Solid-phase extraction of polar hydrophilic aromatic sulfonates followed by capillary zone electrophoresis-UV absorbance detection and ion-pair liquid chromatography-diode array UV detection and electrospray mass spectrometry

A comprehensive comparison of four different polymeric solid-phase extraction (SPE) materials for the extraction of 22 different aromatic sulfonates of environmental concern was performed. The investigated adsorbents were the polystyrene–divinylbenzene materials LiChrolut EN from Merck, Isolute ENV+ from International Sorbent Technology, HR-P from Macherey–Nagel and the new Oasis HLB poly(divinylbenzene-co-N-vinylpyrrolidone) copolymer from Waters. Different SPE parameters like the elution solvent and the drying step of the cartridges were optimized. Analyses were performed by capillary zone electrophoresis–UV absorbance detection (CZE–UV) and ion-pair liquid chromatography–diode array UV detection coupled in series with electrospray mass spectrometry (IP-LC–DAD-ESI-MS) in the negative ionization mode. LC–MS offers a higher separation efficiency than CZE. The best adsorbents were LiChrolut EN and HR-P followed by Isolute ENV+ and Oasis HLB. The recoveries for most of the onefold negatively charged aromatic sulfonates were >50% for the extraction from spiked ground water at 50 μg/l. Recoveries for LiChrolut EN and HR-P were approximately 20% higher than for Isolute ENV+. Very hydrophilic sulfonates containing more than one negative sulfonate group could not be extracted by any of the tested adsorbents.     

Hydrophilic hypercrosslinked polymeric sorbents for the solid-phase extraction of polar contaminants from water

Three new hypercrosslinked polymers with hydrophilic character arising from hydroxyl moieties in their skeletons have been prepared in microsphere format and applied to the off-line solid-phase extraction (SPE) of polar compounds from water samples. For sample volumes of 1000 ml, the recoveries of various polar pesticides, such as oxamyl, methomyl, selected phenolic compounds, as well as some pharmaceuticals, were close to 90%. The HXLPP-polar polymer with the best performance characteristics was applied to real samples. Its performance was also compared to commercially available sorbents, such as LiChrolut EN (hydrophobic, hypercrosslinked), Oasis HLB (hydrophilic, macroporous) and Isolute ENV+ (hydrophilic, hypercrosslinked); the new sorbent out-performed the commercially available sorbents. The polymer was applied successfully in off-line SPE of river water samples followed by liquid chromatography and ultraviolet detection, providing a good linear range and detection limits of 0.2 μg l⁻¹ for the majority of the compounds, with the exception of oxamyl, methomyl, guaiacol and salicylic acid where the detection limit was 0.5 μg l⁻¹.     

Solid-phase extraction of polar compounds with a hydrophilic copolymeric sorbent

A new synthesized copolymer based on N-vinylimidazole-divinylbenzene (VIm-DVB) was tested as a sorbent for the solid-phase extraction (SPE) of polar analytes. In the on-line SPE, this synthesized sorbent enabled 100 ml of sample to be preconcentrated with recoveries as high as 80% for oxamyl, phenol (Ph) and derivates, bentazone and (4-chloro-2-methylphenoxy)acetic acid (MCPA). For the off-line SPE, 1000 ml of sample was extracted and recoveries were higher than 92% for all compounds with the exception of oxamyl (83%) and methomyl (78%). The VIm-DVB sorbent gives better recoveries than the previously synthesized 4-vinylpyridine-divinylbenzene (VP-DVB) resin and similar to such highly crosslinked commercial sorbents as LiChrolut EN or Oasis HLB. Real water samples were used to validate the on-line SPE method. Linearity was good and detection limits were between 0.1 and 0.2 microg l(-1).     

