Determination of Trace Anions

Cyanide was detemiined by Zhu and Fang [21] in natural and waste waters after on-line gas diffusion separation and spectrophotometric determination of a non-stable intermediate reaction product in the pyrazolone/isonicotinic acid method. 

Phosphate was determined in rain water, sea water and ground water at //g 1 levels by Yoshimura et al.[22] using solid phase absorptiometry. The ion-associate formed by the reaction of molybdophosphate with Malachite Green was sorbed on a Sephadex dextran gel packed in a ilow-cell, and the increase in absorbance was monitored to perform the determination of phosphate, resulting in a very sensitive method. 

Fluoride was determined indirectly with ICPES by Manzoori and Miyazaki 

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Application Note No. 113, Determination of Trace Anions in High Purity Waters by High Volume/Direct Injection Ion Chromatography, Dionex Corporation, Sunnyvale, CA, 1996. 

There has been considerable interest in the determination of ions at trace levels as, for example, in applications need high-purity water as in semiconductor processing and the determination of trace anions in amine treated waters. For this investigation, we will define "trace" as determinations at or below 1 pg/1 (ppb) levels. The Semiconductor Equipment and Materials International (SEMI) recommended the use of IC for tracking trace ionic contaminants from 0.025 to 0.5 pg/1 [18]. In addition, the Electric Power Research Institute (EPRI) has established IC as the analytical technique for determining of trace level concentrations of sodium, chloride and sulfate down to 0.25 pg/1 in power plant water [19]. 

Franks, M. C., Pullen, D. L. Technique for the determination of trace anions by the combination of a potentiometric sensor and liquid-chromatography with particular reference to the determination of halides. Analyst 99, 503 (1974)... 

This is just one example how a method may be developed. There are other examples. The best method determination of trace anions in concentrated acids either requires removing the matrix anion, selective detection, or choosing a column that has sufficient capacity and selectivity to allow the matrix to travel quickly through the... 

Improved determination of trace anions in high purity waters by high-volume direct injection with the EG40, Application Update 142, Dionex, Sunnyvale, CA, USA, 2001. 

Determination of trace anions in water matrices con-taming high concentrations of salt can also be made by... 

A. Siriraks, CA. Pohl and M. Toofan, Determination of trace anions in concentrated acids by means of a moderate capacity anion-exchange column,... 

Kaiser, E., Rohrer, J., and Ausserer, W. (1999) Determination of trace anions in concentrated weak acids by ion chromatography. Presentation No. 962, Pittsburg Conference, Orlando. 

Dionex Corporation (2002) Dionex Technical Note No. 44 The Determination of Trace Anions in Concentrated Phosphoric Acid. Dionex Corporation (now part of Thermo Fisher Scientific), Sunnyvale, CA, USA. 

The latest development for this type of application combines the key benefits of electrolytic eluent generation and matrix elimination to fecilitate the determination of trace anionic impurities in borated water [192]. Figure 10.109 shows a schematic diagram of such a system configuration, which is also based on two... 

Dionex Corporation (2007) Dionex Application Update No. 163 Determination of Trace Anions in Organic Solvents Using Matrix Elimination and Preconcentration. 

E. Kaiser, J. Rohrer and W. Ausserer, Determination of Trace Anions in Concentrated Weak Acids by Ion Chromatography , Presentation No. 952, Pittsburg Conference, Orlando 1999. 

Zhao, Y. Q., Y. Z. He, W. E. Gan, and L. Yang. 2002. Determination of nitrite by sequential injection analysis of electrokinetic flow analysis system. Talanta 56 619-625. Hu, Y. Y., Y. Z. He, and L. L. Qian. 2005. On-line ion pair solid-phase extraction of electrokinetic multicommutation for determination of trace anion surfactants in pond water. Anal. Chim. Acta 536 251-257. 

Xu, T., B. Xu, W. Tong, Y. Fang, Indirect determination of trace anionic surfactants in water using atomic absorption spectrophotometry (in Chinese), Huanjing Kexue, 1987,8 3), 76-78. 

Dagnall and West8 have described the formation and extraction of a blue ternary complex, Ag(I)-l,10-phenanthroline-bromopyrogallol red (BPR), as the basis of a highly sensitive spectrophotometric procedure for the determination of traces of silver (Section 6.16). The reaction mechanism for the formation of the blue complex in aqueous solution was investigated by photometric and potentiometric methods and these studies led to the conclusion that the complex is an ion association system, (Ag(phen)2)2BPR2, i.e. involving a cationic chelate complex of a metal ion (Ag + ) associated with an anionic counter ion derived from the dyestuff (BPR). Ternary complexes have been reviewed by Babko.9... 

Jackson, P. E. and Haddad, P. R., Optimization of injection technique in capillary ion electrophoresis for the determination of trace level anions in environmental samples, ]. Chromatogr., 640, 481, 1993. 

