High-resolution mass spectrometry method for the detection, characterization and quantitation of pharmaceuticals in water

Occurrence of pharmaceutical residues in drinking water: a systematic review

The aim of the present paper was to give a complete picture on the drinking water contamination by pharmaceutical residues all over the world. For this purpose, a systematic review was carried out for identifying all available research reporting original data resulting by sampling campaign and analysis of "real" drinking water samples to detect pharmaceutical residues. The investigated databases were PubMed, Scopus, and Web of Science. A total of 124 studies were included; among these, 33 did not find target analytes (all below the limit of detection), while the remaining 91 studies reported the presence for one or more compounds, in concentrations ranging from a few units to a few tens of nanograms. The majority of the studies were performed in Europe and the most represented categories were nonsteroidal anti-inflammatory drugs and analgesics. The most common analytical approach used is the preparation and analysis of the samples by solid-phase extraction and chromatography coupled to mass spectrometry. The main implications resulting from our review are the need for (a) further studies aimed to allow more accurate environmental, wildlife, and human health risk assessments and (b) developing integrated policies promoting less environmentally persistent drugs, the reduction of pharmaceuticals in livestock breeding, and the update of wastewater and drinking water treatment plants for a better removal of drugs and their metabolites.

Target, suspect and non-target screening analysis from wastewater treatment plant effluents to drinking water using collision cross section values as additional identification criterion

The anthropogenic entry of organic micropollutants into the aquatic environment leads to a potential risk for drinking water resources and the drinking water itself. Therefore, sensitive screening analysis methods are needed to monitor the raw and drinking water quality continuously. Non-target screening analysis has been shown to allow for a more comprehensive investigation of drinking water processes compared to target analysis alone. However, non-target screening is challenging due to the many features that can be detected. Thus, data processing techniques to reduce the high number of features are necessary, and prioritization techniques are important to find the features of interest for identification, as identification of unknown substances is challenging as well. In this study, a drinking water production process, where drinking water is supplied by a water reservoir, was investigated. Since the water reservoir provides surface water, which is anthropogenically influenced by wastewater treatment plant (WWTP) effluents, substances originating from WWTP effluents and reaching the drinking water were investigated, because this indicates that they cannot be removed by the drinking water production process. For this purpose, ultra-performance liquid chromatography coupled with an ion-mobility high-resolution mass spectrometer (UPLC-IM-HRMS) was used in a combined approach including target, suspect and non-target screening analysis to identify known and unknown substances. Additionally, the role of ion-mobility-derived collision cross sections (CCS) in identification is discussed. To that end, six samples (two WWTP effluent samples, a surface water sample that received the effluents, a raw water sample from a downstream water reservoir, a process sample and the drinking water) were analyzed. Positive findings for a total of 60 substances in at least one sample were obtained through quantitative screening. Sixty-five percent (15 out of 23) of the identified substances in the drinking water sample were pharmaceuticals and transformation products of pharmaceuticals. Using suspect screening, further 33 substances were tentatively identified in one or more samples, where for 19 of these substances, CCS values could be compared with CCS values from the literature, which supported the tentative identification. Eight substances were identified by reference standards. In the non-target screening, a total of ten features detected in all six samples were prioritized, whereby metoprolol acid/atenolol acid (a transformation product of the two β-blockers metoprolol and atenolol) and 1,3-benzothiazol-2-sulfonic acid (a transformation product of the vulcanization accelerator 2-mercaptobenzothiazole) were identified with reference standards. Overall, this study demonstrates the added value of a comprehensive water monitoring approach based on UPLC-IM-HRMS analysis.

