Identification and mass spectrometric characterization of glycosylated flavonoids in Triticum durum plants by high-performance liquid chromatography with tandem mass spectrometry

A mass spectrometric method for extensive detection and semi-quantitative determination of flavonoid glycosides in stem and leaves of young Triticum durum plants is presented. About 100 g of sample were lyophilized and ground, and the compounds of interest were then extracted, cleaned-up, and fractionated using high-performance liquid chromatography (HPLC). Tandem mass spectrometry analyses were performed using a quadrupole-linear ion trap instrument with an information-dependent data acquisition (IDA) protocol that looped two experiments, enhanced MS scan and enhanced product ion scan. Various glycoconjugates, which are all derivatives of only four flavones, apigenin, luteolin, chrysoeriol and tricin, were identified and belong to the following categories: 7 monoglycosides, 31 diglycosides, 15 triglycosides and 1 tetraglycoside. Among these some acylated glycosides were found. Tricin derivatives are present exclusively as O-glycosides, while apigenin and luteolin are present always as C-glycosides. Semi-quantitative estimation was performed by using the monoglycoside and diglycoside of quercetin as internal standards.     

Rapid and sensitive screening and characterization of phenolic acids, phthalides, saponins and isoflavonoids in Danggui Buxue Tang by rapid resolution liquid chromatography/diode-array detection coupled with time-of-flight mass spectrometry

A novel rapid resolution liquid chromatography (RRLC) method coupled with diode-array detection (DAD) and time-of-flight mass spectrometry (TOFMS) in both positive and negative modes has been developed for quick and sensitive identification of the major compounds in Danggui Buxue Tang (DBT) preparation. Significant advantages of the use of RRLC with 1.8-microm porous particles include the much higher speed of chromatographic separation and great enhancement in sensitivity, compared with the conventional high-performance liquid chromatography (HPLC). With dynamic adjustment of the key role as fragmentor voltage in TOFMS, an efficient transmission of the ions was achieved to obtain the best sensitivity for providing the molecular formula for each analyte, and abundant fragment ions for structural information. The structural characterization of the major compounds in DBT was elucidated with authentic standards by DAD-TOF/MS, including phenolic acids, phthalides, saponins and isoflavonoids. The targets were rapidly screened from the complicated DBT matrix using a narrow mass window of 0.01 Da to restructure extracted ion chromatograms. By accurate mass measurements within 3 ppm error for each molecular ion and subsequent fragment ions, ten phenolic acids and phthalides including three groups of isomers, thirteen major saponins with a 20,24-epoxy-9,19-cyclolanostane-3,6,16,25-tetrol skeleton, sixteen isoflavonoids, corresponding glycosides, malonylglycosides, and acetylglycosides were identified in DBT preparation. The appropriate fragmentation pathways for them were also proposed based on definite elemental composition of the fragment ions.     

Development of a multi-target screening analysis for 301 drugs using a QTrap liquid chromatography/tandem mass spectrometry system and automated library searching

A new multi-target screening (MTS) procedure for drugs in blood and urine for toxicological analysis has been developed using a hybrid triple-quadrupole linear ion trap mass spectrometer (QTrap) for the fast detection and identification of 301 forensically important drugs, e.g. tranquilizers (benzodiazepines), hypnotics, drugs of abuse (opiates, cocaine, amphetamines, cannabinoids), antidepressants, neuroleptics, and some cardiac drugs, in one single liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis. Samples were extracted either with liquid-liquid extraction or solid-phase extraction. A multiple reaction monitoring (MRM) as survey scan and an enhanced product ion (EPI) scan as dependent scan were performed in an information-dependent acquisition (IDA) experiment. Finally, drug identification was carried out by library search with a newly developed MS/MS library based on EPI spectra at three different collision energies in positive mode. The advantage of this newly developed method is the possibility to detect and identify 301 drugs in one single LC/MS/MS run.     

