Determination Of Anionic Surfactants Research Articles

Determination of Anionic Surfactants by High Performance Liquid Chromatography/Mass Spectrometry Using a Pretreatment Column to Reduce Background Noise

Determination of Anionic Surfactants by High Performance Liquid Chromatography/Mass Spectrometry Using a Pretreatment Column to Reduce Background Noise

Microextraction-colorimetric determination of anionic surfactants in natural and waste waters

An eco-friendly, simple, rapid and cheap method for determining anionic surfactants in natural and waste waters by microextraction-colorimetric method has been developed. The essence of the proposed approach consisted in extraction and concentration of analytes in an acidic medium in the form of associates with organic reagents (methylene blue and acridine yellow) by dispersion liquid-liquid microextraction using a mixture of chloroform-acetonitrile as an extracting and dispersing solvent, followed by aggregation of extractant microparticles by centrifugation and subsequent measurements of color characteristics using a smartphone. The values of the basic components of the RGB colorimetric system were used as an analytical signal to calculate the final color: The selection of optimal conditions for microextraction concentration of anionic surfactants from natural waters (the nature of the extracting and dispergating solvents, the volume of the dispergating solvent) was performed for the sodium dodecyl sulfate — methylene blue system. To study the colorimetric characteristics of the prepared extracts, a smartphone «iPhone X» was used as a color-registering device equipped with a specialized software product «RGBer». To minimize the measurement error by fixing the distance to the object under study and lighting conditions, we propose an installation that increases the accuracy and sensitivity of the determination and makes the method more mobile. The total content of the most common components of detergents was determined: sodium dodecyl sulfate, sulfonol, laureth sulfate and disodium laureth-3-sulfosuccinate. The detection limits ranged within 0.01 – 0.02 and 0.05 mg/liter. The range of detectable contents for all analytes was 0.05 – 1.0 mg/liter. For the determined surfactants, the equations of the relationship between the analytical signal and the concentration were obtained. The calibration graphs are linear with coefficients of the approximation reliability ≤0.98. The correctness of the method was tested on samples of natural water using the spike test procedure. The relative standard deviation of the analysis results does not exceed 0.13. The analysis duration is 20 – 30 min.

Electrochemical micropipette-tip for low-cost environmental applications: Determination of anionic surfactants through their interaction with methylene blue

Miniaturization is one of the main requirements in the design of portable devices that allow in-field analysis. This is especially interesting in environmental monitoring, where the time of the sample-to-result process could be decreased considerably by approaching the analytical platforms to the sampling point. We employed traditional mass-produced and low-cost elements (micropipette tips and pins) in an out-of-box application to generate an innovative and cost-effective platform for analytical purposes. We have designed simple and easy-to-use electrochemical cells inside polypropylene micropipette tips with three stainless-steel pins acting as the working, reference and counter electrodes of a potentiostatic system. The pin acting as working electrode was previously coated with carbon ink, meanwhile the rest were used unmodified. In this way, electrochemical in-the-tip measurements were done directly using low volumes (μL) of sample. The devices showed good reproducibility, with a relative standard deviation of 7% (n = 5) for five different tip-based complete electrochemical cells. As a proof-of-concept, its utility has been probed by the determination of an anionic surfactant (sodium dodecyl sulphate, SDS) in water through its interaction with methylene blue (MB). Two different alternatives were presented based on the: 1) increase in the current intensity of the cathodic peak of MB due to the presence of SDS; 2) electrochemical determination of the MB remaining in the aqueous phase after extraction of the pair SDS-MB to an organic medium.

Electrocoating Polypyrrole on Gold-Wire Electrode as Potential Mediator Membrane Candidate for Anionic Surfactant Electrode Sensor

The development of polypyrrole as a potential mediator membrane candidate for sodium dodecyl sulfate (SDS) sensor electrode has been investigated. The polypyrrole membrane was synthesized electrochemically from the pyrrole and coated at the surface of a 1.0 mm diameter of the gold-wire electrode. Electropolymerization of pyrrole and coating of the polypyrrole produced was performed by cyclic voltammetry technique in the electrochemical cell containing supporting electrolyte of 0.01 M NaClO4 with an optimum potential range of -0.9 V–1.0 V, the scanning rate of 100 mV/s, an electric current of 2 mA, and running of potential scanning of 10 cycles. By using the similar optimal parameters of cyclic voltammetry, electropolymerization of 0.01 M pyrrole solution containing 0.001 M SDS also produces a polypyrrole membrane coated at the gold-wire electrode surface. These coated electrodes have the potential response-ability toward DS- anions in the concentration range of 10-7 M–10-5 M with a limit of detection of 10-7 M and sensitivity of electrode of 9.9 mV/decade. This finding shows that the SDS solution’s role is as supporting electrolyte and also as a source of DS- dopant during the pyrrole electropolymerization processes. Dopants are trapped in the polymer membrane during the electrochemical formation of polypyrrole and role as ionophores for DS- anion in the analyte solution. A potential response to the electrode phenomena is excellent basic scientific information for further synthesis of conducting polymer and development of conducting polymer-coated wire electrode model, especially in the construction of ion-selective electrode (ISE) for the determination of anionic surfactants with those models.

