METHODOLOGY FOR SAMPLING AND DETERMINING THE CONCENTRATION OF TOTAL VOLATILE METHYLSILOXANES IN GASES

Abstract

Methodology for sampling and determining the concentration of total volatile methyl siloxanes in gases, applicable to any gaseous phase likely to contain volatile molecules with silicon-oxygen and silicon-carbon bonds resulting from the decomposition of polydimethylsiloxane. The methodology is characterized by a first sampling stage where a gas flow is passed through a sealed sampling system; a second analytical stage carried out in the same sampling system involving a gas / liquid mass transfer process with a chemical reaction where volatile methyl siloxanes are absorbed in the liquid phase and converted to silicon dioxide (SiO2); and a third stage where specific chemical reactions for SiO2 are carried out, producing a color whose intensity is proportional to its concentration in the liquid phase.The concentration of SiO2 is subsequently quantified by spectrophotometry and, through material balances, the resulting concentration of SiO2 can be expressed in terms of milligrams of silicon (Si) per cubic meter of gas, or in terms of milligrams of total volatile methyl siloxanes per cubic meter of gas.