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Purpose: Instrumental capabilities and software tools of modern hybrid mass spectrometry (MS) instruments such as high-resolution mass spectrometry (HRMS), quadrupole time-of-flight (QTOF), and quadrupole linear ion trap (QLIT) were experimentally investigated for the study of emerging contaminants in Henares River water samples., Methods: Automated screening and confirmatory capabilities of QTOF working in full-scan MS and tandem MS (MS/MS) were explored when dealing with real samples. Investigations on the effect of sensitivity and resolution power influence on mass accuracy were studied for the correct assignment of the amoxicillin transformation product 5(R) amoxicillin-diketopiperazine-2',5' as an example of a nontarget compound. On the other hand, a comparison of quantitative and qualitative strategies based on direct injection analysis and off-line solid-phase extraction sample treatment were assayed using two different QLIT instruments for a selected group of emerging contaminants when operating in selected reaction monitoring (SRM) and information-dependent acquisition (IDA) modes., Results and Discussion: Software-aided screening usually needs a further confirmatory step. Resolving power and MS/MS feature of QTOF showed to confirm/reject most findings in river water, although sensitivity-related limitations are usually found. Superior sensitivity of modern QLIT-MS/MS offered the possibility of direct injection analysis for proper quantitative study of a variety of contaminants, while it simultaneously reduced the matrix effect and increased the reliability of the results. Confirmation of ethylamphetamine, which lacks on a second SRM transition, was accomplished by using the IDA feature., Conclusion: Hybrid MS instruments equipped with high resolution and high sensitivity contributes to enlarge the scope of targeted analytes in river waters. However, in the tested instruments, there is a margin of improvement principally in required sensitivity and data treatment software tools devoted to reliable confirmation and improved automated data processing.

In this article, a systematic approach is proposed to assist and simplify the identification of transformation products (TPs) of organic contaminants. This approach is based on the use of characteristic fragmentation undergone by organic contaminants during MS/MS fragmentation events, and the relationship and consistency with the transformations experimented by these chemicals in the environment or during water treatment processes. With this in mind, a database containing accurate-mass information of 147 compounds and their main fragments generated by CID MS/MS fragmentation experiments was created using an LC-QTOF-MS/MS system. The developed database was applied to the identification of tentative TPs and related unexpected compounds in eight wastewater effluent samples. The approach comprises basically three stages: (a) automatic screening, (b) identification of possible TPs and (c) confirmation by MS/MS analysis. Parameters related to the search of compounds in the database have been optimized and their dependence with the exhaustiveness of the study evaluated. Eight degradation products, from the pharmaceuticals acetaminophen, amoxicillin, carbamazepine, erythromycin and azithromycin and from the pesticide diazinon, were identified with a high grade of accuracy. Three of them were confirmed by analysis of the corresponding analytical standards., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The identification of transformation products (TPs) of pharmaceuticals in the environment is essentially a challenging task due to the lack of standards and the instrumental capabilities required to detect compounds (sometimes unknowns) that are produced under environmental conditions. In this work, we report the use of liquid chromatography/electrospray quadrupole time-of-flight mass spectrometry (LC/QTOF-MS/MS) as a tool for the identification of amoxicillin (AMX) and its main TPs in wastewater and river water samples. Laboratory degradation experiments of AMX were performed in both alkaline and acidic media in order to confirm that the expected transformation pathway in the aquatic media is through the β-lactam ring cleavage. A thorough study was carried out with both standards and real samples (wastewater and river water samples). Four compounds were identified as main TPs: both amoxicillin diketopiperacine-2',5' and amoxilloic acid diastereomers. Amoxilloic acid stereoisomers are reported for the first time in environmental matrices. The transformation product (5R)-amoxicillin diketopiperacine-2',5' was frequently detected in river waters. Besides, another AMX transformation product formed during analysis was also structurally elucidated for the first time (amoxicilloic acid methyl ester) via accurate mass measurements. Collected data show that although AMX is not present as such in environmental samples, different TPs occur. This study represent a valuable indicator of the potential of LC/QTOF-MS/MS for the identification and structural elucidation of TPs in the environment using accurate MS/MS experiments, enabling thus the recognition of the environmental transformation pathway., (Copyright © 2011 John Wiley & Sons, Ltd.)

Abstract This study describes the high sensitivity and the reduced ion suppression and matrix effect that can be achieved by supercritical fluid chromatography (SFC) in the analysis of dried spices as complex matrices. Samples selected for the evaluation were cayenne and black pepper, which are representative of complex dried spices. To carry out the evaluation of this technique, blank samples were fortified with a solution containing 162 pesticides at two concentration levels (50 and 200 μg kg−1). During the modified QuEChERS method, EMR sorbent was used as dispersive SPE in the clean-up step. The samples were analysed by supercritical fluid chromatography coupled to tandem mass spectrometry. The validation parameters studied were recovery, inter and intraday precision, linearity and matrix effect. Recoveries for the majority of compounds were in the 70–120% range recommended by DG-SANTE guidelines and showed a precision lower than 20% in terms of RSD. Matrix effect was low (0–20% signal suppression) for 132 pesticides in cayenne and 91 in black pepper. The method was used to analyse 47 real samples of spices from different countries. A high number of these samples presented one or more pesticides (81%). Some of these detected pesticides are not approved in the European Union and, in many cases, the positive findings exposed concentrations that exceed the EU MRLs. Graphical abstract Image 1 Highlights • Increasing sensitivity and reducing matrix effect by using supercritical fluid chromatography coupled to mass spectrometry. • Method development for the analysis of pesticides in spices by SFC-MS/MS. • High reduction of organic wastes in the analysis of samples. • Analysis of real samples of spices and study of the pesticides found as well as their concordance with the European MRL. [ABSTRACT FROM AUTHOR]