A rapid analytical and quantitative evaluation of formaldehyde in squid based on Tri-step IR and partial least squares (PLS)

Formaldehyde abuse for retaining squid freshness is detrimental to public health. The aim is to establish a rapid and quantitative detection method of formaldehyde in squid for screening massive samples. A linear relationship between formaldehyde concentration in squid and formaldehyde concentration in squid soaked water was observed using HPLC. Chemical profile variances of squids were rapidly analyzed by Tri-step infrared spectroscopy. Specifically, with increasing formaldehyde concentration, peak intensities of 2927 cm(-1) (v(as)(CH2)), 1081 cm(-1) (glycogen), 1631 cm(-1) (beta-sheet proteins) decreased while 1655 cm(-1) (cc-helix proteins) increased. Spectral curve-fitting results further disclosed that beta-sheet proteins were transformed to alpha-helix and beta-turn conformations. Furthermore, a quantitative prediction model based on IR spectra was established by PLS (R-2, 0.9787; RMSEC, 5.51). The developed method was applicable for rapid (c.a. 5 min) and quantitative analysis of formaldehyde in squids with LOD of 15 mg/kg. (C) 2017 Elsevier Ltd. All rights reserved.