Determination of δ-hexadecansultone in sodium α-olefinesulphonates and liquid detergents using gas chromatography-mass spectrometry (GC/MS)

Sultones are cyclic esters of hydroxysulfonic acids, which are formed in the process of sulfonation of α-olefins with sulfur trioxide gas. More stable sultones may be present in the final product — an anionic surfactant — sodium α-olefin sulfonate (AOC-Na). AOC-Na is widely used in the production of household chemicals and cosmetic products, including liquid dishwashing detergents. Sultones are strong skin sensitizers, their level in AOC-Na should be strictly controlled and not exceed 5 ppm. Operational and strict control of the sultone content upon AOC-Na production allows timely adjustment at the stage of hydrolysis, which leads to a more complete disclosure of the sultone cycle with the formation of the corresponding olefin sulfonates and hydroxyalkanesulfonates. We propose a method for determining δ-hexadecansultone in liquid dishwashing detergents and sodium α-olefinsulfonates obtained on the basis of α-olefins of C₁₄ – C₁₆ fractions using GC/MS, which provides shortening of sample preparation and keeps the sensitivity with a detection limit of 0.02 mg/kg. The effect of various weakly polar and non-polar organic solvents used for Sultone extraction from AOC-Na and liquid detergent on liquid extraction based on the dispersion of the extractant in an alcohol/water phase is studied. When selecting the solvent we have shown that the use of diethyl ether provided the best extraction of the analyte. Determination of the analyte extraction recovery was performed using the reaction of hydrolysis of the extracted mixture. We specified the operating mode of the device which provided complete separation of the components of the analyzed compounds including the samples of liquid detergent for dishes being a multicomponent mixture of complex composition.

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