Anions simultaneous determination

Simultaneous determination of both cations and anions in acid rain has been achieved using a portable conductimetric ion-exclusion cation-exchange chromatographic analyzer.14 This system utilized the poly(meth-ylmethacrylate)-based weak acid cation exchange resin TSK-Gel OA-PAK-A, (Tosoh , Tokyo, Japan) with an eluent of tartaric acid-methanol-water. All of the desired species, 3 anions and 5 cations, were separated in less than 30 minutes detection limits were on the order of 10 ppb. Simultaneous determination of nitrate, phosphate, and ammonium ions in wastewater has been reported utilizing isocratic IEC followed by sequential flow injection analysis.9 The ammonium cations were detected by colorimetry, while the anions were measured by conductivity. These determinations could be done with a single injection and the run time was under 9 minutes. 

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. 

Papadoyannis, I. N., Samanidou, V. F., and Nitsos, C. C., Simultaneous determination of nitrate and nitrite in drinking water and human serum by anion-exchange chromatography and UV detection, /. Liquid Chromatogr. Related Technol., 22, 2023, 1999. 

Tables 15 and 16 show the absorption maxima of some metal complexes of benzothiazolyl-substituted formazans 230 and 231.283 The wavelengths are metal ion dependent, making formazans useful reagents for the identification of specific metal ions or the simultaneous determination of two ions. The wavelengths are much longer than those of the formazan anion (Table 14). The general trend for electron-rich substituents is toward a larger shift this is to be expected as it tends to enhance the aromatic character of the ring and increase the covalent character of the metal — nitrogen bond. The sharpness of the absorption band has been attributed to coordination to the heterocyclic nitrogen as in 232.57S...

In one study, however, atmospheric pressure chemical ionisation (APCI)-MS was applied for the simultaneous determination of LAS and octylphenol ethoxylates (OPEO) in surface waters after preconcentration by solid-phase extraction (SPE) on Cis cartridges [1]. In the chromatogram from a Ci-reversed phase (RP) column, peaks arising from both the anionic LAS and the non-ionic OPEO were detected after positive ionisation, while in negative ionisation mode, OPEO were discriminated and only the anionic surfactant was observed. Surprisingly, the relative sensitivity for detection of LAS was approximately five times higher in positive ion mode, which led the authors to the conclusion that this ionisation mode was desirable for quantitative work. 

Fig. 2 Ion chromatogram of a sample of melted Alpine ice for direct simultaneous determination of inorganic (F, CP, N03, S04 ) and organic anions (CHaCOO , HCOO , CHaSOa , C2O4"-)...

Instruments are offered in the market for clinical determination of electrolytes in blood, plasma or serum. One of them, for example, carries out simultaneous determinations of Na, K, Ca, Mg, hematocrit and pH. The cations are of the free type (see Section m.A) and are measured with specific ion-selective electrodes. In complex matrices such as blood or its derived fractions the concentration of free Ca and Mg is affected by the pH of the solution, for example, a slight change of pH will produce or neutralize anionic sites in the proteins, binding or releasing these cations furthermore, the response of the Mg-selective electrode is also affected by the concentration of free Ca(II). The correction... 

Classification of methods for simultaneous determination of anions and cations by IC... 

There are still only a few published applications of sorbents with covalently bonded zwitterionic molecules for simultaneous determination of anions and cations. This is related to the difficulties... 

A novel capillary electrophoresis method using solutions of non-crosslinked PDADMAC is reported to be effective in the separation of biomolecules [211]. Soil studies conducted with PDADMAC report the minimization of run-off and erosion of selected types of soils [212]. In similar studies, PDADMAC has found to be a good soil conditioner [213]. The use of PDADMAC for the simultaneous determination of inorganic ions and chelates in the kinetic differentiation-mode capillary electrophoresis is reported by Krokhin [214]. Protein multilayer assemblies have been reported with the alternate adsorption of oppositely charged polyions including PDADMAC. Temperature-sensitive flocculants have been prepared based on n-isopropylacrylamide and DADMAC copolymers [215]. A potentiometric titration method for the determination of anionic polyelectrolytes has been developed with the use of PDADMAC, a marker ion and a plastic membrane. The end-point is detected as a sharp potential change due to the rapid decrease in the concentration of the marker due to its association with PDADMAC [216]. 

