Use of ionic liquid based chitosan as sorbent for preconcentration of fluoroquinolones in milk,egg, fish,bovine, and chicken meat samples by solid phase extraction prior to HPLC determination

The possibility of using ionic liquid based chitosan sorbent for the separation and preconcentration of fluoroquinolone antibiotics (marbofloxacin, enoxacin, ofloxacin, ciprofloxacin, and enrofloxacin) has been studied. For this reason, different ionic liquids were prepared and coated on the chitosan sorbent. The conditions of the preconcentration of fluoroquinolones on a microcolumn have been optimized and the extraction efficiencies of the prepared sorbents have been compared. The compounds were eluted with 5 mL of 20% NH₃ (v/v, MeOH) solution and determined by HPLC with diode array and fluorescence detector. The limits of detection were found as 4.23 µ g L^?1 for marbofloxacin, and 1.09 µg L^?1 for enoxacin; 3.23 × 10^?3 µg L^?1 for ofloxacin; 8.39 × 10^?3 µg L^?1 for ciprofloxacin; and 19.50 × 10^?3 µg L^?1 for enrofloxacin. The developed method was applied for the analysis of fluoroquinolone in milk, egg, fish, bovine, and chicken samples and the recoveries were obtained in the range 70–100%.     

Magnesium oxide microspheres as a novel solid‐phase extraction sorbent for the determination of benzo[a]pyrene in environmental water samples

Magnesium oxide microspheres were developed as a novel SPE sorbent for the determination of benzo[a]pyrene (BaP), one of the most potent carcinogenic agents, in environmental water samples. The parameters controlling the extraction efficiency, such as elution volume, flow rate, pH values, and breakthrough volume, were investigated in detail. Considering the facile preparation and satisfying recovery, a corresponding analytical method has been developed to determine the concentration of BaP in real tap water, river water, and seawater. The recoveries for the spiked BaP were excellent (94–101%).     

Preparation and characterization of magnetic chitosan microsphere sorbent for separation and determination of environmental estrogens through SPE coupled with HPLC

In this paper, a new separation sorbent of magnetic chitosan microsphere was prepared by means of suspension process using magnetic-Fe(3)O(4) nanoparticles as magnetic material and glutaraldehyde as the cross-linker. The morphology and properties of magnetic chitosan microspheres were characterized by FT-IR, SEM and adsorption test, and the results showed that they had good recognition, high selective ability and fast adsorption-desorption dynamics for estriol (E3), 17β-estradiol (E2) and diethylstilbestrol (DES). Applying this material as SPE sorbent, a method for separation, enrichment and analysis of estrogens in samples coupled with HPLC was developed. Under the optimized condition, the detection limit (S/N=3) for three estrogens was 3.2-20.1 ng/L, and the RSD for five replicate extractions of 50 μg/L E3, E2 and DES was 4.6-8.3%. The blank river water spiked with E3, E2 and DES at 0.05 and 0.2 mg/L levels were extracted and determined by the developed method with good recoveries ranging from 85.5 to 103.7%.     

Polypyrrole/silica/magnetite nanoparticles as a sorbent for the extraction of sulfonamides from water samples

A magnetic solid‐phase extraction sorbent of polypyrrole/silica/magnetite nanoparticles was successfully synthesized and applied for the extraction and preconcentration of sulfonamides in water samples. The magnetite nanoparticles provided a simple and fast separation method for the analytes in water samples. The silica coating increased the surface area that helped to increase the polypyrrole layer. The polypyrrole‐coated silica provided a high extraction efficiency due to the π–π and hydrophobic interactions between the polypyrrole and sulfonamides. Several parameters that affected the extraction efficiencies, i.e. the amount of sorbent, pH of the sample, extraction time, extraction temperature, ionic strength, and desorption conditions were investigated. Under the optimal conditions, the method was linear over the range of 0.30–200 μg/L for sulfadiazine and sulfamerazine, and 1.0–200 μg/L for sulfamethazine and sulfamonomethoxine. The limit of detection was 0.30 μg/L for sulfadiazine and sulfamerazine and 1.0 μg/L for sulfamethazine and sulfamonomethoxine. This simple and rapid method was successfully applied to efficiently extract sulfonamides from water samples. It showed a high extraction efficiency for all tested sulfonamides, and the recoveries were in the range of 86.7–99.7% with relative standard deviations of < 6%.     

