New Technologies For The Detection Of Several Typical Antibiotics Using Magnetic Dispersion Solid Phase Extraction By Chromatography And Mass Spectrometry

As a new kind of solid phase extraction material,functionalized magnetic material has attracted more and more attention in recent years.The surface of magnetic material can be modified to meet the needs of extraction,separation and purification of pollutants.Based on adsorption characteristics of different functionalized magnetic material,the novel detection techniques of Chromatography/mass spectrometry were established for detection of tetracycline antibiotics?Tetracycline,Oxytetracycline,Chlorotetracycline,Doxycycline?and quinolone antibiotics?Pefloxacin,Norfloxacin,Fleroxacin,Levofloxacin,Enoxacin,Lomefloxacin,Difloxacin,Sparfloxacin,Danofloxacin,Ciprofloxacin,Enrofloxacin,Gatifloxacin?.The researches not only broaden the application of magnetic material,but also established the sensitivity detection technology of antibiotics.The main research contents include: 1.A new technique for detection of tetracycline antibiotics by HPLC based on MNP-NH2In this study,Fe₃O₄ was used as the magnetic core to prepare amino modified magnetic functional materials.The adsorption properties of TCs on different materials were investigated.Under the optimized conditions,linked with DSPE,we established a new method for detection of tetracycline antibiotics in milk samples.The contents are as follow:?1?Preparation of magnetic materials: On the basis of MNP-NH2 compounded by our laboratory,we prepared different materials which have different specific surface area and amino content by introducing SBA-15 and optimizing the dosage of APTES.The results of FT-IR and elemental analysis verified the success of coupling.And from the consequence of 4-nitrobenzaldehyde colorimetric assay we could know that by controlling the synthesis process of APTES dosage could affect amino account of magnetic materials.?2?The adsorption character for TCs of various materials: Fe₃O₄@SiO₂@APTES showed good adsorption properties for TCs than other materials in acetonitrile.Then,dosage of extraction agent,usage of magnetic material,pH value,adsorption time,eluant composition,elution time and frequency on the absorption effect of the TCs were studied.The results showed: Using NaCl as salting-out agent,MgSO4·7H2O as complexing agent,acetonitrile as extraction agent could extract TCs out from water phase to acetonitrile solution.After that,using 20 mg Fe₃O₄@SiO₂@APTES as absorbent,it could realize highly-effective adsorption for TCs when 90?L 1mol/L NaOH was added in 1mL extraction agent and adsorption time was 10 minutes;using the mixed liquor of water,acetonitrile and perchloric acid?86+10+6?as eluant,it could obtain a good effect when elution time was at least 5minute.All adsorption rates for four kinds of TCs were between 77.36%-99.04%.?3?Determination of TCs in milk sample: Four kinds of TCs in milk sample was detected by adopting to the new technology we constructed.The linear range was from 0.05mg/L to 2.5mg/L,RSD were between 3.85% to 9.30%,the detection limits were reach to 40?g/L,and adding standard recoveries were from 87.78% to 107.48%.Compared with national standard,the proposed method presents many advantages,such as quick speed,simple to handle and reproducibility.2.Study on new detection method for quinolones based on a novel matrix conjugated CHCA to SBA-15There are strong background interferences when determining small molecules by MALDI due to the usual matrixes are small molecule organic acid.To solve this problem,our experiment synthesized a novel material indicated as SBA-15@NH2@ CHCA by using CHCA modified SBA-15.Then applied this material to the detection of quinolones,established a new detection method for twelve kinds of quinolones.This novel matrix not only retained the traditional matrix's absorption and transmission properties of laser energy,but also effectively eliminated the background interferences at low mass area.The contents are as follow:?1?Synthesis of SBA-15@NH2@CHCA: SBA-15@NH2 was prepared by using hydrolysis reaction between APTES and hydroxyl group on the surface of SBA-15.Then,we coupled CHCA with SBA-15@NH2 via amide interaction between EDC and NHS.FT-IR and SEM identified the successful synthesis of SBA-15@NH2@CHCA.?2?Optimizing of use conditions: Types of matrix solvent,concentration of substrate,point method,volume ratio of matrix and sample were optimized.The results showed: Selecting mixture of acetonitrile and 0.1% trifluoroacetic acid?1+1?as matrix solvent,when concentration of matrix was 1mg/m L,volume ratio of matrix and sample was 1:6,point method was mixed method,could obtain well signals.?3?Construction of MALDI-TOF MS method for detecting quinolones: Under the optimized conditions,twelve quinolones were detected by MALDI-TOF MS using SBA-15@NH2@CHCA as matrix.Good analytical signal could be obtained,and were described respectively as follow: Danofloxacin m/z 358?M+H?+,Enrofloxacin m/z 360?M+H?+,Ciprofloxacin m/z 332?M+H?+,Difloxacin m/z 400?M+H?+ and 422?M+Na?+,Enoxacin m/z 321?M+H?+,Gatifloxacin m/z 376?M+H?+,Fleroxacin m/z 370?M+H?+,Lomefloxacin m/z 352?M+H?+,Sparfloxacin m/z 393?M+H?+,Norfloxacin m/z 320?M+H?+,Levofloxacin m/z 362?M+H?+,Pefloxacin m/z 334?M+H?+.The detection limits of these twelve quinolones were between 0.5mg/L to 1.0mg/L.3.The application of magnetic nanoparticle functionalized by graphere oxide in detecting quinolones using MALDI-TOF MSIn this experiment,graphene oxide?GO?was modified by MNP-NH2,and this stuff was applied to separation and enrichment of quinolones.Then combined with MALDI-TOF MS method built above,we constructed a new measurement technique of quinolones based on GO-NH-Fe₃O₄,and was adopted in water samples.Contents including:?1?Synthesis of GO-NH-Fe₃O₄: Depending on Hummer's method,GO-NH-Fe₃O₄ was prepared using GO and MNP-NH2.The analysis of FT-IR and SEM reveals that GO-NH-Fe₃O₄ was successfully prepared,and MNP-NH2 was coupled to GO.This material could disperse well in deionized water.?2?Adsorptive effect of GO-NH-Fe₃O₄ to QNs: Types of magnetic stuffs,pH value,adsorption time,usage of GO-NH-Fe₃O₄,concentration of ammonium hydroxide,elution time and frequency were studied in trial.The results showed: Under neutral or acidulous condition,added 3mL GO-NH-Fe₃O₄ to sample,then mingled at vortex for 30 minutes,the quinolones could adsorb on GO-NH-Fe₃O₄.Targets' signals could find at mass spectrums obviously,and cannot detect in raffinate.Using 200?L 15% ammonium hydroxide-methanol to wash the sorbent one time for 15 minutes,the targets could be desorbed.?3?Determination of QNs in water samples: Under the optimized conditions,using GO-NH-Fe₃O₄ and bonding with MALDI-TOF MS,twelve kinds of quinolones were detected in tap water,water from Hai He River and well water.Results showed: the detection limits of twelve kinds of quinolones were 10?g/L.The method has many advantages,such as quick speed,high throughput etc.,and could meet the demand for QNs screening in environmental water samples.