Multi-class analysis of 46 antimicrobial drug residues in pond water using UHPLC-Orbitrap-HRMS and application to freshwater ponds in Flanders, Belgium

Increasing anthropogenic pressure and agricultural pollution raises concerns regarding antimicrobial resistance and biodiversity loss in aquatic environments. In order to protect and restore water resources and biodiversity, antimicrobial drug residues should be monitored in all aquatic environments including pond water. Consequently, the objective of this research was to develop and validate a novel multi-residue method for the simultaneous quantification of 46 targeted human and veterinary antimicrobial drugs in pond water. A suitable extraction method based on solid-phase extraction (SPE) was developed, assisted by a fractional factorial design. A broad polarity range of compounds was covered (log P from -4.05 to 4.38), including major representatives of the following classes: sulfonamides, tetracyclines, quinolones, macrolides, lincosamides, nitrofurans, penicillins, cephalosporins, diaminopyrimidines, pleuromutilins and phenicols. All analytes were separated using ultra-high performance liquid chromatography (UHPLC) and detected in full-scan by Orbitrap high resolution mass spectrometry (Orbitrap-HRMS). Good linearity was obtained for all compounds with R² ≥ 0.993 and goodness-of-fit coefficient (g) ≤ 11.56%. Method detection limits ranged from 10 to 50 ng L^-1 and method quantification limits were 50 ng L^-1 for all compounds. Acceptable values were obtained for within-day and between-day apparent recoveries (i.e. between 50 and 120%), precision (< 30% and < 45%) and measurement uncertainty (< 50%). Targeted analysis of 18 freshwater ponds throughout Flanders was performed to demonstrate the applicability of the newly developed UHPLC-HRMS method. Overall, 20 antimicrobial drugs were detected with highest concentrations observed for tetracyclines and their transformation products ranging between 51 and 248 ng L^-1. Finally, suspect screening was performed suggesting the presence of 14 additional pharmaceuticals including 3 antimicrobial degradation products (e.g. apo-oxytetracycline, amoxicillin penicilloic acid and penilloic acid) and 11 pesticides.

Single-Molecule Sensing of DNA Intercalating Drugs in Water

The occurrence of pharmaceutical residues in surface water is raising environmental concern. To accompany the evolution of measures for natural resources protection, sensing methods enabling sensitive and rapid water quality monitoring are needed. We recently managed the parallelization of the Tethered Particle Motion (TPM), a single molecule technique, sensitive to the conformational changes of DNA. Here, we investigate the capacity of high throughput TPM (htTPM) to detect drugs that intercalate into DNA. As a proof-of-concept we analyze the htTPM signal for two DNA intercalating dyes, namely, YOYO-1 and SYTOX orange. The efficient detection of intercalating drugs is then demonstrated with doxorubicin. We further evaluate the possibility to detect carbamazepine, an antiepileptic massively prescribed and persistent in water, which had been described to interact with DNA through intercalation. Our results corroborated by other techniques show that, in fact, carbamazepine is not a DNA intercalator. The comparison of the results obtained with different aqueous buffers and solutions allows us to identify optimal conditions for the monitoring of intercalation compounds by htTPM.

The role of analytical chemistry in exposure science: Focus on the aquatic environment

Exposure science, in its broadest sense, studies the interactions between stressors (chemical, biological, and physical agents) and receptors (e.g. humans and other living organisms, and non-living items like buildings), together with the associated pathways and processes potentially leading to negative effects on human health and the environment. The aquatic environment may contain thousands of compounds, many of them still unknown, that can pose a risk to ecosystems and human health. Due to the unquestionable importance of the aquatic environment, one of the main challenges in the field of exposure science is the comprehensive characterization and evaluation of complex environmental mixtures beyond the classical/priority contaminants to new emerging contaminants. The role of advanced analytical chemistry to identify and quantify potential chemical risks, that might cause adverse effects to the aquatic environment, is essential. In this paper, we present the strategies and tools that analytical chemistry has nowadays, focused on chromatography hyphenated to (high-resolution) mass spectrometry because of its relevance in this field. Key issues, such as the application of effect direct analysis to reduce the complexity of the sample, the investigation of the huge number of transformation/degradation products that may be present in the aquatic environment, the analysis of urban wastewater as a source of valuable information on our lifestyle and substances we consumed and/or are exposed to, or the monitoring of drinking water, are discussed in this article. The trends and perspectives for the next few years are also highlighted, when it is expected that new developments and tools will allow a better knowledge of chemical composition in the aquatic environment. This will help regulatory authorities to protect water bodies and to advance towards improved regulations that enable practical and efficient abatements for environmental and public health protection.

