Juan V. Sancho

Bio: Juan V. Sancho is an academic researcher from James I University. The author has contributed to research in topics: Mass spectrometry & Triple quadrupole mass spectrometer. The author has an hindex of 61, co-authored 186 publications receiving 9843 citations. Previous affiliations of Juan V. Sancho include Public Health Research Institute.

Simultaneous Determination of Multiple Phytohormones in Plant Extracts by Liquid Chromatography−Electrospray Tandem Mass Spectrometry

Abstract: A rapid multiresidue method to quantify three different classes of plant hormones has been developed The reduced concentrations of these metabolites in real samples with complex matrixes require sensitive techniques for their quantification in small amounts of plant tissue The method described combines high-performance liquid chromatography with electrospray ionization tandem mass spectrometry Deuterium-labeled standards were added prior to sample extraction to achieve an accurate quantification of abscisic acid, indole-3-acetic acid, and jasmonic acid in a single run A simple method of extraction and purification involving only centrifugation, a partition against diethyl ether, and filtration was developed and the analytical method validated in four different plant tissues, citrus leaves, papaya roots, barley seedlings, and barley immature embryos This method represents a clear advantage because it extensively reduces sample preparation and total time for routine analysis of phytohormones in real plant samples

Current use of high-resolution mass spectrometry in the environmental sciences.

Abstract: During the last two decades, mass spectrometry (MS) has been increasingly used in the environmental sciences with the objective of investigating the presence of organic pollutants. MS has been widely coupled with chromatographic techniques, both gas chromatography (GC) and liquid chromatography (LC), because of their complementary nature when facing a broad range of organic pollutants of different polarity and volatility. A clear trend has been observed, from the very popular GC–MS with a single quadrupole mass analyser, to tandem mass spectrometry (MS–MS) and, more recently, high-resolution mass spectrometry (HRMS). For years GC has been coupled to HR magnetic sector instruments, mostly for dioxin analysis, although in the last ten years there has been growing interest in HRMS with time-of-flight (TOF) and Orbitrap mass analyzers, especially in LC–MS analysis. The increasing interest in the use of HRMS in the environmental sciences is because of its suitability for both targeted and untargeted analysis, owing to its sensitivity in full-scan acquisition mode and high mass accuracy. With the same instrument one can perform a variety of tasks: pre- and post-target analysis, retrospective analysis, discovery of metabolite and transformation products, and non-target analysis. All these functions are relevant to the environmental sciences, in which the analyst encounters thousands of different organic contaminants. Thus, wide-scope screening of environmental samples is one of the main applications of HRMS. This paper is a critical review of current use of HRMS in the environmental sciences. Needless to say, it is not the intention of the authors to summarise all contributions of HRMS in this field, as in classic descriptive reviews, but to give an overview of the main characteristics of HRMS, its strong potential in environmental mass spectrometry and the trends observed over the last few years. Most of the literature has been acquired since 2005, coinciding with the growth and popularity of HRMS in this field, with a few exceptions that deserve to be mentioned because of their relevance.

Critical review of the application of liquid chromatography/mass spectrometry to the determination of pesticide residues in biological samples

Abstract: A critical review is made on the use of hyphenated liquid chromatography/mass spectrometry (LC-MS) for the identification and quantification of pesticides and their metabolites in human biosamples (whole blood, plasma, serum and urine). The first applications of LC-MS in this field began in the early 1990s. Since then, increasing interest has been shown in applying this powerful technique, with most applications dealing with the determination of a variety of chemically diverse metabolites in urine. The use of different LC-MS interfaces and mass spectral detection modes are discussed. Special attention is given to tandem mass spectrometry (MS/MS) due to its inherent advantages of increased sensitivity and selectivity, as well as its advantages for identification and confirmation of analytes in samples. Quantification can be severely affected by matrix effects, the most common being inhibition of the ionisation of analytes in the mass spectrometer, which leads to unacceptable errors if no correction is made. Different approaches can be employed to minimise this undesirable matrix effect, the preferred being the use of labelled internal standards (when available) in isotope dilution methods or the application of an efficient clean-up, performed off-line or automated on-line. Adequate criteria for confirming the identities of residues detected are required in order to avoid false positives. The criterion most commonly used with a triple quadrupole instrument is the monitoring of two MS/MS transitions together with the ion abundance ratio. TOF mass analysers are seldom used in pesticide residue analysis despite their improved resolution and mass accuracy characteristics, which makes them very suitable for confirmation purposes. The main reasons for the relative unpopularity of TOF MS in residue analysis are its limited sensitivity and its high acquisition cost. In this paper, we present a critical assessment on current techniques, trends and future developments, and give illustrative examples to point out the main characteristics of LC-MS for pesticide residue analysis in biological fluids.

Identifying Small Molecules via High Resolution Mass Spectrometry: Communicating Confidence

Abstract: T increased availability of high resolution mass spectrometry (HR-MS) in chemical analysis has dramatically improved the detection and identification of compounds in environmental (and other) samples. This has opened up new research opportunities in environmental sciences, demonstrated by over 200 research papers per year, increasing strongly (source: SCOPUS keywords “high resolution mass spectromet”, subject “envi”). The elucidation of small molecules such as emerging pollutants and their transformation products using HR-MSbased suspect and nontarget analysis is gaining in relevance, also in other fields (e.g., metabolomics, drug discovery, forensics). However, confidence in these HR-MS-based identifications varies between studies and substances, since it is not always possible or even meaningful to synthesize each substance or confirm them via complementary methods (e.g., nuclear magnetic resonance). These varying levels of confidence are very difficult to communicate to readers concisely and accurately. In Figure 1 we propose a level system, which arose from intense discussions within our department, to ease the communication of identification confidence and form the basis of further discussions on this topic. This level system is not intended to replace guidance documents (e.g., EU Guideline 2002/657/EG), but specifically covers the new possibilities in HR-MS-based analysis. Our discussion started with the levels published by the Metabolomics Standards Initiative (MSI), as we experienced many cases that fitted “in between” their proposed levels. While Jeon et al. first refined these levels, these were tailored to the specific investigation. The levels in Figure 1 reconcile differences in the two proposals, contain additional levels pertinent to screening methods and are clarified in the text below.

Mass spectrometry-based metabolomics.

Abstract: This review presents an overview of the dynamically developing field of mass spectrometry-based metabolomics. Metabolomics aims at the comprehensive and quantitative analysis of wide arrays of metabolites in biological samples. These numerous analytes have very diverse physico-chemical properties and occur at different abundance levels. Consequently, comprehensive metabolomics investigations are primarily a challenge for analytical chemistry and specifically mass spectrometry has vast potential as a tool for this type of investigation. Metabolomics require special approaches for sample preparation, separation, and mass spectrometric analysis. Current examples of those approaches are described in this review. It primarily focuses on metabolic fingerprinting, a technique that analyzes all detectable analytes in a given sample with subsequent classification of samples and identification of differentially expressed metabolites, which define the sample classes. To perform this complex task, data analysis tools, metabolite libraries, and databases are required. Therefore, recent advances in metabolomics bioinformatics are also discussed.