| Perfluorinated carboxylic acids (PFCAs) and antibiotics are two groups of emerging organic pollutant and are widely used in industrial production, human health, livestock and poultry. With the expansion of their application scopes, these compounds are detected in a growing number of environmental and biological media, including water, soil, sludge, manure, food and other organisms. These compounds generally have toxicity and can induce health problems if people are exposed to such environments in a long term or eat products being contaminated by these compounds. The use and residue of PFCAs and antibiotics has caused widespread concern. Developing methods for accrate analysis is the basis of effective monitoring.The analysis of PFCAs and antibiotics in real samples often has some difficulties. Due to the lack of suitable chromophores, the analysis of PFCAs using high performance liquid chromatography (HPLC) with fluorimetric detector or ultraviolet-visible detector requires derivation prior to analysis. Meanwhile, the peek tubes in LC/MS instrument are associated with fluorotelomer-based chemicals. They can be leached during analysis and produce high background values. For antibiotics, the existence of protein in complex matrix will interfere with the analysis of antibiotics. This paper aims at developing rapid and accurate methods for the determination of PFCAs and antibiotics, from the point of detection means and sample pretreatment methods. By using a universal charged aerosol detector (CAD), we established a rapid HPLC-CAD method for the analysis of PFCAs in water samples. Meanwhile, we developed a ultrasound-assisted enzymatic method to eliminate the impact of protein on the antibiotic determination. In addition, a variety of solid phase extraction (SPE) adsorbents was employed to adsorb antibiotics and exclude proteins simultaneously. Based on these, we esdablished some SPE-HPLC methods for the analysis of antibiotics in complex matrix. Main contents are as follows:(1) A rapid HPLC-CAD method for the simultaneous determination of PFCAs in environmental water samples was developed. The PFCAs were separated on a Symmerrys Cg analytical column (150 mm×3.9 mm) under a mobile phase consisting of 5 mM ammonium acetate (pH 4.9±0.2) and methanol (30/70, v/v) at the flow rate of 1 mL min-1.Ammonium acetate as ion pairing agent was added to the mobile phase for better separation and peak shapes. The detection limits (LODs) ranged from 1.5 to 4.4 μgL-1, which were further decreased to 75 to 220 ng L"1 after 20-fold pre-concentration by SPE. The method was confirmed to have good precision with intraday and interday relative standard deviation below 4.2%.(2)By combining ultrasound-assisted enzymatic hydrolysis with SPE, a suitable sample preparation method was achieved for the analysis of tetracyclines (TCs) in biological matrice with LC/MS. Ultrasound-assisted enzymatic hydrolysis could break the three dimensional structures of proteins and eliminate its effect on the analysis of TCs. The introduction of ultrasound shortened the pretreatment time from 960 to 4 min. The established method provided good linear ranges in the range of 15-1000 mg kg-1 with LODs ranging from 1.05 to 3.50 mg kg-1. The new method yielded recoveries of TCs in spiked chicken-related samples as high as 89.1%-102.4%, being much higher than those (23.5%-36.2%) obtained using the acid deproteination process.(3) A SPE-HPLC method for the determination of TCs in complex matrices was established using microporous hydroxyapatite (Nano-HA) as SPE sorbent. Nano-HA was synthesized by the co-precipitation reaction between CaCl2 and Na3PO4 using CTAB as soft template. The nanoporous in Nano-HA makes it has the the ability of excluding proteins by size exclusion. Meanwhile, Ca2+in Nano-HA could bind with phenolic hydroxyl and enol groups in TCs so that TCs could adsorb on it. We verified the practicality and accuracy of the method by spiking samples. The recovery of TCs was between 78.5% and 100.3% with the relative standard deviation less than 9.8%. Finally, the method was use to detect TCs in chicken manure samples.(4) A ZIF-67 SPE-HPLC method was established for the determination of fluoroquinolones (FQs) in chicken manure. By using Co(NO3)2 as central metal and 2-methylimidazole as organic ligand, ZIF-67 was synthesized through solvothermal method. The multiple interactions between ZIF-67 and FQs were related to the coordination bonding between open Co2+sites and hydroxyl groups and intermolecular-interactions between imidazole ring and phenyl ring. Its extraction capacity for FQs exceeded that of isostructural ZIF-8, probably due to high affinity for Co2+ ions in ZIF-67. The presence of nanopores also made it have better ability of exclusing protein than macroporous C18 and HLB. The assay had wide linear rangs from 3.9 to 4000 μg kg-1, with LODs between 1.2 and 2.9 μg kg-1.(5) An on-line SPE-HPLC methods was developed for the determination of three classes of antibiotics (TCs, FQs and sulfonamides) in animal tissues based on clickable phenyl periodic mesoporous organosilicas (Phen-PMOs). Phen-PMOs was synthesized by the co-condensation of 1,2-bis(trimethoxysilyl)ethane and 3-azidopropyltrimethoxysilane, in the presence of nonionic surfactant triblock-copolymer PI23 and organic monomer. The π-π effect between benzene and antibiotics and the nano-porous channel in material make it has the ability to enrich antibiotics and exclude protein. By using a sample injection volume of 1 mL, the online SPE operation yielded enhancement factors in the range of 21-70 for the different antibiotics. The proposed method showed good recoveries ranging from 75.5% to 110.3% for different antibiotics, with LODs as low as 1.2 μg kg-1. The inter-day and intra-day precision with relative standard deviation values were below 7.8%. |
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