Rapid Detection Of Benzo(a)pyrene By Surface-enhanced Raman Spectroscopy Combined With Molecularly Imprinted Technology

Benzo(a)pyrene(BaP)is a typical representative of polycyclic aromatic hydrocarbons which is widely found in the environment,food,and pollutants in animals or plants.Due to the widespread distribution of BaP and its strong carcinogenic effects,BaP has attracted worldwide attention.Many countries have listed BaP as one of the important monitoring analytes for food testing.At present,there are many deficiencies in the detection methods of BaP,such as complex sample preparation,time consuming procedures and expensive instruments.Surface enhanced Raman spectroscopy(SERS)is a fast and highly sensitive technology for on-site detection.As a common substrate for SERS,gold nanomaterials have been widely used in rapid detection for food safety research.Nowadays,the technology for synthesizing gold nanomaterials in aqueous phase is well reported,such as the Frens method.Since many hydrophobic toxicants and carcinogens,such as benzo(a)pyrene,aflatoxin,and quintozene,are practically insoluble in water,those hydrophilic colloidal gold nanoparticles are not applicable because of their immiscibility with hydrophobic analytes.Therefore,it is still of considerable interest for SERS detection to develop a synthetic approach for the synthesis of hydrophobic gold nanomaterials with controllable and designable sizes and morphologies.Molecular imprinting techniques have been widely used in sample purification steps because of their excellent selectivity and stability.A molecularly imprinted polymer containing gold nanoparticles was synthesized,and the benzo(a)pyrene in grilled meat was qualitatively and quantitatively analyzed.The main contents of the paper are as follows:(1)We report a versatile one-pot synthesis of hydrophobic gold nanomaterials including round nanodots,short nanobars,long nanorods and silk-like nanowires by the reduction of chloroauric acid with hydrosilane in organic solvents at room temperature.The size and morphology of the gold nanomaterials are easily controlled by changing the feeding molar ratio of chloroauric acid to oleylamine(OAm),oleic acid(OA)and hydrosilane.(2)The SERS enhancement effect of oil-soluble gold nanomaterials on different pretreatment methods were discussed.The BaP was detected with 80 nm colloidal spherical Au nanparticles synthesized by precipitation fractionation.The limit quantification of benzo(a)pyrene in chloroform was 5 ?g/mL,and the detection linear range was 5 ?g/mL to 500 ?g/mL.The detection limit of malachite green was determined by 25 nm colloidal Au nanparticles synthesized by seed-mediated process.The limit quantification of malachite green in chloroform was 5 ?g/mL,and the linear range of detection was 5 ?g/mL to 500 ?g/mL.(3)Au nanoparticles containing molecularly imprinted polymers(MIPs)have been fabricated via bulk polymerization by mixing 80 nm spherical gold nanoparticles,methyl methacrylate monomer,benzo(a)pyrene template molecule and crosslinker.The effect of polymer size and elution process on the detection of BaP was studied.The quantification limit of BaP in n-hexane was 100 ng/mL,the linear range of detection was 100 ng/mL to 10000 ng/mL,and the sample recovery rate was 84.9%-96.7%.The time required for detection is 0.5 min.The residue of BaP in grilled meat is 7.0 ± 0.9 ?g/kg.