Development of an Optode Detector for Determination of Anionic Surfactants by Flow Injection Analysis.

A flow-injection analysis (FIA) method for assaying an anionic surfactant (AS) using AS optode detector was demonstrated. The optode membrane consists of 2-nitrophenyl octyl ether as a plasticizer, lactone form rhodamine B (L-RB) and poly(vinyl chloride). The linear response concentration range of the AS optode to AS was 20 - 100 μmol dm-3 in the FIA system. The sampling rate for an AS ion (40 μmol dm-3 sodium dodecylbenzenesulfonate) in the proposed FIA system was ca. 5 samples h-1. The AS level in commercially available laundry detergents by the proposed FIA system was determined.

Optimization and Applicability of a Novel Sensor for Potentiometric Determination of Anionic Surfactants

AbstractNovel potentiometric sensors for anionic surfactant (AS) determination, with different percentages of tetraoctadecylammonium tetraphenylborate (TODA‐TPB) as sensing materials and different electrolytes (sodium chloride, lithium chloride, sodium dodecyl sulfate (NaDS), sodium tetraphenylborate, sodium acetate, and potassium chloride) at varied concentration levels, were developed and compared. The sensor with best response characteristics was further characterized. It had a fast response time (5 s), a low signal drift (2.0 and 2.9 mV h−1 in a detergent solution and NaDS, respectively), a wide pH working range (3–11), and a longer lifetime of 6 months. This novel sensor was characterized with Nernstian response toward NaDS (−58.0 mV decade−1 of activity), a wide working range (1.3 · 10−7–5 · 10−3 M), and a low limit of detection (1.0 · 10−7 M). It proved to be an accurate and reliable sensor for AS determination in multicomponent mixtures of AS and household wastewater using a potentiometric titration method. Nonionic surfactants, which are commonly mixed with AS in commercial products to obtain better properties of products, had an insignificant impact on AS determination.

A green and cost-effective procedure for determination of anionic surfactants in milk with liquid-liquid microextraction and smartphone-based photometric detection

Aiming at determination of anionic surfactants as milk adulterants, a novel procedure based on simultaneous protein precipitation and liquid-liquid microextraction (LLME) of the ion-pair formed between the analytes and methylene blue is described. Sample treatment, ion-pair extraction, and photometric detection with a smartphone camera were carried out in a single vessel, thus significantly simplifying the procedure and minimizing risks of contamination and analyte loss. The chloroform volume for both sample treatment and extraction of the ion-pair was only 150 μL and usual drawbacks of LLME, such as the need for phase isolation and dilution of the extract before spectrophotometric measurements were avoided. By using sodium dodecylsulfate as a model surfactant, and only 100 μL of sample, 25 μg of methylene blue, and 2.9 mg of EDTA, a linear response was achieved from 10 to 50 mg L−1, r = 0.999 (n = 5), with detection limit (99.7% confidence level) and coefficient of variation of 2.2 mg L−1 and 1.9% (n = 10), respectively. The proposed procedure is a simple, fast, cost-effective, and environmentally friendly approach for detection of milk adulterations by surfactants.

Spectrophotometric determination of anionic surfactants: optimization by response surface methodology and application to Algiers bay wastewater.

A simple analytical method for quantitative determination of an anionic surfactant in aqueous solutions without liquid-liquid extraction is described. The method is based on the formation of a green-colored ion associate between sodium dodecylbenzenesulfonate (SDBS) and cationic dye, Brilliant Green (BG) in acidic medium. Spectral changes of the dye by addition of SDBS are studied by visible spectrophotometry at maximum wave length of 627nm. The interactions and micellar properties of SDBS and cationic dye are also investigated using surface tension method. The pH, the molar ratio ([BG]/[SDBS]), and the shaking time of the solutions are considered as the main parameters which affect the formation of the ion pair. Determination of AS in distilled water gives a significant detection limit up to 3 × 10-6 M. The response surface methodology (RSM) is applied to study the absorbance. A Box-Behnken is a model designed to the establishment of responses given by parameters with great probability. This model is set up by using the three main parameters at three levels. Analysis of variance shows that only two parameters affect the absorbance of the ion pair. The statistical results obtained are interesting and give us real possibility to reach optimum conditions for the formation of the ion pair. As the proposed method is free from interferences from major constituents of water, it has been successfully applied to the determination of anionic surfactant contents in wastewaters samples collected from Algiers bay.

