Determination of the four major surfactant classes in cleaning products by reversed-phase liquid chromatography using serially connected UV and evaporative light-scattering detection

Use of nitrate, sulphate, and iron (III) as electron acceptors to improve the anaerobic degradation of linear alkylbenzene sulfonate: effects on removal potential and microbiota diversification

Linear alkylbenzene sulfonate (LAS) is a synthetic anionic surfactant that is found in certain amounts in wastewaters and even in water bodies, despite its known biodegradability. This study aimed to assess the influence of nitrate, sulphate, and iron (III) on LAS anaerobic degradation and biomass microbial diversity. Batch reactors were inoculated with anaerobic biomass, nutrients, LAS (20 mg L-1), one of the three electron acceptors, and ethanol (40 mg L-1) as a co-substrate. The control treatments, with and without co-substrate, showed limited LAS biodegradation efficiencies of 10 ± 2% and 0%, respectively. However, when nitrate and iron (III) were present without co-substrate, biodegradation efficiencies of 53 ± 4% and 75 ± 3% were achieved, respectively, which were the highest levels observed. Clostridium spp. was prominent in all treatments, while Alkaliphilus spp. and Bacillus spp. thrived in the presence of iron, which had the most significant effect on LAS biodegradation. Those microorganisms were identified as crucial in affecting the LAS anaerobic degradation. The experiments revealed that the presence of electron acceptors fostered the development of a more specialised microbiota, especially those involved in the LAS biodegradation. A mutual interaction between the processes of degradation and adsorption was also shown.

Alcohol ethoxysulfates (AES) in environmental matrices

Extensive use of surfactants in numerous fields resulted in their discharge into various environmental compartments including soil, sediment, and water. Alcohol ethoxysulfates (AES) together with alcohol ethoxylates (AE), alkyl sulfates (AS), and linear alkyl benzene sulfonates (LAS) find wide variety of applications in consumer products including both domestic and industrial applications. Consequently, all these surfactants pose several concerns to both aquatic and human health. In the context of environmental impacts, AES has almost equal importance as that of LAS though the literature on this topic is only emerging. This review provides a detailed overview on the various aspects of the anionic surfactant, AES, such as toxicity of AES, its fate in the ecosystem, technical advancements in the area of identification and quantification, its occurrence and distribution in different environmental compartments spanning across the world, and finally a remark of its potential removal strategy from the environment.

Performance evaluation of two trickling filters removing LAS and caffeine from wastewater: Light reactor (algal-bacterial consortium) vs dark reactor (bacterial consortium)

Micropollutant removal efficiencies of two trickling filters - operated under light and dark conditions were studied and compared. Linear alkylbenzene sulphonate (LAS) and caffeine were selected as model micropollutants. Both lab-scale trickling-filter type reactors were packed with polyurethane foam sponge cubes (2 cm × 2 cm × 2 cm) with 40% occupancy. The trickling filter with the white color LED light was named as Light Reactor (LR), which was operated under light: dark cycle of 12:12 h with a quantum flux of 15 μmoles/m²/s. No light was provided in the other trickling filter, named Dark Reactor (DR). Synthetic wastewater containing glucose (250 mg/L), LAS (12 mg/L), and caffeine (0.05 mg/L) was fed to the reactors at a hydraulic retention time (HRT) of 12- and 8-h at 25 °C for 2 months. The C, N, and P removal at 12-h HRT were 85%, 15%, and 49%, respectively, in LR, the corresponding values in DR were 88%, 18%, and 43%. Similarly, at 8-h HRT 90%, 24%, and 37% was observed in LR and 84%, 19%, and 37% in DR. However, the LAS and caffeine removal decreased from 99 to 96% and 96 to 86% respectively in LR, and from 96 to 79% in DR with decreasing the HRT from 12 to 8-h. The number of LAS degraders in LR (5.5×10⁴ CFU/sponge cube) was higher compared to DR (2.2×10⁴ CFU/sponge cube) at 8-h HRT. The above results indicate that algal-bacterial symbiotic relationship in LR was beneficial for carbon and micropollutants removal from domestic wastewater.

Determination of bisphenol analogues in food-contact plastics using diode array detector, charged aerosol detector and evaporative light-scattering detector

Freshness protection packages and preservative films are widely used food-contact plastic made of polyethylene. Diode array detector (DAD), charged aerosol detector (CAD) and evaporative light-scattering detector (ELSD) were evaluated for determination of 6 bisphenols (bisphenol A, bisphenol S, bisphenol F, bisphenol B, bisphenol AF and tetrabromobisphenol A.) in polyethylene. DAD presented better parameters including limit of quantification (LOQs) ranging from 0.05 to 0.5 μg/g with relative standard deviations (RSDs, n = 5) lower than 1% at two concentration levels. CAD and ELSD are universal detectors with relative consistent response parameters for different analogues which have potential application by using single calibrant for quantification of multiple analytes. Matrix effects were barely observed on three detectors. Samples of freshness protection packages and preservative films were further analyzed and preliminary profiles of bisphenols in products from Beijing market was obtained. Bisphenol S have become most abundant analogue instead of bisphenol A in investigated products.

