On-line coupling of solid-phase extraction to liquid chromatography-tandem mass spectrometry for the determination of macrolide antibiotics in environmental water

An automated on-line solid-phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) system was developed for the determination of macrolide antibiotics including erythromycin (ETM), roxithromycin (RTM), tylosin (TLS) and tilmicosin (TMC) in environmental water samples. A Capcell Pak MF Ph-1 column packed with restricted access material (RAM) was used as SPE column for the concentration of the analytes and clean-up of the sample. One milliliter water sample was injected into the conditioned SPE column and the matrix was washed out with 3 mL high purity water. By rotation of the switching valve, macrolides (MLs) were eluted in the back-flush mode and transferred to the analytical column by the chromatographic mobile phase. The matrix effect was evaluated by the directly injection LC-MS and on-line SPE-LC-MS methods. The limits of detection (LODs) and limits of quantification (LOQs) obtained are in the range of 2-6 and 7-20 ng L⁻¹, respectively, which means that the proposed method is suitable for trace analysis of MLs at low level concentration. The intra- and inter-day precisions are in the range of 2.9-7.2% and 3.3-8.9%, respectively. In the three fortified levels (20, 200 and 2000 ng L⁻¹), recoveries of MLs ranging from 86.5% to 98.3% are obtained.     

Analysis of priority pesticides and phenols in Portuguese river water by liquid chromatography-mass spectrometry

Summary The determination of selected pesticides and phenols in Portuguese river water samples was carried out from April to September, 1999. The method involved 200 mL samples taken by offline, solid phase extraction by OASIS polymeric cartridges followed by liquid chromatography-atmospheric pressure, chemical ionization-mass spectrometry (LC-APCI-MS). Recoveries of pesticides were 50–96% and 72–120% for the Platform and HP 1100 instruments, respectively. Chlorophenols gave recoveries of 60–91%. Triazines and transformation products like desethylatrazine (DEA) and desisopropylatrazine (DIA) and compounds such as diuron and chlorophenols were positively identified by LC-APCI-MS. The levels detected of the different compounds varied from 0.01–2.61 μg L⁻¹, the most frequently detected compounds being, atrazine, simazine, terbuthylazine, alachlor, metolachlor, Irgarol, diuron, 2,4,6-trichlorophenol, desisopropylatrazine and desethylatrazine.     

Simultaneous extraction of tetracycline, macrolide and sulfonamide antibiotics from agricultural soils using pressurised liquid extraction, followed by solid-phase extraction and liquid chromatography-tandem mass spectrometry

The veterinary antibacterial agents chlortetracycline (CTC), oxytetracycline (OTC), sulfadiazine (SDZ), erythromycin (ERY) and tylosin (TYL A, B, C and D) were extracted from soil using pressurized liquid extraction (PLE). Citric acid (pH 4.7) and methanol was used as extraction buffer, followed by tandem-solid-phase extraction (SPE) clean-up (SAX + HLB) for all compounds. For quantification two slightly different methods were employed using LC-MS-MS with MRM detection. The soil extraction method was validated using a loamy sand soil and a sandy soil, representing two typical Danish agricultural soils. Recoveries were 50-80% for the tetracyclines (CTC and OTC) and sulfadiazine (SDZ) and 60-100% for the macrolides (TYL and ERY). Limits of detection for the soil extraction method (LOD(soil)) were 0.6-5.6 microg kg(-1) soil for CTC and OTC, 0.9-2.9 microg kg(-1) soil for SDZ and 2.4-5.5 microg kg(-1) soil for TYL A and ERY. Furthermore, the method was applied to field samples taken from two agricultural fields fertilised with liquid manure containing CTC and TYL A. These results showed a decline in the content of antibacterial agents throughout the sampling period of 155 days from 10 to 15 microg CTC kg(-1) soil and 20-55 microg TYL A kg(-1) soil to below or near the LOD(soil) listed above. Finally, the method was applied to barley grains harvested from the fields. None of the antibacterial agents were measured in grain samples, but recoveries for spiked grain samples were similar to soil recoveries.     