Comparison of C18 silica and multi‐walled carbon nanotubes as the adsorbents for the solid‐phase extraction of Chlorpyrifos and Phosalone in water samples using HPLC

A comparison between C₁₈ silica and multi‐walled carbon nanotubes (MWCNTs) in the extraction of Chlorpyrifos and Phosalone in environmental water samples was carried out using HPLC. Parameters affecting the extraction were type and volume of elution solvent, pH and flow rate of sample through the adsorbent. The optimum conditions obtained by C₁₈ cartridge for adsorption of these pesticides were 4 mL dichloromethane as elution solvent, sample pH of 5, flow rate of 1 mL/min, and those for MWCNT cartridge were 3 mL dichloromethane, pH of 5 and flow rate of 10 mL/min, respectively. Optimized mobile phase for separation and determination of these compounds by HPLC was methanol/water (80:20 v/v) with pH=5 (adjusted with phosphate buffer). Under optimal chromatographic and SPE conditions, LOD, linear range and precision (RSD n=8) were 3.03×10^?3, 0.01–5.00 μg/mL and 2.7% for Chlorpyrifos and 4.03×10^?4, 0.01–5.00 μg/mL and 2.3% for Phosalone, in C₁₈ cartridge, respectively. These values for MWCNT were 4.02×10^?6, 0.001–0.500 μg/mL and 1.8% for Chlorpyrifos and 1.02×10^?6, 0.001–0.500 μg/mL and 1.5% for Phosalone, respectively.     

分子印迹固相萃取-高效液相色谱法测定饲料中莱克多巴胺

以莱克多巴胺为模板分子,丙烯酰胺为功能单体,乙二醇二甲基丙烯酸酯为交联剂,合成了对莱克多巴胺具有高选择性的分子印迹聚合物。考察了甲醇、乙腈、丙酮和氯仿-甲醇与三乙胺构成致孔剂合成的聚合物性能及其形貌特征。通过正交试验优化的聚合反应配方为: 1.0 mmol莱克多巴胺,4.0 mmol丙烯酰胺,20.0 mmol乙二醇二甲基丙烯酸酯,6.0 mL乙腈-三乙胺(30:1, v/v), 50.0 mg偶氮二异丁腈。建立的基于分子印迹固相萃取-高效液相色谱测定饲料试样中莱克多巴胺的方法,在0.50～100 mg/L质量浓度范围内有良好的线性关系(r=0.9994);饲料试样中1.0、10及100 mg/kg 3个添加水平的莱克多巴胺平均回收率大于80%;批内、批间测定的相对标准偏差小于10%;检出限(信噪比为3)达到0.1 mg/kg。该方法灵敏、可靠,用于饲料等复杂基质中莱克多巴胺检测的效果优于相关标准分析方法。     

Development of a validated HPLC method for the determination of B-complex vitamins in pharmaceuticals and biological fluids after solid phase extraction

An HPLC method was developed for the simultaneous determination of seven water-soluble vitamins, viz. thiamine, riboflavin, nicotinic acid, nicotinamide, pyridoxine, cyanocobalamin, and folic acid, in multivitamin pharmaceutical formulations and biological fluids (blood serum and urine). Separation was achieved at ambient temperature on a Phenomenex Luna C18 (150 x 4.6 mm) analytical column. Gradient elution was performed starting at a 99:1 A:B v/v composition, where A: 0.05 M CH3COONH4/CH3OH (99/1) and B: H2O/CH3OH (50/50), at a flow rate of 0.8 mL/min. After a 4-min isocratic elution the composition was changed to 100% of B in 18 min and elution continued isocratically for 8 min. Detection was performed with a photodiode array detector at 280 nm. Each vitamin was quantitatively determined at its maximum wavelength. Spectral comparison was used for peak identification in real samples. Detection limits were in the range of 1.6-3.4 ng, per 20-microL injection, while linearity held up to 25 ng/microL. Accuracy, intra-day repeatability (n = 6), and inter-day precision (n = 7) were found to be satisfactory. Theobromine (2 ng/microL) was used as internal standard. Sample preparation of biological fluids was performed by SPE on Supelclean LC-18 cartridges with methanol-water 85/15 v/v as eluent. Extraction recoveries from biological matrices ranged from 84.6% to 103.0%.     

