Sodium dodecylbenzen sulfonate (DBS) and linear alkylbenzene sulfonate (LAS) are widely used in dishwashing products. Residual levels of these surfactants are commonly found on the surfaces of dishware following dishwashing. Residual surfactants and detergents can act as potential toxicants and may pose health risks. This study explored the applicability of dielectric barrier discharge plasma (DBDP) for the degradation of residual surfactants in order to minimize their harmful effects. The plasma was generated using 10 kV pulsed DC power supply at different input currents (2.0-3.0 A) and at various inter-electrode gaps (2.0-3.0 mm). Under simulatory treatment conditions, diluted surfactants (DBS and LAS) and DBS-containing dishwashing detergents dispersed on slide glasses were exposed to DBDP for predetermined periods of time. Results indicated that, under optimal treatment conditions of 3.0 A current and 2.0 mm inter-electrode gap, tested surfactants and surfactants in detergents were degraded in the range of 60- 70% following the plasma treatment for 120 min. Modeling of degradation kinetics indicated that Weibull distribution was the best-fit model, and decimal degradation times (δ) were calculated. Pure surfactants were degraded at relatively higher level than surfactants in detergents. Among these anionic surfactants, DBS was more rapidly degraded than LAS by plasma treatment.

Residual detergents and surfactants on utensils have brought about health issues because they can be absorbed to human digestion system together with containing foods. In the present study, a dielectric barrier discharge plasma (DBDP) was used to explore the applicability of non-thermal plasma for the degradation of residual surfactants and dishwashing detergents in order to reduce the intake of the residues remaining on utensils as the result of incomplete rinsing during dishwashing procedures. DBDP was generated at current intensity 2.0 - 3.0 A, and electrode gap 2.5 mm. Diluted dishwashing detergents and surfactants were spotted on slide glasses and exposed to DBDP for different periods of time. The results indicated that the dishwashing detergents and surfactants were degraded by 46.9 - 84.3% after up to 120 min treatments. Weibull equation was the best fit model to the degradation patterns of surfactants, and the decimal degradation time(δ) of 180.2 - 688.9 min were observed according to currents. Surfactants contained in detergents were degraded more effectively than the surfactants themselves. Among the anion surfactants, DDBS was more rapidly degraded than LAS and ABS.

In this study, we developed and validated microanalysis methods for the determination of linear alkylbenzenesulfonate (LAS), sodium lauryl sulfate (SLS), and alpha olefin sulfonate (AOS). The conditions for the analysis of the surfactants using HPLC with FLD, RID, and ELSD detectors were investigated. The methods were validated by determining the linearity, limits of detection (LODs), limits of quantification (LOQs), recovery, precision, and accuracy. LAS analysis by FLD revealed calibration curves that were linear in the range of 10-200 mg/L for an LAS mixture. The calibration curves for C10-C13 had correlation coefficients of 0.995, 0.997, 0.996, and 0.997, respectively. SLS analysis using RID generated a linear calibration curve in the range of 10-300 mg/L. The calibration curve for SLS C12 had a correlation coefficient of 0.9994. AOS analysis using ELSD resulted in a correlation coefficient of 0.9940. For LAS, the LODs and LOQs were 0.09-0.56 and 0.30-1.87 mg/L, respectively. For SLS C12, the LOD and LOQ were 0.07 and 2.33 mg/L, respectively. For AOS C14, the LOD and LOQ were 16.55 and 21.83 mg/L, respectively. The recoveries were 97.17-98.84% for LAS C10-C14, 97.94% for SLS C12, and 96.11% for AOS C14. The established methods provide acceptable precision and accuracy. Our methods could be useful for the detection of anionic surfactants in dishwashing detergents.