| A kind of sample pretreatment technology integrating sampling,enrichment,desorption and sampling is SPME.It has the advantages of simple operation,good extraction efficiency and high sensitivity.In SPME,the coating is the core of the solid phase microextraction technology.The advantages and disadvantages of the coating directly affect the applicable range of the analytical test,the extraction efficiency,the enrichment factor,the sensitivity,and the detection limit.Therefore,the coating is the focus of the development of SBSE technology.This experimental group has prepared a new PDMS/（HO）1Q[7] coating,but the mechanism that influences the coating’s extraction performance is not yet clear.Therefore,the PDMS/（HO）1Q[7] solid-phase microextraction stir bar prepared by the sol-gel method is used in this paper.Its possible extraction mechanism and extraction performance were discussed,and PDMS/（HO）1Q[7] solid-phase microextraction stir bar was used to detect estrogenic drug residues in meat products.The main contents are as follows:1.Introduced three main forms of solid-phase microextraction technology: Fiber SPME,In-tube SPME and SBSE;solid phase microextraction coating types and preparation methods;a brief review of the cucurbit and solid phase microextraction stir bar about analysis and application in the biological,environmental and food.2.The crude products Q[7] and（HO）1Q[7] were separated and purified by silica gel column chromatography.The elution was carried out with an eluent of acetic acid dihydrazide formic acid（V/V/V=10:10:2）and the composition of the eluate was followed by silica gel thin layer chromatography.Separately collect the eluates of Q[7] and（HO）1Q[7],spin dry,and dry under infrared light to obtain the target product.it was characterized by IR、nuclear magnetic resonance and high resolution mass spectrometry.3.The purified and isolated（HO）1Q[7] was prepared by sol-gel method and coated with PDMS/（HO）1Q[7] sol-gel coating on the support rod.A PDMS/（HO）1Q[7] coating sol-gel coated solid phase microextraction stir bar was prepared under the protection of a 180°C aging temperature with N2 finally..The self-made extracting bar were characterized by IR,Surface topography,thermal stability and precision investigation.IR characterization results showed that（HO）1Q[7] was firmly bonded to the PDMS coating;the surface structure of the coating was seen to be uniform and induced by scanning electron microscopy;no cracks were found;thermal stability of the coating was examined by thermogravimetry Good quality,the quality has changed 11.55% at 150°C,which meets the requirement of temperature control for most analytical tests.The result of the investigation of the coating precision is that one of the extracted small bars continuously extracts 3 estrogens 5 times.The RSD% was between 1.7% and 5.1%,indicating good reproducibility of the extracted small bars;the RSD% of the five extracted bars and the three estrogens extracted at the same time ranged from 3.6% to 6.4%,indicating good precision of the extracted bars.To meet the needs of analytical testing.4.The extraction mechanism of PDMS/（HO）1Q[7] sol-gel coating was discussed through three experiments.First of all the isothermal titration calorimetry was performed on Q[7] and（HO）1Q[7] with 10 guests molecules respectively.The experimental results showed that the binding constants of Q[7] and（HO）1Q[7] with 10 guests were different not much,（HO）1Q[7] is slightly smaller than Q[7].Indicating that Q[7] and（HO）1Q[7] interact strongly with 10 objects,but introduced-OH makes the binding constant of（HO）1Q[7] is slightly smaller than that of Q[7].In the second experiment,the mode of interaction between Q[7] and（HO）1Q[7] with 9 guest molecules was investigated by 1HNMR NMR.The results show that these 9 guest molecules interact with both Q[7] and（HO）1Q[7] modes,both as cavities and as deshields,and the mode of action of the two is similar.;the third experiment examines the self-made PDMS/（HO）1Q [7],self-made PDMS /（HO）1Q [6],self-made PDMS and commercial PDMS coating extraction extraction efficiency of 4’4-bipyridine.The results show that it is precisely because of the porous nature of the coating prepared by the sol-gel method and the higher molecular recognition of（HO）1Q [7] that the homemade PDMS/（HO）1Q [7] has higher extraction efficiency.5.The self-made PDMS/（HO）1Q[7] sol-gel coating solid-phase microextraction stir bar was also used to determine the ability of simultaneous extraction of different polar compound mixtures.Seven mixed polar compounds were selected and compared with commercial coatings.In addition,analytical parameters such as standard curve,recovery rate,enrichment factor,and linear range were produced.The results showed that the self-made PDMS/（HO）1Q[7] coating had better recovery（94.36%120.78%）for different polar substances,higher enrichment multiple（1060）,and wider Linear range（1×10-5 to 1×10-9）and lower detection limit（1.2×10-10 to 8.9×10-9 g/m L）.It shows that self-made PDMS/（HO）1Q[7] sol-gel coating solid-phase microextraction stir bar is suitable for the extraction of different polar compound mixtures.6.Using self-made PDMS/（HO）1Q[7] sol-gel coating solid-phase microextraction stir bar to establish A “PDMS/（HO）1Q[7] SBSE-LD-HPLC-UV ”extraction for the detection of three kinds of meat foods.The influence of experimental factors on the extraction effect was systematically optimized to determine the optimum extraction conditions.The established analytical method has a linear range of 0.2-5000μg/L,the correlation coefficient is between 0.9985-0.9998,the detection limit is between 0.06-1.4μg/L,and the enrichment factor is between 19.3-25.2.Standard addition method for spiked pork and chicken meat recovery tests.The results showed that the average recoveries of the three estrogens were between 72.7% and 113.4%.In addition,the precision of the established analytical method was also investigated.The RSD% of extracted intraday extractions ranged from 3.9% to 6.6%,and the RSD between daytime extractions ranged from 2.8% to 7.5%.It shows that the established analytical method has a wide linear range,high accuracy and good precision,and meets the requirements for the detection of estrogen residues in meat products. |
