Trace enrichment of (fluoro)quinolone antibiotics in surface waters by solid-phase extraction and their determination by liquid chromatography-ultraviolet detection

A new and simple analytical methodology for the simultaneous analysis of acidic and zwitterionic (fluoro)quinolones in surface waters at trace concentration level is presented. The method is based on the preconcentration of these analytes by a solid-phase extraction procedure and their subsequent quantification by liquid chromatography using ultraviolet detection. The breakthrough volumes of the selected (fluoro)quinolones in four different sorbents--C18, styrenedivinylbenzene (SDB), C18-cation-exchange and SDB-cation-exchange--have been evaluated and varied between 25 and 150 ml depending on the antibiotic and the sorbent used. An exhaustive study of the influence of sample pH on the preconcentration step has been carried out in order to find a suitable procedure for extraction of acidic and zwitterionic FQs in one single step. Under optimum conditions, it was possible to percolate up to 250 ml of water solution onto both C18 and SDB-cation-exchange cartridges with quantitative recoveries for all the analytes tested. However, matrix components of the surface water samples analysed negatively affected the recoveries of the analytes in the SDB-cation-exchange cartridge and thus, C18 cartridges were finally selected for the analysis of the (fluoro)quinolones in lake and river water. The limits of detection achieved with this procedure varied between 8 and 20 ng l(-1) proving its suitability for the determination of the (fluoro)quinolones in water samples at a realistic environmental concentration level.     

Determination of quinolones and fluoroquinolones in hospital sewage water by off-line and on-line solid-phase extraction procedures coupled to HPLC-UV

In this work, the development of two solid-phase extraction procedures (off-line and on-line formats) for the identification and quantification of several (fluoro)quinolones in hospital sewage water by HPLC-UV is described. Both procedures are based on the use of C18 and anion exchange (SAX) sorbents for the preconcentration and clean-up steps, respectively, and all variables influencing both steps were optimised. In the off-line format, after its pH was adjusted to 2.5, sample was preconcentrated on a C18 cartridge and eluted with 4 mL of methanol/ammonia (94/6). The methanolic extract must be diluted up to 10 mL with water to allow quantitative retention of the analytes on the SAX cartridge. In the on-line format, the addition of 2.5% of NH4Cl to the sewage water sample (pH = 2.5) was necessary to increase the breakthrough volumes of the analytes in the C18 precolumn. Quantitative transfer of the (fluoro)quinolones from the C18 precolumn to the SAX precolumn was accomplished by pumping 2 mL of a mixture methanol/water (40/60, pH = 9.2) at 2 mL min(-1). Elution of the analytes from the SAX precolumn by means of the chromatographic mobile phase required the inclusion of an additional isocratic step at the beginning of the gradient program. Both off-line and on-line solid phase extraction procedures coupled to HPLC-UV were applied to the analysis of a sewage water sample collected in the sewer system at the output of the St Dimphna Hospital (Geel, Belgium). The fluoroquinolone ciprofloxacin was found in this sample and quantified at 5.8 +/- 0.4 microg L(-1) (off-line method) and 5.6 +/- 0.5 microg L(-1) (on-line method). The analysis of spiked samples containing the seven (fluoro)quinolones studied provided quantitative recoveries in all cases with low RSD values (from 6 to 12%), and all the analytes could be identified by means of their UV spectra with match factors varying from 950 to 985 depending on the (fluoro)quinolone.     

Lab-on-valve for the automatic determination of the total content and individual profiles of linear alkylbenzene sulfonates in water samples

Methods for the total content and individual determination of linear alkylbenzene sulfonates (LAS) in water samples based on the use of a lab-on-valve (LOV) module alone or coupled to CE equipment, respectively, have been developed. The total content of LAS has been determined by intrinsic absorption measurements (DA method) and after reaction with a methyl orange-cetylpyridine chloride mixture (MO method) with detection limits (LODs) of 21 ng/L and 15 microg/L, respectively, quantification limits (LOQs) of 70 ng/L, 50 microg/L, and development times of 100 and 124 s, respectively. The method for individual separation-quantification of LAS at very low concentration is based on automatic SPE preconcentration in the LOV module coupled on-line with the CE equipment. The LODs and LOQs thus obtained range between 1-21 and 4-70 ng/L, respectively, with linear dynamic ranges from the LOQ to 10 microg/L. Preconcentration factors of 10,000 and high efficiency to eliminate interferents by SPE enable application of the method to treated effluent, waste, surface and sea waters.     

