive Elements, Wear Metals, and Contaminants in Used Lubricating Oils and Determination of Selected Elements in Base Oils by Inductively Coupled Plasma Optical Emission Spectrometry

5 Apparatus

6 Reagents and Materials

6.1 Isooctane. analytically pure.

6.2 Silicon organic standard material. prepare or purchase the silicon organic standard solution with concentration no less than 500mg/kg; for instance, dilute the hexamethyldisiloxane with purity greater than 99% with isooctane, then prepare the 1000mg/kg silicon organic standard solution.

NOTE: for the motor gasoline sample with silicon content greater than 100mg/kg, it is more suitable to use hexamethyldisiloxane as standard material; while the base oil-based silicon organic standard solution may result in higher test results.

6.3 Argon, oxygen. purity no less than 99.995% (volume fraction).

6.4 10% (mass fraction) nitric acid solution.

6.5 Quality control (QC) sample. select the motor gasoline with the similar silicon content as to-be-tested motor gasoline as the quality control sample, it can also be obtained by diluting the proper amount of silicon organic standard material with isooctane. The quality control sample is recommended to seal in the glass bottle with threaded cap, and store in the dark at less than 10°C environment.

11 Test Procedures

11.2 The blank solution and specimen solution shall be measured for three repeated times. The average blank response value shall be subtracted from the signal response value of each specimen solution before determining the average response value of silicon in the specimen solution.

12 Result Calculation

The silicon content X [in (mg/kg)] in the motor gasoline sample shall be calculated by Formula (1).

Where:

Ic - average response value of silicon in specimen solution;

Ibk - average response value of blank solution;

S - standard curve slope (kg/mg);

Kg - mass dilution factor, namely, sample mass/ total mass of sample plus dilution solvent (g/g).

13 Quality Control

13.1 Determine the quality control sample's average value and control limit before use the quality control sample.

13.2 It is recommended to use quality control sample to check once every day when the sample is measured. When measuring large quantities of samples, increase the inspection frequency of quality control sample.

13.3 If the obtained results exceed the control limit, in order to ensure the accuracy of the test results, re-calibrate the instrument and re-measure the sample.

14 Precision