Both IC and CE are separation techniques used to examine aqueous samples for anions, cations and trace levels of organic acids. CE produces separations by a different mechanism than IC, and produces sharper peaks. Therefore, CE can easily perform some separations that are difficult by IC. The determination of inorganic anions by IC and CE was compared [841],... 

To date, a few methods have been proposed for direct determination of trace iodide in seawater. The first involved the use of neutron activation analysis (NAA) [86], where iodide in seawater was concentrated by strongly basic anion-exchange column, eluted by sodium nitrate, and precipitated as palladium iodide. The second involved the use of automated electrochemical procedures [90] iodide was electrochemically oxidised to iodine and was concentrated on a carbon wool electrode. After removal of interference ions, the iodine was eluted with ascorbic acid and was determined by a polished Ag3SI electrode. The third method involved the use of cathodic stripping square wave voltammetry [92] (See Sect. 2.16.3). Iodine reacts with mercury in a one-electron process, and the sensitivity is increased remarkably by the addition of Triton X. The three methods have detection limits of 0.7 (250 ml seawater), 0.1 (50 ml), and 0.02 pg/l (10 ml), respectively, and could be applied to almost all the samples. However, NAA is not generally employed. The second electrochemical method uses an automated system but is a special apparatus just for determination of iodide. The first and third methods are time-consuming. 

HTAC cationic micelles also markedly enhance the CL intensity of fluorescein (FL) in the oxidation of hydrogen peroxide catalyzed by horseradish peroxidase (HRP) [39], However, no CL enhancement was observed when anionic micelles of sodium dodecyl sulphate (SDS) or nonionic micelles of polyoxyethylene (23) dodecanol (Brij-35) were used (Fig. 9). CL enhancement is attributed to the electrostatic interaction of the anionic fluorescein with the HTAC micelles. The local concentration of fluorescein on the surface of the micelle increases the efficiency of the energy transferred from the singlet oxygen (which is produced in the peroxidation catalyzed by the HRP) to fluorescein. This chemiluminescent enhancement was applied to the determination of traces of hydrogen peroxide. The detection limit was three times smaller than that obtained in aqueous solution. 

At slightly acidic pH values weak dibasic acids H2L give on dissociation anions HL , forming ion pairs MHL with metal ions. These ion pairs are neutral for M(l), which is the case of Na(I), K(I) and ammonium ions, and electrophoretically mobile for M(ll), such as Ca(II) and Mg(II). A chromophore BH/B consisting of a weak base B, which at slightly acidic pH values is in equilibrium with its conjugate acid BH, also has electrophoretic mobility due to the latter ion and may serve for indirect UVD of the M(ll) ions. These principles have been applied as a CE method for determination of trace concentrations of Ca(II) and Mg(II) in aqueous solutions containing more than 5000-fold concentrations... 

The effect of the preconcentration time and of the voltage on the sensitivity of a CE determination of trace inorganic and organic anions in matrix-free pure water has been studied [42] and compared with IC IC yields similar or better detection limits (nl/ml level), but requires trace enrichment times much... 

Determination of trace elements or anions. (i) Direct injection of sample into carrier stream of... 

The indirect method is a calibration approach complementary to the set of standards method in the sense that it allows determination of additional analytes with the use of a given detection system. For instance, it is often used for the determination of many anions in trace amounts by atomic absorption spectrometry [3]. It is interesting that the method gives a chance to positively exploit the interference effect. Reaction between the interferent and analyte in the set of standards method can be exploited such that the signal is measured for the analyte (now considered the reagent) and the interferent takes the role of analyte. 

Chao, T. T., Fishman, M. J., Ball, J. W. Determination of traces of silver in water by anion exchange and atomic absorption chromatography. Anal. Chim. Acta 47, 189 (1969)... 

Tin(ll) can be determined with the use of the ion-associate of SnCl with Crystal Violet (formula 4.27) (4-heptanone, e = 8.5-10 ) [48]. The associates of SnCU with Malachite Green [49] and Butylrhodamine B [50] has been extracted into benzene. Usually, TiCH is used to keep tin as Sn(II). The flotation of the ion-associate of SnCli with Rhodamine 6G by means of DIPE enables the separation and determination of traces of Sn(Il) in tin(IV) chloride [51]. The anionic complex of tin(IV) with 3,5-dinitrocatechol can be associated with Brilliant Green (CCU+CeHe, 8 = 1.75-10 ) and Nile Blue A (8 = 1.3-10 ) [52]. The ion-associate of the Ti(rV)-3-nitroalizarin complex with Brilliant Green (CHCI3, 8 = 2.0-10 ) [53], and the complex with thiocarbamide and Xylenol Orange [54] have also been used for Sn determination. 

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