Determination of quaternary ammonium compounds in seawater samples by solid-phase extraction and liquid chromatography-mass spectrometry

A method for the simultaneous determination of two biocidal quaternary ammonium compounds; didecyldimethylammonium chloride (didecyldimethyl quat) and dodecylbenzyldimethylammonium chloride (benzyl quat), in seawater by solid phase extraction (SPE) followed by liquid chromatography-mass spectrometry (LC-MS) was developed. The optimised procedure utilised off-line extraction of the analytes from seawater using polymeric (Strata-X) SPE cartridges. Recoveries ranged from 80 to 105%, with detection limits at the low parts-per-trillion (ng/l) level for both analytes. To demonstrate sensitivity, environmental concentrations were measured at three different locations along the North East coast of England with measured values in the range 120-270ng/l.     

Determination of benzothiazoles from complex aqueous samples by liquid chromatography-mass spectrometry following solid-phase extraction

A method was developed for the determination of benzothiazoles from municipal wastewater, which may originate from their use as corrosion inhibitors, vulcanization accelerators or fungicides. Extraction is performed by SPE using a polymeric sorbent, followed by LC-MS analysis with electrospray ionization. Due to the diversity of the analytes, two LC-MS runs are required: 2-aminobenzothiazole, benzothiazole and 2-methylthiobenzothiazole are detected in the positive ion mode, while benzothiazole-2-sulfonic acid (BTSA), 2-mercaptobenzothiazole and 2-hydroxybenzothiazole are determined in the negative ion mode. Limits of quantification range from 20 to 200 ng/L in treated wastewater. Reliable quantification with R.S.D.s below 25% is achieved by standard addition in a limited number of samples of each sample series. A significant reduction of matrix effects in positive electrospray ionization is achieved by reducing the flow directed into the ESI-interface. When applied to untreated municipal wastewater most analytes were found at concentrations in the high ng/L- to low microg/L-range with the most polar BTSA being the dominant compound of this class. Removal of benzothiazoles in biological wastewater treatment appears to be limited.     

Combined solid-phase extraction and gas chromatography-mass spectrometry used for determination of chloropropanols in water

A sensitive and rapid derivatization method for the simultaneous determination of 1,3-dichloro-2-propanol (1,3-DCP) and 3-chloropropane-1,2-diol (3-MCPD) in water samples has been developed. The aim was to research the optimal conditions of the derivatization process for two selected reagents. A central composite design was used to determine the influence of derivatization time, derivatization temperature and reagent volume. A global desirability function was applied for multi-response optimization. The analysis was performed by gas chromatography-mass spectrometry. During the optimization of the extraction procedure, four different types of solid-phase extraction (SPE) columns were tested. It was demonstrated that the Oasis HLB cartridge produced the best recoveries of the target analytes. The pH value and the salinity were investigated using a Doehlert design. The best results for the SPE of both analytes were obtained with 1.5 g of NaCl and pH 6. The proposed method provides high sensitivity, good linearity (R(2)≥0.999) and repeatability (relative standard deviations % between 2.9 and 3.4%). Limits of detection and quantification were in the range of 1.4-11.2 ng/mL and 4.8-34.5 ng/mL, respectively. Recoveries obtained for water samples were ca. 100% for 1,3-DCP and 3-MCPD. The method has been successfully applied to the analysis of different samples including commercially bottled water, an influent and effluent sewage.     