Evaluation of a new hypercrosslinked polymer as a sorbent for solid-phase extraction of polar compounds

A new hypercrosslinked polymer (HXLGp) with hydrophilic character due to the presence of hydroxyl moieties has been tested as a sorbent for the solid-phase extraction (SPE) of several polar compounds from water samples. This new sorbent enables the on-line extraction of 300 ml of sample with recoveries higher than 80% for polar compounds such as oxamyl, methomyl or desisopropylatrazine (DIA). The HXLGp has also been compared to other commercially available sorbents such as Oasis HLB (hydrophilic macroporous), to hydrophobic hypercrosslinked resins and to a previously synthesized sorbent based on N-vinylimidazole-divinylbenzene. The results are consistently better with the new synthesized sorbent. The method was successfully applied to the on-line SPE-HPLC of tap and river water samples. The validation with river water samples provided good linearity range and detection limits between 0.03 for methomyl and 4-nitrophenol (4NP) to 0.2 microg l(-1) for phenol (Ph).     

Use of solid-phase extraction in various of its modalities for sample preparation in the determination of estrogens and progestogens in sediment and water.

The environmental analysis of estrogens and progestogens at physiologically active concentrations (low ng/l range) requires the use of very sensitive and selective methods, which, in most cases, make necessary an extraction/purification step. In this study, various procedures for the determination of several estrogens (estriol, estradiol, ethynyl estradiol, estrone, and diethylstilbestrol) and progestogens (progesterone, norethindrone, and levonorgestrel) in environmental matrices, including water and river sediment, are described. In all procedures, final analysis of the target compounds is performed by reversed-phase liquid chromatography-diode array detection-mass spectrometry, whereas sample preparation always includes a solid-phase extraction (SPE) step. For this SPE step. various types of sorbents, protocols, and devices have been used, and their respective advantages and disadvantages are discussed. For the off-line SPE of estrogens and progestogens from water samples, a syringe type cartridge LiChrolut RP-18 (500 mg) was selected out of two other sorbents--LiChrolut EN (200 mg) and Isolut ENV (500 mg)--for use with the automated sample preparation instrument ASPEC XL. For the on-line SPE and analysis of water samples the 10 mm x 2 mm I.D. HySphere-Resin-GP cartridge, was preferred to the C18 Baker, the PLRP-S, and the Oasis HLB. for use with the Prospekt system. A completely manual protocol based on the use of Sep-Pak C18 Plus cartridges was developed for purification of sediment extracts. All procedures were shown to be linear over a wide range of concentration, exhibited satisfactory repeatability and accuracy, and reached limits of detection usually in the low ng/l and ng/g range. Comparatively, the on-line method was shown to be advantageous in terms of automation and general method performance.     

Highly sensitive simultaneous determination of sulfonamide antibiotics and one metabolite in environmental waters by liquid chromatography-quadrupole linear ion trap-mass spectrometry

The present work describes the development of a highly sensitive analytical method based on liquid chromatography-quadrupole linear ion trap-mass spectrometry (LC-QqLIT-MS) for the determination of nine sulfonamide antibiotics and one N4-acetylated metabolite in environmental waters (wastewater, surface water and groundwater) and bottled mineral water. Special emphasis was devoted to the elimination of matrix components during solid-phase extraction (SPE) by the evaluation of three different extraction/purification strategies: single cartridges (Oasis HLB and Oasis MCX) and tandem (TD) extraction (combination of both). The method developed proved to be suitable for sulfonamide determination in all kinds of waters tested. The method was shown to be linear in a wide concentration range, with correlation coefficients higher than 0.999 for all compounds except for sulfadimethoxine (R2 0.997). The overall instrumental repeatability was satisfactory, with the exception of the metabolite (RSD 34%). Method limits of detection achieved for sulfonamides were in the range 0.01-1.13 ng L(-1) and for the metabolite 0.08-461 ng L(-1). Recovery rates were estimated at 500 ng L(-1) spike level in the four water matrices selected. The highest recovery achieved in all matrices was that corresponding to the Oasis HLB cartridge. In environmental waters, recovery values obtained were higher than 61% for the surface water and, in general, higher than 90% for groundwater and wastewater. Bottled mineral water exhibited recovery rates higher than 92%, with the exception of sulfamethoxypiridazine (82%) and sulfapyridine (86%) In order to demonstrate the applicability of the developed method, several water samples were analyzed. Results evidenced the requirement for consideration of N4-acetylated metabolites of sulfonamides in environmental residue analysis to avoid the underestimation of removal rates of such pharmaceutical compounds during wastewater treatments.     

