Spectrophotometric Determination Of Cationic Surfactants Research Articles

Spectrophotometric determination of cationic surfactants in aqueous media using chrome azurol S as colour forming agent and 1-butanol as extracting solvent

A simple spectrophotometric method for the determination of cationic surfactants (CS) is developed using an anionic dye, chrome azurol S (CAS) as an ion-association complex forming agent, and 1-butanol as an extracting solvent. In the aqueous solution CS such as cetyltrimethylammonium bromide (CTAB), cetylpyridinium chloride (CPC) and dodecyltrimethylammonium bromide (DTAB) reacts with CAS to form an ion-association complex which is extracted into 1-butanol to form a pink-violet coloured organic phase. The final concentration of CAS in surfactant solution is 165 μM. The pH of the medium is maintained at ~6.4. The coloured compound exhibits maximum absorbance at 520 nm with a molar absorption coefficient in the range of (2.6–2.9) × 104 L mol−1 cm−1. Beer's law is obeyed in the concentration range of 0–82 μM, 0–88 μM and 0–84 μM for CTAB, CPC and DTAB, respectively in normal condition. However, to minimize the interference of cations, the masking with EDTA has been proposed. In case of CTAB determination in EDTA masked double distilled water, the linear dynamic range (LDR) is found as 27–55 μM. The proposed method is rapid, user-friendly and economical. The method is applied in mixed CS systems, and it showed good results. To check the reliability of the method, it has been applied for CS determination in real water samples masked with EDTA and spiked with CS of known concentration. The results obtained for recovery are quite satisfactory.

Spectrophotometric Determination of Cationic Surfactants Based on Their Effect on the Complexes of Chrome Azurol S with Be2+ and Al3+ Cations

AbstractSimple, rapid, and sensitive spectrophotometric methods have been proposed for the determination of cationic surfactants (CS) as cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium (DTAB), and cetylpyridinium bromide (CPB). The methods are based on the effects of CSs on the complexes of Al3+ and Be2+ with Chrome Azurol S (CAS). The optimum reaction conditions such as CAS concentration, metal ion concentration, and pH have been studied and found to be 2.0 × 10−4 mol L−1 CAS, 0.5 mg L−1 Al3+ or 0.4 mg L−1 Be2+ and pH 5.4. The analytical characteristics of the methods such as limit of detections, limit of quantifications, and linear ranges have been obtained. CTAB, CPB, and DTAB could be determined by the Al–CAS complex in the ranges of 0.50–40.00, 0.20–10.00, and 0.40–10.00 µmol L−1, and for the Be–CAS complex in the ranges of 0.08–5.00, 0.08–3.00, and 0.20–6.00 µmol L−1, respectively. The limit of the detections of the method for the determination of CTAB, CPB, and DTAB for the Be–CAS complex has been found as 0.025, 0.024, and 0.061 µmol L−1, respectively. The interfering effect of some anions and cations was also tested. The method was applied to the determination of CS CTAB in conditioner shampoo and water samples.

Spectrophotometric Determination of Cationic Surfactants Using Patent Blue V: Application to the Wastewater Industry in Algiers

AbstractPatent Blue V has been applied in a solvent extraction spectrophotometric method for the determination of cationic surfactants (CS) in industrial wastewaters. The method is based on the introduction of Patent Blue V as an anionic dye, and the formation of an ion pair association with CS in chloroform under the studied extraction conditions. The maximum wavelength of absorption for the ion pair is located at 627 nm, and a molar absorption coefficient of higher than 3.6 × 105 l mol−1 cm−1 was obtained. The calibration curve was linear between 0 and 5.48 × 10−6 M, and exhibited a significant coefficient of correlation. Based on the calculated values for the relative standard deviation (%) over the studied concentration range, the method was found to be highly sensitive, and the deduced limit of detection for the method was found to be very low (8.6 × 10−8 M of CTAB). It was also found that a washing step was necessary for the organic extract in order to remove interferences caused by foreign ions and species present in unknown samples. To validate this method, the procedure was used to determine the CS contents of samples collected from textile industry wastewaters in the Algiers region. The results obtained showed good agreement for the proposed method.

