Cationic detergents, determination

The present paper deals with kinetics of coagulation of Phthallylsulfathiazole stabilized xylene in water emulsion in the presence of some cationic detergents. Rate of flocculation, rate of coalescence and rate of creaming have been determined. To estimate the stability of the present systems their zeta potentials have been measured and stability factors calculated. Temperature effect on the system was also studied. 

Because the size of lipoplex is a key factor in determining the tissue distribution as well as the cellular uptake, it would be a challenge to reduce the size of lipoplex to increase transfection efficiency. Recently, Dauty et al.43 succeeded in formulating plasmid DNA into stable nanometric particles with a diameter of less than 40 nm by synthesizing a dimerizable cationic detergent. 

Direct observation of an ordered phase of NA bases on sohd electrodes by techniques, such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM), may help determine the orientation of the molecules in the compact film [83, 92-98], These techniques were also recently apphed to the surface of mercury [99-101], It was found that cationic detergent benzalkonium chloride (BAG), used for DNA spreading on mica in scanning force microscopy, forms a condensed film at the mercury electrode surface. The corresponding pit on C-E curves resembled the pits of bases and... 

ISO 2871-1 1988 Surface active agents—Detergents— Determination of cationic active matter content— Part 1 High-molecular-mass cationic-active matter. International Organization for Standardization, Geneva. 

Figure 11.34 The effect of surfactants on the determination of iron. Phenanthroline method 20 //g Fe in 25 ml. Curve (1) cationic detergent (100 % active material) (2) anionic detergent (100% active material) (3) non-ionic detergent (100% active material) (4) industrial LAS-type detergent (74% LAS and 6% sodium tripolyphosphate) (5) formulated detergent (13% active material) (6) washing powder (15% LAS and 25% sodium tripolyphosphate) (7) mixed detergent (7 % LAS and 3 % non-ionic detergent) (8) sodium pyrophosphate (anhydrous) (9) sodium tripolyphosphate (10) soap. Broken line indicates turbidity. From Pakalns and Farrar [220].

International Organization for Standardization, Surface active agents—detergents—determination of cationic-active matter content. Part 2 Cationic-active matter of low molecular mass (between 200 and 500), ISO 2871-2 1990. Available from national ISO affiliates. 

Amphoteric Detergents. These surfactants, also known as ampholytics, have both cationic and anionic charged groups ki thek composition. The cationic groups are usually amino or quaternary forms while the anionic sites consist of carboxylates, sulfates, or sulfonates. Amphoterics have compatibihty with anionics, nonionics, and cationics. The pH of the surfactant solution determines the charge exhibited by the amphoteric under alkaline conditions it behaves anionically while ki an acidic condition it has a cationic behavior. Most amphoterics are derivatives of imidazoline or betaine. Sodium lauroamphoacetate [68647-44-9] has been recommended for use ki non-eye stinging shampoos (12). Combkiations of amphoterics with cationics have provided the basis for conditioning shampoos (13). 

An unknown commercial detergent may contain some combination of anionic, nonionic, cationic, and possibly amphoteric surfactants, inorganic builders and fillers as weU as some minor additives. In general, the analytical scheme iacludes separation of nonsurfactant and inorganic components from the total mixture, classification of the surfactants, separation of iadividual surfactants, and quantitative determination (131). 

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. 

Direct determination of surfactants in complex matrices can also be carried out using ion-selective electrodes. Depending on the membranes and additives used, the detergent electrodes are optimized for the detection of anionic surfactants [81], cationic surfactants [82], and even nonionic surfactants [83]. The devices are sensitive to the respective group of surfactants but normally do not exhibit sufficient stability and reproducibility for their use in household appliances. With further optimization of membrane materials, plasticizers and measurement technology, surfactant-selective electrodes offer high potential for future applications. 

Many anionic surfactants can react with a cationic dye such as methylene blue to form strong ion pairs that can be extracted by a suitable organic solvent and can be determined using colorimetric techniques. The anionic surfactants that respond to the methylene blue test are primarily the sulfonate (RS03 Na+) and the sulfate ester (R0S03 Na+) type substances. On the other hand, soaps and the alkali salts of fatty acids (C-10 to C-20) used in certain detergents do not respond to the above test. The various anionic surfactants and their characteristic structural features are presented in Figure 2.32.1. 

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