ISO 2561:2012 pdf download.Plastics- Determination of residual styrene monomer in polystyrene (PS)and impact-resistant polystyrene (PS-I) by gas chromatography.
ISO 2561 specifies a method for the determination of the residual styrene monomer in polystyrene (PS) and impact-resistant polystyrene (PS-I) by gas chromatography. It may also be used for the simultaneous determination of other volatile aromatic hydrocarbons in PS and PS-I.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 472, Plastics — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 apply.
4 Principle
The polymer sample is dissolved in solvent, which for polystyrene contains an internal standard. Either a small volume of the polymer solution is injected directly into a gas chromatograph (method A) or a small volume of the supernatant solution remaining after precipitation of polymer by addition of a precipitator is injected (method B), in order to obtain separation of styrene and other volatile materials. Method A is simple and has much the same accuracy as method B. However, there is a possibility that contamination of the injector with polymer and oligomers will occur over time, leading to erroneous results.
5 Reagents and materials
5.1 Internal standard
The internal standard shall be selected based on consideration of the retention times of the materials contained in the polymer sample and solvent. Recommended candidates are n-butylbenzene, cyclopentanol, 1,2,4-trimetylbenzene and 1,4-diethylbenzene of sufficient purity for analytical use.
5.2 Solvent
Use analytical-grade dimethylformamide, butanone, dichioromethane or tetrahydrofuran. Tetrahydrofu ran is used for only method A.
5.3 Precipitator
Use analytical-grade 2,2,4-trimethylpentane or ethanol.
5.4 Aromatic hydrocarbons
Use analytical-grade styrene and (if required) other aromatic hydrocarbons such as ethylbenzene, cumene
or a-methylstyrene. Styrene shall give a clear mixture when mixed with an equal volume of ethanol.
5.5 Carrier gases and fuel gases for gas chromatograph
Use helium or nitrogen as carrier gas. Use hydrogen and air as fuel gases.
6 Apparatus
6.1 General
Normal laboratory equipment and the following apparatus are required. Typical operating conditions are described in Annex A.
6.2 Gas chromatograph
6.2.1 Injection port: Use an injection port for liquid samples. When using an open tubular column (hereafter called an OT column), an injection port with splitter may be applicable.
6.2.2 Column: The column diameter and length, as well as the packing material and liquid phase, shall be selected based on consideration of column resolution and calibration curve linearity. Both packed columns and OT columns are acceptable. OT columns are recommended in the light of accuracy.
6.2.3 Detector: Use a hydrogen flame ionization detector (FID).
6.3 Data processor
Use a recorder or microcomputer to record the signals from the detector.ISO 2561 pdf download.