Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This regulation is a revision with respect to JJG 700-1999 Gas Chromatographs based on and according to JJF 1002-2010 The Rules for Drafting National Metrological Verification Regulation, JJF 1001-2011 General Terms in Metrology and Their Definitions, JJF 1059.1-2012 Evaluation and Expression of Uncertainty in Measurement and GB/T 30431-2013 Gas Chromatograph for Laboratory.
In addition to a number of editorial changes，the following technical changes have been made with respect to JJG 700-1999:
——The baseline noise and drift of flame photometric detector (FPD) are changed from both ≤ 5pA and ≤ 0.1 nA to ≤ 0.5 nA (see Table 1 in Chapter 3);
——Repeatability of qualitative measurement is added and error of the attenuator is deleted (see Table 1 in Chapter 3);
——Verification indexes of noise and drift with output signal of the electron capture detector in Hz are added (see Table 1 in Chapter 3);
——The purity of carrier gas is modified so that it shall meet the operation requirement of the instrument and shall be no less than 99.995 % in general (see 5.1.3);
——The maximum permissible error is added for the micrometer syringe (see 5.2.2);
——Temperature range and the maximum permissible error are added for platinum resistance thermometer (see 5.2.3);
——Measurement range and grade are added for the flowmeter (see 5.2.4);
——For the performance verification conditions for general purpose detectors, the temperature setting for TCD and FID gas verification column oven is changed from the previous 30℃ and 50℃ to 50℃ and 80℃ (see Table 4 in 5.4.4);
——The temperature of electron capture detector (ECD) is changed from the previous 230 ℃ to 250℃ (see Table 4 in 5.4.4);
——The sample injection times and measurement times of flow rate of carrier gas for detection limit verification are changed from the previous six times to seven times (see 5.4.2);
——The molar fraction of gas reference material used for the detection limit verification of the thermal conductivity detector (TCD) is changed from previous 1% mol/mol to (100 ~ 10,000) μmol/mol (see Table 2 in 5.2.1);
——The molar fraction of gas reference material used for the detection limit verification of the flame ionization detector (FID) is changed from previous 100 μmol/mol to (100 ~ 10,000) μmol/mol (see Table 2 in 5.2.1);
——The calibration of micrometer syringe in the previous Annex A is deleted and previous Annex B is changed to Annex A subsequently;
——The column temperature in the correction formula for carrier gas flow rate in Annex A is changed to detector temperature;
——Formula for conversion of molar fraction of gas reference material to concentration is added (see Annex B).
The previous editions of this regulation are as follows:
——JJG 700-1999;
——JJG 700-1990.
Verification Regulation of Gas Chromatographs
1 Scope
This regulation is applicable to initial verification, subsequent verification and in-service inspection of gas chromatographs equipped with thermal conductivity detector (TCD), flame ionization detector (FID), flame photometric detector (FPD), electron capture detector (ECD) and nitrogen phosphorous detector (NPD).
2 Overview
A gas chromatograph (hereinafter referred to as the instrument) is an instrument in which the sample is carried into the chromatographic column by a carrier gas, separated based on the distribution of sample components in the gas phase and stationary phase of chromatographic column as well as the different adsorption coefficients and tested with the detector. Qualitative and quantitative analysis is made according to retention time and response value of the components.
The instrument consists of the gas path system, sample injection system, separation system, temperature control system, detection system and data processing system.
3 Metrological Performance Requirements
Metrological performance of the instrument shall meet the requirements specified in Table 1.
Table 1 Metrological Performance Requirements for Gas Chromatographs
Verification item Metrological performance requirements
TCD ECD* FID FPD NPD
Stability of carrier gas flow rate (10min) ≤1% ≤1% 一 — —
Stability of column oven temperature (10min) ≤0.5%
Repeatability of temperature programming ≤2%
Baseline noise ≤0.1mV ≤0.2mV ≤1pA ≤0.5nA ≤1pA
Baseline drift
(30min) ≤0.2mV ≤0.5mV ≤10pA ≤0.5nA ≤5pA
Sensitivity ≥800mV·mL/mg — — 一 —
Detection limit ≤5pg/mL ≤0.5ng/s ≤0.5ng/s(S) ≤5pg/s(N)
≤0.1ng/s(P) ≤10pg/s(P)
Repeatability of qualitative measurement ≤1%
Repeatability of quantitative measurement ≤3%
* If the output signal of the instrument is expressed in Hz, the baseline noise shall be ≤5Hz and baseline drift (30 min) ≤20Hz.