Development of graphene-carbon nanotube-coated magnetic nanocomposite as an efficient sorbent for HPLC determination of organophosphorus pesticides in environmental water samples

A magnetic solid-phase extraction (MSPE) method coupled to high performance liquid chromatography with UV (HPLC-UV) was proposed for the determination of organophosphorus pesticides (OPPs) at trace levels in environmental water samples. The ternary nanocomposite of graphene-carbon nanotube-Fe₃O₄ (G-CNT-Fe₃O₄) has been synthesised via a simple solvothermal process and the resultant material was characterised by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Significant factors that affect the extraction efficiency, such as amount of magnetic nanocomposite, extraction time, ionic strength, solution pH and desorption conditions were carefully investigated. The results demonstrated that the proposed method had a wide dynamic linear range (0.005–200 ng mL^?1), good linearity (R² = 0.9955–0.9996) and low detection limits (1.4–11 pg mL^?1). High enrichment factors were achieved ranging from 930 to 1510. The results show that the developed method is suitable for trace level monitoring of OPPs in environmental water samples.     

Silica Gel-Immobilized 5-aminoisophthalohydrazide: A novel sorbent for solid phase extraction of Cu,Zn and Pb from natural water samples

A novel silica sorbent, silica gel-immobilized 5-aminoisophthalohydrazide (SiO₂-APH), was prepared by the condensation of 3-chloropropyl-functionalized silica gel with 5-aminoisophthalohydrazide (APH) derived from dimethyl 5-aminoisophthalate as a starting material and used for separation and preconcentration of Cu, Zn, and Pb metals in water samples using Flame Atomic Absorption Spectrometry (FAAS). The characterization of the new sorbent was carried out by Elemental Analysis, Thermogravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Important analytical parameters including as pH, amount of sorbent, type and amount of eluting solvent, sample volume, vortex and ultrasonic bath time, matrix ions that effect the developed SiO₂-APH-solid phase extraction (SPE) method were investigated and optimum parameters were detected. Recoveries of examined metals were obtained as 98% for Cu and Pb and 101% for Zn. The relative standard deviation (RSD, n = 8) of Cu, Zn and Pb metals were 3.2, 2.8 and 1.6%, respectively. Limit of detections (LODs) (n = 10) were found as 2.7 μg L⁻¹ for Cu, 7.4 μg L⁻¹ for Zn and 3.5 μg L⁻¹ for Pb μg L⁻¹. The accuracy of the new method was assessed by analyzing of TMDA-51.4 and TMDA-70.2 certified reference materials. The results obtained for metals were in a good agreement with certified values. Addition/recovery test was applied to the real well, river, dam and stream water samples to check the accuracy of the method. The results showed that the developed SiO₂-APH-SPE method can be effectively used as an alternative method for determination of Cu, Zn, and Pb metals in water samples.     

Application of multiwalled carbon nanotubes as solid phase extraction sorbent for preconcentration of trace copper in water samples

The adsorption behavior of multiwalled carbon nanotubes (MWNTs) toward copper has been investigated systemically, and a new method has been developed for the determination of trace copper in water samples based on preconcentration with a microcolumn packed with MWNTs prior to its determination by flame atomic absorption spectrometry. The optimum experimental parameters for preconcentration of copper, such as pH of the sample, sample flow rate and volume, elution solution and interfering ions, have been investigated. Copper can be quantitatively retained by MWNTs in the pH range 5-8, and then eluted completely with 0.5 M HNO3. The detection limit of this method for Cu was 0.42 ng/mL, and the RSD was 3.5% at the 10 ng/mL Cu level. The method was validated using a certified reference material, and has been successfully applied for the determination of trace copper in water samples.     