Evaluation of surfactant removal efficiency in selected domestic wastewater treatment plants in Poland

The aim of this study was to evaluate the work of a two types of household sewage treatment plant: wetland wastewater treatment plant (ORS type) and treatment plant of SBR type (SBR-K-6 type). Physicochemical analyses of selected pollution indices (BOD₅, COD, total suspension, total phosphorus) and surfactants were carried out and compared with currently applicable values of such indexes according to the Regulation of the Minister of the Environment in Poland on the conditions to be met when discharging sewage into water or soil, and on the substances particularly harmful to the aquatic environment. The removal efficiency of organic compounds, expressed as COD and BOD₅, reached the threshold of 90%, which is required in regulations. In contrast, the effects of removal of biogenic compounds were low - in case of total nitrogen the removal rate reached approx. 40% and the desired admissible concentration of 30 mg N/L was not achieved. The reduction efficiency of total suspended solids reached 57.0 and 59.6% for the ORS and SBR-K-6 type objects, respectively, and therefore the required threshold of minimum 90% was not reached. Anionic surfactants were removed by up to 98 and 88% in the ORS and SBR-K-6 type wastewater treatment plants, respectively. Lower removal efficiency was achieved in case on non-ionic surfactants, which reached 76% for the ORS type object and 56% for the SBR-K-6 type object. This article proven high wastewater treatment efficiency and lower than necessary concentrations in the effluent from domestic wastewater treatment plants may be achieved mainly by proper exploitation of the devices and appropriately selected vegetation.

Determination of Propionylbrassinolide and Its Impurities by High-Performance Liquid Chromatography with Evaporative Light Scattering Detection

The discovery of brassinolide in 1979, a milestone in brassinosteroids research, has sparked great interest of brassinolide analogs (BLs) in agricultural applications. Among these BLs, propionylbrassinolide has captured considerable attention because it shows plant growth regulating activity with an excellent durability. Two impurities of propionylbrassinolide were isolated and purified by semi-preparative high-performance liquid chromatography (HPLC), and the chemical structures were confirmed. For simultaneous separation and determination of propionylbrassinolide and impurities, an efficient analytical method based on HPLC with evaporative light scattering detector (HPLC-ELSD) was developed. The optimized analysis was performed on a C18 reversed phase column (250 mm × 4.60 mm, 5 μm) with isocratic elution of acetonitrile and water (90:10, v/v) as the mobile phase. The drift tube temperature of the ELSD system was set to 50 °C and the auxiliary gas pressure was 150 kPa. The regression equations demonstrated a good linear relationship (R² = 0.9989-0.9999) within the test ranges. The limits of detection (LODs) and quantification (LOQs) for propionylbrassinolide, impurity 1 and 2 were 1.3, 1.2, 1,3 and 4.3, 4.0, 4.2 mg/L, respectively. The fully validated HPLC-ELSD method was readily applied to quantify the active ingredient and impurities in propionylbrassinolide technical concentrate. Moreover, the optimized separation conditions with ELSD have been successfully transferred to mass spectrometry (MS) detector for LC-MS determination.

Determination of Dodecanol and Short-Chained Ethoxylated Dodecanols by LC-MS/MS (with Electrospray Ionization) After Their Derivatization (with Phenyl Isocyanate)

Abstract

This report describes the application of LC-MS/MS for the separation of dodecanol (C₁₂OH) and homogenous fatty alcohols ethoxylated (AE) containing a dodecyl moiety and 1-9 ethoxy groups. These ethoxylates and free alcohol were derivatized for LC-MS/MS analysis with phenyl isocyanate (PIC). The derivatives of analytes with PIC were separated using a C18 column. Gradient elution with a mixture of ethyl acetate and acetonitrile (5 mM) was employed. The described determination method is characterized by low detection limits (range from 0.005 µg L^-1 for: C₁₂OH, C₁₂EO_2-7 to 1 µg L^-1 for C₁₂EO₁) and quantification limits (range from 0.01 µg L^-1 for: C₁₂EO_5-7 to 2 µg L^-1 for C₁₂EO₁). The developed and validated method was used in combination with liquid-liquid extraction (using ethyl acetate) in order to identify and quantitatively determine the C₁₂OH and C₁₂EO_1-9 present in environmental samples collected from Warta river water in Poznan.

Graphical abstract

Self-Assembled Curved Macroporous Photonic Crystal-Based Surfactant Detectors

Surfactants are extensively used as detergents, dispersants, and emulsifiers. Thus, wastewater containing high-concentration surfactants discharged to the environment pose a serious threat to the ecosystem. Unfortunately, conventional detection methods for surfactants suffer from the use of sophisticated instruments and cannot perform detections for various surfactants by a single analysis. The article reports the development of simple and sensitive surfactant detection using doctor-blade-coated three-dimensional curved macroporous photonic crystals on a cylindrical rod. The photonic crystals exhibit different hydrophobicities at various angular positions after surface modification. The penetration of aqueous surfactant solutions in the interconnected macropores causes red-shift as well as reduction in amplitude in the optical stop bands, resulting in surfactant detection with visible readout. The correlation between the surface tension, as well as the solution-infiltrated angular position, and the concentration of aqueous surfactant solutions has also been investigated in this study.