Quantitative Analysis of Gaseous BTEX Compounds

Determination of gaseous products (hydrocarbons from the BTEX group) released from the tested moulding sands was carried out using gas chromatography. The test methodology was consistent with the described patent [35 ] and the literature [8 ,36 (link),37 (link)]: gasses were released during pouring the measuring shapes with liquid metal adsorbed on a layer of activated carbon. The adsorbed products were eluted with diethyl ether ((C₂H₅)₂O) obtaining research material for the quantitative analysis of aromatic hydrocarbons. The amount of solvent needed to fully extract the compounds from the BTEX group of the gasses adsorbed on the column with activated carbon was 40 mL (in four cycles of 10 mL). The extracts obtained for individual samples were analysed by gas chromatography with a flame ionization detector FID according to the following process parameters: an initial temperature of 40 °C (3 min hold) was raised at 10 °C/min to 150 °C (5 min hold) using constant helium flow of 1 cm³/min during the whole analysis. The split ratio was 1:30 and the sample size was 1 µL. The separated gaseous products were identified using the Thermo Scientific TRACE Ultra gas chromatograph, equipped with a 30 m long RTX 5MS (ResteK, Bellefonte, PA, USA) chromatographic column with an internal diameter of 0.25 mm. The internal standard was a mixture of BTEX dissolved in diethyl ether prepared in the appropriate weight ratio.