A New Sensor for Determination of Anionic Surfactants in Detergent Products with Carbon Nanotubes as Solid Contact

AbstractA new solid‐state sensor for potentiometric determination of surfactants with a layer of multi‐walled carbon nanotubes was prepared. As a sensing material, 1,3‐didecyl‐2‐methylimidazolium–tetraphenylborate ion‐pair was used. The investigated sensor showed a Nernstian response for both dodecylbenzenesulphonate (DBS, 57.6 mV/decade of activity between 5 × 10−7 to 1 × 10−3 M) and sodium lauryl sulfate (LS, 58.4 mV/decade of activity between 2 × 10−7 to 2 × 10−3 M). It responded in 8–10 s for each ten‐fold concentration change in the range of 1 × 10−6 to 3 × 10−3 M. The detection limits for DS and DBS were 2 × 10−7 and 3 × 10−7 M, respectively. The sensor revealed a stable response (signal drift 2.6 mV/h) and exhibited satisfactory selectivity performances for LS over most of the anions generally used in surfactant‐based commercial detergents. The main application of this sensor was the end‐point determination in potentiometric titrations of anionic surfactants. The (diisobutyl phenoxy ethoxy ethyl)dimethyl benzyl ammonium chloride (Hyamine), cetyltrimethylammonium bromide, hexadecylpyridinium chloride monohydrate (HDPC) and 1,3‐didecyl‐2‐methylimidazolium chloride were tested as potential cationic titrants, and all exhibited analytically usable titration curves with well‐defined equivalence points. The standard solution of HDPC was used as a cationic titrant by all potentiometric titrations. The operational life‐time of the sensor described was prolonged to more than 3 months.

Determination of anionic surfactants in real samples using a low-cost and high sensitive solid contact surfactant sensor with MWCNTs as the ion-to-electron transducer

Long-life, low-cost and fast-response graphite pencil lead surfactant sensors based on MWCNTs.

Simultaneous determination of anionic and nonionic surfactants in commercial laundry wastewater and anaerobic fluidized bed reactor effluent by online column-switching liquid chromatography/tandem mass spectrometry.

This study presents a new method developed for the simultaneous determination of anionic surfactant (linear alkylbenzene sulfonate - LAS, 4 homologs) and nonionic surfactant (linear alcohol ethoxylate - LAE) in commercial laundry wastewater. The surfactants were identified and quantified using online column-switching solid-phase extraction (SPE) coupled with liquid chromatography/tandem mass spectrometry (LC-MS/MS). Ten and three transitions (m/z) were identified for LAS and LAE, respectively. The detection and quantification limits were 75 and 200μg/L for LAS, respectively, and 75μg/L for LAE. This method was applied to the determination of the surfactants in the influent and effluent of an anaerobic fluidized bed reactor that was used for the treatment of commercial laundry wastewater. After 480days of operation with a hydraulic retention time (HRT) of 18h, the removal of 45.9±5.6% LAS and 99.2±4.3% LAE from an influent with surfactant concentrations of 26.1±12.9mg/L and 23.8±6.8mg/L, respectively, was obtained. Under these conditions, the breakage of longer-chain LAS homologs with the release of carbon units was observed with an increase in the number of shorter homolog chains. This SPE online sample treatment method is simple, fast and effective for the analysis of both surfactants. This technique is pioneering in its simultaneous measurement of two surfactant categories in anaerobic fluidized bed reactors.

Determination of Anionic Surfactants in Dishwashing Detergents by High-performance Liquid Chromatography

