Determination of chloride

Reagent The carrier stream is prepared by dissolving 0.626 g of mer-cury(II) thiocyanate, 30.3 g of iron(III) nitrate, 4.72 g of concentrated nitric acid, and 150 mL of methanol in water, making the final volume up to 1 L. 

Standard Solutions Standard solutions in the range 5-75 ppm Cl are made by suitable dilution of a stock solution containing 1000 ppm Cl (1.648 g of sodium chloride per liter). 

Exercise Carrier stream is pumped through the system and the individual Cl standards are injected successively in quadruplicate, thus yielding a recording such as that shown in Fig. 2. b (left). (Note that the waste is toxic and should be collected, not discharged into the sink.) 

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Directions are provided for the determination of chloride in samples using CZE. The buffer solution includes pyromellitic acid which allows the indirect determination of chloride by monitoring absorbance at 250 nm. 

Janusa and co-workers report the determination of chloride by CZE. Analysis of a series of external standards gives the following calibration curve. 

A single-channel manifold also can be used for systems in which a chemical reaction generates the species responsible for the analytical signal. In this case the carrier stream both transports the sample to the detector and reacts with the sample. Because the sample must mix with the carrier stream, flow rates are lower than when no chemical reaction is involved. One example is the determination of chloride in water, which is based on the following sequence of reactions. ... 

Silver diethyldithiocarbamate [1470-61-7] is a reagent commonly used for the spectrophotometric measurement of arsenic in aqueous samples (51) and for the analysis of antimony (52). Silver iodate is used in the determination of chloride in biological samples such as blood (53). 

This method may be applied to the determination of chlorides, bromides,... 

Either the Mohr titration or the adsorption indicator method may be used for the determination of chlorides in neutral solution by titration with standard 0.1M silver nitrate. If the solution is acid, neutralisation may be effected with chloride-free calcium carbonate, sodium tetraborate, or sodium hydrogencarbonate. Mineral acid may also be removed by neutralising most ofthe acid with ammonia solution and then adding an excess of ammonium acetate. Titration of the neutral solution, prepared with calcium carbonate, by the adsorption indicator method is rendered easier by the addition of 5 mL of 2 per cent dextrin solution this offsets the coagulating effect of the calcium ion. If the solution is basic, it may be neutralised with chloride-free nitric acid, using phenolphthalein as indicator. 

Determination of chloride as silver chloride Discussion. The aqueous solution of the chloride is acidified with dilute nitric acid in order to prevent the precipitation of other silver salts, such as the phosphate and carbonate, which might form in neutral solution, and also to produce a more readily filterable precipitate. A slight excess of silver nitrate solution is added, whereupon silver chloride is precipitated ... 

Two procedures are commonly employed for the colorimetric determination of chloride. 

ISO 4323 1977, Soaps Determination of chlorides content—Potentiometric method. 

Seligson, S. McCormick. G. J. and Sleeman, R. Electrometric method for the determination of chloride in serum and other biological fluids. Clin. Chem. (1958), 4, 159 -169. 

Many fluorescent molecular sensors for halide ions (except F ) are based on collisional quenching of a dye. In particular, the determination of chloride anions in living cells is done according to this principle. Examples of halide ion sensors are given in Figure 10.29. 

The determination of chloride using an instrument known as a chloride meter is probably the most common application of coulometry in biochemistry. The instrument is designed to generate silver ions electrolytically from a silver anode. These ions are removed from the solution as undissociated silver chloride, which is either deposited on the anode or precipitated in the solution. A low concentration of carrier electrolyte (nitrate ions) permits a small current... 

For example. Figure 8 shows both RSD and RCB data for determination of chloride and lead in water. In Figure 8a, the least-squares curve of best fit closely fits the lead standard data, and the calibration process has little adverse effect on precision. RSD s and RGB s are almost equal. On the other hand, chloride standard data in Figure 8b does not closely fit the mathematical model, and the RSD data overstates the precision of the analysis by a factor of about two. 