Niederer [100] used ion trap mass spectrometry and negative ion chemical ionisation to determine nitro- and oxypolyaromatic hydrocarbons in soils. Meyer et al. [101] have described a simple and reproducible method which provides the simultaneous determination of polycyclic aromatic hydrocarbons and het-eropolycyclic aromatic hydrocarbons (N, S, O) and their metabolites in contaminated soils. Contaminants extracted from the soil sample were separated by polarity and acid-base characteristics using solid-phase extraction on silica gel and a strong basic anion exchange material. A subfraction containing PANHs and neutral metabolites was subsequently fractionated into neutral and basic... 

Karlson and Frankenberger [60] have developed a simple column ion-chromatographic column method for the determination of selenite in soil extracts with the simultaneous determination of chloride, nitrite, nitrate and phosphate. Separation of the anions was conducted on a low-capacity ion-exchange column, and anions were quantified by conductiometric detection. The eluent stream consisted of 1.5 mmol/1 phthalic acid and adjusted to pH 2.7 with formic acid. 

Several papers have reported use of a weak acid/crown ether eluent in ion-exclusion/cation exchange chromatography with conductimetric detection on a weakly acidic cation-exchange column to effect the simultaneous determination of both cations and anions. Resolution was significantly improved when 18-crown-6 was present in the eluent. Detector response was positive for anions and negative for cations. [76-80] A sample chromatogram is shown in Figure 9. 

Ikedo, M., Mori, M., Xu, Q., Taoda, H., Sato, S., Hu, W., and Tanaka, K. (2003) Simultaneous Determination of Anions and Cations in Raw Material of Ceramic Glaze by Ion-exclusion/cation-exchange Chromatography with a Weakly Acidic Cation-exchange Resin, Bunseki Kagaku 52, 1173-1180. 

A simpler and technologically superior approach is the measurement of the direct electrical conductance. The background conductivity of the mobile phase is electronically subtracted, not requiring a suppressor device. One example of direct conductivity detection is the simultaneous determination of potassium nitrate and sodium monofluorophosphate in dentrifices [76]. Alendronate, a bisphonate, can be directly detected in intravenous solutions and tablets using an anion-exchange column and conductivity detection [77]. Another example, from one of the author s (JA) laboratory is shown in Figure 5.3. Direct conductivity detection makes it possible to selectively detect choline in the presence of an equal molar amount of an antibiotic which is not detected. 

Jones and Tarter [11] have applied this technique to the simultaneous determination of metals (sodium, potassium, calcium, magnesium) and anions (chloride, sulphate, nitrate, bromide) in potable waters. The technique uses a cation separator column, a conductivity detector, an anion separator column and an anion suppressor column. Two different eluants were used lithium carbonate-lithium acetate dihydrate, and copper phthalate. 

Gonzalez et al. [8] have applied micelle analysis in the kinetic multicomponent analysis for the simultaneous determination of thiocyanate, sulphite and sulphide in non saline waters. The method involved reaction of the anions with S,S dithiobis(2-nitrobenzoic acid) in aqueous cetyltrimethyl ammonium bromide micelles. Cyanide, sulphide and sulphite were determined at concentrations, respectively, down to 0.5-1.5/10 4M 0.2-1 xl0 4M and 0.2-1.5><10 4M with a relative error of less than 5%. 

Simultaneous determination of chromium(lll) and chromium(VI) in water extract from metal fumes Sample solution at pH 5 reacted with disodium ethylenediamine tetraacetic acid at 50 °C for 1 hour HPLC on anion exchange column with Na2C03 eluting solution and simultaneous UV and AAS detection 0.2 ng by UVfor chromium(VI) 2.0 ng by UV 5.0 ng by AAS for chromium (IV) 5 ng by AAS for chromium (III) 95-105% at 0.002-2.0 pg Suzuki and Serita 1985... 

Suzuki Y, Serita F. 1985. Simultaneous determination of water-soluble trivalent and hexavalent chromium by anion exchange high-pressure liquid chromatography. Ind Health 23 207-220. 

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