Determination of pharmaceutical residues in waters by solid-phase extraction and large-volume on-line derivatization with gas chromatography-mass spectrometry

This work presents a modified method to analyze selected pharmaceutical residues (clofibric acid, ibuprofen, carbamazepine, naproxen, ketoprofen and diclofenac) in water samples. Various solid-phase extraction cartridges were investigated. The newly developed Oasis HLB (polystyrene-divinylbenzene-N-vinyl pyrrolidone terpolymer) solid-phase extraction (SPE) cartridge provides the optimal sample extraction results. The analytes were then identified and quantitatively determined by gas chromatography-mass spectrometry (GC-MS) via on-line derivatization in the injection-port using a large-volume (10 microl) sample injection with tetrabutylammonium (TBA) salts. This injection-port derivatization technique provides sensitivity, fast and reproducible results for pharmaceutical residues analysis. Mass spectra of butylated derivatives and tentative fragmentation profiles are proposed. Molecular ions and some characteristic ions were used as the quantitation ions to obtain maximum detection sensitivity and specificity. The quantitation limits of these compounds ranged from 1.0 to 8.0 ng/l in 500 ml tap water samples. Recovery of these residues in spiked various water samples ranged from 50 to 108% while RSD ranged from 1 to 10%. The selected analytes were detected in concentrations of 30 to 420 ng/l in wastewater treatment plant effluent and river water samples.     

Multi-Residue Analysis of Some Polar Pesticides in Water Samples with SPE and LC–MS–MS

In the present study a multi-residue analytical method was developed for monitoring some polar pesticides such as acephate, methamidophos, carbofuran, isoproturon, dimethoate in water with SPE (solid-phase extraction) and LC–MS–MS. Acetochlor was taken as surrogate, and alachlor as internal standard. SPE with different types of columns was compared with LLE (liquid-liquid extraction). Further, the breakthrough volume for different pesticides was determined. The results showed that the selected pesticides can be determined very sensitively with LC–MS–MS. The minimum detectable quantity (MDQ) for each pesticide was about 1.0 ng. To date, SPE cartridge studies showed that the Oasis HLB cartridges were suitable for further studies. However, for Oasis HLB cartridge, different pesticide showed different breakthrough volume. The results showed that for acephate and methamidophos, the breakthrough volume was about 30 mL of water sample, much less than the breakthrough volume of other pesticides studied. Because of the higher vapor pressure and higher Henry's constant of methamidophos, dimethoate and carbofuran, much attention should be paid on their losses in the evaporation step of the experiment. This analytical method can be applied to determine pesticide contamination in environmental water samples. Revised: 12 September 2005 and 21 October 2005     

一种亲水-亲油复合固相萃取填料的制备及其在食品安全检测中的应用

合成了一种以二乙烯苯和N-乙烯吡咯烷酮为单体的高分子聚合物固相萃取填料(DVB-NVP),以6种不同极性的化合物为模型化合物,结合高效液相色谱法(HPLC)对该填料进行了系统的评价,并与传统的C18填料及商品化同类型填料做对比;对填料进行了磺酸化修饰(DVB-NVP-SO₃H),并将合成的填料应用于复杂基质中化合物的分析。结果表明:该填料对不同极性化合物的回收率在95.55%~101.08%之间,优于商品化C18填料,与商品化同类型填料相当。DVB-NVP对于白酒中邻苯二甲酸二甲酯、邻苯二甲酸二乙酯、邻苯二甲酸二丁酯的分析回收率分别为102.55%、102.99%、102.11%,相对标准偏差分别为2.11%、1.69%、0.79%; DVB-NVP-SO₃H用于对猪肉中的可乐定和赛庚啶进行分析,回收率分别为89.23%和91.42%,相对标准偏差分别为8.21%和8.86%,符合生物样品分析要求。所合成的填料具有普适性,并具有较高的回收率,应用前景广泛。     

Effective sorbents for solid-phase extraction in the analysis of quinolones in animal tissues by capillary electrophoresis

In this work, several commercial sorbents (Zorbax C18, Bond Elut C18, Isolute ENV+, Oasis HLB, Oasis MAX, SDB-RPS, and MPC-SD) were compared for the solid-phase extraction of the series of quinolones regulated by the European Community in chicken tissues in order to establish a method for the determination of this series of quinolones by capillary electrophoresis and diode array detection. Sorbents were chosen in order to achieve maximum recoveries and optimal clean-up efficiency. Better results were obtained using SDB-RPS and Oasis MAX which would provide suitable limits of detection, below of the maximum residue limits (MRLs) regulated.     

