Fluorescent whitening agents in commercial detergent: A potential marker of emerging anthropogenic pollution in freshwater of Bangladesh

Abstract

Fluorescence whitening agents (FWAs), popular optical brighteners, are extensively used in commercial detergents to increase brightening of washed products. This study characterizes FWA in commercial detergents and quantifies its residue in sewerage linked lakes and the Ganges River water using three dimensional excitation emission matrix (3DEEM) fluorescence and Parallel Factor (PARAFAC) analysis. Concentrations of FWA in commercial detergents were varied between 0.57–12.84 mg/g, which was 0.23–5.14 times higher than the usage guideline of FWA in commercial and household detergents. Most of the detergents used DSBP, but some low priced detergents might not be used any FWA. Photodecay method was used for FWA analysis to circumvent the interferences of natural organic matter (NOM) and it showed about 12–23 times and 2–8 times higher values than the detection limit in lakes and the Ganges River water, respectively. DSBP (4,4'-bis(2-sulfostyryl) biphenyl disodium salt) concentration was ranged between 4.7–10.42 μg/L and 0.4995–2.59 μg/L in lakes and the Ganges River water, respectively and DAS1 (Disodium 4,4’-bis[(4-anilino-6-morpholino-1,3,5-triazin-2-yl)amino]stilbene-2,2’-disulfonate) concentration was insufficient to detect due to its rapid signal reduction under photo-irradiation and also interferences of NOM during fluorescence measurement. FWA concentration in the Ganges River was higher in the monsoon than pre monsoon and post monsoon. Seasonal variability of FWAs in the Ganges River might be related to high terrestrial derived input of organic matter into the river channel during monsoon. This study confirmed the potential ability of 3DEEM–PARAFAC to monitor FWA in freshwater as an anthropogenic molecular marker.