Determination of cephalosporin antibiotics in water samples by optimised solid phase extraction and high performance liquid chromatography with ultraviolet detector

A reliable and robust analytical method based on solid phase extraction (SPE) and high performance liquid chromatography (HPLC) with ultraviolet (UV) detector was developed for the simultaneous determination of five cephalosporin antibiotics (Ceftazidime, Cefradine, Cefaclor, Cefotaxime and Cefoperazone) in various water samples. Under optimised conditions, it was applicable to preconcentrate up to 500?ml of water samples in the OASIS HLB cartridges with reasonable recoveries for all the cephalosporin antibiotics tested. Recoveries were as follows: deionised water, tap water and groundwater, between 84.2 and 98.9%; surface water, between 71.2 and 81.0%; influent and effluent of wastewater treatment plant (WWTP), between 56.9 and 72.1%. The method detection limits (MDLs) for different water samples were in the range of 26 to 59?ng?l^?1. Real water samples were analysed using the proposed approach to demonstrate the applicability and validation. Negative results were obtained for the tap water and groundwater. However, all the selected cephalosporin antibiotics were identified in the influent and effluent of a local WWTP at ng?l^?1–µg?l^?1 level. In addition, Ceftazidime was found in surface water with a concentration of 0.75–2.60?µg?l^?1. The results indicate that the ‘pseudo-persistent’ contamination of cephalosporin antibiotics in the water environment could not be neglected.     

Multi-walled carbon nanotube-based dispersive solid phase extraction with following back-extraction for HPLC/UV determination of Rosmarinic acid in lemon balm and Rosemary plant samples

In this paper, dispersive solid phase extraction with following back-extraction and HPLC/UV determination of Rosmarinic acid have been investigated. Multi-walled carbon nanotubes were used as sorbent in the suggested method. The effectiveness of some parameters such as extraction time, sorbent dosage, pH and ionic strength of the aqueous solution on Rosmarinic acid adsorption were studied. The extraction time of 5.0 min, adsorbent weight of 5.0 mg, and pH of 2.5 were obtained as the optimum experimental parameters. Adsorption of Rosmarinic acid molecules was almost independent from ionic strength. For back-extraction purpose a basic solution containing methanol was brought into contact with sorbent to desorb Rosmarinic acid molecules from sorbent containing adsorbed Rosmarinic acid molecules. Linear range of HPLC method for Rosmarinic acid quantification was 1.80–21.62 mg/L (R² = 0.998). The relative standard deviation, limit of detection, and limit of quantification for the suggested method were 0.81%, 0.68 mg/L, and 2.86 mg/L, respectively. The proposed method was applied for extraction and HPLC/UV determination of Rosmarinic acid in Lemon balm and Rosemary plant samples. Comparison between obtained chromatograms before adsorption and after desorption processes showed that suggested extraction/back-extraction process has good selectivity and efficiency for separation of Rosmarinic acid molecules from interfering molecules existing in the plant extracts. The proposed method is efficient, low cost, fast, and simple for separation, extraction, and determination of Rosmarinic acid.     

Preparation of phenothiazine bonded silica gel as sorbents of solid phase extraction and their application for determination of nitrobenzene compounds in environmental water by gas chromatography-mass spectrometry

In this paper, two phenothiazine bonded silica (PTZ-Si) sorbents were prepared and used as sorbents of solid-phase extraction (SPE) for the determination of nitrobenzene compounds in environmental water samples by gas chromatography-mass spectrometry (GC-MS). Different synthesis routes were proposed to obtain high bonded amount of PTZ on the surface of silica gel. PTZ molecule was derived to its amino or acyl chloride derivatives for reacting with isocyanate or amino silane coupling agent, which was further reacted with the surface silanol groups of silica gel to obtain the PTZ-Si sorbents. The resultant PTZ-Si sorbents were characterized by nitrogen sorption porosimetry (NSP), Fourier transform infrared spectroscopy (FT-IR) and elemental analysis (EA) to assure the successful bonding of PTZ on the surface of silica gel. Then the PTZ-Si sorbents were served as SPE sorbents for the enrichment of nitrobenzene compounds. Several parameters affecting the extraction performance were investigated. Under the optimized conditions, the proposed method was applied to the analysis of six nitrobenzene compounds in environmental water samples. Good linearities were obtained for all nitrobenzene compounds with R(2) larger than 0.9958. The limits of detection were found to be in the range of 0.06-0.3 ng/mL. The method recoveries of nitrobenzene compounds spiked in water samples were from 71.4% to 124.3%, with relative standard deviations (RSDs) less than 10.1%.     