In this study, we developed and validated microanalysis methods for the determination of linear alkylbenzenesulfonate (LAS), sodium lauryl sulfate (SLS), and alpha olefin sulfonate (AOS). The conditions for the analysis of the surfactants using HPLC with FLD, RID, and ELSD detectors were investigated. The methods were validated by determining the linearity, limits of detection (LODs), limits of quantification (LOQs), recovery, precision, and accuracy. LAS analysis by FLD revealed calibration curves that were linear in the range of 10-200 mg/L for an LAS mixture. The calibration curves for C10-C13 had correlation coefficients of 0.995, 0.997, 0.996, and 0.997, respectively. SLS analysis using RID generated a linear calibration curve in the range of 10-300 mg/L. The calibration curve for SLS C12 had a correlation coefficient of 0.9994. AOS analysis using ELSD resulted in a correlation coefficient of 0.9940. For LAS, the LODs and LOQs were 0.09-0.56 and 0.30-1.87 mg/L, respectively. For SLS C12, the LOD and LOQ were 0.07 and 2.33 mg/L, respectively. For AOS C14, the LOD and LOQ were 16.55 and 21.83 mg/L, respectively. The recoveries were 97.17-98.84% for LAS C10-C14, 97.94% for SLS C12, and 96.11% for AOS C14. The established methods provide acceptable precision and accuracy. Our methods could be useful for the detection of anionic surfactants in dishwashing detergents.

Submicrometric Magnetic Nanoporous Carbons Derived from Metal-Organic Frameworks Enabling Automated Electromagnet-Assisted Online Solid-Phase Extraction.

We present the first application of submicrometric magnetic nanoporous carbons (μMNPCs) as sorbents for automated solid-phase extraction (SPE). Small zeolitic imidazolate framework-67 crystals are obtained at room temperature and directly carbonized under an inert atmosphere to obtain submicrometric nanoporous carbons containing magnetic cobalt nanoparticles. The μMNPCs have a high contact area, high stability, and their preparation is simple and cost-effective. The prepared μMNPCs are exploited as sorbents in a microcolumn format in a sequential injection analysis (SIA) system with online spectrophotometric detection, which includes a specially designed three-dimensional (3D)-printed holder containing an automatically actuated electromagnet. The combined action of permanent magnets and an automatically actuated electromagnet enabled the movement of the solid bed of particles inside the microcolumn, preventing their aggregation, increasing the versatility of the system, and increasing the preconcentration efficiency. The method was optimized using a full factorial design and Doehlert Matrix. The developed system was applied to the determination of anionic surfactants, exploiting the retention of the ion-pairs formed with Methylene Blue on the μMNPC. Using sodium dodecyl sulfate as a model analyte, quantification was linear from 50 to 1000 μg L(-1), and the detection limit was equal to 17.5 μg L(-1), the coefficient of variation (n = 8; 100 μg L(-1)) was 2.7%, and the analysis throughput was 13 h(-1). The developed approach was applied to the determination of anionic surfactants in water samples (natural water, groundwater, and wastewater), yielding recoveries of 93% to 110% (95% confidence level).

A new graphene-based surfactant sensor for the determination of anionic surfactants in real samples

A new high-sensitivity potentiometric all-solid-state sensor for the determination of anionic surfactants is constructed based on the dimethyldioctadecylammonium-tetraphenylborate (DDA-TPB) ion pair as a sensing material and graphene. Graphene nanoparticles are used for immobilization of the sensing material in the membrane, preventing the leaching of electroactive material from the membrane, thus reducing its electrical resistance and signal noise.The sensor exhibits a Nernstian response for dodecylbenzenesulfonate (DBS) and a sub-Nernstian response for dodecyl sulfate (DS) in the concentration range of 2.5×10−7–4.5×10−3M.The detection limits for DS and DBS are 1.5×10−7 and 2.5×10−7M, respectively. The sensor demonstrates a stable potentiometric response with a signal drift of −1.2mV/h and exhibits excellent selectivity performance for DS over almost all of the organic and inorganic anions commonly used in commercial products.The main application of the sensor is in the detection of the endpoint in potentiometric titrations of anionic surfactants. The magnitudes of inflexion at the equivalence point range from 174 to 270mV. The sensor shows satisfactory analytical performance within a pH range of 2–7.The two-component mixtures containing sodium decanesulfonate (C10) and sodium dodecanesulfonate (C12) are also successfully differentially titrated.

Determination of anionic surfactants in wastewater treatment plant in Algiers City

AbstractA spectrophotometric method was adapted for the determination of anionic surfactants (AnS) using the Crystal Violet. Anionic surfactant gives an ion pair with the dye, which is extracted with an organic solvent. The developed method has been studied and optimized for various parameters, such as the effect of the buffer solution on the extraction of the ion pair (pH 8.1) and the volume of solvent extraction (15 mL). Determination of AnS in distilled water gives good precision and a significant detection limit up to 2.5 × 10−6 M. Interferences have been eliminated by determining AnS in seawater. An application part for this method was carried out in the determination of AnS in an estuary treatment plant in Algiers city. Many results have been obtained and some interesting observations are made. For this, the optimized method for anionic surfactant determination gives significant and reproducible results.