Comparison of Three Analytical Methods for the Determination of Quinolones in Pig Muscle Samples

This work presents a comparison between three analytical methods developed for the simultaneous determination of eight quinolones regulated by the European Union (marbofloxacin, ciprofloxacin, danofloxacin, enrofloxacin, difloxacin, sarafloxacin, oxolinic acid and flumequine) in pig muscle, using liquid chromatography with fluorescence detection (LC–FD), liquid chromatography–mass spectrometry (LC–MS) and liquid chromatography-tandem mass spectrometry (LC–MS/MS). The procedures involve an extraction of the quinolones from the tissues, a step for clean–up and preconcentration of the analytes by solid-phase extraction and a subsequent liquid chromatographic analysis. The limits of detection of the methods ranged from 0.1 to 2.1 ng g^?1 using LC–FD, from 0.3 to 1.8 using LC–MS and from 0.2 to 0.3 using LC–MS/MS, while inter- and intra-day variability was under 15 % in all cases. Most of those data are notably lower than the maximum residue limits established by the European Union for quinolones in pig tissues. The methods have been applied for the determination of quinolones in six different commercial pig muscle samples purchased in different supermarkets located in the city of Granada (south-east Spain).     

Comparison of Three Analytical Methods for the Determination of Quinolones in Pig Muscle Samples

This work presents a comparison between three analytical methods developed for the simultaneous determination of eight quinolones regulated by the European Union (marbofloxacin, ciprofloxacin, danofloxacin, enrofloxacin, difloxacin, sarafloxacin, oxolinic acid and flumequine) in pig muscle, using liquid chromatography with fluorescence detection (LC–FD), liquid chromatography–mass spectrometry (LC–MS) and liquid chromatography-tandem mass spectrometry (LC–MS/MS). The procedures involve an extraction of the quinolones from the tissues, a step for clean–up and preconcentration of the analytes by solid-phase extraction and a subsequent liquid chromatographic analysis. The limits of detection of the methods ranged from 0.1 to 2.1 ng g⁻¹ using LC–FD, from 0.3 to 1.8 using LC–MS and from 0.2 to 0.3 using LC–MS/MS, while inter- and intra-day variability was under 15 % in all cases. Most of those data are notably lower than the maximum residue limits established by the European Union for quinolones in pig tissues. The methods have been applied for the determination of quinolones in six different commercial pig muscle samples purchased in different supermarkets located in the city of Granada (south-east Spain).

     

Determination of estrogens and progestogens by mass spectrometric techniques (GC/MS, LC/MS and LC/MS/MS)

Steroid sex hormones and related synthetic compounds have been shown to provoke alarming estrogenic effects in aquatic organisms, such as feminization, at very low concentrations (ng/L or pg/L). In this work, different chromatographic techniques, namely, gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS), are discussed for the analysis of estrogens, both free and conjugated, and progestogens, and the sensitivities achieved with the various techniques are inter-compared. GC/MS analyses are usually carried out after derivatization of the analytes with bis(trimethylsilyl)trifluoroacetamide (BSTFA). For LC/MS and LC/MS/MS analyses, different instruments, ionization techniques (electrospray (ESI) and atmospheric pressure chemical ionization (APCI)), ionization modes (negative ion (NI) and positive ion (PI)) and monitoring modes (selected ion monitoring (SIM) and selected reaction monitoring (SRM)) are generally employed. Based on sensitivity and selectivity, LC/ESI-MS/MS is generally the method of choice for determination of estrogens in the NI mode and of progestogens in the PI mode (instrumental detection limits (IDLs) 0.1-10 ng/mL). IDLs achieved by LC/ESI-MS in the SIM mode and by LC/ESI-MS/MS in the SRM mode were, in general, comparable, although the selectivity of the latter is significantly higher and essential to avoid false positive determinations in the analysis of real samples. Conclusions and future perspectives are outlined.     

