| Non-steroidal anti-inflammatory drugs(NSAIDs)are a kind of drugs commonly used in the treatment of human arthritis,skin allergy,antipyretic and detumescence as well as relieve postoperative pain and inflammation in a variety of situations.Its therapeutic effect is mainly reflected in three aspects of anti-inflammatory,analgesic or antipyretic.Most of these drugs are non-prescription drugs,which are easy to purchase in various ways.Due to the abuse of NSAIDs by humans and animals,some drugs and their non-metabolites are directly discharged into environmental water samples in the form of urine and feces.A number of studies have shown that there are already a large numbers of NSAIDs in environmental water samples.The long-term accumulation of NSAIDs in the environment can cause aquatic life death,destroy ecosystem balance,besides affect human and animal health.Nevertheless,the NSAIDs are often not completely removed during the traditional wastewater treatment process,because of the hydrophilicity and stability of these drugs.Therefore,it is of great significance to develop a simple,fast,efficient and feasible NSAIDs removal technology.Solid phase microextraction(SMPE),as an effective technical means for pre-concentration microanalysis environmental samples,having the advantages of simple operation,low solvent consumption,low cost and could be combined with a variety of detection technologies,which is suitable for the pre-treatment of trace NSAIDs in environmental samples.In order to improve the enrichment effect of sample pretreatment and reduce the matrix effect,it is necessary to find an extraction material with the advantages of low cost and good adsorption performance as the stationary phase of SPME.Cotton fiber is regarded as an excellent adsorption material according to its advantages of adjustable shape,large porosity and low cost,but its separation and enrichment effect on NSAIDs is not ideal.Modification is an effective way to change the surface properties of cotton fiber,so as to improve its separation and enrichment ability for NSAIDs in environmental water samples.Layered double hydroxides(LDHs)are pillared compounds composed of positively charged metal hydroxides and exchangeable anions filled between layers,which can be used as a new type of SPE material.LDHs can capture the anions in the sample based on the anion exchange via strong electrostatic adsorption.Starting from the construction of high performance SPE stationary phase,we prepared LDHs modified cotton fiber composite.The composite was used for sample pretreatment technology,and then the constructed SPE column was combined with high performance liquid chromatography(HPLC)for high sensitivity NSAIDs detection.The proposed method was also successfully applied to the determination of NSAIDs in actual environmental water samples.The specific contents are as follows:(1)A wrinkled cobalt nickel-layered double hydroxide arrays composite(Co Ni-LDH@PDC)was successfully fabricated by in-situ growing on polydopamine-coated cotton gauze.Thanks to the wrinkled morphology of Co Ni-LDH,the anion exchange rate and adsorption capacity of the fabricated composite were remarkably improved.A piece of 2×3cm modified cotton gauze was packed into a pipette tip for simultaneous extraction and concentration three kinds of NSAIDs including ketoprofen,fenbufen and ibuprofen,following high-sensitivity analysis through HPLC.Potential factors affecting the SPE process,such sampling rate,sample p H,sample loading volume,eluent types and concentration were studied in detail.Under the optimized conditions,the detection limits of the three NSAIDs were 0.075,0.18 and 0.17?g·L-1,besides,the linear ranges were 0.20?3000,0.50?200 and0.50?3000?g·L-1 for ketoprofen,fenbufen and ibuprofen,respectively.The recoveries of NSAIDs in tap water and drinking water samples were 77.3%?92.4%and 82.6%?95.6%,respectively.Moreover,the proposed SPME column was stable enough for 30 days experiments of extraction and desorption without obvious loss of extraction efficiency.(2)With nickel nitrate,aluminum nitrate and urea as precursors,the Ni Al-LDHs modified cotton gauze composites materials was successfully fabricated via in situ growth on polydopamine-coated cotton fiber through one-step hydrolysis.Because of the lamellar structure,the specific surface area and the anion exchange capacity were both effectively improved.The prepared composite was loaded into a pipette tip as a SPME column to extraction and analysis three kinds of NSAIDs as ketoprofen,fenbufen and ibuprofen based on SPME-HPLC technology.Under the optimal experimental conditions,the material showed strong adsorption capacity towards the analyzed NSAIDs,and the maximum adsorption capacity reached 212 mg·g–1.The chromatographic response of the three kinds of NSAIDs after the enrichment of the constructed extraction column was significantly increased.The linear detection range was 0.2?5000?g·L-1,with the correlation coefficients above 0.998and the detection limit was 0.10?0.20?g·L–1.These experimental results indicated that the established method has wide linear range and high sensitivity.Furthermore,the composite still retained high extraction efficiency and good reusability even after ten times of use.It opens up a new way to the establish of an efficient,convenient and reproducible method for the extraction and analysis of trace NSAIDs in complex environmental water samples. |
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