Highly sensitive spectrophotometric determination of cationic surfactants in ground waters as their Cu(II)–TPPS aggregates preceded by solid-phase fractionation

A highly sensitive spectrophotometric determination of cationic surfactants in ground waters was established by forming their Cu(II)–TPPS aggregates, preceded by solid-phase extraction with an SCX cartridge. Cationic surfactants (CSs) were quantitatively trapped and isolated by the SCX solid phase. The use of Cu(II)–TPPS anionic chromophore could reduce the interference by unintentional metal ions coexisting in surrounding waters. The method was very sensitive in the determination of CSs less than 10 −5 M levels with acceptable recovery and calibration data. The colorimetric sensitivity was very dependent on the alkyl-chain length of the surfactants, and a CS having 23 carbon atoms gave the highest sensitivity. Overall recoveries were 95–97% with R.S.Ds. less than 3% in the cases over 10 −6 M levels. In the cases in 10 −7 M levels, however, a portion of the analyte would be adsorbed by reservoir walls, which could seriously affect the trace determination. The preliminary addition of 4,4′-bipyridyl into the sample solution was effective in decreasing such unintentional analyte losses, leading up to 73% recovery. The developed method was applied to the analysis of river water at ppb levels of CSs with a fractional concentration through a SCX solid phase subjected by 500-mL aliquots of sample.

Membrane Filters as Solid-Phase Extraction Media for the Spectrophotometric Determination of Cationic Surfactants in River Water and Sediment

Membrane Filters as Solid-Phase Extraction Media for the Spectrophotometric Determination of Cationic Surfactants in River Water and Sediment

A spectrophotometric flow procedure for the determination of cationic surfactants in natural waters using a solenoid micro-pump for fluid propulsion

An automatic flow-analysis procedure for spectrophotometric determination of cationic surfactants in surface water using a solenoid micro-pump for propelling solutions of reagents and sample is described. The proposed method is based on a ternary formation complex between chromazurol S, the Fe(III) ion, and the cationic surfactant. The flow network comprised four solenoid micro-pumps controlled by a microcomputer, which performed the sampling step by loading a reaction coil with sample and reagent solutions and displacing the sample zone through the analytical path. The system is simple, easy to operate, and very flexible, with sufficient sensitivity to determine cationic surfactants in water without any pre-concentration or separation step. After determining the best operational conditions, favourable features such as a linear response between 0.34 and 10.2 mg L−1 of surfactant (R = 0.999), a relative standard deviation of 0.6% (n = 11) for a sample containing 3.4 mg L−1 of surfactant, a detection limit of 0.035 mg L−1 of surfactant, and a sampling throughput of 72 determinations per hour were achieved. The system was used to determine cationic surfactant in river-water samples, and recovery values between 91 and 106% were achieved.

Characterization of the interlaboratory reproducibility of results in quantitative gas-chromatographic analysis using the internal normalization method

Micellar preconcentration of 1 : 2 associates of Bromophenol Blue with cetyltrimethylammonium bromide is proposed to improve the procedure for the spectrophotometric determination of cationic surfactants. The preconcentration procedure involves quantitative extraction by reversed micelles of Triton N-42 in decane followed by the decomposition of the micellar solution with chloroform. The loss of 10-7−10-5 M cetyltrimethylammonium bromide in 5-100-fold preconcentration was not supported by the added-found method (RSD = 3–5%). The determination limit for cetyltrimethylammonium bromide is 2 × 10-7 M.

Determination of Cationic Surfactants in Environmental Samples by Flow Injection Analysis

A new simple flow injection analysis (FIA) procedure for the spectrophotometric determination of cationic surfactants (CSs), i.e. dodecyltrimethylammonium bromide (DTAB), cetyltrimethylammonium bromide (CTAB), and cetylpyridinium chloride (CPC), is described. The method is based on absorptivity enhancement of the Bi(III)-I− complex in the presence of CSs. Among the investigated compounds, highest sensitivity is obtained with CPC, so it was selected for detailed study. The apparent value of molar absorptivity of the complex in terms of CPC is (6.00)×103 L mol−1 cm−1 at λmax 505 nm for FIA determination. The detection limit (3σ criterion) of the method for FIA determination is 110 µg L−1. The sample throughput is >140 samples h−1. The effect of analytical and FIA variables in the determination of CPC is described. The composition of the complex is discussed. The method is free from interferences of common ions. The method has been applied to the analysis of surfactant contamination in environmental samples, i.e. pond water, municipal/industrial wastewater, sewage, sediment and soil.

