Novel Covalent Organic Frameworks Combined With Solid Phase Extraction For Analysis Of Trace Organic Pollutants In Food Samples

Persistent organic pollutants(POPs)are synthetically synthesized,which can persist in the environment and accumulate through the bio-food network,ultimately damaging human health chemicals.These compounds are characterized by high toxicity,long half-life,high fluidity and strong bioaccumulation,which are extremely harmful to humans at the top of the biological chain.There are many kinds of types of POPs.In this paper,Sulfonamides antibiotics(SAs)and disinfection by-products(DBPs)were used as research objects.Two solid phase extraction methods based on novel covalent organic framework materials were established to detect trace amounts DBPs and SAs in different matrix samples.In this paper,the new covalent organic framework materials used as solid phase extraction adsorbents are melamine/o-phthalaldehyde covalent organic framework materials(MOP-COFs)and melamine/2,4,6-Trihydroxy-benzene-1,3,5-tricarbaldehyde(TpTt-COFs)nitrogen-rich covalent organic frameworks.The materials were characterized by X-ray diffraction analysis(XRD),thermogravimetric analysis(TG),fourier transform infrared spectroscopy(FT-IR)and scanning electron microscopy(SEM).The method validation and actual samples testing proved the feasibility of the method.(1)In this work,melamine / o-phthalaldehyde covalent organic framework was used as a novel trapping media in solid-phase extraction of sulfonamides antibiotics at ultra-trace levels in real samples.Six sulfonamides antibiotics(SAs),including sulfadiazine(SDZ),sulfathiazole(ST),sulfapyridine(SPD),sulfamethyldiazine(SM1),sulfamethazine(SM2),sulfamethoxazole(SMX),were absorbed on the SPE cartridge.Important factors affecting extraction effect were optimized by single factor optimization method,and the optimized relevant parameters were as follows: eluent and its volume,8 mL MA;sample flow rate,3mL/min;elution flow rate,3mL/min;sample pH,pH=4 and sample volume,200 mL.SAs were detected and quantified by liquid chromatography-tandem mass spectrometry.Low limits of detection(0.047 ng/L-0.357 ng/L),wide linearity(0.0005 ng/L-50 ng/L),good repeatability and high recovery(82.5~104.8 %)for sulfonamides antibiotics were obtained under the optimized conditions.The optimized method was used in the analysis of sulfonamides antibiotics in real environmental samples(drinking water,tap water,pool water,milk and royal jelly)successfully.The novel COFs as a solid phase trapping material was agood choice for the rapid and effective analysis of sulfonamides antibiotics at ultra trace levels in actual samples.(2)Trihalomethanes(THMs)and halonitromethanes(HNMs)are two important disinfection by-products that can cause health risks for human beings.In this work,a new nitrogen-rich covalent organic frameworks(NR-COFs),melamine/2,4,6-Trihydroxy-benzene-1,3,5-tricarbaldehyde(TpTt-COFs)was synthesized and first used as a novel trapping media in solid-phase extraction(SPE)of THMs and HNMs at ultra-trace levels in real drinking water samples.THMs and HCNM were absorbed on a SPE cartridge;then,the THMs and HCNM were eluted with the optimized volume of dichloromethane.The concentrated elution were detected and quantified by gas chromatography-tandem mass spectrometry.Low limits of detection(0.345-6.250 ng/L),wide linearity(0.002-50 ng/L),high enrichment factors(1000),good repeatability(1.3%-3.2%)and reproducibility(1.3%-3.4%)for THMs and TCNM were obtained under the optimized conditions.The optimized method was used in the analysis of THMs and TCNM in real environmental samples successfully.The novel COFs as a SPE trapping material was a good choice for the rapid and effective analysis of THMs and TCNM at ultra-trace levels in future.