Cationic surfactants samples

The investigation leads to the elaboration of solid-phase spectrophotometric and test methods of different cationic surfactants determination in water. The detection limits of cationic surfactants with hydrocarbon radical length is 0.7 mg/dm, is 0.2 mg/dm, C is 0.009 mg/dm and is 0.003 mg/dm by using a 100 cm sample. Metrological performance of method was examined on the natural samples. Proposed method is highly sensitive, simple, rapid and guarantees ecological purity of analysis. 

It should be noted that Cypridina luciferin emits a fairly strong chemiluminescence in aqueous solutions in the presence of various lipids and surfactants, even in the complete absence of luciferase. The luminescence is especially conspicuous with cationic surfactants (such as hexadecyltrimethylammonium bromide) and certain emulsion materials (such as egg yolk and mayonnaise). Certain metal ions (especially Fe2+) and peroxides can also cause luminescence of the luciferin. Therefore, great care must be taken in the detection of Cypridina luciferase in biological samples with Cypridina luciferin. 

Crisp et al. [212] has described a method for the determination of non-ionic detergent concentrations between 0.05 and 2 mg/1 in fresh, estuarine, and seawater based on solvent extraction of the detergent-potassium tetrathiocyana-tozincate (II) complex followed by determination of extracted zinc by atomic AAS. A method is described for the determination of non-ionic surfactants in the concentration range 0.05-2 mg/1. Surfactant molecules are extracted into 1,2-dichlorobenzene as a neutral adduct with potassium tetrathiocyanatozin-cate (II), and the determination is completed by AAS. With a 150 ml water sample the limit of detection is 0.03 mg/1 (as Triton X-100). The method is relatively free from interference by anionic surfactants the presence of up to 5 mg/1 of anionic surfactant introduces an error of no more than 0.07 mg/1 (as Triton X-100) in the apparent non-ionic surfactant concentration. The performance of this method in the presence of anionic surfactants is of special importance, since most natural samples which contain non-ionic surfactants also contain anionic surfactants. Soaps, such as sodium stearate, do not interfere with the recovery of Triton X-100 (1 mg/1) when present at the same concentration (i.e., mg/1). Cationic surfactants, however, form extractable nonassociation compounds with the tetrathiocyanatozincate ion and interfere with the method. 

The main difficulties in CE analysis of cationic surfactants arise from their strong adsorption to the capillary wall and their ability to form micelles at low concentrations. The addition of organic modifiers in high amounts or separation in absolutely non-aqueous media disrupt micelle formation within the sample and also effectiveness of the organic modifier to disrupt micelles of alkylbenzyl dimethyl ammonium... 

Equidistant or clustered signals, characteristic of some anionic, nonionic or cationic surfactants (cf. Fig. 2.5.1(a) and (b). So the presence of non-ionic surfactants of alkylpolyglycolether (alcohol ethoxylate) type (AE) (structural formula C H2 i i-0-(CH2-CH2-0)x-H) could be confirmed in the formulation (Fig. 2.5.1(a)) applying APCI-FIA-MS in positive mode. AE compounds with high probability could also be assumed in the heavily loaded environmental sample because of the patterns of A m/z 44 equally spaced ammonium adduct ions ([M + NH4]+) shown in its FIA-MS spectrum in Fig. 2.5.1(b). 

This Gemini cationic surfactant could not be recovered from samples of biodegradation experiments performed in a lab-scale aerobic bioreactor [50] either because of complete biodegradation (mineralisation) or because of irreversible adsorption at the surface of the biodegradation device. 

Detections of cationic surfactants in commercial products and environmental samples... 

Few data have been published on cationic surfactants in aquatic sediments. Levels from 3 to 67 mg kg-1 were determined in sediment samples from Rapid Creek [54] and 6-69 mg kg-1 concentrations were found in sediment samples from Japan [4]. DTD MAC was reported in digested sewage sludge at levels ranging from 0.15 to 5.87 gkg-1 [22]. Also, cationic surfactants were determined in urban coastal environments and they were reported as markers [18,55]. In our work, concentrations of BAC ranged from 23 to 206 p,gkg 1 in sediment samples from different rivers near to wastewater treatment plants,... 

Soil Column Tests. In the sand penetration test, a minimal amount of water was used. No consideration was given to the hydrostatic pressure which would occur in nature from a body of surface water. A new soil infiltration test was developed to take this into consideration. This test used a maximum amount of water (200 mL) on a minimum amount of treated soil (10 g) and was restricted only by the dimensions of the laboratory equipment. Our aim was to prepare an hydrophobe for soil which would support water over an extended period of time. Whereas water passed through soil treated with hydrophilic compounds within 8 hr, 2 weeks or more were required for penetration through an hydrophobe-treated soil. In the latter case the water level dropped 6 mm or less each day, showing that the cationic surfactant greatly hindered, but did not completely restrict the passage of water. The tests were usually terminated after 2 weeks, due to the large number of samples to be tested. 

Fig.3 XRD patterns of MCM-41 samples synthesized with different additional cations (a) calcined samples, (b) after hydrothermal treatment (cation/surfactant = 1.4)...

Materials. Sodium dodecylsulfate (SDS) and fully deuterated sodium dodecylsulfate (SDS-d ) were obtained from Sigma and Cambridge Isotope Laboratories respectively, and used as received. The cationic surfactants, dodecyltrimethylammonium chloride (DTAC), dodecyltrimethylammonium bromide (DTAB), and didodecyldimethylammonium bromide (DDAB) were purchased from Eastman Kodak, and purified by repeated recrystallization from an ethanol/acetone solvent pair. Even so, a small amount of surface active impurity was observed in surface tension plots for DTAC. The tetradecyldimethylamine oxide (C14AO) was a commercial sample (Ammonyx MO) obtained from Stepan (Control No. 533-30027). This sample is primarily C14AO, but also contains other chain length components. Sodium chloride (NaCl) was obtained from EM Science and used as received. Water was purified by a three stage Bamstead water purification system. 

Table IV. Monoalkyl/dialkyl cationic surfactant mixtures sample composition...

Flowing FS-MMLLE with on-line hyphenation to FtPLC has also been investigated. Sandahl et al. were the first to interface FS-MMLLE with reversed-phase HPLC for the on-line extraction of methyl-thiophanate in natural water, obtaining an LOD of 0.5 pg L-1.89 Also, a parallel FS-SLM and FS-MMLLE design was coupled on-line to reverse-phase HPLC for the extraction of methyl-thiophanate (by MMLLE) and its metabolites (by SLM) in natural water.90 In addition, on-line coupling of FS-MMLLE and normal-phase HPLC has been successfully applied in the determination of vinclozolin (Ee =118 and LOD = 1 pg I. ) in surface water91 and of in-sample ion-paired cationic surfactants (Ee > 250 and LOD = 0.7-5 ug L-1) in river water and wastewater samples.92... 

Several ELISA methods for determining cationic surfactants have been reported although we have not found any examples of their application to real environmental samples. The detectability obtainable by these methods is very good an LOD of 0.04 pg L 1 has been reported for benzyldo-methyldodecylammonium chloride (BDD12AC), a component of benzalkonium chloride (BAK).94... 

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