Determination of type B fumonisin mycotoxins in maize and maize-based products by liquid chromatography/tandem mass spectrometry using a QqQlinear ion trap mass spectrometer

A sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for determining the type B fumonisin mycotoxins in corn-based foodstuffs is described. Fumonisins FB1 and FB2 were extracted from a 1 g sample by homogenization with acetonitrile/water (75:25, v/v, 50 mmol/L formic acid, 25 mL final volume) and the extract was defatted on C18 phase. Volumes of 5 mL of crude extracts were cleaned up on Carbograph-4 cartridges. The final solution was analyzed by HPLC with electrospray ionization mass spectrometry in positive ion mode using multiple reaction monitoring with a QqQ linear ion trap mass spectrometer. Recoveries for spiked corn-based foodstuffs ranged from 91-105% (RSD% < or =8%), and method detection limits were < or =2 ng/g for FB1 and < or =1 ng/g for FB2. Two different spiking levels were tested (5000 and 100 ng/g for FB1, 1000 and 20 ng/g for FB2). Quantitation was achieved by an external calibration procedure using matrix-matched standards, with diclofenac added post-cleanup as internal standard for the LC/MS/MS analyses. Calibration curves showed linearity in the concentration range 0.005-5 ng/microL of final extract (0.992 < or = R2< or =0.995). Two other fumonisins, FB3 and FB4, were identified in naturally contaminated samples of corn meal using an information-dependent acquisition protocol that looped three experiments, including neutral loss scan, enhanced resolution scan, and enhanced product ion scan. FB3 and FB4 quantitation was estimated as peak area ratios relative to the FB2 response in view of the lack of both standards. This work also includes an application of the present LC/MS/MS method to some maize and maize-based product samples (corn meal, cornflakes and popcorn) collected from Italian stores. FB1 and FB2 contamination levels exceeding the European Union recommendation were found in 8 out of 15 corn meal samples.     

Evaluation of atmospheric pressure ionization interfaces for quantitative measurement of sulfonamides in honey using isotope dilution liquid chromatography coupled with tandem mass spectrometry techniques

A comparison was made between electrospray, atmospheric pressure chemical and atmospheric pressure photospray ionizations to evaluate the MS/MS responses of standard sulfonamides and honey spiked samples. The sample preparation entails an acidic hydrolysis followed by a liquid/liquid extraction. Full method validation was realised by LC-APPI-MS/MS. Decision limit and detection capability were calculated for each analyte (at 50 microg/kg) and ranged between 53.6 and 56.9 and 57.5 and 63.2 microg/kg, respectively. Limits of detection and of quantification ranged, respectively, at 0.4-4.5 and 1.2-15.0 microg/kg. Precursor ion scan experiments of m/z 92 were also carried out as a survey experiment, linked with an enhanced product ion scan experiment to potentially identified additional sulfonamides via a library search.     

'N-in-one' strategy for metabolite identification using a liquid chromatography/hybrid triple quadrupole linear ion trap instrument using multiple dependent product ion scans triggered with full mass scan

This paper describes a new strategy that utilizes the fast trap mode scan of the hybrid triple quadrupole linear ion trap (QqQ(LIT)) for the identification of drug metabolites. The strategy uses information-dependent acquisition (IDA) where the enhanced mass scan (EMS), the trap mode full scan, was used as the survey scan to trigger multiple dependent enhanced product ion scans (EPI), the trap mode product ion scans. The single data file collected with this approach not only includes full scan data (the survey), but also product ion spectra rich in structural information. By extracting characteristic product ions from the dependent EPI chromatograms, we can provide nearly complete information for in vitro metabolites that otherwise would have to be obtained by multiple precursor ion scan (prec) and constant neutral loss (NL) analysis. This approach effectively overcomes the disadvantages of traditional prec and NL scans, namely the slow quadrupole scan speed, and possible mass shift. Using nefazodone (NEF) as the model compound, we demonstrated the effectiveness of this strategy by identifying 22 phase I metabolites in a single liquid chromatography/tandem mass spectrometry (LC/MS/MS) run. In addition to the metabolites reported previously in the literature, seven new metabolites were identified and their chemical structures are proposed. The oxidative dechlorination biotransformation was also discovered which was not reported in previous literature for NEF. The strategy was further evaluated and worked well for the fast discovery setting when a ballistic gradient elution was used, as well as for a simulated in vivo setting when the incubated sample (phase I metabolites) was spiked to control human plasma extract and control human urine.     

The application of 2-D dual nanoscale liquid chromatography and triple quadrupole-linear ion trap system for the identification of proteins

2-D nanoscale LC combined with a triple quadrupole-linear ion trap mass spectrometer was applied to the analysis of a complex peptide mixture. A 2-D dual nanoscale LC-MS/MS system was compared to a conventional one. Peptides were separated with a strong cation exchange (SCX) microcolumn in the first dimension and two C18 nanocolumns were used as second dimension. MS experiments were performed using information-dependent data acquisition, where two precursor ions were selected from an enhanced MS (EMS) or an enhanced multicharged ion (EMC) as survey scan. The major benefit of EMC instead of EMS was a two-fold reduction of the data file and a 15% increase of characterized proteins. The advantage of the 2-D dual nanoscale LC-MS/MS system versus the conventional 2-D nanoscale LC-MS/MS system was reflected in the significant increase of peptides which were successfully identified within the same time frame. The first factor contributing to this increase was that the mass spectrometer was collecting twice the number of relevant MS/MS data. The second factor is the use of twice the number of SCX salt fractions in the first dimension, allowing a better sample fractionation, thereby reducing the number of peptides transferred to the second chromatographic dimension per salt fraction.     