Application of Membrane Filters for Spectrophotometric Determination of Cationic Surfactants in River Water and Sediment

Cationic surfactant (CS+) in urban river water and sediment was extracted and determined spectrophotometrically with 2 membrane filters. The CS+ in the water samples, mostly in the form of an ion associate with the coexisting anionic surfactant (AS), was collected on a polytetrafluoroethylene (PTFE) membrane filter and eluted with methanol. Bromphenol blue (BPB), hydrochloric acid, and water were added to the methanol solution successively, and the mixed solution was filtered through a mixed cellulose ester membrane filter. The CS+-BPB- ion associate, formed by a counter ion exchange, was collected on the filter and dissolved into N,N-dimethylformamide (DMF) together with the mixed cellulose ester membrane filter. After addition of 2 drops of triethanolamine, the absorbance of the DMF solution was measured. The CS+ in sediment samples was extracted with methanol by ultrasonic irradiation; the methanol solution was then passed through a PTFE membrane filter and evaporated to dryness. The CS+ was redissolved in a small amount of methanol. For water samples, recoveries and relative standard deviations for 0.30 microM benzyldimethyl-tetradecylammonium ion, a standard material, were > or =93 and < or =5%, with a detection limit of 0.02 microM. Concentrations of CS+ in sediments were much higher than those in water samples, indicating that CS+ is adsorbed on the surface of the sediment.

Simple method for spectrophotometric determination of cationic surfactants without liquid–liquid extraction

A simple method for the spectrophotometric determination of cationic surfactants was studied. The ion associate of tetradecyl-dimethylbenzylammonium chloride (Zephiramine) and tetrabromophenolphthalein ethyl ester (TBPE) were adsorbed onto the walls of a PTFE vessel by vigorous shaking. After discarding the resulting solution, the ion associate was dissolved in methyl cellosolve and its absorbance was measured at 605 nm. The molar absorptivity for Zephiramine was 7.88×10 4 l mol −1 cm −1.

Spectrophotometric determination of cationic surfactants in water samples containing anionic surfactants.

Concerning the spectrophotometric determination of cationic surfactants (CS) with anionic dyes, when a large amount of anionic surfactants (AS) is contained in a water sample, CS can not be determined, because it reacts with AS to form a CS-AS ion associate and doesn't react with anionic dyes. A method is proposed to avoid interference from AS based on the extraction of the CS-AS ion associate formed into an organic solvent from water samples to separate it from any excess of AS and color development by replacing AS in the CS-AS ion associate extracted with anionic dyes. In the presence of dodecylsulfate (LAS) as AS and sodium chloride, CS, such as alkyl trimethyl ammonium salts, tetraalkyl ammonium salts, alkyl dimethyl benzyl ammonium salts and alkyl pyridinium salts, was extracted as the CS-AS ion associate into 1, 2-dichloroethane. When a tetrabromophenolphtalein ethylester dye anion (TBPE) was used at pH8.510 as anoinic dyes, a CS-TBPE ion associate was formed in 1, 2-dichloroethane and was measured spectrophotometrically at 610 nm. The absorbance was propotional to the concentration of CS. Good results were obtained on recovery tests using river and sea water samples containing AS in the range of 0.120.16 mg as LAS/1.

Spectrophotometric determination of cationic surfactants by formation of ternary complexes with Fe(III) and chrome azurol

AbstractAn extraction‐free spectrophotometric method for the determination of cationic surfactants, such as cetylpyridinium chloride, cetyltrimethylammonium bromide and zephiramine is proposed, which is based on the formation of ternary complexes with Fe(III) and chrome azurol S. The molar ratio of the complex is 2:1:1 (Fe(III):chrome azurol S: cationic surfactant). The method is simple, rapid and sensitive, giving an apparent molar absorptivity of 4.5×104 L·mol−1‐cm−1 and a linear range of 0.1–6.0 μmol/L cationic surfactants. The total cationic surfactant content can be determined directly in aqueous solutions by measuring the absorbance at 680 nm (pH 5.8). The method has been successfully applied to water samples.