Comparison of different sample treatments for the analysis of ochratoxin A in must, wine and beer by liquid chromatography

Ochratoxin A (OTA) is a mycotoxin produced by some species of Aspergillus and Penicillium verrucosum. It has been found in foods and feed all over the world. There is a great concern about OTA because it is nephrotoxic and probably, carcinogenic to humans. Most of analytical methods developed for OTA in wine, beer and other products are based on LC with fluorescence detection (LC-FLD). In the present work, various procedures for extraction and/or clean-up for determination of OTA in musts, wine and beer by LC-FLD were compared: (1) dilution with polyethylen glycol 8000 and NaHCO3 solution and clean-up an on immunoaffinity column (IAC); (2) extraction with chloroform and IAC clean-up; solid-phase extraction (SPE) on (3) reversed-phase (RP) C18; (4) RP phenylsilane and (5) Oasis HLB cartridges. SPE on phenylsilane and Oasis HLB have not been reported for OTA analysis in beverages. The same LC-FLD conditions and concentration ratio were used. The former procedure was simple, rapid and provided flat baselines, free from most impurity peaks, high OTA recoveries and quite repeatable results. RP C18 using methanol-acetic acid (99.5:0.5) as elution solvent provided good recoveries and precision, thus becoming a cheaper but interesting alternative at 0.1-1 ng/ml spiking levels. Oasis HLB cartridges were usually better than phenylsilane. Possible binding of OTA to proteins or other components was tested by acid treatment before extraction but no significant differences with controls appeared.     

Simultaneous solid-phase extraction of acidic, neutral and basic pharmaceuticals from aqueous samples at ambient (neutral) pH and their determination by gas chromatography-mass spectrometry

Seven polymeric solid-phase extraction (SPE) sorbents were evaluated with regard to their ability to extract acidic, neutral and basic pharmaceuticals and estrogens simultaneously from water at neutral pH. Highest recoveries (70-100%) for the majority of the analytes were obtained with styrene-methacrylate and styrene-N-vinylpyrrolidone co-polymers. The latter one (Oasis HLB) was chosen for further refinement of an extraction method for the quantitative determination of acidic and neutral drugs in surface water samples at detection limits below 1 ng/l. A sequential elution protocol was applied for clean-up and separation of the extracted analytes into fractions suitable for further compound specific processing. The neutral analytes as well as the acidic compounds after derivatisation were quantified by GC-MS. Caffeine, ibuprofen, its metabolites and diclofenac were detected in river water samples in the 1-100 ng/l range.     

禽蛋中头孢噻肟残留的高效液相色谱-串联质谱法测定

建立了高效液相色谱-串联质谱(LC-MS/MS)测定禽蛋中头孢噻肟药物残留的方法。禽蛋样品中的头孢噻肟用纯水提取,乙腈沉淀蛋白,Oasis HLB(500 mg,6 mL)固相萃取柱净化,8 mL甲醇洗脱。采用Zorbax XDB-C18(2.1 mm×50 mm,3.5μm)色谱柱,以0.2%甲酸水-乙腈为流动相,0.3 mL/min梯度洗脱,经高效液相色谱分离后,采用电喷雾质谱正离子模式电离,多反应选择离子检测(MRM)模式测定。检测离子对为m/z456.1/396.1、m/z456.1/324.1,其中m/z456.1/396.1为定量离子对。在1.35~135μg/L范围内标准曲线的线性关系良好,相关系数为0.999 3;在1.0、50.0、100μg/kg3个添加水平的平均加标回收率为87%~99%,相对标准偏差为1.9%~3.9%;方法检出限为0.3μg/kg,定量下限为1.0μg/kg。该方法简便、灵敏、准确、可靠,适用于禽蛋中头孢噻肟药物残留的分析。     