Determination of Anionic Surfactants by Means of Photometric Titration with Methylene Blue Dye

AbstractQuantitative determination of dodecyl sulfate and dioctyl sulfosuccinate has been performed with methylene blue dye in titration mode. The new approach consists in the titration of surfactant solution by standardized dye solution, simultaneously measuring absorbance at 660 nm with an immersion probe. Due to the formation of sparingly soluble ion pairs, the registered photometric titration curves are dependent on surfactant concentration. The analytical signal is the titrant volume needed to reach a certain absorbance value. The main advantage of the proposed method is that no toxic organic solvent is used. An additional advantage is that the analysis procedure can be carried out using an automatic titrator. The determination range is dependent on the end‐point absorbance value. Standard deviation values fall in the range from 2 to 7 %. The method may be useful for routine process control in the surfactant industry.

English

Surfactants (surface active agents) are substances which incorporate a hydrophobic non-polar and a hydrophilic polar group, and have the tendency to accumulate at the phase boundary. This feature causes the wide application of surfactants. In 2012, the world surfactant market amounted to 27,040 million USD, and with average annual increase of 6.18 %, this amount in 2017 is estimated at 36,518 million USD2. ASs are used as components in cosmetic formulations, household products, industrial cleaners. Their wide application leads to water pollution, and thus endangers the flora and fauna3. The standard method for the determination of anionic surfactants (ASs) in wastewater is MBAS4 (Methylene Blue Active Substances), while twophase titration5 is used for determining AS in commercial products. Both standard methods have many drawbacks (use of carcinogenic organic solvents, difficulties in determination of anionic surfactants in turbid solution, the subjectivity of the person performing the analysis, inability of auto mation...). The limitations of the standard methods for the determination of AS impose the need for continuous development of new surfactant sensors, which are less expensive, miniaturized, easier to use. The Environmental Protection Act of Croatia does not allow the use of surfactants whose biodegradability is less than 90 %6, thus, the determination of low concentrations of AS in effluents is of great importance. Today, there are a number of techniques that are able to detect, identify, and quantify the surfactant in samples of a complex matrix7. The first methods for determination of ASs were developed from simple volumetric methods5, followed by spectrophotometric methods8,9, chromatography10–12, microfluidic techniques such as flow-injection analysis (FIA)13, capillary electrophoresys14, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR)15. The polymeric membrane ion-selective electrodes (ISEs)16–19 successfully replace standard methods for determination of ASs in various samples. ISEs are a simpler and cost-effective alternative to standard methods. ISEs have evolved from the coated-wire electrodes and liquid polymeric membrane electrodes containing ion-pair based sensing material. The widest use have found ISEs with PVC liquid membrane. Low concentrations of ASs can be determined by ISFET sensors20, biosensors21 or ISEs associated with FIA system. The aim of this study was the application of a newly developed screen-printed microsensor, based on dimethyldioctadecylammonium-tetraphenylborate (DDA-TPB) ion pair as a sensing material, for determination of ASs in industrial wastewater. Particular attention was paid to the determination of low concentrations of ASs. Application of a New Potentiometric Sensor for Determination of Anionic Surfactants in Wastewater

Determination of anionic surfactants using methods of impedance spectroscopy and chemometrics

A procedure is developed for the determination of anionic surfactants (ASs) in water-oil emulsions by impedance spectroscopy with the chemometric processing of experimental data. The conditions of recording impedance titration curves were optimized and the performance characteristics of the procedure were estimated. It was shown that impedance spectroscopic titration is applicable to the determination of AS in aqueous solutions and water-oil emulsions in the presence of organic and inorganic substances. Examples of determination of ASs based on sodium olefin sulfonate are given.

Planar electrodes based on carbon nanotubes for the potentiometric determination of homologous sodium alkyl sulfates

Planar electrodes based on carbon nanotubes, manufactured by screen printing, are proposed for the determination of anionic surfactants in aqueous solutions. A comparative analysis of the electroanalytical characteristics of planar and solid-state sensors based on various ionophores, namely, ion associates of (1) sodium dodecyl sulfate with a cationic complexes of copper(II) and N,N′-bis(salicylidene)ethylenediamine and (2) sodium dodecyl sulfate with cetylpyridinium, is performed. It is shown that planar electrodes can be used to quantify homologous sodium alkyl sulfates in the concentrations range of 4 × 10−7 (5 × 10−6) to 1 × 10−2 (5 × 10−4) M at pH 4–10 in water bodies and to determine the total concentration of anionic surfactants in detergents.

A New Microsensor for the Determination of Anionic Surfactants in Commercial Products

A New Microsensor for the Determination of Anionic Surfactants in Commercial Products