TiO2 nanotubes： A novel solid phase extraction adsorbent for the sensitive determination of nickel in environmental water samples

A novel method was developed for the sensitive determination of nickel in environmental water samples by using TiO2 nanotubes, a new nanomaterial, as solid phase extraction absorbent. In general, TiO2 nanomaterials were often used for catalytic degradation of pollutants in environmental field, and only a very few application in environmental analytic chemistry. In present work, TiO2 nanotubes was firstly used for the enrichment of nickel and the factors would influence the preconcentration performance were optimized. Under the optimal conditions, TiO2 nanotubes exhibited its good enrichment capacity for nickel and the detection limit of the proposed method was 1 ng· mL^-1. The proposed method was validated with real water samples, and excellent results were obtained with the spiked recoveries in the range of 94.4-99.2%, respectively.     

Zinc oxide/polypyrrole nanocomposite as a novel solid phase microextraction coating for extraction of aliphatic hydrocarbons from water and soil samples

In this work, ZnO/PPy nanocomposite coating was fabricated on stainless steel and evaluated as a novel headspace solid phase microextraction (HS-SPME) fiber coating for extraction of ultra-trace amounts of environmental pollutants; namely, aliphatic hydrocarbons in water and soil samples. The ZnO/PPy nanocomposite were prepared by a two-step process including the electrochemical deposition of PPy on the surface of stainless steel in the first step, and the synthesis of ZnO nanorods by hydrothermal process in the pores of PPy matrix in the second step. Porous structure together with ZnO nanorods with the average diameter of 70 nm were observed on the surface by using scanning electron microscopy (SEM). The effective parameters on HS-SPME of hydrocarbons (i.e., extraction temperature, extraction time, desorption temperature, desorption time, salt concentration, and stirring rate) were investigated and optimized by one-variable-at-a-time method. Under optimized conditions (extraction temperature, 65 ± 1 °C; extraction time, 15 min; desorption temperature, 250 °C; desorption time, 3 min; salt concentration, 10% w/v; and stirring rate, 1200 rpm), the limits of detection (LODs) were found in the range of 0.08–0.5 μg L⁻¹, whereas the repeatability and fiber-to-fiber reproducibility were in the range 5.4–7.6% and 8.6–10.4%, respectively. Also, the accuracies obtained for the spiked n-alkanes were in the range of 85–108%; indicating the absence of matrix effects in the proposed HS-SPME method. The results obtained in this work suggest that ZnO/PPy can be promising coating materials for future applications of SPME and related sample preparation techniques.     

Preparation of an efficient sorbent by washing then pyrolysis of olive wood for simultaneous solid phase extraction of chloro-phenols and nitro-phenols from water

Simultaneous preconcentration of phenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol was improved by using olive wood (OW) washed with ethanol then pyrolyzed at 200 °C as preconcentrating sorbent. Various OW sorbents were prepared by either washing OW (with ethanol, ether, dichloromethane, tetrahydrofuran or n-hexane); or by pyrolysis (at 100, 150, 200, 250 or 300 °C); or by combined pyrolysis/washing. The adsorbents were characterized by elemental analysis, total acidity/basicity, methylene blue relative surface area, point of zero charge, distribution coefficients of the phenols, and sample loading flow rate. It seems that washing and pyrolysis have removed compounds covering the OW pores, which improved the OW porosity and exposed more acidic groups on the OW surface. The pores and the surface acidic groups seem to play major role in phenols sorption. Ethanol-washed OW then pyrolyzed at 200 °C gave the best preconcentration performance towards phenols (300 mg sorbent, 150 mL of the sample (pH 7), and elution with 3 mL of acetonitrile). The method was linear up to 100 μg L⁻¹; limit of quantification: 0.20-0.48 μg L⁻¹. The method could detect phenol and 2,4-dinitrophenol in industrial wastewater with spiked recovery range from 80.2% to 91.4% (±1.1 to 5.5%RSD) for all the phenols.     

