Sensitive and simple colorimetric methods for visual detection and quantitative determination of semicarbazide in flour products using colorimetric reagents

After baking the flour, azodicarbonamide, an approved food additive, can be converted into carcinogenic semicarbazide hydrochloride (SEM) and biurea in flour products. Thus, determine SEM in commercial bread products is become mandatory and need to be performed. Therefore, two accurate, precision, simple and economics colorimetric methods have been developed for the visual detection and quantitative determination of SEM in commercial flour products. The 1st method is based on the formation of a blue-coloured product with lambda max at 690 nm as a result of a reaction between the SEM and potassium ferrocyanide in an acidic medium (pH 6.0). In the 2nd method, a brownish-green colored product is formed due to the reaction between the SEM and phosphomolybdic acid (PMA) in a basic medium (pH 9.0). The resulting product absorbs light at lambda max 750 nm. The colorimetric methods can be used either as sensors to detect the SEM by bare eye observation as little as 10 ppm and 2.0 ppm within 4-2 min or by spectrophotometry as the determination methods with linearity ranges 8.0-180 ppm and 0.5-30 ppm for the 1st and 2nd methods respectively. The developed methods were successfully applied to determine the SEM in the commercial bread products with a relative standard deviation (RSD) <3 %, <2 % and recovery of 94-103 %, 96-101 % for methods (1st and 2nd) respectively. The visual detection limits of the sensors can be used as a platform for SEM field-portable detection due to their lower limitations than the reported SEM in flour products, which opens the doors for on-site detection of SEM with instrument free.

Automated summary

Two simple, accurate, precise, and economical colorimetric methods have been developed for the visual detection and quantitative determination of SEM in commercial flour products. These methods can detect SEM by bare eye observation at very low concentrations and can also be used for quantitative determination using a spectrophotometer.