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Determination of small molecules in food matrices by molecularly imprinted polymers and surface enhanced Raman spectroscopy Gao, Fang


The research work focuses on developing novel methods for determining small molecules in food matrices using molecularly imprinted polymers (MIPs) and surface enhanced Raman spectroscopy (SERS). MIPs are synthesized as artificial antibodies towards target molecules utilizing interactions between templates and functional monomers to impress complementary binding sites on polymers. MIPs selectively isolate templates from food extracts. SERS technique provides rapid and sensitive detection of MIPs-separated molecules. Statistical analysis including unsupervised principal component analysis (PCA), supervised simple linear regression and partial least square regression (PLSR) is employed to analyze SERS spectra. Chloramphenicol in milk and honey was determined using MIPs-packed solid phase extraction cartridge to isolate chloramphenicol from food matrices and dendritic silver to acquire SERS spectra of the eluted chloramphenicol. These spectra obtained from different spiked contents (0, 0.1, 0.5, 1, 5 ppm) of chloramphenicol in milk and honey were analyzed by PCA and PLSR (R > 0.9). MIPs particles were spread onto a thin layer chromatography (TLC) plate to determine Sudan I in paprika powder. Separation of Sudan I from paprika extract by an MIPs-TLC plate takes 30-40 s. SERS spectra obtained from Sudan I spot on the plate can be acquired within 1 s with gold colloid serving as SERS active substrate. A PLSR (R² = 0.978) model was constructed based on spiking levels (5, 10, 40, 70 and 100 ppm) of Sudan I in paprika powder. Histamine level in canned tuna was investigated using MIPs-polyvinyl chloride (PVC)-SERS method. MIPs-PVC films (recognition element) selectively extracted histamine from tuna extract. A gold colloid solution served as an eluting solvent to extract histamine from MIPs-PVC film and conducted a SERS detection of histamine. A PLSR model (R² = 0.947, RMSECV = 3.526) was built on SERS spectra of histamine with different spiking levels (3, 30 and 90 ppm) in canned tuna. The spectral results suggest the powerful separation of MIPs and sensitive detection of SERS. With statistical analysis, we have confirmed that SERS signals obtained by this MIPs-SERS approach rapidly and accurately quantify chloramphenicol in milk and honey, Sudan I in paprika powder and histamine in canned tuna.

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