Micropollutants in drinking water from source to tap - Method development and application of a multiresidue screening method

A multi-residue screening method for simultaneous measurement of a wide range of micropollutants in drinking water (DW) resources was developed. The method was applied in a field study in central Sweden on water from source to tap, including samples of surface water (upstream and downstream of a wastewater treatment plant, WWTP), intake water before and after a DW treatment plant (DWTP, pilot and full-scale), treated DW leaving the plant and tap water at end users. Low detection limits (low ng L^-1 levels) were achieved by using large sample volumes (5 L) combined with ultra performance liquid chromatography high resolution mass spectrometry (UPLC-HRMS). In total, 134 different micropollutants were analyzed, including pesticides, pharmaceuticals and personal care products (PPCPs), drug-related compounds, food additives, and perfluoroalkyl substances (PFASs). Of these 134 micropollutants, 41 were detected in at least one sample, with individual concentrations ranging from sub ng L^-1 levels to ~80 ng L^-1. Two solid phase extraction (SPE) cartridges (Oasis HLB and Bond-Elut ENV) were shown to be complementary in the field study, with three compounds detected exclusively using HLB. The total concentration in treated drinking water (56-57 ng L^-1) was at a similar level as upstream from the WWTP (79-90 ng L^-1). The composition of micropollutants changed along the water path, to a higher fraction of food additives and PFASs. Median treatment efficiency in the full-scale DWTP was close to 0%, but with high variability for individual compounds. In contrast, median treatment efficiency in the pilot-scale DWTP was ~90% when using nanofiltration followed by a freshly installed granulated active carbon (GAC) filter.

UHPLC-QTOF MS screening of pharmaceuticals and their metabolites in treated wastewater samples from Athens

After consumption, pharmaceuticals are excreted as parent compounds and/or metabolites in urine and faeces. Some are not completely removed during wastewater treatments, forcing sewage treatment plants (STPs) to apply alternative technologies to guarantee quality of treated water. To monitor the removal efficiency of STPs, not only unchanged compounds and metabolites have to be taken into account, but also formation of possible transformation products (TPs). In this work, QTOF MS has been used for screening metabolites/TPs of pharmaceuticals in effluent wastewater from Athens. A customised database was built with the exact masses of metabolites reported in literature for the parent drugs found in an initial screening. Additionally, TPs identified in previous degradation experiments performed at our laboratory were included. Up to 34 metabolites/TPs were detected for omeprazole, venlafaxine, clindamycin, clarithromycin, clopidogrel or dipyrone, among others. Seven corresponded to TPs whose reference standards were available at our lab, seven were TPs previously identified in laboratory degradation experiments, eight were TPs tentatively identified by QTOF MS without reference standards, and twelve TPs were discovered after using the common fragmentation pathway approach. Tentative identification of TPs was supported by prediction of their chromatographic retention time based on the use of advanced chemometric QSRR models.

Optimization of the Ion Source-Mass Spectrometry Parameters in Non-Steroidal Anti-Inflammatory and Analgesic Pharmaceuticals Analysis by a Design of Experiments Approach

The flow rates of drying and nebulizing gas, heat block and desolvation line temperatures and interface voltage are potential electrospray ionization parameters as they may enhance sensitivity of the mass spectrometer. The conditions that give higher sensitivity of 13 pharmaceuticals were explored. First, Plackett-Burman design was implemented to screen significant factors, and it was concluded that interface voltage and nebulizing gas flow were the only factors that influence the intensity signal for all pharmaceuticals. This fractionated factorial design was projected to set a full 2(2) factorial design with center points. The lack-of-fit test proved to be significant. Then, a central composite face-centered design was conducted. Finally, a stepwise multiple linear regression and subsequently an optimization problem solving were carried out. Two main drug clusters were found concerning the signal intensities of all runs of the augmented factorial design. p-Aminophenol, salicylic acid, and nimesulide constitute one cluster as a result of showing much higher sensitivity than the remaining drugs. The other cluster is more homogeneous with some sub-clusters comprising one pharmaceutical and its respective metabolite. It was observed that instrumental signal increased when both significant factors increased with maximum signal occurring when both codified factors are set at level +1. It was also found that, for most of the pharmaceuticals, interface voltage influences the intensity of the instrument more than the nebulizing gas flowrate. The only exceptions refer to nimesulide where the relative importance of the factors is reversed and still salicylic acid where both factors equally influence the instrumental signal. Graphical Abstract ᅟ.