4 General Technical Requirements
4.1 Appearance
The instrument shall be free of damages affecting its normal operation. The switches, knobs, or buttons shall be operable and controllable normally and the display of indicator light shall be clear and correct. The manufacturer name, model, serial number and date of manufacture shall be indicated on the instrument. Domestic instruments shall be provided with the mark and number of China Metrology Certification.
4.2 Gas Path System
Use leakage test fluid to test all the joints where the gas will pass from the gas source to the instrument under normal operating conditions, and there shall be free of leakage.
5 Control of Metrological Instruments
Metrology control of the instrument includes initial verification, subsequent verification and in-service inspection.
5.1 Verification Conditions
5.1.1 Verification environment conditions
Ambient temperature: (5 ~ 35) °C, relative environmental humidity: (20 ~ 85)%; flammable, explosive and corrosive substances that are not related to the test shall not be stored in the room where there shall be free of mechanical vibration or electromagnetic interference.
5.1.2 Instrument installation requirements
The instrument shall be fixed on the workbench in a stable and firm manner. The connectors of the cable shall be closely matched and well earthed. Stainless steel pipes or copper pipes are recommended for the gas path (of carrier gas and oxidant gas).
5.1.3 Carrier gas, fuel gas and oxidant gas
The purity of the carrier gas shall meet the requirements for the use of the instrument, and it is generally not less than 99.995%. Fuel gas and oxidant gas must not contain substances that affect the normal operation of the instrument.
5.2 Reference Materials and Equipment Used for Verification
Reference materials used for verification shall be those with certificate approved and issued by national metrological administration; the equipment used for verification shall pass the verification of the metrological authority.
5.2.1 Reference materials
See Table 2 for reference materials used for verification.
Table 2 Reference Materials Used for Verification
Name of reference material Content Related expanded uncertainty (k=2) Purpose Remark
Benzene - toluene solution 5mg/mL, 50mg/mL ≤3% TCD Liquid
Normal cetane - isooctane solution (10~1000)ng/μL FID
Methyl parathion - anhydrous ethanol solution 10ng/μL FPD
Azobenzene - malathion - isooctane solution Azobenzene 10ng/μL NPD
Malathion
Gamma hexachlorocyclohexane - isooctane solution 0.1ng/μL ECD
Methane in nitrogen (helium, hydrogen and argon) (100~10000)μmol/mol TCD Gas
(10~10000)/μmol/mol FID
5.2.2 Micrometer syringe
Measurement range: 10 μL, with the maximum permissible error of ±12%.
5.2.3 Platinum resistance thermometer
Temperature measurement range: no less than 300℃, with the maximum permissible error of ± 0.3 ℃.
5.2.4 Flowmeter
Measurement range of soap film flowmeter: (0 ~ 100) mL/min, with accuracy not inferior to Grade 1.5.
5.2.5 Barometer
Measurement range: (800 ~ 1,060) hPa, with maximum permissible error of ±2.0hPa.
5.2.6 Stopwatch
The minimum division value shall be no greater than 0.01s.
Introduction i
1 Scope
2 Overview
3 Metrological Performance Requirements
4 General Technical Requirements
4.1 Appearance
4.2 Gas path System
5 Control of Metrological Instruments
5.1 Verification Conditions
5.2 Reference Materials and Equipment Used for Verification
5.3 Verification Items
5.4 Verification Method
5.5 Treatment of Verification Results
5.6 Verification Period
Annex A Correction of Carrier Gas Flow Rate
Annex B Conversion of Molar Fraction of Gas Reference Materials to Concentration
Annex C Verification Record Format
Annex D Inside Page Format for Verification Certificate/Verification Result Notice