Determination of antibiotics in aquatic environment by solid-phase extraction followed by liquid chromatography-electrospray ionization mass spectrometry

A robust and sensitive solid-phase extraction followed by liquid chromatography-electrospray ionization mass spectrometric (LC-ESI-MS) method for determination of antibiotics viz., fluoroquinolones, sulfamethoxazole, trimethoprim and cephalosporines in surface waters was developed. The sample recoveries on Oasis HLB cartridges were found to be >80%. Identification was carried out by LC-ESI-MS/MS. The positive ion ESI mass spectra containing the peaks of quasimolecular ions [M+H](+) allowed the determination of molecular masses whereas the fragment ions obtained by MS/MS of [M+H](+) ions permitted the structural assignment. Quantification was carried out by selective ion monitoring (SIM) using the quasimolecular ions [M+H](+) of the parent compounds. The detection and quantification limits were found to be in the range of 0.6-8.1 and 2.0-24.0 microg/L. The surface waters of different lakes and tanks of Hyderabad, India were found to contain a few antibiotics.     

固相萃取-高效液相色谱-串联质谱法同时测定养殖海水中23种抗生素

建立了固相萃取-高效液相色谱-串联质谱(SPE-HPLC-MS/MS)同时检测水中6类23种抗生素的分析方法。水样用固相萃取柱富集净化,通过对比水样在不同上样pH、洗脱液用量等条件下的回收率,优化了前处理方法。采用0.1%(v/v)甲酸-1 g/L甲酸铵水溶液和甲醇-乙腈(1:1, v/v)体系作为流动相,经过梯度洗脱进行分离,在HPLC-MS/MS多反应监测模式下进行定性定量分析。结果显示,23种抗生素的方法检出限(MDL)范围为0.1~2.9 ng/L,加标回收率为47.3%~132.6%。采用该方法对东营海水养殖区5个养殖池水样进行了检测,除青霉素类之外的各类抗生素均有检出,其中磺胺增效剂甲氧苄氨嘧啶的检出率达100%,氯霉素类抗生素氟甲砜霉素检出的最高质量浓度达到261.0 ng/L。结果表明,所建立的方法高效、灵敏、可靠,可用于海水中多种抗生素的分析。     

Analysis of steroids in environmental water samples using solid-phase extraction and ion-trap gas chromatography-mass spectrometry and gas chromatography-tandem mass spectrometry

This paper describes an improved method for the extraction and determination of three steroids, oestrone, 17beta-oestradiol, and the synthetic contraceptive steroid 17alpha-ethinyloestradiol in aqueous matrices. Samples of wastewater and environmental water were spiked with internal standards, comprising isotopically labelled analogues of the steroids to be determined. The samples were extracted using solid-phase extraction disks and the extracts were then derivatized to form tert.-butyldimethylsilyl derivatives. The derivatised steroids were determined in the final extracts by GC-MS or GC-MS-MS allowing an operational detection limit for each steroid in effluent samples of 1 ng l(-1).     

Fully automated liquid chromatography-mass spectrometry determination of 17beta-estradiol in river water

Surface modified molecularly imprinted polymers (SM-MIPs) for 17beta-estradiol (E2), utilizing 6-ketoecradiol as a pseudo template were prepared. MIPs for E2 were synthesized using 4-vinyl pyridine and ethylene dimethacrylate as a functional monomer and cross-linking agent, respectively. MIPs selectively retained E2 and provided excellent chromatographic resolution from interfering compounds inherent in river water sample matrices. Therefore, freshly prepared MIPs were applied to quantitative mass spectrometric (negative electrospray ionization mode) detection of low levels of E2 in river water sample. In order to pre-concentrate the target compound for HPLC analysis, column switching was coupled with a pretreatment column packed with the MIPs. The repeatability of actual determinations of river water sample, in which background E2 was not detected, spiked with 50 ng/L of E2 was 2.2% RSD with a detection limit and qualification limit of 1.8 and 5.4 ng/L, respectively. Surface modification of MIP particlefs packed in the pretreatment column provided selective affinity and on-line concentration of low levels of E2 while simultaneously eliminating sample matrix interference, resulting in a significant increase in sensitivity and reproducibility for liquid chromatography-mass spectrometry analysis of E2 in river water sample.     