Determination of ibuprofen enantiomers in human plasma by HPLC–MS/MS: validation and application in neonates

Aim: An adaptive method to determine ibuprofen enantiomers with limited volume of plasma required is necessary for investigating PK of ibuprofen in neonates. Results: Enantiomer separation was achieved on a Lux cellulose 3 column with mobile phase consisting of methanol water (85:15, v/v) and formic acid (0.0075%) at isocratic rate of 0.2 ml/min. Calibration curve is linear for each enantiomer at the range of 0.1–60 μg/ml. Validation was conducted and results met requirements regarding to intra- and inter-run precision, accuracy and recovery. No matrix effect or interference was observed from neonatal plasma or comedications. Only 20 μl of plasma was requested in this study. Conclusion: This assay was specific and reliable to quantify ibuprofen enantiomers in neonate plasma.

POCIS passive samplers as a monitoring tool for pharmaceutical residues and their transformation products in marine environment

In the last years, several scientific studies have shown that carbamazepine (CBZ) is one of the most frequently detected pharmaceutical in aquatic environment. However, little data is available on its detection and its transformation products (TPs) in marine water. The use of polar organic chemical integrative sampling (POCIS) passive samplers as a semi-quantitative and qualitative tool for screening of pharmaceuticals and TPs in seawater has been studied. Furthermore, the uptake rates of the target compounds were also determined under laboratory experiments to characterize the levels accumulated in devices. The results confirmed the presence of residues of anticonvulsant CBZ as well as some of its main metabolites, over a 1-year monitoring campaign carried out in French coast on the Mediterranean Sea. The work reports for the first time the presence of two TPs (10,11-dihydro-10,11-trans-dihydroxycarbamazepine (TRANS) and 10-hydroxy-10,11-dihydrocarbamazepine (10OH)) in marine water. The results contribute in assessing the environmental and human health risk of pharmaceuticals on coastal areas.

Screening of pharmaceuticals and illicit drugs in wastewater and surface waters of Spain and Italy by high resolution mass spectrometry using UHPLC-QTOF MS and LC-LTQ-Orbitrap MS

The existence of pharmaceuticals and illicit drugs (PIDs) in environmental waters has led many analytical chemists to develop screening methods for monitoring purposes. Water samples can contain a huge number of possible contaminants, commonly at low concentrations, which makes their detection and identification problematic. Liquid chromatography coupled with high resolution mass spectrometry (LC-HRMS) has proven itself effective in the screening of environmental contaminants. The present work investigates the use of the most popular HRMS instruments, quadrupole time-of-flight and linear trap quadrupole-Orbitrap, from two different laboratories. A suspect screening for PIDs was carried out on wastewater (influent and effluent) and surface water samples from Castellón, Eastern Spain, and Cremona, Northern Italy, incorporating a database of 107 PIDs (including 220 fragment ions). A comparison between the findings of both instruments and of the samples was made which highlights the advantages and drawbacks of the strategies applied in each case. In total, 28 compounds were detected and/or identified by either/both instruments with irbesartan, valsartan, benzoylecgonine and caffeine being the most commonly found compounds across all samples.

Introduction of a routine quan/qual approach into research DMPK: experiences and evolving strategies

After graduating with an Oceanography degree from Swansea University, Lloyd has spent over 20 years in the field of bioanalysis and metabolite profiling. He started his career in large pharma at Wyeth UK, where he was involved in setting up the first GC and LC–MS/MS systems for both QC and early DMPK assays, employing EI/CI, thermospray, and the then new electrospray ionization techniques. Lloyd then joined Celltech, now UCB, where he is primarily tasked with metabolite profiling by LC–MS and NMR to support both early research projects and late-stage clinical studies.