Chloride ion-selective electrodes The most important region of application is the determination of chlorides in waters, including sea water (for a review, see [167]), in serum [110,112,371] (review in [167]) and in soil [151,219,341], The determination of chloride ions in sweat made screening for cystic fibrosis possible in new-born babies (review, [45,55a, 262]). Br , I and S " interfere in the determination of chlorides in phosphate rocks [81]. Sulphite can be determined directly using an electrode with an Hgj CI2 - HgS membrane [398] on the basis of the reaction... 

The solid-membrane ISE has certain disadvantages for the determination of chloride inside cells and thus ion-selective microelectrodes containing ion-exchanger Corning No. 477315 (based on a nitroxylene mixture) are used [223]. Reviews of intracellular applications of this electrode can be found in [23, 78, 86, 211,217]. 

R. Ramasamy, P. Zhao, W.L. Gitomer, A.D. Sherry, C.R. Malloy, Determination of chloride potential in perfused rat hearts by NMR spectroscopy. Am. J. Physiol. 

AOAC 983.14 (2005) (determination of chloride, expressed as sodium chloride)... 

ISO (2006a). Cheese and Processed Cheese Products—Determination of Chloride Content— Potentiometric Titration Method (Standard ISO 5943/IDF 88). International Organization... 

An official procedure [10,11] describes a method for the determination of chloride in a saturated calcium sulfate extract of soil. The extract is acidified and the concentration of chloride is determined by titration with mercuric nitrate using diphenylcarbazone as indicator. Mercuric ion in the presence of chloride forms mercuric chloride, which, although soluble, provides insufficient mercuric ion to form the mercuric-diphenylcarbazone complex. When all of the chloride has been removed in this way, addition of further mercuric ion produces the violet complex. 

Davy and Bembrick [12] have described a method for the determination of chloride in water extracts in soils based on measurement of the EMF developed between two silver-silver chloride electrodes in a cell with a liquid function and suitable electrolyte. 

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. 

Bradfield and Cooke [13] give details of a procedure for the determination of chloride (as well as nitrate phosphate and sulfate) in aqueous extracts of plant materials by an ion chromatographic technique with indirect ultraviolet detection. Recoveries ranged from 84 to 108%. This technique is discussed in further detail in Sect. 10.11. 

Bradfield and Cooke [13] described an ion chromatographic method using a UV detector for the determination of chloride, nitrate, sulfate and phosphate in water extracts of plants and soils. Plant materials are heated for 30 minutes at 70 °C with water to extract anions. Soils are leached with water... 

Argentometric titration involves the titrimetric determination of an analyte using silver nitrate solution as titrant. Its application in environmental analysis is limited to the determination of chloride and cyanide in aqueous samples. The principle of the method is described below. 

Often, greater accuracy may be obtained, as in Volhard type titration, by performing a back titration of the excess silver ions. In such a case, a measured amount of standard silver nitrate solution is added in excess to a measured amount of sample. The excess Ag+ that remains after it reacts with the analyte is then measured by back titration with standard potassium thiocyanate (KSCN). If the silver salt of the analyte ion is more soluble than silver thiocyanate (AgSCN), the former should be filtered off from the solution. Otherwise, a low value error can occur due to overconsumption of thiocyanate ion. Thus, for the determination of ions (such as cyanide, carbonate, chromate, chloride, oxalate, phosphate, and sulfide, the silver salts of which are all more soluble than AgSCN), remove the silver salts before the back titration of excess Ag.+ On the other hand, such removal of silver salt is not necesary in the Volhard titration for ions such as bromide, iodide, cyanate, thiocyanate, and arsenate, because the silver salts of these ions are less soluble than AgSCN, and will not cause ary error. In the determination of chloride by Volhard titration, the solution should be made strongly acidic to prevent interference from carbonate, oxalate, and arsenate, while for bromide and iodide analysis titration is carried out in neutral media. 

The same group most recently reported the use of neutral lanthanide(III) tris-diketonates of type 88 for the determination of chloride [63]. The response in luminescence of the Eu(III) complex for chloride in acetonitrile solution was large enough to be seen by the naked eye. Incorporation of the complexes in... 

International Standard Organization. 1989. Water quality. Determination of chloride. Silver nitrate titration with chromate indicator (Mohr s method). ISO 9297. International Organization for Standardization, Case Postale 56, CH-1211, Geneva 20 Switzerland. 

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