Simultaneous determination of sulfonamides, tetracyclines and tiamulin in swine wastewater by solid-phase extraction and liquid chromatography-mass spectrometry

Little is known about the contamination level of antibiotics in swine wastewater in China. The highly complex matrix of swine wastewater, which generally has a chemical oxygen demand (COD) concentration as high as 15,000 mg/L, makes it difficult to detect antibiotics at trace levels. In this work, a highly selective and sensitive analytical method was developed for simultaneous determination of three classes of commonly used veterinary antibiotics including five sulfonamides, three tetracyclines and one macrolide in swine wastewater using solid-phase extraction (SPE) and liquid chromatography-mass spectrometry (LC-MS). The method detection limits (MDL) in the swine wastewater were determined to be between 5 and 91 ng/L, depending on specific antibiotics. Except sulfamethizole, all the other eight antibiotics were detected in the swine wastewaters collected from three concentrated swine feeding plants located in the Beijing (China) area, showing a concentration range of 0.62-32.67 microg/L. These results reveal the representative concentration levels of selected antibiotics in the swine wastewaters of Beijing area.     

Simultaneous determination of 17 ginsenosides in rat urine by ultra performance liquid chromatography-mass spectrometry with solid-phase extraction

A rapid analytical method for quantifying 17 ginsenosides in rat urine by ultra performance liquid chromatography (UPLC) coupled to electrospray ionization mass spectrometry (ESI-MS) is described. All analytes were extracted by solid-phase extraction optimized to obtain good recovery and quantified using digoxin as an internal standard. ESI-MS was optimized for different cone voltages at positive ionization mode to allow simultaneous analysis of all analytes in a relatively short time. Qualitative methodological considerations, including the linear range, precision, limit of quantification, limit of detection, recovery and sensitivity are also provided.     

Determination of the nucleosides and nucleobases in Tuber samples by dispersive solid-phase extraction combined with liquid chromatography-mass spectrometry

A simple, fast and inexpensive method based on dispersive solid phase extraction (DSPE) combined with LC–MS was developed for simultaneous determination of 7 nucleosides and nucleobases (i.e., adenine, hypoxanthine, uridine, adenosine, guanine, guanosine, and inosine) in Tuber fruiting-bodies and fermentation mycelia. The DSPE procedure was firstly introduced to remove the protein interference from sample solutions, and D3520 macroporous resin was chosen as the DSPE sorbent because of its high removal capability on protein interferences, but low adsorption rate on analytes. Besides, key parameters on DSPE procedure (i.e., macroporous resin type, macroporous resin amount, methanol concentration, and vortex time) were optimized, and the protein removal efficacy could achieve about 95% after the process optimization. Though the method validation test, the DSPE-LC–MS method was confirmed to be precise, accurate and sensitive, and the column blinding problem was solved successfully. By using this established method, the total amount of nucleosides and nucleobases in the fermentation mycelia was determined to range from 4881.5 to 12,592.9 μg g⁻¹, which was about 2–25 times higher than the fruiting-bodies (from 498.1 to 2274.1 μg g⁻¹). The formulation of nucleosides and nucleobases in the fermentation mycelia maintained relatively constant, while the formulation in Tuber fruiting-bodies varied significantly with their species. Hierarchical cluster analysis (HCA) showed the formulation similarity of nucleosides and nucleobases between Tuber fermentation mycelia and the fruiting-bodies of Tuber indicum and Tuber himalayense. From the viewpoint of nucleosides and nucleobases, this work confirms the potentiality of Tuber fermentation mycelia as the alternative resource for its fruiting-bodies.     

