Validation of a paper strip method for detecting formaldehyde contamination in fresh fish

BACKGROUND: Illegal treatment of seafood with formaldehyde can danger consumers as it is a toxic carcinogenic chemical comes under list of class I carcinogen by "International Agency for Research on Cancer". Faster testing methods for field level detection can prevent marketing of formaldehyde contaminated fishes as instrumental testing are time consuming. Rapid paper strip method for screening the formaldehyde contamination in fresh fish named 'CIFTest' was developed by ICAR-Central Institute of Fisheries Technology is a qualitative non-destructive test method. Validation details of this testing technique are highly relevant as this test is recommended for rapid on-site screening of formaldehyde contamination by food safety officials. OBJECTIVE: The present study describes the validation of rapid paper strip-based detection of formaldehyde contamination in fresh fish based on ISPAM guidelines for qualitative binary chemistry methods given by AOAC International. METHODS: Validation study covered performance characteristics limit of detection (LOD), selectivity, specificity, probability of detection (POD), applicability, ruggedness, and comparison with instrumental method. RESULTS: LOD of the kit is determined as 4 mg/Kg. Appearance of green to blue colouration in the paper strip indicate the presence of the formaldehyde. The test kit is selective and specific in detecting the targeted compound formaldehyde in comparison to non-targeted compounds namely acetaldehyde and propionaldehyde. POD determined at LOD is 95% and β error is 5%. Observed 95% POD from 4 mg/Kg onwards of formaldehyde in fish. The method is rugged and applicable in different fish matrices. Randomly screened positive samples were in the range of 4.1 to 26.78 mg/Kg by HPLC analysis. CONCLUSION: The study confirms that the developed paper strip is adequate and validated for assessing the formaldehyde contamination in fresh fish qualitatively. HIGHLIGHTS: Paper strip-based testing using 'CIFTest' kit, is highly suitable and valid method for faster screening of formaldehyde contamination in fresh fish.