Standardization and validation of a high-performance thin-layer chromatography method for the quantification of aflatoxin B1 and its application in surveillance of contamination level in marketed food commodities from the Mumbai region

Aflatoxin B1 (AFB1) is a natural carcinogenic contaminant of agricultural product regulated at parts per billion (ppb) level; therefore, a validated method for the analysis of AFB1 is extremely important. In this study, a high-performance thin-layer chromatography (HPTLC) method was standardized and validated with respect to linearity, sensitivity, precision, and accuracy for the quantification of AFB1. Three extraction techniques using different solvent systems, namely QuEChERS (quick, easy, cheap, effective, rugged and safe) method, Contaminants Branch method and Best Foods method were evaluated for AFB1 extraction efficiency in food commodities, wherein QuEChERS method using acetonitrile‒methanol (40:60, V/V) gave maximum recovery of AFB1 in all commodities. Maximum AFB1 was recovered in dried chilli sample (89.98%), whereas the least recovery was obtained in wheat sample (68.20%). The optimized HPTLC method with chloroform‒acetone (9:1, V/V) as the mobile phase showed a compact AFB1 band at RF value of 0.36 ± 0.02. The linear regression analysis of AFB1 showed good linearity over 10, 20, 40, 60, 80, 100, 120 ng/spot with a regression value of 0.9923 and %RSD less than 1. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 1.133 ng/band and 3.434 ng/band, respectively. The optimized HPTLC method was further used to assess the AFB1 content in marketed samples of groundnut, corn, rice, wheat and dried chillies from the Mumbai region and it was found that 8 groundnut samples, 5 corn samples, 5 wheat samples, and 7 chilli samples out of 20 each had AFB1 concentration above Indian permissible regulatory limit of 30 ppb.