BS ISO 23322:2021 pdf download – Paints and varnishes — Determination of solvents in coating materials containing organic solvents only — Gas-chromatographic method
6.1.4 Detector6.1.4.1General
One of the following two detectors shall be used. spectrometer (MS) or other mass-selective detector (MSD)
To prevent condensation, the detector temperature shall be at least 10 K above the maximum oventemperature. ionization detector
The flame ionization detector (FID) is operated at temperatures between 230 °C and 300°C.To preventcondensation, the detector temperature shall be at least 10 K above the maximum oven temperature.The detector gas supply, injection volume, split ratio and gain setting shall be optimized so that thesignals (peak areas) used for the calculation are proportional to the amount of substance.
6.1.5 Capillary separation column
The column shall be made of glass or fused silica.Columns of sufficient length to resolve volatiles andof maximum internal diameter 0,32 mm, of a suitable polarity and with a suitable film thickness shallbe used.
6.1.6Analytical system performance criteria
The analytical system performance criteria shall be demonstrated.The resolution,R, of the peaks to beseparated shall be at least 1,5.
For the compounds under investigation it has to be ensured that the sample concentration lies withinthe quantification range of the analytical system.
NOTE The limit of quantification can deviate for single compounds. If necessary, the compound specific limitof quantification can be determined for the considered single compound[s).
6.2Injection syringe
The injection syringe for hot or cold injection systems shall have a capacity of at least twice the volumeof the sample to be injected into the gas chromatograph.
6.3 Data processing
Suitable software shall be used for integration, calibration, quantification and other data handlingprocesses.
6.4Sample vial
A suitable sample vial is one made of chemically inert material, for example glass, which can be sealedfor example with a rubber membrane having a coating of poly(tetrafluoroethylene) (PTFE).The vesselshall be filled to about 90 % of capacity.
7 Reagents
7.1 General
Table 1 shows a non-exhaustive list of an internal standards and extraction solvents.
7.2Internal standard
The internal standard should be a compound which is not present in the sample and is completelyseparated from the other components in the chromatogram. It shall be inert with respect to the sampleconstituents, stable in the required temperature range, and of known purity. The preferred internalstandard is DEA.
NOTE lf DEA is not suitable as internal standard, internal standards such as glycol ethers can be suitable.
7.3.1 Carrier gas: Dry oxygen-free helium, nitrogen or hydrogen having a purity of at least 99,995 %(volume fraction).
7.3.2 Detector gases: Hydrogen having a purity of at least 99,995 % (volume fraction) and (synthetic)air-free of organic compounds.
7.3.3 Auxiliary gas: Nitrogen or helium of the same quality as the carrier gas.
Suitable filters shall be installed in the gas chromatograph connection pipes to adsorb residualimpurities (see the gas chromatograph operating instructions).
7.4Calibration substances
The solvent used for the calibration shall have a purity of at least 99 %(mass fraction) or shall be ofknown purity.
7.5 Extraction solvent
For better handling of the direct injection,the sample may be diluted with suitable extractionsolvents (e.g. acetone, CAS-No 67-64-1,methanol,CAS-No 67-56-1, acetonitrile,CAS-No 75-05-8 ortetrahydrofuran,CAS-No 109-99-9). The extraction solvents shall have a purity of at least 99 %(mass fraction) or be of known purity and shall not contain any substances which interfere with thedetermination by for example causing overlapping peaks in the chromatogram. Always carry out aseparate run injecting the solvent alone in order to observe contaminants and possible interferencepeaks, especially in trace analysis.
The suitability of a solvent or solvent mixture other than acetone, methanol and THF shall be checked by determining the recovery rates of analytes from the sample under investigation.
8 Sampling
Take a representative sample, as described in ISO 15528.
9 Choice of sample injection system
The choice between hot injection, cold injection and headspace injection depends on the type of the product under test. It will be necessary to use the cold injection system for products which at high temperature release substances which interfere with the determination.BS ISO 23322 pdf download.