Rapid screening and characterization of drug metabolites using a multiple ion monitoring-dependent MS/MS acquisition method on a hybrid triple quadrupole-linear ion trap mass spectrometer

A novel LC/MS/MS method that uses multiple ion monitoring (MIM) as a survey scan to trigger the acquisition of enhanced product ions (EPI) on a hybrid quadrupole-linear ion trap mass spectrometer (Q TRAP) was developed for drug metabolite identification. In the MIM experiment, multiple predicted metabolite ions were monitored in both Q1 and Q3. The collision energy in Q2 was set to a low value to minimize fragmentation. Results from analyzing ritonavir metabolites in rat hepatocytes demonstrate that MIM-EPI was capable of targeting a larger number of metabolites regardless of their fragmentation and retained sensitivity and duty cycle similar to multiple reaction monitoring (MRM)-EPI. MIM-based scanning methods were shown to be particularly useful in several applications. First, MIM-EPI enabled the sensitive detection and MS/MS acquisition of up to 100 predicted metabolites. Second, MIM-MRM-EPI was better than MRM-EPI in the analysis of metabolites that undergo either predictable or unpredictable fragmentation pathways. Finally, a combination of MIM-EPI and full-scan MS (EMS), as an alternative to EMS-EPI, was well suited for routine in vitro metabolite profiling. Overall, MIM-EPI significantly enhanced the metabolite identification capability of the hybrid triple quadrupole-linear ion trap LC/MS.     

Metabolic profile of glyburide in human liver microsomes using LC‐DAD‐Q‐TRAP‐MS/MS

The sulfonylurea urea drug glyburide (glibenclamide) is widely used for the treatment of diabetes milletus and gestational diabetes. In previous studies monohydroxylated metabolites were identified and characterized for glyburide in different species, but the metabolite owing to the loss of cyclohexyl ring was identified only in mouse. Glyburide upon incubation with hepatic microsomes resulted in 10 metabolites for human. The current study identifies new metabolites of glyburide along with the hydroxylated metabolites that were reported earlier. The newly identified drug metabolites are dihydroxylated metabolites, a metabolite owing to the loss of cyclohexyl ring and one owing to hydroxylation with dehydrogenation. Among the 10 identified metabolites, there were six monohydroxylated metabolites, one dihydroxylated metabolite, two metabolites owing to hydroxylation and dehydrogenation, and one metabolite owing to the loss of cyclohexyl ring. New metabolites of glyburide were identified and characterized using liquid chromatography–diode array detector–quadruple‐ion trap–mass spectrometry/mass spectrometry (LC‐DAD‐Q‐TRAP‐MS/MS). An enhanced mass scan–enhanced product ion scan with information‐dependent acquisition mode in a Q‐TRAP‐MS/MS system was used to characterize the metabolites. Liquid chromatography with diode array detection was used as a complimentary technique to confirm and identify the metabolites. Metabolites formed in higher amounts were detected in both diode array detection and mass spectrometry detection. Copyright © 2012 John Wiley & Sons, Ltd.     

A novel approach for identification and characterization of glycoproteins using a hybrid linear ion trap/FT-ICR mass spectrometer

Combining source collision-induced dissociation (CID) and tandem mass spectral acquisition in a pseudo-MS(3) experiment using a linear ion trap results in a highly selective and sensitive approach to identifying glycopeptide elution from a protein digest. The increased sensitivity is partially attributed to the nonselective nature of source CID, which allows simultaneous activation of all charge states and coeluting glycoforms generating greater ion abundance for the mass-to-charge (m/z) 204 and/or 366 oxonium ions. Unlike source CID alone, a pseudo-MS(3) approach adds selectivity while improving sensitivity by eliminating chemical noise during the tandem mass spectral acquisition of the oxonium ions in the linear ion trap. Performing the experiments in the hybrid linear ion trap/Fourier transform-ion cyclotron resonance (FT-ICR) enables subsequent high-resolution/high-mass accuracy full-scan mass spectra (MS) and parallel acquisition of MS/MS in the linear ion trap to be completed in 2 s directly following the pseudo-MS(3) scan to collate identification and characterization of glycopeptides in one experimental scan cycle. Analysis of bovine fetuin digest using the combined pseudo-MS(3), high-resolution MS, and data-dependent MS/MS events resulted in identification of four N-linked and two O-linked glycopeptides without enzymatic cleavage of the sugar moiety or release of the sialic acids before analysis. In addition, over 95% of the total protein sequence was identified in one analytical run.     

