Chrome azurol S

The results of the complexation study of Cu(II), Pb(II), Zn(II), Fe(III), Hg(II), Cd(II), Sn(IV), Zr(IV), Ti(IV) with arsenazo III, sulfonazo III, SPADNS, Eriochrome T, Acid Chrome Dai k Blue, Xylenol Orange, Methyl Thymol Blue, Pyrocatechol Violet, Chrome Azurol S, Eriochrome Cyanin R, Basic Blue K, Methyl Violet, Brilliant Green, Rhodamine C and Astraphoxin in solid phase. The obtained data ai e used for the working out of a new method of metal determination. 

D. B. Alexander and D. A. Zuberer, Use of chrome azurol S reagents to evaluate siderophore production by rhizosphere bacteria. Biol. Fertil. Soils 14 39 (1991). 

Syoyama and Nogima reported a colorimetric method for the detection of procaine in urine, where the drug and other phenethylamines were extracted [46]. The extraction involved ion association with Chrome Azurol S (C.I. Mordant blue 29), and was applied to a screening test for the drug and other related amines. 

Al, Fe Cation exchange Dionex CS2 resin Post column derivitisation with Chrome Azurol S-acetyl methyl ammonium bromide (TritionX-100) [23]... 

Fig. 13 shows an example of how important it is to avoid contamination, and its influence on the final result of the analysis. The analytical procedure was a pre-concentration of aluminum by adsorption of its complex with an organic reagent (chrome azurol S) onto a polymeric material (polyethylene powder) packed into a column. Standard solutions were prepared and the procedure carried out after adopting stepwise precautions to avoid contamination. It can be seen that, only after adopting all steps, was the contamination controlled. The graph also shows that the lower the aluminum content in the sample the higher is the contribution of the contamination sources. 

C23H16O9CLS, 2",6"-dichloro-4 (chrome Azurol S), H4L -hydroxy-3,3 -dimethyl-3"-sulphofuchsone-5,5 -dicarboxylic acid ... 

Eriochrome Cyanine R (ECR) (formula 4.17) and Chrome Azurol S (CAS) (formula 4.18) have carboxylate groups besides hydroxyl and sulphonate groups [41,42]. These reagents can be purified by various methods [43,44]. ECR and CAS react with many metals in weakly acidic or neutral solutions [45-47]. The yellow-orange colour of the reagents changes to blue or violet solutions of the metal chelates. 

The extraction method using 8-hydroxyquinoline is not very sensitive, but it is highly selective. The really sensitive methods for spectrophotometric determination of aluminium are based on ternary systems, including triphenylmethane reagents (mainly Chrome Azurol S and Eriochrome Cyanine R) and some surfactants. 

Chrome Azurol S (CAS) (formula 4.18) reacts with aluminium ions to form (pH 4-7) a water-soluble blue complex which has been a basis for the determination of aluminium [16-18]. 

A considerable increase in the sensitivity of the determination of aluminium with Chrome Azurol S is observed in the presence of cationic or non-ionic surfactants, if present in sufficient molar excess with respect to the chromogenic reagent. The presence of surfactants gives rise to a considerable bathochromic shift (Fig. 6.1). 

Fig. 6.1. Absorption spectra of Chrome Azurol S (CAS) (vs. water), (1), AI-CAS complex (vs. reagent solution) (2), and the ternary AI-CAS-CTA complex (3) (vs. reagent solution) (pH 5.3)...

A number of non-ionic surfactants was used for determination of aluminium with Chrome Azurol S. They include Dispergator BO [21], OP-10 [25], Sintanol DS-7 and Sintanol DS-10 [25-27], and others [28]. The sensitivities are similar to those found with cationic surfactants. The values of A>. can be larger than 200 nm [25]. 

Methods of determining aluminium with the use of Chrome Azurol S, Eriochrome Cyanine R, and Pyrocatechol Violet have been compared [60,61]. 

The Chrome Azurol S method was used to determine aluminium in water [82], steel [83,84], uranium alloys [85], iron ores [86], and magnetic alloys [87]. Higher contents of aluminium (-10%) in magnesium and titanium compounds were determined by the differential spectrophotometry techniques [88]... 