Formation of ternary ion associates using diprotic acid dyes and its application to determination of cationic surfactants

A sensitive and selective method is described for the determination of cationic surfactants, such as benzethonium, benzalkonium, cetylpyridinium and trimethylstearylammonium, based on the formation and extraction of ternary ion associates with an acid dye (bromophenol blue or bromochlorophenol blue) and quinidine. Quinidine reacts with divalent anionic dyestuffs to form a bulky 1∶1 complex anion, which is extractable into 1,2-dichloroethane as ternary ion associates with cationic surfactants in nearly neutral media. The ternary ion associate gives a blue product. Linearity of the calibration curve is improved and the extractability of the cationic surfactants is enhanced in the presence of quinidine. In addition, many other amines do not interfere with the determination. The blue ion associates can be used for the selective and sensitive spectrophotometric determination of cationic surfactants.

Spectrophotometric determination of cationic surfactants in water with an anionic dye-Disulphine Blue.

After removal of anionic surfactants by an ion-exchange technique, cationic surfactants were extracted as their chlorides into chloroform. Ion pairs of the cationic surfactants and Disulphine Blue formed in the chloroform phase were measured spectrophotometrically as follows : A 50 ml of a sample solution containing cationic surfactants (above 1 μg as Zephiramine) is passed through an anion-exchange column (Amberlite IRA-401, 15 ml) at a rate of 1 ml/min and the column is washed with 50 ml of 50% methanol. Five milliliters of sodium chloride solution (10%) and 10 ml of chloroform are added to the eluate. The mixture is then shaken for 1 min to extract cationic surfactants into chloroform. The chloroform phase is shaken for 1 min with a mixture of 10 ml of citrate buffer solution (0.1 M, pH 5), 5 ml of sodium sulfate solution (0.4 M) and 1.5 ml of Disulphine Blue solution (1.17×10-4 M). The absorbance of the chloroform phase is measured at 628 nm. Cationic surfactants in water above 20 μg/1 could be determined by the proposed method.

Spectrophotometric determination of cationic surfactants in frozen and fresh squid by ion-pair formation with Methyl Orange

A spectrophotometric method for the determination of cationic surfactants, such as hexadecylpyridinium chloride, cetyltrimethylammonium bromide, tetrabutylammonium nitrate and hyamine 1622, is proposed, which is based on their extraction into chloroform as ion pairs with Methyl Orange. The method is simple, rapid and sensitive, giving a molar absorptivity of 2.7 × 104 l mol–1 cm–1 and a limit of determination of 1.0 p.p.m. In determinations of total cationic surfactant content in samples of frozen and fresh squid, an average molecular mass of 400 was assumed, which is close to the mean molecular mass of the surfactants determined.

Continuous solvent-extraction method for the spectrophotometric determination of cationic surfactants

A rapid and automated spectrophotometric method for the determination of cationic surfactants, using the AutoAnalyzer, has been developed. This method is based on the continuous solvent extraction of the ion-pair complex formed in the reaction of Orange II with a cationic surfactant. Good traces and identical molar responses were obtained with seven different types of surfactant using methanol in the Orange II reagent. Fatty amines in mixtures of the amines and quaternary ammonium surfactants were determined by changing the pH of the aqueous phase. The proposed method was applied to the determination of cationic surfactants in several commercial products. The results agreed with those obtained by the two-phase titration procedure. The detection limit is 5 µM and the capacity is 10–20 samples per hour, with a relative precision of better than 1.5%.

The spectrophotometric determination of cationic surfactants with picric acid

Bromophenol blue and bromothymol blue have been used in the past for the spectrophotometric determination of cationic surfactants, by extraction into 1,2-dichloroethane of the blue complex formed between the dye and the surfactant. The method is shown to be unsatisfactory because the dyes can exist in both blue and yellow forms, and often an uncontrollable change of colour occurs in the organic phase. Picric acid, which produces a stable, intensely coloured complex with surfactants, is suggested as a substitute. The pH of the aqueous solutions is restricted to the range 4 to 12; high ionic strengths are not deleterious.

Spectrophotometric determination of cationic surfactants with Orange II

Spectrophotometric determination of cationic surfactants with Orange II