液相色谱-串联质谱结合谱库检索测定猪组织中的9种β-兴奋剂残留量

建立了猪组织中9种β-兴奋剂(克伦特罗、莱克多巴胺、沙丁胺醇、利托君、特布他林、班布特罗、妥布特罗、西马特罗和异舒普林)多残留的液相色谱-四极杆/线性离子阱串联质谱(QTrap LC-MS/MS)检测方法。样品经β-葡萄糖醛苷酶/芳基硫酸酯酶酶解提取,液液萃取净化,以乙腈-甲酸水溶液为流动相,经C18柱分离后用QTrap LC-MS/MS进行多反应监测(MRM)、信息相关采集(IDA)、增强子离子扫描(EPI)和谱库检索分析。9种β-兴奋剂的线性范围为0.1～50.0 μg/L,线性关系良好(r＞0.99);样品中9种目标物在0.5、1.0和5.0 μg/kg添加水平下的回收率为72.0%～95.1%,相对标准偏差为3.1%～12.1%;方法检出限为0.1～0.2 μg/kg。实际样品检测结果表明,本方法可实现猪组织样本中β-兴奋剂残留量的灵敏、准确的定性和定量分析。     

Characterization of acylated flavonoid-O-glycosides and methoxylated flavonoids from Tagetes maxima by liquid chromatography coupled to electrospray ionization tandem mass spectrometry

Liquid chromatography coupled to negative electrospray ionization (ESI) tandem mass spectrometry (MS/MS) employing a triple quadrupole mass spectrometer was used in the structural determination of acylated flavonoid-O-glycosides and methoxylated flavonoids occurring in Tagetes maxima. The compounds were identified by experiments in full scan mode (MS), and tandem mass experiments (MS/MS) of precursor ion scan, product ion scan, and neutral loss scan modes. In order to characterize the aglycones of the flavonoid glycosides, in-source fragmentation of the deprotonated molecule [M-H]- followed by product ion scan of the resulting aglycone [A-H]- were performed. This combined approach allowed the identification of 51 phenolic compounds, including flavonoid-O-glycosides acylated with galloyl, protocatechuoyl, coumaroyl or caffeoyl groups, methoxylated flavonoids, and hydroxycinnamic acid and phenolic acid derivatives, none of them previously reported in Tagetes maxima.     

Profiling isoflavone conjugates in root extracts of lupine species with LC/ESI/MSn systems

Extracts obtained from roots of three lupine species (Lupinus albus, L. angustifolius, L. luteus) were analysed using LC/UV and LC/ESI/MS(n). The experiments were performed using two mass spectrometric systems, equipped with the triple quadrupole or ion trap analysers. Thirteen to twenty isomeric isoflavone conjugates were identified in roots of the investigated lupine species. These were di- and monoglycosides of genistein and 2'-hydroxygenistein with different patterns of glycosylation, both at oxygen and carbon atoms; some glycosides were acylated with malonic acid. It was not possible to establish the glycosylation sites of the aglycone only on the basis of the registered mass spectra; however, it was possible to differentiate C- and O-glucosides of isoflavones. Only comparison of retention times with those of standard compounds permitted to indicate the correct glycosylation pattern. In the case of diglycosides, the glycosylation pattern (O-diglucoside or O-glucosylglucoside) was distinguishable on the basis of the relative intensities of daughter ions in the mass spectra of protonated molecular ions. It was not possible to elucidate the site of malonylation on the sugar moiety from mass spectra, however, protonated molecules [M + H](+) of isoflavone glucosides with different placement of the malonyl group on the sugar ring were recognized in the extracts. In addition to the isoflavone glycosides, some flavone or flavonol glycosides were identified in the samples on the basis of collision-induced daughter ion spectra of the aglycone ions. A comparison of results obtained with the triple quadrupole and ion trap analysers was done in the course of the investigations.     