Determination of phenothiazines in human body fluids by solid-phase microextraction and liquid chromatography/tandem mass spectrometry

Eleven phenothiazine derivatives with heavy side-chains were found to be extractable from human whole blood and urine samples by solid-phase microextraction (SPME) with a polyacrylate-coated fiber. The fiber was then injected into the desorption chamber of an SPME-liquid chromatography (LC) interface for LC/tandem mass spectrometry (MS/MS) with positive ion electrospray (ES) ionization. All compounds formed base peaks due to [M + 1](+) ions by LC/ES-MS/MS. By use of LC/ES-MS/MS, the product ions produced from each [M + 1](+) ion showed base peaks due to side-chain liberation. Selected reaction monitoring (SRM) and selected ion monitoring (SIM) were compared for the detection of the 11 phenothiazine derivatives from human whole blood and urine. SRM showed much higher sensitivity than SIM for both types of sample. Therefore, a detailed procedure for the detection of drugs by SRM with SPME-LC/MS/MS was established and carefully validated. The extraction efficiencies of the 11 phenothiazine derivatives spiked into whole blood and urine were 0. 0002-0.12 and 2.6-39.8%, respectively. The regression equations for the 11 phenothiazine derivatives showed excellent linearity with detection limits of 0.2-200 ng ml(-1) for whole blood and 4-22 pg ml(-1) for urine. The intra- and inter-day precisions for whole blood and urine samples were not greater than 15.1%. The data obtained after oral administration of perazine or flupentixol to a male subject are presented.     

Methods for the determination of neutral drugs as well as betablockers and β2-sympathomimetics in aqueous matrices using GC/MS and LC/MS/MS

An analytical method has been developed which allows the determination of 22 different neutral and weakly basic drugs belonging to several different medicinal classes like antiphlogistics, betablockers, β₂-sympathomimetics, lipid regulators, antiepileptic agents, psychiatric drugs and vasodilators in waste water as well as in river and drinking water. A method including solid phase extraction, derivatization by silylation and detection by GC/MS permits detection down to 5 ng/L. The recovery rates mostly exceeded 70%. However, the determination of phenazone, carbamazepine, cyclophosphamide, ifosfamide and pentoxiphylline is frequently disturbed by organic co-extractants in real samples of rivers and waste waters. Therefore, a time saving alternative method has been developed, combining solid phase extraction (as an enrichment step) together with detection by LC-electrospray/MS/MS allowing the measurement of 5 neutral drugs. Detection limits down to 10 ng/L have been achieved even for organically highly contaminated waters like sewage treatment plant effluents. Received: 18 November 1997 / Revised: 18 March 1998 / Accepted: 21 March 1998     

甲基睾酮人体代谢物的选择反应监控检测法

采用ＧＣ／ＭＳ／ＭＳ的选择反应监控（ＳＲＭ）法检测尿中甲基睾酮的人体代谢物，与ＧＣ／ＭＳ的选择离子检测（ＳＩＭ）法比较，ＳＲＭ法有更高的选择性和确证能力。该种检测方法的建立，可以更有效地判定阳性尿。     

An overview of analytical methodologies for the determination of antibiotics in environmental waters

The widespread occurrence of antibiotics as contaminants in the aquatic environment has increased attention in the last years. The concern over the release of antibiotics into the environment is related primarily to the potential for the development of antimicrobial resistance among microorganisms. This article presents an overview of analytical methodologies for the determination of quinolone (Qs) and fluoroquinolone (FQs), macrolide (MLs), tetracycline (TCs), sulfonamide (SAs) antibiotics and trimethoprim (TMP) in different environmental waters. The analysis of these antibiotics has usually been carried out by high-performance liquid chromatography (HPLC) coupled to mass spectrometry (MS) or tandem mass spectrometry (MS/MS) and to a lesser extent by ultraviolet (UV) or fluorescence detection (FD). A very important step before LC analysis is sample preparation and extraction leading to elimination of interferences and prevention of matrix effect and preconcentration of target analytes.     

