SN/T 3321.2-2013Limestone and dolomite. Part 2: Determination of carbon and sulfur content. High frequency combustion with infrared absorption method (English PDF)

5.1 Methanol

5.2 Solvents. it is used to dissolve the polymer, AND it shall not contain any

interference which has the same retention time as that of the volatile component

to be measured. Typical polymer solvents include.

a) Dimethylformamide (DMF);

b) Dimethylacetamide (DMAC);

c) Propylene carbonate;

d) O-dichlorobenzene.

Note. The volatile contaminants in the solvent can be removed through an inert

gas purging for 24 h ~ 48 h.

5.3 Diluent. it is used to dilute and prepare the standard working solution of

volatile organic compounds, its retention time in the gas chromatography shall

be inconsistent with that of the substance to be measured, AND the commonly

used diluent includes.

a) Water;

b) n-Hexadecane.

5.4 Volatile organic standard sample. the highest concentrations available for

commercial analysis of volatile organic compounds by this method. Examples

of volatile organic compounds that may be present in the styrene polymer

package are as follows.

a) Styrene;

b) Acrylonitrile.

c) Butadiene;

d) Benzene;

Note. Suitable detectors include the following detectors.

a) Flame ionization detector (FID), which is used for the detection of

conventional organic volatiles;

b) Mass spectrometer (MSD), which is used for the detection of conventional

organic volatiles;

c) Electron capture detector (ECD), which is used for the detection of halides;

d) Nitrogen and phosphorus detector (NPD), which is used for the detection

of acrylonitrile.

6.2 Gas chromatographic column. Select a capillary gas chromatographic

column which can separate the components to be measured. As for the volatile

organic analysis of the styrene polymer package (1, 3-butadiene, acrylonitrile,

styrene, benzene, toluene, ethylbenzene, cumene), it is preferable to select HP-

INNOWA x 60 m x 0.32 mm (inner diameter) x 0.25 µm OR its equivalent.

6.3 Automatic headspace sampler. it is composed of the thermostatic sample

tray and the related accessories as required to reach to the requirements for

headspace vapour automatic sample injection.

6.4 Headspace bottle. 20 mL ~ 25 mL, with a rubber stopper gasket.

6.5 Syringe. it is calibrated; and the gas-tight syringes for headspace gas

chromatographic sample injection can be heated during sampling and injection

process.

6.6 Low-temperature freezing mill. with sieves of different apertures.

6.7 Constant temperature oven. it can maintain the temperature of 80 °C ~

6.8 Analytical balance. its sensitivity is 0.0001 g.

Note 1. AVOID contacting with heated portion of the chromatograph, such

as detectors, columns, sample trays, hot vials, etc.

Note 2. Once heated, pressure is created in the sample vial containing the

polymer volatile components. After analysis, it shall use the syringe to empty

the pressure in the vial.

8.1.3 Headspace analysis conditions

The headspace heating temperature and time conditions are selected in

accordance with 8.1.2. Other headspace conditions are dependent on the

instrument used. OPTIMIZE the relevant parameters to obtain stable analysis

results and large detection signal values. The typical headspace analysis

conditions are shown in Appendix A.

8.2 Calibration

8.2.1 Calibration with solvent dissolution

Accurately PIPETTE the standard working solution A of certain volume [5.6.b)]

into the headspace bottle; the pipetted solution volume shall be consistent with

the volume of the solvent which is used to dissolve the sample in 7.4; quickly

SEAL the headspace bottle; PREPARE for the headspace-gas

chromatographic analysis. The calibration curve shall contain at least 5 different

concentrations.

8.2.2 Calibration without solvent dissolution

USE the calibrated syringe (6.5) to pipette a certain volume (2.0 µL ~ 10.0 µL)

of standard working solution B [5.6.c)] to the bottom of the headspace bottle;

quickly SEAL the headspace bottle; PREPARE for the headspace-gas

chromatographic analysis. The calibration curve shall contain at least 5 different

concentrations.

8.2.3 If the substrate of the sample to be measured has a great influence on

the measurement results of some volatile organic compounds, USE the

aforementioned two methods for measurement; if the recovery rate of the

sample to be measured cannot reach to the analysis requirements, it is allowed

to use the standard addition method in the Appendix B for detection.

Note. The calibration method described above requires periodic and repeated

calibration of the standard sample, AND the repeated calibration period is

determined based on the stability status of the chromatograph.

8.3 Headspace sample injection

8.3.1 Automatic sample analysis

PLACE the calibrated sample as mentioned in 8.2 AND the tested samples as

prepared in 7.4 and 7.5 into the constant temperature sample tray of the

automatic headspace sample injector (6.3); SET the headspace analysis

conditions in accordance with 8.1.3; then RUN it.

APPENDIX A

(Informative)

Typical headspace-gas chromatographic conditions

A.1 Examples of typical gas chromatographic conditions

USE the measurement chromatographic conditions of the volatile organic

compounds in styrene polymer packages as an example, since the

measurement results are depending onto the instruments used, so it is not

possible to provide the universal parameters for gas chromatography. The set

parameters shall ensure that, during the chromatographic measurement, the

measured components and other components can be effectively separated; the

following parameters are proved to be feasible.

a) Chromatography column. HP-INNOWAX capillary column 60 m x 0.32 mm

(inner diameter) x 0.25 µm, or the...

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