Fluoride spectrophotometric determination

Shapiro, L. Spectrophotometric determination of silica at high concentrations using fluoride as a depol5nnerizer. 

Clark and Tedder have studied the fluorination of carbon tetrachloride by flowing together F2 and CCI4, both diluted in nitrogen. FCl was converted to HF and HCl followed by titration of fluoride and spectrophotometric determination of the chloride. Experiments at 20 °C are interpreted in terms of the mechanism... 

As well as the zirconium-Eriochrome Cyanine R complex, the coloured complexes of zirconium with other organic reagents are used for indirect spectrophotometric determination of fluoride. These include Alizarin S [44-46], SPADNS [6,16,47,48], Xylenol Orange [49-52] Chrome Azurol S [53], and rutin [54]. 

K. Shimada, T. Shimoda, H. Kokusen, S. Nakano, Automatic microdistillation flow-injection system for the spectrophotometric determination of fluoride, Talanta 66 (2005) 80. 

H. Wada, H. Mori, and G. Nakagawa, Spectrophotometric Determination of Fluoride with Lanthanum/Alizarin Complexone by Flow Injection Analysis. Anal. Chim. Actay 172 (1985) 297. 

Fluoride can be determined with three significant figures using a fluoride electrode. Otherwise, the recommended procedure is a spectrophotometric determination with lanthanum alizarin complexone. 

Solvent extraction by a crown hydroxamic acid in chloroform for the determination of La in monazite sand has been reported by Agrawal and Shrivastav (1997). La can be determined spectrophotometrically in the oiganic phase between 1.2 and 20 ppm, or by ICP/AES with a detection limit of O.lSppb. A two-fold excess of Y, Ce, Pr, or Nd did not interfere with the spectrophotometric determination, and higher concentrations could be tolerated when fluoride or oxalate were present in the aqueous phase. 

A method for the determination of fluorine in fluorinated polymers such as polytetrafluoroethylene (PTFE) is based on decomposition of the sample by oxygen flask combustion followed by spectrophotometric determination of the fluoride produced by a procedure involving the reaction of the cerium(III) complex of alizarin complexan (1,2-dihydroxy-anthraquinone-3-ylmethylamine N,N-diacetic acid). The blue colour of the fluoride-containing complex (maximum absorption, 565 nm) is completely distinguishable from either the yellow of the free dye (maximum absorption, 423 nm) or the red of its cerium(III) chelate (maximum absorption, 495 nm). 

A Spectrophotometric Determination with Microdistillation Combined FIA Method La(III)-alizarine complexone (La-ALC) fluoride ternary complex formations based spectrophotometric fluoride determination method was reported by Shimaada et al. [54]. The spectroscopic detection does not have the selectivity needed in the low concentration ranges therefore, a separation step was inserted into the analytical procedme. 

Absorption spectrophotometric analysis procedures have been developed for a number of environmental species. For water contaminants alone, these include procedures for the determination of arsenic, boron, bromide ion, cyanide, fluoride, nitrate, phenols, phosphate, selenium, sUica, sulfide, surfactants, and tannin and lignin. A typical such procedure is the spectrophotometric determination of phenol in water by the reaction with 4-aminoantipyrene... 

Alizarine fluorine blue is the 3-methylamino-A, A -bisacetic acid derivative of alizarine, the Ce or La chelate of which binds with fluoride ions to form a ternary complex. This was the first reagent that could be used for the direct spectrophotometric determination of fluoride. 

A method has been described [ 1 ] for the determination of borate in soils based on the conversion of borate in a hot water extract to fluoroborate by the action of orthophosphoric acid and sodium fluoride. The concentration of fluoroborate is measured spectrophotometrically as the blue complex formed with methylene blue which is extracted into 1,2-dichloroethane. Nitrates and nitrites interfere, but these can be removed by reduction with zinc powder and orthophosphoric acid. 

Spectrophotometric techniques based on molecular absorption radiation for determining nutrients (NO3, N02, NII4, N2, phosphorus, and silicon) as well as chlorine, fluoride, cyanide, sulfate, and sulfide. 

Fluoride Determine as directed in Method III under Fluoride Limit Test, Appendix IIIB, except in the Procedure, use 10 mL of 1 N hydrochloric acid to dissolve the sample. Lead Determine as directed in the Flame Atomic Absorption Spectrophotometric Method under Lead Limit Test, Appendix IIIB, using a 10-g sample. 

There are also indirect spectrophotometric methods, in which the element determined provokes a change in colour. This group comprises most of the methods for the determination of fluoride. Being capable of forming stable complexes with some metals, fluoride anions can decompose colour complexes of those metals. Thus, in the method involving a sulphosalicylate complex of Fe(lII) the solution is discoloured by F and a change of colour is observed in the method based on the use of the Zr complex with ECR. Still another example is the determination of phosphate with the use of lanthanum chloranilate. Phosphate anions react to form the less soluble LaP04 and release coloured chloranilate ions. 

Once in solution, the preferred method for measurement of boron is inductively coupled plasma atomic emission spectroscopy (ICP-AES) or inductively coupled plasma mass spectrometry (ICP-MS). The most widely used nonspectrophotometric method for analysis of boron is probably ICP-MS because it uses a small volume of sample, is fast, and can detect boron concentrations down to 0.15 pgL . When expensive ICP equipment is not available, colorimetric or spectrophotometric methods can be used. However, these methods are often subject to interference (e.g., nitrate, chloride, fluoride), and thus must be used with caution. Azomethine-H has been used to determine boron in environmental samples (Lopez et al. 1993), especially water samples. Another simple, sensitive spectrophotometric method uses Alizarin Red S (Garcia-Campana et al. 1992). 

The advantage of discrete analyzers is that sample crossover in the system itself is the lowest possible. Volumes of 75 pi of reagent and sample volumes as large as 100 pi are sufficient. In an automated system with a throughput of 200 determinations per hour in the same sample 6 to 10 components (such as ammonium, alkalinity, aluminum, boron, bromide, calcium, chloride, chromium(VI), cyanide, fluoride, iron, magnesium, nitrate, nitrite, phosphate, etc.) can be determined. In discrete analyzers normally conventional spectrophotometric methods are used. These methods are prone to interference of the matrix of the sample. As a good concept for interference studies still is not available, interferences are as yet not sufficiently studied systematically even for routine analyses. 

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