A method for the qualitative and quantitative characterization of waterborne organosilicon substances

A novel method has been developed for the qualitative and quantitative characterization of (a) waterborne organosilicon substances, which are present as low‐molecular‐weight silanols (such as silicone hydrolysis products), and (b) higher‐molecular‐weight materials (e.g., silicones), which can be caused to undergo hydrolysis to yield such low‐molecular‐weight silanol‐functional materials. This method is capable of good to excellent accuracy and precision in the parts per million range and, with suitable precautions, has the potential for extension to determinations in the low parts per billion range. Although particularly valuable for the analysis of water‐soluble species, this method can also be adapted to yield useful information concerning water‐insoluble organosilicon materials present in aqueous systems, such as colloidal suspensions, surface films, or sedimentary slurries. Because of its inherent sensitivity and selectivity, this method constitutes a valuable tool for measuring and characterizing the silicone content of industrial and municipal waste waters, surface and ground waters, foods and biological tissues, etc. The determination of water‐soluble organosilanol species is accomplished by the acid‐catalyzed trimethylsilylation of the silanol functionality with hexamethyldisiloxane (HMDS) followed by gas‐liquid chromatographic assay of the resulting HMDS extract. Water‐insoluble components are determined by subjecting the sample to acidic predigestion before the addition of the HMDS‐derivatizing and extracting reagent. The possibility of dimethyl‐ or monomethyl‐silicon artifacts arising from inadvertent trace cleavage of methyl groups from the HMDS can be determined and/or precluded by the use of hexaethyldisiloxane or perdeutero‐HMDS when appropriate.