An improved method for analyzing chlormequat and mepiquat in source waters by solid-phase extraction and liquid chromatography-mass spectrometry

A liquid chromatography-mass spectrometry (LC-MS) method for the identification and quantification of chlormequat (CQ) and mepiquat (MQ) in source waters with high sensitivity and specificity was established using WCX cartridges (150 mg/6 mL) for pre-concentration of the samples and using the CAPCELL PAK CR 1:4 (2.0 mm × 150 mm 5 μm, SCX:C18 = 1:4) column containing strong cationic exchange resins and C18 for separation. The method could solve the problem for pre-concentrating ionic compounds from water samples and avoid the MS instrument fouling problem accompanied with the use of ion-pair reagents. After the optimization of analytical conditions, quantification was achieved in the positive electrospray ionization mode using selected ion monitoring. The samples were analyzed with multi-channel mode with quantification performed at 30 V cone voltage to ascertain the sensitivity and qualitative analysis performed at 60 V cone voltage simultaneously. The method detection limits (MDLs) of CQ and MQ in source water were determined to be 14 and 22 ng L⁻¹. Finally, the method was used to quantify CQ and MQ in several source waters, which gave a level ranging from below the quantitation limit to 28 ng L⁻¹.     

Analysis of free estrogens and their conjugates in sewage and river waters by solid-phase extraction then liquid chromatography-electrospray-tandem mass spectrometry

Summary ‘Free’ steroidal estrogens have been identified as compounds possibly responsible for endocrine-disruption of aquatic fauna populating rivers in which municipal sewage-treatment plants (STP) discharge their effluents. Natural and synthetic estrogens are excreted, as glucuronides and sulfates, by man, in the urine but these are bioconverted back to the unconjugated forms in wastewater discharges. For this reason we have developed a sensitive analytical procedure, without derivatization, for identification and quantitation of conjugated and free estrogens in surface and waste waters. The hormones were extracted and fractionated, by use of Carbograph cartridges, into neutral and acid fractions which were then analyzed by liquid chromatography-tandem mass spectrometry. Recoveries were between 66 and 100% and limits of detection (LOD) between 15.0 and 0.003 ng L⁻¹, depending on the compound and the water matrix. When this methodology was applied to real sewage and river water we could measure the main free estrogens at ng L⁻¹ levels. Among the conjugates we always observed the presence of estrone 3-sulfate (at levels between 8.0 and 0.5 ng L⁻¹).     

Analysis of unknown organic pollutants in sewage by solid-phase extraction combined with gas chromatography-mass spectrometry

A rapid, simple, and reliable method of solid-phase extraction (SPE) combined with gas chromatography (GC)-mass spectrometry (MS) is developed for the analysis of a wide range of polarity of unknown organic pollutants in sewage. Wastewater samples are extracted by passing them through disposable C(18) cartridges, and the extracts are then analyzed by GC-MS. Different SPE parameters for ten organic compounds in the list of priority pollutants suggested by the China Environmental Protection Agency (EPA) are studied, and their breakthrough volumes are determined. Extraction recoveries for the tested compounds are greater than 60%, except the recovery of 1,2-dichloroethane is 48%. The relative standard deviations are less than 7.8% (n = 3). The developed approach is successfully applied for the identification of organic components in a sewage sample. Over 220 organic pollutants are identified, with 5 of these present in the list of priority pollutants suggested by the U.S. EPA and 4 from the list by the China EPA.     

Multiresidue determination of pesticides in juice by solid-phase extraction and gas chromatography-mass spectrometry

A multiresidue method based on solid-phase extraction was developed for the simultaneous determination of 50 pesticides in commercial juices. The extraction procedure was carried out in C₁₈ columns preconditioned with acetonitrile and water. The subsequent elution of pesticides was performed with a mixture of hexane-ethyl acetate (1:1, v/v) prior to the determination by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM), using one target and two qualifier ions. Standards were prepared spiking blank juice samples to counteract the observed matrix effect. Average recoveries for all the pesticides studied were higher than 91% with relative standard deviations lower than 9% in the concentration range of 0.02-0.1 μg/mL and the detection limits achieved ranged from 0.1 to 4.6 μg/L. The proposed method was applied to the analysis of these compounds in commercial juices and diazinon, ethion and procymidone were the pesticides encountered, although the levels found were very low.     