Determination of eight nitrosamines in water at the ng L(-1) levels by liquid chromatography coupled to atmospheric pressure chemical ionization tandem mass spectrometry

In this work, we have developed a sensitive method for detection and quantification of eight N-nitrosamines, N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMor), N-nitrosomethylethylamine (NMEA), N-nitrosopirrolidine (NPyr), N-nitrosodiethylamine (NDEA), N-nitrosopiperidine (NPip), N-nitroso-n-dipropylamine (NDPA) and N-nitrosodi-n-butylamine (NDBA) in drinking water. The method is based on liquid chromatography coupled to tandem mass spectrometry, using atmospheric pressure chemical ionization (APCI) in positive mode with a triple quadrupole analyzer (QqQ). The simultaneous acquisition of two MS/MS transitions in selected reaction monitoring mode (SRM) for each compound, together with the evaluation of their relative intensity, allowed the simultaneous quantification and reliable identification in water at ppt levels. Empirical formula of the product ions selected was confirmed by UHPLC-(Q)TOF MS accurate mass measurements from reference standards. Prior to LC-MS/MS QqQ analysis, a preconcentration step by off-line SPE using coconut charcoal EPA 521 cartridges (by passing 500 mL of water sample) was necessary to improve the sensitivity and to meet regulation requirements. For accurate quantification, two isotope labelled nitrosamines (NDMA-d(6) and NDPA-d(14)) were added as surrogate internal standards to the samples. The optimized method was validated at two concentration levels (10 and 100 ng L(-1)) in drinking water samples, obtaining satisfactory recoveries (between 90 and 120%) and precision (RSD<20%). Limits of detection were found to be in the range of 1-8 ng L(-1). The described methodology has been applied to different types of water samples: chlorinated from drinking water and wastewater treatment plants (DWTP and WWTP, respectively), wastewaters subjected to ozonation and tap waters.     

Improved capillary electrophoretic separation of nine (fluoro)quinolones with fluorescence detection for biological and environmental samples

A capillary electrophoretic method has been developed for the separation of nine (fluoro)quinolones. Detection is done by fluorescence measurement with broad wavelength band excitation between 240 and 400 nm. Best separation is achieved in a carrier electrolyte containing 50 mM H3PO4 adjusted to pH 7.55-acetonitrile (60:40, v/v). Detection limits are in the low microgl(-1) range. The suitability to real samples has been demonstrated by analyzing blood samples and surface water samples. Sample preconcentration and sample clean-up can easily be done by solid-phase extraction. Different phases based on alkyl- or phenyl-modified silica as well as on polymers have been investigated for this purpose. The method should also be useful for determination of residues of (fluoro)quinolones in food or other matrices.     

Sensitive SPE GC-MS-SIM screening of endocrine-disrupting herbicides and related degradation products in natural surface waters and robustness study

This paper describes a very sensitive capillary gas chromatographic mass spectrometric selective ion monitored method for the simultaneous determination of three chloro-s-triazine herbicides, Atrazine (AT), Simazine (SI) and Propazine (PP), three thiomethyl-s-triazine ones: Ametryn (AM), Prometryn (PM) and Terbutryne (TB) and three chloro-s-triazine degradation products, Deethyl-atrazine (DEA), Deisopropyl-atrazine (DIA) and Deethyldeisopropyl-atrazine (DD) with herbicide activity too. The instrumental parameters affecting GC separation and MS/SIM detection were investigated and from this study the best conditions were selected. A previous extraction and preconcentration step was applied by means of an off-line solid phase extraction process getting so an enrichment factor of 10⁴. The analytical performance characteristics of our method (stability, precision, linearity, LODs, LOQs, accuracy and robustness) were evaluated by means of a validation study on tap and deionised water samples using di-phenyl amide (DPA) as internal standard to achieve quantification. Natural water samples from different locations suspected to contamination were analysed by this off line SPE-GC-MS-SIM procedure and the results were also confirmed by an HPLC method.     