The application of liquid chromatography high-resolution mass spectrometry for simultaneous quantitative and qualitative (quan/qual) analysis has gained momentum across a range of different scientific arenas in recent years. The ability to acquire high quality quantitative data, whilst also capturing qualitative data for either parallel or retrospective analysis, is a powerful resource, especially in view of ever-reducing cycle times, laboratory space and budgets. The quan/qual approach employing a Q-Exactive™ Orbitrap high-resolution mass spectrometer has been successfully introduced into UCB's research DMPK department. This article describes our experiences in introducing quan/qual, issues that we discovered in establishing this new working paradigm, the evolution of the strategy and its future potential.

Simultaneous screening of targeted and non-targeted contaminants using an LC-QTOF-MS system and automated MS/MS library searching

Simultaneous high-resolution full-scan and tandem mass spectrometry (MS/MS) analysis using time of flight mass spectrometry brings an answer for increasing demand of retrospective and non-targeted data analysis. Such analysis combined with spectral library searching is a promising tool for targeted and untargeted screening of small molecules. Despite considerable extension of the panel of compounds of tandem mass spectral libraries, the heterogeneity of spectral data poses a major challenge against the effective usage of spectral libraries. Performance evaluation of available LC-MS/MS libraries will significantly increase credibility in the search results. The present work was aimed to evaluate fluctuation of MS/MS pattern, in the peak intensities distribution together with mass accuracy measurements, and in consequence, performance compliant with ion ratio and mass error criteria as principles in identification processes for targeted and untargeted contaminants at trace levels. Matrix effect and ultra-trace levels of concentration (from 50 ng l(-1) to 1000 ng l(-1) were evaluated as potential source of inaccuracy in the performance of spectral matching. Matrix-matched samples and real samples were screened for proof of applicability. By manual review of data and application of ion ratio and ppm error criteria, false negatives were obtained; this number diminished when in-house library was used, while with on-line MS/MS databases 100% of positive samples were found. In our experience, intensity of peaks across spectra was highly correlated to the concentration effect and matrix complexity. In turn, analysis of spectra acquired at trace concentrations and in different matrices results in better performance in providing correct and reliable identification.

Multi-residue method for the determination of over 400 priority and emerging pollutants in water and wastewater by solid-phase extraction and liquid chromatography-time-of-flight mass spectrometry

This article describes the development and validation of a liquid chromatography high-resolution mass spectrometry method for the simultaneous determination of over 400 multi-class priority and emerging pollutants with different physicochemical properties in environmental waters (surface water and wastewater). The proposed approach is based on the use of a database consisting of retention time/exact mass (of selected ions) pairs implemented with specific software for data analysis. The targeted list comprises 430 contaminants belonging to different compound categories, including 105 multiclass pharmaceuticals (analgesics/anti-inflammatories, antibiotics, lipid regulators, β-blockers, antiepileptic/psychiatrics ulcer healings, diuretics, hormones and bronchodilatadors), life-style products (caffeine, nicotine), 21 drugs of abuse and their metabolites, 279 pesticides and some of their more relevant metabolites, nitrosamines, flame retardants, plasticizers and perfluorinated compounds. The proposed approach included a simple offline solid phase extraction (SPE) step using polymeric cartridges (Oasis HLB) with 200mL of water sample loaded, followed by analysis by rapid resolution liquid chromatography electrospray time-of-flight mass spectrometry (LC-TOFMS) in both positive and negative modes. The identification of the positive findings is accomplished with the data from accurate masses of the target ions along with retention time data and characteristic in-source fragment ions. The overall method performance was satisfactory with limits of quantification lower than 10ngL(-1) for the 44% of studied compounds. Recoveries between 50% and 130% were obtained for the 65% of the analytes (281 compounds). Matrix effects occurring with wastewater matrices were also assessed. The developed method was applied to the determination of target analytes in real surface water and wastewater samples.

