Determination of formaldehyde content by spectrophotometric method in some fresh water and marine fishes of Bangladesh

Abstract

The present study was conducted for quantitative analysis of formaldehyde presence in some important freshwater and marine fish species by spectrophotometric method using Nash reagent in conjunction with TCA extraction. The freshwater fish rohu, Labeo rohita ; tilapia, Oreochromis nilotica; Thai koi, Anabas testudineus; kachki, Corica soborna; and marine fish loyitta, Harpodon nehereus; chhuri, Lepturacanthus savala from local markets and from freshly caught samples were evaluated for determination of formaldehyde concentration. Formaldehyde concentration obtained in fishes from three different wet markets of Mymensingh mechhua bazar was ranged between 1.4 and 7.35 µg/g. On the other hand, formaldehyde concentration in freshly caught fishes rohu, tilapia and Thai koi collected from ponds of Freshwater Station, Bangladesh Fisheries Research Institute (BFRI), Mymensingh showed natural formaldehyde in their muscle having values of 1.45; 1.85 and 2.60 µg/g, respectively. The marine fish viz. loyitta and chhuri collected from the landing center of BFDC at Cox’s Bazar and investigation in frozen, thawed condition showed to contain naturally occurring formaldehyde as 3.9 and 1.55 µg/g, respectively. Spectrophotometrically determination of formaldehyde concentration showed highest value of 7.35 µg/g in market sample of kachki, and naturally occurring formaldehyde concentration showed higher value of 2.6 µg/g in Thai koi from freshwater and 3.9 µg/g in loyitta fish from marine source. The present study suggested that fish from wet market contained a certain amount of added formaldehyde and fishes from both freshwater and marine sources shows to contain natural occurring formaldehyde in their muscle at different concentration.