The methods involving Chrome Azurol S and surfactants were used for determining aluminium in water [27,89-93], steel [94,95], copper alloys [26], magnesium alloys [21], chromium alloys [96], and titanium [3]. Trace amounts of aluminium were determined in tap water by means of CAS and CP (pH 5.7 30% ethanol) using the flow-injection technique (FIA) [91]. 

Triphenylmethane and azo reagents are used in most methods for determining beryllium. Methods using Chrome Azurol S or Eriochrome Cyanine R and some cationic surfactants are very sensitive. The selectivity of methods for beryllium determination is improved by the use of EDTA as masking agent. 

Chrome Azurol S (CAS, formula 4.18) forms a coloured chelate complex with Be, and this has been used for the determination of Be [18-21], In acetate (or hexamine) buffer and in the presence of EDTA as masking agent, the Chrome Azurol S method is highly selective for beryllium. The absorbance of the complex depends on the pH, and on the concentrations of CAS, EDTA, and the acetate buffer. The absorbance increases with increasing CAS concentration, and decreases with increasing EDTA and acetate concentrations. A pH of 5 is the most suitable. Below this pH, the absorbance of CAS increases considerably, and above it the absorbance of the beryllium complex is decreased more by EDTA. 

Chrome Azurol S (CAS) 0.1% solution. Dissolve 100 mg of the reagent in water and dilute to 100 ml in a volumetric flask. 

Maximal and stable absorbance of the triple complex is obtained with a large excess of surfactant in relation to CAS. In these systems, ternary complexes are formed in which the ratio CAS Be is greater than in binary systems (without surfactant). Figure 9.1 shows the absorption spectra of Chrome Azurol S and the binary and ternary (with CTA) complexes of beryllium... 

Eriochrome Cyanine R (ECR) (formula 4.17) reacts with beryllium ions [4,9,10,16,30] similarly to Chrome Azurol S (see Section 9.2.1). At pH 9.7, A-max of ECR is 435 nm and that of its water-soluble beryllium complex is 525 nm. The molar absorptivity of the complex is 1.5 10 . EDTA, tartrate and cyanide are used as the main masking agents for interfering metals. In the presence of cationic surfactants, the sensitivity is increased several times, and significant bathochromic shifts are observed. In the case of CTA, e = 8.7-1 O at 590 nm (pH 7) [31,32]. Beryllium was also sorbed on anion exchange resins impregnated with ECR [33]. 

The Chrome Azurol S method has been applied for determining beryllium in, for example, bronzes [54] and water [55], In the presence of a surfactant, beryllium was determined in minerals [15], sewage [56], coal dust [57,58], and aluminium alloys [59]. 

Various organic reagents are used for direct determination of calcium, such as murexide (ammonium purpurate) (e = 1.4-10 at 500 nm) [2,49], Metalphthalein [50], Calcein [51,52], Chrome Azurol S (in the presence of 1,10-phenanthroline) [53], Alizarin S [54], 8-hydroxyquinoline (extraction into CHCI3 in the presence of n-butylamine or butoxyethanol) [55], and Emodine (l,3,8-trihydroxy-6-methylanthraquinone) [56]. Calcium has been determined as a complex with Emodine, in the presence of Be and Mg, by the derivative spectrophotometry technique. The anionic complexes of calcium with bromo-oxine [57] or HTTA [58] have been extracted into benzene as ion associates with Rhodamine B. Calcium was also determined as a complex with o-cresolphthalein [59-63], or thymolphthalein [64]. 

Methods for chromium with use of triphenylmethane reagents are less sensitive examples are Chrome Azurol S (e = 5.9-10 ) [43,44], Xylenol Orange (e = 1.0-10" ) [45], and Malachite Green [46]. A much higher sensitivity is obtained when Cr(III) is determined with the use of Eriochrome Cyanine R in the presence of surfactant CTA (e = 6.8-10" ) [47]. Cr(lll) was determined with Eriochrome Cyanine by means of the derivative spectrophotometry [48]. 

Among the other methods mentioned above. Chrome Azurol S was used for determining Cr in steel [44], and Rhodamine 6G was used for determining Cr in steels, geological samples, and sewage [51]. 

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]. 

Numerous methods for determining fluoride are based on compounds of thorium with organic reagents, such as Alizarin S [55], Xylenol Orange [48], Arsenazo I [4], and chloranilic acid [56]. An exceptionally sensitive method is based on the ternary system Th-Chrome Azurol S-CTA (e= 1.0-10 at 635 nm) [57]. 

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