Investigation of PPCPs in wastewater treatment plants in Greece: occurrence, removal and environmental risk assessment

In the present work, an extensive study on the presence of eighteen pharmaceuticals and personal care products (PPCPs) in eight wastewater treatment plants (WWTPs) of Greece has been conducted. The study covered four sampling periods over 1-year, where samples (influents; effluents) from eight WWTPs of various cities in Greece were taken. All WWTPs investigated are equipped with conventional activated sludge treatment. A common pre-concentration step based on SPE was applied, followed by LC-UV/Vis-ESI-MS. Further confirmation of positive findings was accomplished by using LC coupled to a high resolution Orbitrap mass spectrometer. The results showed the occurrence of all target compounds in the wastewater samples with concentrations up to 96.65 μg/L. Paracetamol, caffeine, trimethoprim, sulfamethoxazole, carbamazepine, diclofenac and salicylic acid were the dominant compounds, while tolfenamic acid, fenofibrate and simvastatin were the less frequently detected compounds with concentrations in effluents below the LOQ. The removal efficiencies showed that many WWTPs were unable to effectively remove most of the PPCPs investigated. Finally, the study provides an assessment of the environmental risk posed by their presence in wastewaters by means of the risk quotient (RQ). RQs were more than unity for various compounds in the effluents expressing possible threat for the aquatic environment. Triclosan was found to be the most critical compound in terms of contribution and environmental risk, concluding that it should be seriously considered as a candidate for regulatory monitoring and prioritization on a European scale on the basis of realistic PNECs. The results of the extensive monitoring study contributed to a better insight on PPCPs in Greece and their presence in influent and effluent wastewaters. Furthermore, the unequivocal identification of two transformation products of trimethoprim in real wastewaters by using the advantages of the LTQ Orbitrap capabilities provides information that should be taken into consideration in future PPCP monitoring studies in wastewaters.

Performance assessment of microflow LC combined with high-resolution MS in bioanalysis

BACKGROUND

There continues to be consistent pressure for bioanalytical scientists to achieve lower limits of quantitation. The reasons range from smaller sample volumes available for analysis, to more potent analytes and the growth of biologics in drug development. This has led scientists to investigate alternative LC techniques, including microflow and nanoflow. These techniques have been shown to increase sensitivity of electrospray methods and reduce ionization matrix effects. Because high-resolution MS has significant benefits for the analysis of biologics, this type of mass spectrometer is becoming increasingly important in bioanalysis.

RESULTS

For microflow analysis, a new ion source and significant extra sample preparation or chromatographic separation are not required. However, increased sensitivity and reduced matrix effects were consistently demonstrated when compared with UHPLC flow rates. The extent of matrix effects observed were compound dependent.

DISCUSSION

This paper presents the utility of combining high-resolution/accurate mass with microflow LC from a quantitative standpoint. This includes evaluating the typical quantitative parameters of sensitivity, linearity/dynamic range, precision and accuracy. It also includes the evaluation of changes in signal suppression using microflow LC and microspray ionization. The benefits and disadvantages of using the combination of these two technologies for quantitative bioanalysis are also discussed.

Comparison of high-resolution and tandem mass spectrometry for the analysis of nerve agent metabolites in urine

RATIONALE

Although use is prohibited, concerns remain for human exposure to nerve agents during decommissioning, research, and warfare. High-resolution mass spectrometry (HRMS) was compared to tandem mass spectrometry (MS/MS) analysis for the quantitation of five urinary metabolites specific to VX, Russian VX, soman, sarin and cyclosarin nerve agents. The HRMS method was further evaluated for qualitative screening of metabolites not included in the test panel.

METHODS

Nerve agent metabolites were extracted from urine using solid-phase extraction, separated using hydrophilic interaction chromatography and analyzed using both tandem and high-resolution mass spectrometry. MS/MS results were obtained using selected reaction monitoring with unit resolution; HRMS results were obtained using a mass extraction window of 10 ppm at a mass resolution of 50 000. The benchtop Orbitrap HRMS instrument was operated in full scan mode, to measure the presence of unexpected nerve agent metabolites.

RESULTS

The assessment of two quality control samples demonstrated high accuracy (99.5-104%) and high precision (2-9%) for both HRMS and MS/MS. Sensitivity, as described by the limit of detection, was overlapping for both detectors (0.2-0.7 ng/mL). Additionally, the HRMS method positively confirmed the presence of a nerve agent metabolite, not included in the test panel, using the accurate mass and relative retention time.