A new gas chromatography/mass spectrometry method for the simultaneous analysis of target and non-target organic contaminants in waters

In this study we developed a GC–MS method for the analysis of priority pollutants, personal care products (PCPs) and other emerging contaminants in waters using large volume injection with backflushing. Analyses are performed in the SIM/scan mode, so that in addition to the targeted organic contaminants, this method allows the simultaneous screening of non-target compounds. The scan data are analysed using Deconvolution Reporting Software (DRS) which screens the results for 934 organic contaminants. Deconvolution helps identify contaminants that are buried in the chromatogram by co-extracted materials and significantly reduces chromatographic resolution requirements, allowing shorter analysis times. All compounds have locked retention times and we can continually update and extend the mass spectral library including new compounds. Linearity and limits of detection in SIM and full-scan mode were studied. Method detection limits (MDLs) in effluent wastewater ranged in most of the cases from 1 to 36 ng/L in SIM mode and from 4 to 66 ng/L in full-scan mode; while in river water from 0.4 to 14 and 2–29 ng/L in SIM and full-scan mode, respectively. We obtained a linearity of the calibration curves over two orders of magnitude. The method has been applied to the screening of a large number of organic contaminants – not only to a subset of targets – in urban wastewaters from different wastewater treatment plants and also in river waters. Most of the target compounds were detected at concentration levels ranging from 11 to 8697 ng/L and from 7 to 1861 ng/L in effluent wastewater and river waters, respectively. Additionally, a group of 12 new compounds were automatically identified using the AMDIS and NIST libraries. Other compounds, such as the 4-amino musk xylene, a synthetic fragrance metabolite, which was not included in the databases, but has been manually searched in the full-scan chromatograms.     

Hydrophilic interaction liquid chromatography/tandem mass spectrometry for the analysis of diallyldimethylammonium chloride in water

We report a selective, sensitive and fast liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the determination of diallyldimethylammonium chloride (DADMAC) in water. Hydrophilic interaction liquid chromatography (HILIC) was used to avoid ion-pairing reagents, which are generally employed to retain cationic compounds. The complementary information obtained in a triple quadrupole mass spectrometer and in an ion trap Orbitrap has been used to study the fragmentation of the DADMAC cation [M](+) and for the correct assignment of the products ions. The HILIC/MS/MS method developed, using electrospray ionization in positive ion mode and selected reaction monitoring (SRM) acquisition mode, led to a reliable determination and confirmation of the DADMAC cation in water samples down to 50 ng L(-1). The low detection limit achieved, in combination with the absence of matrix effects, allowed the direct analysis of samples without any pretreatment, preconcentration or clean-up step. DADMAC was determined in samples collected in a drinking water treatment plant (DWTP) in Barcelona (Spain) and it was found in the influent at the μg L(-1) level.     

Methods for the determination of neutral drugs as well as betablockers and β2-sympathomimetics in aqueous matrices using GC/MS and LC/MS/MS

An analytical method has been developed which allows the determination of 22 different neutral and weakly basic drugs belonging to several different medicinal classes like antiphlogistics, betablockers, β₂-sympathomimetics, lipid regulators, antiepileptic agents, psychiatric drugs and vasodilators in waste water as well as in river and drinking water. A method including solid phase extraction, derivatization by silylation and detection by GC/MS permits detection down to 5 ng/L. The recovery rates mostly exceeded 70%. However, the determination of phenazone, carbamazepine, cyclophosphamide, ifosfamide and pentoxiphylline is frequently disturbed by organic co-extractants in real samples of rivers and waste waters. Therefore, a time saving alternative method has been developed, combining solid phase extraction (as an enrichment step) together with detection by LC-electrospray/MS/MS allowing the measurement of 5 neutral drugs. Detection limits down to 10 ng/L have been achieved even for organically highly contaminated waters like sewage treatment plant effluents.     

