Colorimetric determination of phenol and bisphenol-Л concentrations
in extracts from epoxide coatings contacting with food
A method for the determination of trace amounts of bisphenol-A (1—5 mg/1) and phenol (0.1—1 mg/1) in extracts from epoxide coatings contacting with food was elaborated. The analysis was carried out by two colorimetric methods. The methods are based on two colorimetric reactions of both phenols inalkaline solution either with 4-aminoantipyrine-potassium ferricyanide (reagent 1 ) with the formation of red indophenols or with 2 ,6 –dichloroquinonechlorimide (reagent 2) with the formation of blue compounds. In the case of reagent 1, the calculated molar absorbancy indexes were 1.6·104 for bisphenol-A and 1.3·104 for phenol at 509 nm, and in the case of reagent 2, these indexes were 3·103 for bisphenol- A and 1.8·104 for phenol at 611 nm. Concentrations of bisphenol-A and phenol were calculated from a system to two linear equations. Relative error of the method was below 6%. This method was applied in the analysis of extracts from commercial epoxide lacquers obtained with standardized model solutions.
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