| Popis: |
Sulfonate surfactants are too polar to be directly determined by gas chromatography (GC) and so derivatization chemistry (sulfonyl chloride formation, silylation and pyrolytic methylation) of these analytes is necessary. Pyrolytic methylation, rarely applied to sulfonates, was chosen due to its simple sample preparation and the derivatization happening in the GC injection port. In this work, application of pyrolytic methylation to sulfonate surfactants was tried, but poor reproducibility was found explaining the limited literature on this topic. Sulfate surfactants can be indirectly detected through GC-MS by its degradation products formed in the injection port. Straight chain alkyl sulfates were analyzed with success based on the expected alcohol product. Sodium laureth sulfate (SLS), an alkyl ethoxylated sulfate and important commercial detergent, has apparently not been previously considered for GC-MS detection. It was found that 1-dodecanol is the primary degradation product of interest. However, dimethyl sulfate and 1-dodecene were investigated as quantitative markers for linearity studies from SLS chromatograms and reproducibility. The method was then applied to a real-world dishwashing liquid sample to qualitatively determine SLS through ion exchange extraction. The presence of the zwitterionic surfactant lauramine oxide in this commercial product was deemed a potential interference through dodecene formation upon GC-MS analysis. |
