Identifications and characteristics of organic ultraviolet filters in indoor air

Background  Organic ultraviolet (UV) filters are widely used in personal care products. So far, relevant studies on organic UV filters in indoor dust have been reported.

Objective  This study aims to establish a thermal desorption combined with gas chromatography-mass spectrometry (TD-GCMS) method to identify organic UV filters in indoor air collected from different indoor environments, so as to reveal the pollution levels and characteristics of organic UV filters in indoor environment.

Methods  Based on the standard indoor air sampling protocol, a total of 60 samples were collected from eight different kinds of indoor environments (male and female dormitory rooms, offices, labs, barber shops, printing shops, hotels, and private cars) on and nearby Minhang Campus of Shanghai Jiao Tong University from August to November, 2020. The concentrations of six common organic UV filters, including homosalate (HMS), 2-ethylhexyl salicylate (EHS), 3-(4-methylbenzylidene)-camphor (4-MBC), isoamyl 4-methoxycinnamate (IMC), octocrylene (OC), and octyl 4-methoxycinnamate (EHMC), in the air of different indoor environments were detected by TD-GCMS. Furthermore, the correlations of individual organic UV filters in different indoor environments were analysed.

Results  Under optimized detection conditions, the correlation coefficients of the quantitative standard curves of selected six organic UV filters were all at or above 0.997. The relative standard deviations of 1 mg·L⁻³ samples ranged from 1.74% to 7.11%, and the recoveries ranged from 67.17% to 106.5%. The relative standard deviations of 10 mg·L⁻³ samples ranged from 3.59% to 8.76%, and the recoveries ranged from 78.80% to 126.60%. The detection rates of the other five organic UV filters except IMC were all at or more than 92% in eight different kinds of indoor air. The median concentration of total organic UV filters was 75.17 ng·m⁻³, and EHS presented the highest median concentration of 28.55 ng·m⁻³. Regarding different indoor environments, the highest concentration of total organic UV filters was found in the female dormitory samples, 154.98 ng·m⁻³. The respective pair-analysis among HMS, EHMC, OC, and EHS of all indoor air samples reached a significant level of correlation (r=0.40-0.61, P<0.01).

Conclusion  The TD-GCMS method is satisfactory for the determination of organic UV filters in indoor air. EHS, EHMC, HMS, OC, and 4-MBC are identified in selected eight indoor environments, and they may have similar sources of pollution.