磁性多壁碳纳米管固相萃取-气相色谱-质谱法检测水样中的13种邻苯二甲酸酯类化合物

建立了磁性多壁碳纳米管(MWCNTs)固相萃取结合气相色谱-质谱检测水样中13种邻苯二甲酸酯类化合物(PAEs)的方法。优化了萃取时间、水样pH值、解吸溶剂的种类和用量、解吸时间等影响萃取效率的主要条件。最终确定萃取时间为10 min,水样pH 5～7,解吸溶剂为2 mL丙酮,解吸时间为5 min。在优化的条件下,各组分的萃取回收率为89.7%～100.5%。方法具有较高的灵敏度,检出限(信噪比(S/N)为3)为0.08～0.47 μg/L。3种实际样品的加标回收率为84.5%～107.5%,相对标准偏差为1.9%～12.8%。该方法操作简便、省时,准确、灵敏、环保,可用于水样中PAEs的检测,并成功地应用于自来水、瓶装饮用水和湖水样品的分析,13种PAEs均未检出。     

Simultaneous determination of pharmaceutically active compounds in wastewater samples by solid phase extraction and high-performance liquid chromatography with diode array and fluorescence detectors

In the present work, an analytical method for the simultaneous determination of five anti-inflammatory drugs (acetaminophen, diclofenac, ibuprofen, ketoprofen and naproxen), an antiepileptic drug (carbamazepine) and a nervous stimulant (caffeine) is proposed for the routine analysis of these pharmaceuticals in wastewater influents and effluents from WWTPs. The method involves pre-concentration and clean-up by solid phase extraction (SPE) using Oasis HLB extraction cartridges. Final analysis of the selected pharmaceutical compounds was carried out by high-performance liquid chromatography (HPLC) with diode array detector (DAD). Confirmation of the presence of the fluorescence compounds (ibuprofen and naproxen) was performed by on-line fluorescence detection. Recoveries were ranged from 71 to 103% with relative standard deviation below 15.1%. Limits of quantification were in the range 6.2–319.8 and 3.0–160.0 ng ml⁻¹ for influent and effluent wastewater samples, respectively. The described method was applied to the determination of the drugs in wastewater samples from four treatment plants in Seville.     

Evaluation of polychlorotrifluoroethylene as sorbent material for on-line solid phase extraction systems: determination of copper and lead by flame atomic absorption spectrometry in water samples

Polychlorotrifluoroethylene (PCTFE) in the form of beads was applied, as packing material for flow injection on-line column preconcentration and separation systems coupled with flame atomic absorption spectrometry (FAAS). Its performance characteristics were evaluated for trace copper determination in environmental samples. The on-line formed complex of metal with diethyldithiophosphate (DDPA) was sorbed on the PCTFE surface. Isobutyl methyl ketone (IBMK) at a flow rate of 2.8 mL min⁻¹ was used to elute the analyte complex directly into the nebulizer-burner system of spectrophotometer. The proposed sorbent material reveal, excellent chemical and mechanical resistance, fast adsorption kinetics permitting the use of high sample flow rates up to 15 mL min⁻¹ without loss of retention efficiency. For copper determination, with 90 s preconcentration time the sample frequency was 30 h⁻¹, the enhancement factor was 250, which could be further improved by increasing the loading (preconcentration) time. The detection limit (3s) was c_L = 0.07 μg L⁻¹, and the precision (R.S.D.) was 1.8%, at the 2.0 μg L⁻¹ Cu(II) level. For lead determination, the detection limit was c_L = 2.7 μg L⁻¹, and the precision (R.S.D.) 2.2%, at the 40.0 μg L⁻¹ Pb(II) level. The accuracy of the developed method was evaluated by analyzing certified reference materials and by recovery measurements on spiked natural water samples.