4 research outputs found
The Power of Hyphenated Chromatography/Time-of-Flight Mass Spectrometry in Public Health Laboratories
Laboratories devoted to the public health field have
to face the
analysis of a large number of organic contaminants/residues in many
different types of samples. Analytical techniques applied in this
field are normally focused on quantification of a limited number of
analytes. At present, most of these techniques are based on gas chromatography
(GC) or liquid chromatography (LC) coupled to tandem mass spectrometry
(MS/MS). Using these techniques only analyte-specific information
is acquired, and many other compounds that might be present in the
samples would be ignored. In this paper, we explore the potential
of time-of-flight (TOF) MS hyphenated to GC or LC to provide additional
information, highly useful in this field. Thus, all positives reported
by standard reference targeted LCāMS/MS methods were unequivocally
confirmed by LCāQTOF MS. Only 61% of positives reported by
targeted GCāMS/MS could be confirmed by GCāTOF MS, which
was due to its lower sensitivity as nonconfirmations corresponded
to analytes that were present at very low concentrations. In addition,
the use of TOF MS allowed searching for additional compounds in large-scope
screening methodologies. In this way, different contaminants/residues
not included in either LC or GC tandem MS analyses were detected.
This was the case of the insecticide thiacloprid, the plant growth
regulator paclobutrazol, the fungicide prochloraz, or the UV filter
benzophenone, among others. Finally, elucidation of unknowns was another
of the possibilities offered by TOF MS thanks to the accurate-mass
full-acquisition data available when using this technique
Evaluation of Uncertainties Associated with the Determination of Community Drug Use through the Measurement of Sewage Drug Biomarkers
The aim of this study was to integrally address the uncertainty
associated with all the steps used to estimate community drug consumption
through the chemical analysis of sewage biomarkers of illicit drugs.
Uncertainty has been evaluated for sampling, chemical analysis, stability
of drug biomarkers in sewage, back-calculation of drug use (specific
case of cocaine), and estimation of population size in a catchment
using data collected from a recent Europe-wide investigation and from
the available literature. The quality of sampling protocols and analytical
measurements has been evaluated by analyzing standardized questionnaires
collected from 19 sewage treatments plants (STPs) and the results
of an interlaboratory study (ILS), respectively. Extensive reviews
of the available literature have been used to evaluate stability of
drug biomarkers in sewage and the uncertainty related to back-calculation
of cocaine use. Different methods for estimating population size in
a catchment have been compared and the variability among the collected
data was very high (7ā55%). A reasonable strategy to reduce
uncertainty was therefore to choose the most reliable estimation case
by case. In the other cases, the highest uncertainties are related
to the analysis of sewage drug biomarkers (uncertainty as relative
standard deviation; RSD: 6ā26% from ILS) and to the back-calculation
of cocaine use (uncertainty; RSD: 26%). Uncertainty can be kept below
10% in the remaining steps, if specific requirements outlined in this
work are considered. For each step, a best practice protocol has been
suggested and discussed to reduce and keep to a minimum the uncertainty
of the entire procedure and to improve the reliability of the estimates
of drug use
Evaluation of Uncertainties Associated with the Determination of Community Drug Use through the Measurement of Sewage Drug Biomarkers
The aim of this study was to integrally address the uncertainty
associated with all the steps used to estimate community drug consumption
through the chemical analysis of sewage biomarkers of illicit drugs.
Uncertainty has been evaluated for sampling, chemical analysis, stability
of drug biomarkers in sewage, back-calculation of drug use (specific
case of cocaine), and estimation of population size in a catchment
using data collected from a recent Europe-wide investigation and from
the available literature. The quality of sampling protocols and analytical
measurements has been evaluated by analyzing standardized questionnaires
collected from 19 sewage treatments plants (STPs) and the results
of an interlaboratory study (ILS), respectively. Extensive reviews
of the available literature have been used to evaluate stability of
drug biomarkers in sewage and the uncertainty related to back-calculation
of cocaine use. Different methods for estimating population size in
a catchment have been compared and the variability among the collected
data was very high (7ā55%). A reasonable strategy to reduce
uncertainty was therefore to choose the most reliable estimation case
by case. In the other cases, the highest uncertainties are related
to the analysis of sewage drug biomarkers (uncertainty as relative
standard deviation; RSD: 6ā26% from ILS) and to the back-calculation
of cocaine use (uncertainty; RSD: 26%). Uncertainty can be kept below
10% in the remaining steps, if specific requirements outlined in this
work are considered. For each step, a best practice protocol has been
suggested and discussed to reduce and keep to a minimum the uncertainty
of the entire procedure and to improve the reliability of the estimates
of drug use
Untargeted Metabolomics in Doping Control: Detection of New Markers of Testosterone Misuse by Ultrahigh Performance Liquid Chromatography Coupled to High-Resolution Mass Spectrometry
The use of untargeted metabolomics
for the discovery of markers
is a promising and virtually unexplored tool in the doping control
field. Hybrid quadrupole time-of-flight (QTOF) and hybrid quadrupole
Orbitrap (Q Exactive) mass spectrometers, coupled to ultrahigh pressure
liquid chromatography, are excellent tools for this purpose. In the
present work, QTOF and Q Exactive have been used to look for markers
for testosterone cypionate misuse by means of untargeted metabolomics.
Two different groups of urine samples were analyzed, collected before
and after the intramuscular administration of testosterone cypionate.
In order to avoid analyte losses in the sample treatment, samples
were just 2-fold diluted with water and directly injected into the
chromatographic system. Samples were analyzed in both positive and
negative ionization modes. Data from both systems were treated under
untargeted metabolomic strategies using XCMS application and multivariate
analysis. Results from the two mass spectrometers differed in the
number of detected features, but both led to the same potential marker
for the particular testosterone ester misuse. The in-depth study of
the MS and MS/MS behavior of this marker allowed for the establishment
of 1-cyclopentenoylglycine as a feasible structure. The putative structure
was confirmed by comparison with synthesized material. This potential
marker seems to come from the metabolism of the cypionic acid release
after hydrolysis of the administered ester. Its suitability for doping
control has been evaluated