Simultaneous determination of triclosan，triclocarban and p-chloro-m-xylenol in disinfectant，personal care products and oiltment by nonaqueous capillary electrophoresis

Abstract

Triclosan （TCS）， triclocarban （TCC）， and p-chloro-m-xylenol （PCMX） are some of the most widely used antibiotics because of their broad-spectrum and highly-efficient bactericidal effects. In the context of disinfection， the National Standard GB 38598-2020 stipulates that the contents of the effective ingredients present in a disinfectant must be specified， wherein their range must fall within 90%-110% of the specified central value. To ensure a suitable product quality， analysis by high performance liquid chromatography （HPLC） is recommended by both the GB/T 27947-2020 and GB/T 34856-2017. However， the results analyzed according to the National Standard method often exceed the declared contents， thereby indicating the necessity to establish a new method based on a completely different principle （e. g.， capillary electrophoresis）， especially since it was not possible to analyze TCS， TCC， and PCMX in a single injection using the National Standard method. Moreover， using this method， large amounts of methanol were consumed， which could be potentially harmful to both operators and the environment. In terms of their water solubilities， this decreases in the order of PCMX>TCS>TCC， wherein TCC is insoluble in water. As such， the use of nonaqueous capillary electrophoresis （NACE） based on running buffer solutions prepared in pure organic solvents （e. g.， methanol or acetonitrile） is necessary. In this paper， a new NACE approach combined with an ultraviolet detection method was developed for the simultaneous analysis of TCS， TCC， and PCMX in disinfectants， personal care products， and ointments. For this purpose， an uncoated fused silica capillary （20 cm×50 μm， total length=30.2 cm） was used as the separation column with a separation buffer composed of 14 mmol/L sodium borate， 2 g/L polyethylene glycol （PEG） 20000， and 0.5 mmol/L dodecyltrimethylammonium bromide （DTAB） in methanol. Following optimization of the separation parameters， the complete and simultaneous separation of TCS， TCC， and PCMX was achieved when the sample solution was prepared using 5 g/L PEG 20000 in methanol-acetonitrile （50∶50， v/v）. It was possible to directly inject the sample into the analysis system after a simple dilution with the sample medium， and no interference was observed in any of the sample electropherograms when a separation voltage and detection wavelength of -12 kV and 214 nm were employed， respectively. Furthermore， TCS， TCC， and PCMX showed good linear relationships with their corrected peak areas within a mass concentration range of 1-100 mg/L， and the correlation coefficients （r） were all greater than 0.99. Moreover， the limits of detection （LODs， S/N=3） and limits of quantification （LOQs， S/N=10） were determined to be 0.2 and 1 mg/L， respectively. The spiked recoveries ranged from 94.5% to 104.4% with relative standard deviations of ≤4.8% in all cases. Subsequently， the established method was used to analyze 31 commercial samples， including hand sanitizer， disinfectant， baby powder， and antibacterial cream. A comparative analysis of HPLC， the developed NACE method， and our previously reported micellar electrokinetic chromatographic （MEKC） method was also carried out for the quantitative determination of TCS， TCC， and PCMX. Although no statistically significant differences were observed among the three methods， the results determined for 16 out of the 31 samples did not match the claimed contents. These results therefore indicate the necessity to further control the compositions of disinfectant products. Our results indicate that the newly established NACE method can be an important alternative to HPLC for routine laboratory analyses， especially considering that it minimizes waste generation， requires only a simple sample pretreatment process， and exhibits a good selectivity to the target compounds. It is therefore hoped that the NACE method will be incorporated into the National Standard method in the near future.