CONCLUSIONS

The precision, accuracy, and sensitivity were comparable between the current MS/MS method and this newly developed HRMS analysis for five nerve agent metabolites. HRMS showed additional capabilities beyond the current method by confirming the presence of a metabolite not included in the test panel.

Comparison of the quantitative performance of a Q-Exactive high-resolution mass spectrometer with that of a triple quadrupole tandem mass spectrometer for the analysis of illicit drugs in wastewater

RATIONALE

Analysis of drugs in wastewater is gaining more interest, as new approaches to estimate drug consumption from the amount of drug residues in wastewater have been proposed. The aim of this study was to compare the quantitative performance of high-resolution mass spectrometry with that of triple quadrupole mass spectrometry.

METHODS

A Q-Exactive mass spectrometer was operated in full scan (HRFS) (70 000 FWHM) and product scan (HRPS) (17 500 FWHM) modes. The first and third quadrupoles of the QqQ MS/MS instrument were operated at 0.7 FWHM. A mass-extracted window of 5 ppm around the theoretical m/z of each analyte was used to construct chromatograms. An HESI-II ion source was used for the ionization of target compounds. In-line-SPE-LC configuration was used for the extraction and separation of target analytes.

RESULTS

All three methods showed good linearity and repeatability. High-resolution detection of product ions exhibited better sensitivity and selectivity for some compounds. For most of the tested compounds, LOQs ranged from 0.46 to 20 ng L(-1) . Good agreement between measured and nominal concentrations was observed for most of the compounds at different levels of fortification. Both MS/MS methods showed good selectivity, while HRFS gave some false positive results.

CONCLUSIONS

The Q-Exactive mass spectrometer proved to be suitable for trace detection and quantification of most of the tested drugs in wastewater, with performance comparable to that of the commonly used MS/MS triple quadrupole, but with better selectivity.

Determination of pharmaceuticals, personal care products, and pesticides in surface and treated waters: method development and survey

Water is fundamental to the existence of life since it is essential to a series of activities, such as agriculture, power generation, and public and industrial supplies. The residual water generated by these activities is released into the environment, reaches the water systems, and becomes a potential risk to nontarget organisms. This paper reports the development and validation of a quantitative method, based on solid-phase extraction and liquid chromatography tandem mass spectrometry, for the simultaneous analysis of 18 pharmaceuticals and personal care products (PPCPs) and 33 pesticides in surface and drinking waters. The accuracy of the method was determined by calculating the recoveries, which ranged from 70 to 120 % for most pesticides and PPCPs, whereas limits of quantification ranged from 0.8 to 40 ng/L. After the validation step, the method was applied to drinking and surface waters. Pesticides and PPCPs were found in concentrations lower than 135.5 ng/L. The evaluation of different water sources with regard to contamination by pesticides and PPCPs has been quite poor in southern Brazil.

High-resolution MS in regulated bioanalysis: where are we now and where do we go from here?

While triple quadrupole MS remains the workhorse of bionanalytical laboratories, LC coupled with high-resolution MS (LC–HRMS) is making headway in drug discovery. LC–HRMS is well suited for quantitative bioanalysis with the inherent advantage of post-acquisition data mining, which is not possible with triple quadrupole systems operated in SRM mode. LC–HRMS can, thus, accomplish the core task of a bioanalytical laboratory – accurate determination of a targeted analyte – with the added bonus of being able to monitor other compounds of interest either at the time of sample analysis, or as an afterthought, after sample analysis, with no additional effort in sample preparation, chromatographic optimization or sample reinjection. Despite these advantages, LC–HRMS has not been broadly adopted in regulated bioanalytical laboratories. The slow progress in embracing the technology may be due, in part, to difficulties in replacing an entire fleet of triple quadrupole MS. Additional reasons are that data mining is of less benefit in development, especially late-stage, than in discovery and that the technical and regulatory challenges associated with the change of platform are perceived to be significant. In addition, the current platform of LC–HRMS introduced by instrument companies has not been tailored to the core responsibility of the bioanalytical community. In marketing current LC–HRMS systems, there is a tendency to combine the needs of the bioanalytical community with those of the drug metabolism community, despite their inherent differences. As a result, the current HRMS systems available lack some basic features desired for bioanalysis, but include features that are not important for bioanalysis making the systems unnecessarily complex and expensive. A simple, cost effective, ideal HRMS system for a bioanalytical laboratory would provide HRMS with high resolving power (the higher the better), no MS/MS capability, and with software suitable for quantitative analysis and appropriate for use in regulated laboratories. Under this scenario, one can foresee a future where part of the regulated bioanalytical work will be accomplished using LC–HRMS, reserving triple quadrupole-based LC–MS/MS for assays that require exquisite sensitivity.