Preparation of polymer based sorbents for solid phase extraction of polyphenolic compounds

This article discusses the preparation of different polymeric sorbents for solid phase extraction. Various monomers like acrylamide, methacrylic acid and 4-vinylpyridine (VP), cross-linkers such as divinylbenzene (DVB) and ethyleneglycoldimethacrylate (EDMA), porogens like tetrahydrofuran (THF) and dimethylsulphoxide (DMSO) / acetonitrile (ACN) with different ratios were investigated in order to optimize recoveries. Resulting polymers were characterized through scanning electron microscope (SEM) and compared with Oasis HLB (Waters, MA, USA) and Strata-X (Phenomenex, Torrance, USA) on the basis of extraction performance, recovery efficiency and loading capacity. Sample applied was a mixture of flavonoid standards (rutin, myricetin, luteolin, quercetin, apigenin and kaempferol). HPLC hyphenated with PDA was used for the analysis of samples. Results showed that among the prepared SPE materials, 4-VP-co-EDMA produced best results. Comparison of the produced polymers with of Oasis HLB and Strata-X resulted in comparable efficiencies; especially the polymer 4-VP-co-EDMA gave almost similar results for all analytes to those of commercially available SPE materials. A general trend of decrease in retention efficiency with increase in polarity has been observed in both synthesized and already available SPE materials. The newly synthesized polymeric materials can be employed as SPE sorbents for efficient extraction of polyphenolic compounds especially for flavonoid aglycons.     

Rapid and simultaneous determination of nonsteroidal anti-inflammatory drugs in human plasma by LC–MS with solid-phase extraction

A rapid, selective and sensitive analytical method for the simultaneous determination of 16 nonsteroidal anti-inflammatory drugs (NSAIDs) in human plasma was carried out using Oasis HLB solid-phase extraction (SPE), followed by reversed-phase high-performance liquid chromatography and quadrupole mass spectrometry with electrospray ionization operated in the negative ion mode. The recoveries of NSAIDs from human plasma by SPE were greater than 76.7%. The use of a short column packed with small particles enabled rapid and simultaneous determination within 7 min. The detection limits for the NSAIDs were 0.01–0.9 μg/ml using the selected ion monitoring mode.     

SPE and LC-MS/MS determination of 14 illicit drugs in surface waters from the Natural Park of L’Albufera (València, Spain)

A simple and robust method using solid-phase extraction (SPE) and liquid chromatography tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of 14 drugs of abuse and their metabolites (cocainics, amphetamine-like compounds, cannabinoids, and opiates) in surface waters has been developed. Seven SPE adsorbents (Oasis HLB, Oasis MCX, Oasis Wax, Supelselect HLB, Strata-X, Strata-XCW), amount of sorbent bed, water volume, and pH were investigated. The highest recoveries, as well as the simplest protocol, were obtained for Oasis HLB cartridges (6 mL/200 mg) using 250 mL of water. The proposed method was linear in a concentration range from 0.03–6 to 300–60,000 ng/L depending on the compound, with correlation coefficients higher than 0.998. Matrix effects have been studied in surface water samples, and several isotope-labeled internal standards have been evaluated as a way to compensate the signal suppression observed. Limits of detection (LODs) and quantification (LOQs) ranged from 0.01 to 1.54 ng/L and from 0.03 to 5.13 ng/L, respectively. Recoveries were 71–102% at the LOQ level and 77–104 at 50 ng/L. The intra-day and intermediate precisions were from 1% to 8% and from 2% to 11%, respectively. The present work reports for the first time the occurrence of drugs of abuse residues in surface water samples from the Natural Park of L’Albufera (Valencia, Spain). Codeine, cocaine, benzoylecgonine, ecgonine methylester, amphetamine, 3,4-methylendioxy methamphetamine, morphine, and methadone were quantified with median values of 11.10, 0.02, 5.59, 0.08, 0.21, 0.75 and 0.14 ng/L respectively, and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol was detected in one sample at levels <LOQ.     

