There has been a significant increase in the use of CZE for analyzing dyes, especially artificial colourants added to foodstuff, such as brilliant blue and azorubine in red wines and a variety of azo dyes in alcoholic beverages, not to mention synthetic dyes in ice creams and milk beverages. adopted CZE for studying the formation of carcinogenic aryl amines in azo dyes. described the CZE separation of fluorescein dyes by exploiting host-guest complexation with β-cyclodextrin. Perhaps the first report appeared in 1998, when Pérez-Ruiz et al. After a timid approach, , the CZE analysis, has gained momentum and has been applied to a variety of cases.
The main analytical methods applied to the characterization of metal dyes are HPLC and capillary zone electrophoresis (CZE). These can be transformed into carcinogenic compounds under anaerobic conditions. This is particularly true with azo dyes, which alone constitute about 50% of all industrial colourants produced worldwide. The complex chemical formulae of dyes, along with the presence of heavy-metal ions, has the potential of inducing chronic toxicity, for instance through mutagenic and carcinogenic effects. Unfortunately, it is estimated to grow to 10–15% of unexhausted dyes, after the colouring process, are discharged into the waste streams irrespective of the substrate involved (e.g., leather, plastic). Approximately 10,000 different dyes and pigments are produced annually worldwide and used extensively in the dye and printing industries. The total worldwide consumption of dyes in several industries such as textile, leather, paper, pulp, plastics is estimated will grow to 2.3 million metric tons in 2013. Acid Brown 434, were analyzed by the same protocol with very good results.
As additional examples two other commercial metal-based dyes, C.I. Two of them were identified by isolation from the commercial mixture. More than twelve compounds present in the commercial mixture, but undetectable by the analytical protocols known in literature, were fully separated by the MECK mode capillary electrophoresis with low % Relative Standard Deviation of the main electrophoretic parameters. Acid Black 194, and one of the main impurities were isolated by silica flash chromatography and identified by mass spectrometry and NMR. The three chrome(III) complexes deriving from the industrial synthesis of C.I. Acid Black 194 was analyzed by reversed-phase HPLC, Capillary Zone Electrophoresis and Micellar ElectroKinetic Chromatography under different operative conditions, with the scope to detect the impurity distribution typical of any production processes and synthetic batch.
0 kommentar(er)