Analysis and quantification of vitamin D metabolites in serum by ultra-performance liquid chromatography coupled to tandem mass spectrometry and high-resolution mass spectrometry--a method comparison and validation

RATIONALE

The aim of the work was to develop and validate a method for the quantification of vitamin D metabolites in serum using ultra-high-pressure liquid chromatography coupled to mass spectrometry (LC/MS), and to validate a high-resolution mass spectrometry (LC/HRMS) approach against a tandem mass spectrometry (LC/MS/MS) approach using a large clinical sample set.

METHODS

A fast, accurate and reliable method for the quantification of the vitamin D metabolites, 25-hydroxyvitamin D2 (25OH-D2) and 25-hydroxyvitamin D3 (25OH-D3), in human serum was developed and validated. The C3 epimer of 25OH-D3 (3-epi-25OH-D3) was also separated from 25OH-D3. The samples were rapidly prepared via a protein precipitation step followed by solid-phase extraction (SPE) using an HLB μelution plate. Quantification was performed using both LC/MS/MS and LC/HRMS systems.

RESULTS

Recovery, matrix effect, inter- and intra-day reproducibility were assessed. Lower limits of quantification (LLOQs) were determined for both 25OH-D2 and 25OH-D3 for the LC/MS/MS approach (6.2 and 3.4 µg/L, respectively) and the LC/HRMS approach (2.1 and 1.7 µg/L, respectively). A Passing & Bablok fit was determined between both approaches for 25OH-D3 on 662 clinical samples (1.11 + 1.06x). It was also shown that results can be affected by the inclusion of the isomer 3-epi-25OH-D3.

CONCLUSIONS

Quantification of the relevant vitamin D metabolites was successfully developed and validated here. It was shown that LC/HRMS is an accurate, powerful and easy to use approach for quantification within clinical laboratories. Finally, the results here suggest that it is important to separate 3-epi-25OH-D3 from 25OH-D3.

Importance of MS selectivity and chromatographic separation in LC-MS/MS-based methods when investigating pharmaceutical metabolites in water. Dipyrone as a case of study

Pharmaceuticals are emerging contaminants of increasing concern because of their presence in the aquatic environment and potential to reach drinking-water sources. After human and/or veterinary consumption, pharmaceuticals can be excreted in unchanged form, as the parent compound, and/or as free or conjugated metabolites. Determination of most pharmaceuticals and metabolites in the environment is commonly made by liquid chromatography (LC) coupled to mass spectrometry (MS). LC coupled to tandem MS is the technique of choice nowadays in this field. The acquisition of two selected reaction monitoring (SRM) transitions together with the retention time is the most widely accepted criterion for a safe quantification and confirmation assay. However, scarce attention is normally paid to the selectivity of the selected transitions as well as to the chromatographic separation. In this work, the importance of full spectrum acquisition high-resolution MS data using a hybrid quadrupole time-of-flight analyser and/or a suitable chromatographic separation (to reduce the possibility of co-eluting interferences) is highlighted when investigating pharmaceutical metabolites that share common fragment ions. For this purpose, the analytical challenge associated to the determination of metabolites of the widely used analgesic dipyrone (also known as metamizol) in urban wastewater is discussed. Examples are given on the possibilities of reporting false positives of dypirone metabolites by LC-MS/MS under SRM mode due to a wrong assignment of identity of the compounds detected.