Solid phase microextraction procedure for the determination of alkylphenols in water by on-fiber derivatization with N-tert-butyl-dimethylsilyl-N-methyltrifluoroacetamide

Environmental risks and toxicity of surfactants: overview of analysis, assessment, and remediation techniques

This work comprehensively reviewed the toxicity and risks of various surfactants and their degraded products in the environmental matrices, various analytical procedures, and remediation methods for these surfactants. The findings revealed that the elevated concentration of surfactants and their degraded products disrupt microbial dynamics and their important biogeochemical processes, hinder plant-surviving processes and their ecological niche, and retard the human organic and systemic functionalities. The enormous adverse effects of surfactants on health and the environment necessitate the need to develop, select, and advance the various analytical and assessment techniques to achieve effective identification and quantification of several surfactants in different environmental matrices. Considering the presence of surfactants in trace concentration and environmental matrices, excellent analysis can only be achieved with appropriate extraction, purification, and preconcentration. Despite these pre-treatment procedures, the chromatographic technique is the preferred analytical technique considering its advancement and shortcomings of other techniques. In the literature, the choice or selection of remediation techniques for surfactants depends largely on eco-friendliness, cost-implications, energy requirements, regeneration potential, and generated sludge composition and volume. Hence, the applications of foam fractionation, electrochemical advanced oxidation processes, thermophilic aerobic membranes reactors, and advanced adsorbents are impressive in the clean-up of the surfactants in the environment. This article presents a compendium of knowledge on environmental toxicity and risks, analytical techniques, and remediation methods of surfactants as a guide for policymakers and researchers.

Development of a fabric phase sorptive extraction with high-performance liquid chromatography and ultraviolet detection method for the analysis of alkyl phenols in environmental samples

A novel analytical method has been developed and validated for the quantification of alkyl phenols in aqueous and soil samples. Fabric phase sorptive extraction, a new sorptive microextraction technique, has been employed for the preconcentration of some endocrine-disruptor alkylphenol molecules, namely, 4-tert-butylphenol, 4-sec-butylphenol, 4-tert-amylphenol, and 4-cumylphenol, followed by high-performance liquid chromatography with ultraviolet detection. Various parameters influencing the fabric phase sorptive extraction performance, namely, extraction time, eluting solvent, elution time and pH of the sample matrix, were optimized. The chromatographic separation was carried out with a mobile phase of acetonitrile/water (60:40 v/v) at an isocratic flow rate of 1.0 mL/min using a reversed-phase C₁₈ column at λ_max 225 nm. The calibration curves of target analytes were prepared in the concentration range 5-500 ng/mL with good coefficient of determination values (R² > 0.992). Extraction efficiency values were 74.0, 75.6, 78.0, and 78.3 for 4-tert-butylphenol, 4-sec-butylphenol, 4-tert-amylphenol, and 4-cumylphenol, respectively. The limits of detection range from 0.161 to 0.192 ng/mL. Subsequently, the new fabric phase sorptive extraction with high-performance liquid chromatography and ultraviolet detection was successfully applied for the recovery of alkyl phenols from spiked ground water, river water, and treated water from a sewage treatment plant, and soil and sludge samples.

Internally heated membrane interfaced to a gas chromatography flame ionization detector

Volatile Organic Compounds (VOCs) mixtures in aqueous solutions have been investigated using a simple and efficient all-in-one on-line sampling, isolation, enrichment and pre-concentration internally heated membrane connected to a gas chromatography flame ionization detector (GC-FID). In our previous study with the internally heated membrane, no GC column was used in the instrument. In this new study, we introduce a GC column in the instrument design and this makes it possible for mixtures to be investigated. This new experimental design enabled high resolution separation of analyte mixtures capable of being adsorbed, diffused, and desorbed from the device for detection with an FID. With the new design we present data from investigation of competitive adsorption effects on the membrane. The data showed that analyte adsorption and diffusion onto the membrane can be affected when mixtures of analytes are introduced. The application of multiple linear regressions approach to the data enabled us to correct for the problem of competitive adsorption. Analyte adsorption and diffusion was affected by the diffusion coefficients of the analytes; the higher the diffusion coefficient the better the extraction from the membrane. Increasing the sampling time from 1 to 4 min increases the response by 77%. The sampling time responses were linear up to 4 min sampling time. Above 4 min sampling time, the data deviate from linearity. The effect of adding salt to standards has no effect on analyte absorption onto the membrane. The detection limits for key VOCs studied with an internal standard calibration ranged from 0.2 to 194 ng cm(-3).

Determination of three alkylphenol isomers in various water samples using a new HPLC method based on a duet stationary phase

The level of three alkylphenols (APs) 4-nonylphenol, 4-octylphenol and 4-tert-octylphenol was monitored in various water samples using a new developed and validated HPLC method. The HPLC method employed a column with a mixed-mode stationary phase (C18/SCX) using a mobile phase of water to methanol = 15:85 (v/v) delivered at a flow rate of 1 mL/min at room temperature. Both diode array, DAD and fluorescence, FLD detectors were employed. The method is linear when APs concentration ranged from 0.025 to 0.5 μg/mL with a DAD detection at 279 nm and between 0.0008 and 0.1 μg/mL when the detection was made by FLD (excitation at 220 nm, emission at 315 nm). The limit of detection and limit of quantitation for alkylphenols were found to be 5 and 15 ng/mL, respectively (detection by DAD). The method was employed with good results for the determination of APs in the presence of polycyclic aromatic hydrocarbons in various water samples.