Rapid screening and characterization of drug metabolites using a new quadrupole-linear ion trap mass spectrometer

The application of a new hybrid RF/DC quadrupole-linear ion trap mass spectrometer to support drug metabolism and pharmacokinetic studies is described. The instrument is based on a quadrupole ion path and is capable of conventional tandem mass spectrometry (MS/MS) as well as several high-sensitivity ion trap MS scans using the final quadrupole as a linear ion trap. Several pharmaceutical compounds, including trocade, remikiren and tolcapone, were used to evaluate the capabilities of the system with positive and negative turbo ionspray, using either information-dependent data acquisition (IDA) or targeted analysis for the screening, identification and quantification of metabolites. Owing to the MS/MS in-space configuration, quadrupole-like CID spectra with ion trap sensitivity can be obtained without the classical low mass cutoff of 3D ion traps. The system also has MS(3) capability which allows fragmentation cascades to be followed. The combination of constant neutral loss or precursor ion scan with the enhanced product ion scan was found to be very selective for identifying metabolites at the picogram level in very complex matrices. Owing to the very high cycle time and, depending on the mass range, up to eight different MS experiments could be performed simultaneously without compromising chromatographic performance. Targeted product ion analysis was found to be complementary to IDA, in particular for very low concentrations. Comparable sensitivity was found in enhanced product ion scan and selected reaction monitoring modes. The instrument is particularly suitable for both qualitative and quantitative analysis.     

同位素稀释-超高效液相色谱-线性离子阱串联质谱分析谷物及其制品中呕吐毒素及其衍生物和代谢物

建立了谷物及其制品中脱氧雪腐镰刀菌烯醇、3-乙酰脱氧雪腐镰刀菌烯醇、15-乙酰脱氧雪腐镰刀菌烯醇、去环氧脱氧雪腐镰刀菌烯醇的同位素稀释-超高效液相色谱-线性离子阱串联质谱( UHPLC-QTRAP-MS/MS)定性确证和定量测定方法。样品经乙腈-水(84：16, V/V)混合溶液提取,乙腈饱和的正己烷除脂,HLB固相萃取柱净化,Waters Atlantis? T3色谱柱分离,以乙腈-0.02%氨水溶液为流动相进行梯度洗脱,在负离子模式下,采用多反应监测( MRM)-信息依赖性采集( IDA)-增强子离子扫描( EPI)模式检测,在线EPI谱库定性分析,同位素内标定量,在1~300μg/L 浓度范围内,4种目标物的线性相关系数均大于0.999,检出限为0.1μg/kg,定量限为0.3μg/kg,添加5,50和200μg/kg的3个浓度水平,4种目标物的平均回收率均在81.3%~101.7%之间,相对标准偏差均小于5%,将该技术应用于FAPAS阳性玉米质控样品和5种代表性的样品进行测试,结果表明,本方法简单、准确、快速,适用于谷物及其制品中呕吐毒素及其衍生物和代谢物的快速确证和定量测定。     

Comparison of different mass spectrometric detection techniques in the gas chromatographic analysis of pyrethroid insecticide residues in soil after microwave-assisted extraction

A comparative study was carried out for the simultaneous determination of 11 pyrethroid insecticides in soil by gas chromatography (GC) - ion trap (IT)- mass spectrometry (MS), by means of two different ionization modes; electron impact and negative chemical ionization and three data acquisition procedures; full scan, selected ion monitoring and MS/MS. Pyrethroids investigated were tetramethrin, bifenthrin, phenothrin, λ-cyhalothrin, permethrin, cyfluthrin, cypermethrin, flucythrinate, esfenvalerate, fluvalinate and deltamethrin. Soil samples were treated with toluene/water by microwave-assisted extraction for 9 min at 700 W and a cleaning up with florisil was performed. Clean soil samples were spiked with pyrethroids at a spiking level of 10, 25 and 50 ng/g. The method employed provides a concentration factor of 10. The ionization gas employed in the negative chemical ionization mode was methane. The use of MS/MS acquisition, in electron impact ionization, provided the best results, due to its high selectivity and sensitivity, giving very low limits of detection from 0.08 to 0.54 ng/g. In negative chemical ionization full scan and selected ion monitoring methods detection limits from 0.12 to 1.40 ng/g were found. The proposed methods were applied to several levels from 10 to 50 ng/g of spiked soils, being electron impact MS/MS method which minimizes matrix spectrum interferences and provided recovery average values from 84% to 120% with relative standard deviations which varied from 3.2 to 7.2%.     