Development of analytical methods for multiresidue determination of quinolones in pig muscle samples by liquid chromatography with ultraviolet detection, liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry

This paper presents a comparison between liquid chromatography with ultraviolet detection (LC-UV), liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods developed for the multiresidue determination of 8 quinolones, around their maximum residue levels (MRLs) in pig muscle. The procedure involves common extraction of the quinolones from the tissues by traditional extraction, a step for clean-up and preconcentration of the analytes by solid-phase extraction (SPE) and a subsequent liquid chromatographic analysis. The methods present satisfactory results of linearity, precision and limits of quantification much lower than the MRLs established by the European Union for quinolones in pig tissues.     

Comparison of high resolution gas chromatography with electron impact and negative ion mass spectrometry detection for the determination of coplanar polychlorobiphenyl congeners in sewage sludges

The three most toxic coplanar PCB 77, 126 and 169 have been identified and quantified at ultra trace levels (0.02-4.8 ng/gdw) in swiss sewage sludge samples applying high resolution capillary gas chromatography (HRGC) and electron impact (EI) as well as negative ion chemical ionization (NCI) mass spectrometry (MS). NCI mass spectra have been dominated by the molecular ion as base peak and virtually no fragmentation has been observed. Detection limits of the planar PCB under single ion monitoring (SIM) conditions have been typically 100 fg for NCI-MS and 1 pg for EI-MS. NCI-MS was the preferred detection method for the determination of very low concentrations of these important contaminants in sewage sludge samples.     

C_(18)膜萃取/液相色谱-质谱联用法测定极地水体中有机磷酸酯

建立了C_(18)膜萃取/液相色谱-质谱联用技术测定极地水体中10种有机磷酸酯(OPEs)的方法。根据优化后的样品前处理及仪器方法,利用C_(18)膜富集4 L水体中的10种OPEs,经二氯甲烷超声提取,在电喷雾正离子模式下,采用选择反应监测(SRM)模式进行分析,线性相关系数为0.994 4~0.999 9。10种OPEs的加标回收率为64.1%~115%,方法检出限为0.08~0.55 ng/L。该方法适用于极地水体中10种OPEs的分析,利用该方法对北极水体样品中的10种OPEs进行检测,测得冰川融水中∑OPEs的质量浓度为0.64~6.64 ng/L,海水中∑OPEs的质量浓度为0.09~2.03 ng/L。     

Comparison of tandem and conventional mass spectrometry using electron capture negative ionization in the detection of chemically oxidized dexamethasone in human plasma

Chemistry and Biochemistry, Michigan State University, East Lansing, Michigan, USA Dexamethasone, a synthetic steroid, can be oxidized chemically to a ketonic steroid structure that is readily detected by electron capture negative ionization mass spectrometry (ECNI/MS). Previous work from this laboratory has demonstrated that the chemical oxidation procedure provides advantages of low detection limits and high selectivity for detection of oxidized dexamethasone against chemical background that would otherwise interfere with detection of this steroidal drug in biological samples using more conventional methodology. This report describes the extent to which tandem mass spectrometry (MS/MS) can further enhance the selectivity of the oxidation/ECNI methodology for the detection of dexamethasone during the analysis of human plasma and presents evidence that sample introduction by direct inlet probe (DIP) can be used successfully under ECNI conditions. For purposes of comparing the methodologies, the same human plasma samples are analyzed by ECNI, first with detection by conventional mass spectrometry using selected ion monitoring (SIM) and then by MSIMS using selected reaction monitoring (SRM) with sample introduction by the gas chromatographic (GC) inlet and by the DIP. The results indicate that use of the DIP is a viable means of sample introduction for ECNI when sample processing involves the specialized oxidation procedure described herein because the sample matrix does not compete significantly for the thermal electrons in the ion source. Whereas SIM and SRM provide comparable results when sample introduction is achieved by the GC inlet, the MS/MS approach offers the possibility for sample introduction using the DIP, which significantly simplifies and shortens the analysis.