Optimization and Simultaneous Determination of Alkyl Phenol Ethoxylates and Brominated Flame Retardants in Water after SPE and Heptafluorobutyric Anhydride Derivatization followed by GC/MS

A gas chromatography–mass spectrometry (GC–MS) method was investigated for the simultaneous analysis of two types of endocrine disrupting compounds (EDCs), i.e., alkylphenol ethoxylates and brominated flame retardants (BFRs), by extraction and derivatization followed by GC–MS. Different solid phase extraction (SPE) cartridges (Cleanert PestiCarb, C₁₈, Cleanert-SAX and Florosil), solvents (toluene, tetrahydrofuran, acetone, acetonitrile and ethyl acetate) and bases (NaHCO₃, triethylamine and pyridine) were tested and the best chromatographic analysis was achieved by extraction with Strata-X (33 μm, Reverse Phase) cartridge and derivatization with heptafluorobutyric anhydride at 55 °C under Na₂CO₃ base in hexane. It was observed that APE together with lower substituted PBBs (PBB1, PBB10, PBB18 and PBB49), HBCD and TBBPA can be determined simultaneously under the same GC conditions. This simple and reliable analytical method was applied to determining trace amounts of these compounds from wastewater treatment plant samples. The recoveries of the target compounds from simulated water were above 60 %. The limit of detection ranged from 0.01 to 0.15 μg L⁻¹ and the limit of quantification ranged from 0.05 to 0.66 μg L⁻¹. There were no appreciable differences between filtered and unfiltered wastewater samples from Leeuwkil treatment plant although concentration of target analytes in filtered influent was slightly lower than the concentration of target analytes in unfiltered influent water. The concentrations of the target compounds from the wastewater treatment were determined from LOQ upwards.

HPLC-FLD determination of 4-nonylphenol and 4-tert-octylphenol in surface water samples

A simple, sensitive and reliable HPLC-FLD method for the routine determination of 4-nonylphenol, 4-NP and 4-tert-octylphenol, 4-t-OP content in water samples was developed. The method consists in a liquid-liquid extraction of the target analytes with dichloromethane at pH  3.0-3.5 followed by the HPLC-FLD analysis of the organic extract using a Zorbax Eclipse XDB C8 column, isocratic elution with a mixed solvent acetonitrile/water 65:35, at a flow rate of 1.0 mL/min and applying a column temperature of 40°C. The method was validated and then applied with good results for the determination of 4-NP and 4-t-OP in Ialomiţa River water samples collected each month during 2006. The concentration levels of 4-NP and 4-t-OP vary between 0.08-0.17 μg/L with higher values of 0.24-0.37 μg/L in the summer months for 4-NP, and frequently <0.05 μg/L but also between 0.06-0.09 μg/L with higher values of 0.12-0.16 μg/L in July and August for 4-t-OP and were strongly influenced by sesonial and anthropic factors. The method was also applied on samples collected over 2 years 2007 and 2008 from urban wastewaters discharged into sewage or directly into the rivers by economic agents located in 30 Romanian towns. Good results were obtained when the method was used for analysis of effluents discharged into surface waters by 16 municipal wastewater treatment plants, during the year 2008.

Determination and residual characteristic of alkylphenols in household food detergents of Taiwan

The non-ionic surfactants are mostly composed of alkylphenols for the ingredients of synthetic food detergents. Due to the ability to mimic hormones, it has been noticed that the exposures of alkylphenols might cause a variety of adverse effects. To assess the associate risks from possible exposures, concentrations of alkylphenols, including 4-nonylphenol (4-NP), technical nonylphenol isomers (t-NP(S)), and 4-tert-octylphenol (4-t-OP), in household food detergents of Taiwan were determined. Gas chromatography with mass spectrometer (GC/MS) was used to analyze alkylphenols in samples. The Taguchi experimental design was utilized to study the possible factors that might affect the residual characteristics of alkylphenols from detergents on dishware and fruits. By the analysis of variance, the orders of importance of different parameters were determined. The results showed that the concentrations of alkylphenols in food detergents ranged from 1.71 x 10(-5) to 2.13 x 10(-3) (APs/detergent, mgg(-1)). For residual characteristics, the cleaning temperature was found to be the only significant factor that will affect the 4-t-OP left on the dishware, while the concentrations of detergents used will affect the left of t-NPs and 4-NP on dishware as well. On the other hand, the varieties of fruits, the concentrations of detergents, and the concentrations of alkylphenols were found to have significant effects for the t-NPs left on fruits. As for the exposure assessments, the maximum dose of APs exposures from the use of household food detergents in Taiwan was also estimated in the study.