Simultaneously quantifying parent drugs and screening for metabolites in plasma pharmacokinetic samples using selected reaction monitoring information-dependent acquisition on a QTrap instrument

Bioanalytical support of plasma pharmacokinetic (PK) studies for drug discovery programs primarily involves the quantitative analysis of dosed compounds using liquid chromatography/atmospheric pressure ionization tandem mass spectrometry (LC/MS/MS) operated in selected reaction monitoring (SRM) mode. However, there is a growing need for information on the metabolism of new chemical entities (NCEs), in addition to the time-concentration profiles from these studies. In this paper, we present a novel approach to not only quantify parent drugs with SRM, but also simultaneously screen for metabolites using a hybrid triple quadrupole/linear ion trap (QqQ(LIT)) instrument. This was achieved by incorporating both the conventional SRM-only acquisition of parent compounds and the SRM-triggered information-dependent acquisition (IDA) of potential metabolites within the same scan cycle during the same LC/MS/MS run. Two test compounds were used to demonstrate the applicability of this approach. Plasma samples from PK studies were processed by simple protein precipitation and the supernatant was diluted with water before injection. The fast scanning capability of the linear ion trap allowed for the information-dependent acquisition of metabolite MS/MS spectra (<1 s/scan), in addition to the collection of adequate data points for SRM-only channels. The MS/MS spectra obtained from potential metabolites in post-dose samples correlated well with the spectra of the parent compounds studied, therefore providing additional confirmatory structure information without the need for repetitive analyses. Relative quantitative time-concentration profiles of identified metabolites were also obtained. Furthermore, this articulated SRM+SRM-IDA approach generated equivalent quantitative results for parent compounds to those obtained by conventional SRM-only analysis. This approach has been successfully used to support discovery PK screening programs.     

Integrated rapid resolution liquid chromatography–tandem mass spectrometric approach for screening and identification of metabolites of the potential anticancer agent 3,6,7-trimethoxyphenanthroindolizidine in rat urine

An integrated approach combining data acquisition using MS^E and multi-period product ion scan (mpMS/MS), with high-resolution characteristic extracted ion chromatograms (hcXIC) as a data mining method, was developed for in vivo drug metabolites screening and identification. This approach is illustrated by analyzing metabolites of a potential anticancer agent, 3,6,7-trimethoxyphenanthroindolizidine (CAT) in rat urine based on rapid resolution liquid chromatography combined with tandem mass spectrometry (RRLC–MS/MS). Untargeted full-scan MS^E enabled the high-throughput acquisition of potential metabolites, and targeted mpMS/MS contributed to the sensitivity and specificity of the acquisition of molecules of interest. The data processing method hcXIC, based on the structure of CAT, was shown to be highly effective for the metabolite discovery. Through the double-filtering effect of the characteristic ion and accurate mass, conventional extracted ion chromatograms that contained a substantial number of false-positive peaks were simplified into chromatograms essentially free of endogenous interferences. As a result, 21 metabolites were detected in rat urine after oral administration of CAT. Based on the characteristic fragmentation patterns of the phenanthroindolizidine alkaloid, the structures of 9 metabolites were identified. Furthermore, the interpretation of the MS/MS spectra of these metabolites enabled the determination of demethylation position as well as the differentiation between N-oxidized and hydroxylated metabolites.     

Evaluation of various liquid chromatography-quadrupole-linear ion trap-mass spectrometry operation modes applied to the analysis of organic pollutants in wastewaters

The LC-MS/MS analysis of a group of 14 organic pollutants in wastewater – including pharmaceuticals (analgesics/anti-inflammatories, lipid regulators and diuretics), pesticides (diuron) and disinfectants (chlorophene) – has been carried out using a hybrid triple quadrupole-linear ion trap-mass spectrometer (QqLIT). In order to take advantage of the capabilities of the QqLIT system, two methods have been developed and compared, based on the application of different operation modes. One of them uses selected reaction monitoring (SRM), which is the standard mode for quantitative LC-MS/MS analysis. The other is based on the use of an information dependent acquisition scan function (IDA), which allows the combination of a SRM acting as the survey scan and an enhanced product ion scan (EPI) as dependent scan within the same analysis. Performance of both methods was compared, especially in terms of their limits of detection and identification capability. The advantages and limitations of both techniques are discussed. Finally, the two methodologies developed were applied to real samples for evaluation of effluent wastewater in a treatment plant on the south-eastern Mediterranean coast of Spain. The presence of most of the target compounds was detected at mean concentrations ranging from 50 ng/L (mefenamic acid) to 3373 ng/L (hydrochlorothiazide).