Simultaneous determination of various pharmaceutical compounds in water by solid-phase extraction-liquid chromatography-tandem mass spectrometry

A solid-phase extraction (SPE) followed by liquid chromatography-electrospray ionisation tandem mass spectrometry (LC-ESI-MS-MS) method was developed and validated for simultaneous analysis of 11 pharmaceutical residues (propranolol, sulfamethoxazole, meberverine, thioridazine, carbamazepine, tamoxifen, mecoprop, indomethacine, diclofenac, meclofenamic acid and monensin) in environmental water samples. The collision energy chosen for the multiple reaction monitoring (MRM) experiment was optimised. A number of parameters that may affect the recovery of the pharmaceuticals, such as the type of SPE cartridges, eluents, as well as water properties including pH value, salinity and concentration of colloid and surfactant were investigated. It is shown that the Oasis HLB SPE cartridge produced the best recoveries of the target pharmaceuticals while methanol was efficient in eluting pharmaceuticals from SPE cartridges. The recovery of some target compounds was enhanced with increasing salinity, but reduced by increasing pH value, and unaffected by surfactant concentration (0-10 microg/l). The recovery of most compounds was slightly increased by the presence of colloids (0-10 mg/l), which however caused a reduction in recovery for sulfamethoxazole and meberverine. The optimised method was further verified by performing spiking experiments in river water and seawater matrices, with good recovery and reproducibility for all except two compounds. The established method was successfully applied to environmental water samples from East Sussex, UK, for the determination of the target pharmaceuticals.     

气相色谱-质谱法测定水体中5种典型有机紫外防晒剂

建立了水体中5种典型有机紫外防晒剂甲氧基肉桂酸乙基己酯（ethylhexyl methoxycinnamate,EHMC）、二苯酮-3（benzophenone-3,BP-3）、4-甲基苄亚基樟脑（4-methylbenzylidene camphor,4-MBC）、奥克立林（octocrylene,OC）和胡莫柳酯（homosalate,HMS）的气相色谱-质谱检测方法。对HMS、BP-3衍生化条件进行了系统的优化。以100 μL双（三甲基硅烷基）三氟乙酰胺（N,O-bis（trimethylsilyl） trifluoroacetamide,BSTFA）为衍生化试剂,在100 ℃下反应100 min。水样固相萃取选用Oasis HLB萃取柱（0.5 g）,洗脱溶剂为乙酸乙酯-二氯甲烷（1：1,v/v）,水样pH 3~5。该方法对5种化合物的检出限范围为0.5~1.2 ng/L,定量限范围为1.4~4.0 ng/L。最佳实验条件下,加标水样回收率为87.85%~102.34%,相对标准偏差（n=3）均小于5%。该方法成功地应用于昆明市第一污水厂进出口水样中目标物质的分析。     

Matrix effects in the gas chromatographic-mass spectrometric determination of brominated analogues of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone

Brominated analogues (BMXs) of the strong drinking water mutagen MX (3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone) were found to be subject to strong matrix induced chromatographic response enhancement effects. We evaluated different ways to reduce errors in quantification including comparison of gas chromatographic inlet systems, improved clean up of sample extracts, and preparation of calibration standards in the sample matrix. The best quantitative accuracy and long term performance were achieved when the calibration standards were prepared in sample matrix, samples were cleaned up with C18-resin in conjunction with solid phase extraction (SPE) with Oasis HLB cartridges, and gas chromatography with PTV splitless injection was used. This method enables the determination of MX and BMXs from 500 ml water sample with quantitation limits of 1 ng/l or less.     

CE Analysis of Cephalosporins in Environmental Waters

This study investigates an off-line solid phase extraction (SPE) for improving the sensitivity in the capillary electrophoretic (CE) analysis of four cephalosporins. Two sorbents—LiChrolut-C₁₈ and Oasis HLB—were used in a SPE process to detect cephalosporins in natural waters (tap, river and hospital sewage) and their performances were compared. By using Oasis HLB sorbent higher recoveries for river water were obtained (94–107% when 500 mL of sample were analyzed). The off-line SPE–CZE method was validated for river water with good detection limits (3 μg L⁻¹) and the linearity ranged between 5 and 200 μg L⁻¹.