Determination of anions

Hu et al. [13] investigated the separation mechanism in more detail and have applied the method to the determination of nitrate, bromide, and iodide in seawater. 

To overcome these difficulties, Ito and Sunahara [17] suggested the use of the matrix ions as the eluent ions, for example, the use of relatively high concentrations of sodium chloride solution. 

In the most recent method described by Hu et al. [13] for the direct determination of ultraviolet-absorbing inorganic anions in saline matrixes an octadecylsilica column modified with a zwitterionic surfactant (3-(NN-dimethylmyristylammonio)propanesulfonate) is used as the 

2 Blasius, E., Janzen, K.P., Adrian, W. et al. Zeitschrift fiir Analytische Chemie, 284, 337 (1977). 

This technique has been applied predominantly to organic and organo-metallic compounds with a small number of applications to cations and anions. 

---

SOLID-PHASE SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF ANIONIC SURFACTANTS WITHOUT LIQUID-LIQUID EXTRACTION... 

Ion chromatography permits the determination of both inorganic and organic ionic species, often in concentrations of 50 g L"1 (ppb) or less. Since analysis time is short (frequently less than 20 minutes) and sample volumes may be less than 1 mL, IC is a fast and economical technique. It has found increasing application in a number of different areas of chemical analysis and particularly for the quantitative determination of anions. The state-of-the-art has been reviewed.26... 

TABLE 17 Titration Methods for the Determination of Anionic Surfactants... 

A ring test proved that surfactant-selective electrodes are suitable for quantitative determination of anionic surfactants including alkanesulfonates [21]. The precision of this method, however, does not yet correspond to the state-of-the-art of the two-phase titration. Therefore, further development is needed to enhance the reproducibility and competitiveness of surfactant-sensitive titration. 

Sodium dodecyl sulfate is the universal analytical standard for the determination of anionic and cationic active matter. It is used to determine the analytical concentration factor of the cationic surfactant in the titration of anionic active matter and as titrant to determine the cationic active matter. 

A highly sensitive method for the determination of anionic surfactants, particularly sodium dodecyl sulfate, has been described [275]. The method is based on the formation of fluorescent ionic complexes of the anionic surfactant with acridine red and acridine yellow. The complexes are extracted with dichloro-... 

ISO 2271 1989, Surface active agents Determination of anionic-active matter by manual or mechanical direct two-phase titration procedure. 

ISO 7875-1 1984, Water quality. Determination of surfactants—Part 1 Determination of anionic surfactants by the methylene blue spectrometric method. 

Frenzel, W., Schepers, D., and Schulze, G., Simultaneous ion chromatographic determination of anions and cations by series conductivity and flame photometric detection, Anal. Chim. Acta, 277, 103, 1993. 

Kwon, S.-M., Lee, K.-P., Tanaka, K., and Ohta, K., Simultaneous determination of anions and cations by ion-exclusion chromatography-cation-exchange chromatography with tartaric acid/18-crown-6 as eluent, /. Chromatogr. A, 850, 79, 1999. 

CE has been used for the analysis of anionic surfactants [946,947] and can be considered as complementary to HPLC for the analysis of cationic surfactants with advantages of minimal solvent consumption, higher efficiency, easy cleaning and inexpensive replacement of columns and the ability of fast method development by changing the electrolyte composition. Also the separation of polystyrene sulfonates with polymeric additives by CE has been reported [948]. Moreover, CE has also been used for the analysis of polymeric water treatment additives, such as acrylic acid copolymer flocculants, phosphonates, low-MW acids and inorganic anions. The technique provides for analyst time-savings and has lower detection limits and improved quantification for determination of anionic polymers, compared to HPLC. 

Physicochemical Basis of Quantitative Determination of Anionic Surfactant Concentrations by Using an Autotitrator... 

As part of the studies undertaken in our laboratory it was necessary to be able to determine quantitatively the surfactant present in large numbers of samples (> 100 per week) arising, for example, from core flooding experiments. The chosen method needed to be rapid to reduce analysis time, and to require little manipulation of the sample to reduce errors. In this paper we report the development of a method for the determination of anionic surfactants based upon autotitration and comment on the physico-chemical basis of the technique. 

Numerous methods have been developed for the determination of anionic surfactants and these have been reviewed by Longman (l). 

BASIS OF MANUAL PHOTOMETRIC TITRATION. The determination of anionic surfactants by a photometric titration employs a cationic indicator to form a coloured complex with the surfactant which is insoluble in water but readily soluble in chlorinated solvents (1 ). The end point of the titration occurs when there is a loss of colour from the organic phase. A considerable improvement in this technique is achieved by the use of a mixture of anionic and cationic dyes (4 ), for example disulphine blue and dimidium bromide (Herring s indicator (3)). The sequence of colour changes which occurs during the two phase titration of an anionic surfactant (AS) with a cationic titrant (CT) using a mixed indicator consisting of an anionic indicator (AD) and cationic indicator (CD) is summarised in Scheme 1 ... 

Chapters 2 and 3 discuss the determination of anions. Direct application of many of the classical procedures for anions fail for seawater owing to interfering effects of the simple matrix. Suitable modifications are discussed that are amenable to seawater. Dissolved gases in seawater are of interest in certain contexts and their determination is discussed in Chap. 4. 

Very limited work has been published on the determination of anions in estuary and coastal waters. However, there is no doubt that the open seawater analysis methods discussed in Chap. 2 would in many instances be applicable to estuary and coastal waters. 

Gagnon [203] has described a rapid and sensitive AAS method developed from the work of Crisp et al. [200] for the determination of anionic detergents at the ppb level in natural waters. The method is based on determination by atomic absorption spectrometry using the bis(ethylene-diamine) copper (II) ion. The method is suitable for detergent concentrations up to 50 ig/l but it can be extended up to 15 mg/1. The limit of detection is 0.31 ig/1. 

Petts KW, Parkes D (1978) Determination of anionic detergents within a concentration range 0 - 1 mg/1 in sewage effluents and waters by autoanalyser. Water Research Centre report TR75... 

---