Stability of fluoroquinolone antibiotics in river water samples and in octadecyl silica solid-phase extraction cartridges

Airborne particulate matter has been sampled at a location close to a metallurgical plant in North-Rhine-Westphalia, Germany, and first results on the chromium(VI) content in the collected dust are presented. A special procedure using a scrubber as sampling device was used to preserve Cr(VI) during the sampling procedure. The scrubber solution which consisted of 0.1 mol L^–1 TRIS-buffer solution was adjusted to a slightly alkaline pH of 8.6 to reduce the oxidation potential of Cr(VI) and to avoid possible oxidation of Cr(III) to Cr(VI), for example by oxygen (or ozone at ambient concentrations). After sampling Cr(VI) was pre-concentrated on an anion-exchange material and eluted with aqueous 0.6 mol L^–1 sodium perchlorate solution. After elution, a species-selective complex of Cr(VI) with diphenylcarbazide (DPC) was prepared; this was extracted into n-hexanol and quantified by UV–visible spectrophotometry. A detection limit of 0.9 ng m^–3 for Cr(VI) in ambient aerosols can be achieved with this method.     

Analysis of polar pesticides in water and wine samples by automated in-tube solid-phase microextraction coupled with high-performance liquid chromatography-mass spectrometry

A simple and sensitive method for the determination of polar pesticides in water and wine samples was developed by coupling automated in-tube solid-phase microextraction (SPME) to high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS). To achieve optimum performance, the conditions for both the in-tube SPME and the ESI-MS detection were investigated. In-tube SPME conditions were optimized by selecting the appropriate extraction parameters, especially the stationary phases used for SPME. For the compounds studied, a custom-made polypyrrole (PPY)-coated capillary showed superior extraction efficiency as compared to several commercial capillaries tested, and therefore, it was selected for in-tube SPME. The influence of the ethanol content on the performance of in-tube SPME was also investigated. It was found that the amount of pesticides extracted decreased with the increase of ethanol content in the solutions. The ESI-MS detection conditions were optimized as follows: nebulizer gas, N2 (30 p.s.i.; 1 p.s.i.=6894.76 Pa); drying gas, N2 (10 l/min, 350 degrees C); capillary voltage, 4500 V; ionization mode, positive; mass scan range, 50-350 amu; fragmentor voltage, variable depending on the ions selected. Due to the high extraction efficiency of the PPY coating and the high sensitive mass detection, the detection limits (S/N = 3) of this method for the compounds studied are in the range of 0.01 to 1.2 ng/ml, which are more than one order of magnitude lower than those of the previous in-tube SPME-HPLC-UV method. A linear relationship was obtained for each analyte in the concentration range of 0.5 to 200 ng/ml with MS detection. This method was applied to the analysis of phenylurea and carbamate pesticides in spiked water and wine samples.     

HPLC-MS/MS检测猪肉中六种大环内酯类抗生素

建立了以高效液相色谱-质谱(HPLC-MS/MS)检测猪肉中替米考星(TILM)、红霉素(ERY)、泰乐菌素(TYL)、吉他霉素(KIT)、罗红菌素(ROX)及交沙霉素(JOS)等6种大环内酯类抗生素的多残留分析方法.样品用乙腈提取后,经正己烷脱脂,过C18 柱净化,4%氨甲醇洗脱后经氮气吹干,采用多反应监测,对6种大环内酯类药物作定性和定量分析.在10～1000μg/L的范围内,6种药物线性良好(R>0.998).在50、100、200μg/Kg添加水平下,6种药物的回收率在62.2%～102%,相对标准偏差为2.7%～16%.替米考星和吉他霉素的检出限(S/N=3)为0.1μg/Kg,其它药物为0.05μg/kg.