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Roy-Lachapelle A.,University of Montreal | Solliec M.,University of Montreal | Sinotte M.,Direction du Suivi de Letat de Lenvironnement DSEE | Deblois C.,Center Dexpertise en Analyse Environnementale | Sauve S.,University of Montreal
Journal of Agricultural and Food Chemistry | Year: 2015

Microcystins (MCs) are cyanobacterial toxins encountered in aquatic environments worldwide. Over 100 MC variants have been identified and have the capacity to covalently bind to animal tissue. This study presents a new approach for cell-bound and free microcystin analysis in fish tissue using sodium hydroxide as a digestion agent and Lemieux oxidation to obtain the 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) moiety, common to all microcystin congeners. The use of laser diode thermal desorption-atmospheric pressure chemical ionization coupled with Q-Exactive mass spectrometry (LDTD-APCIHRMS) led to an analysis time of approximately 10 s per sample and high-resolution detection. Digestion/oxidation and solid phase extraction recoveries ranged from 70 to 75% and from 86 to 103%, respectively. Method detection and quantification limits values were 2.7 and 8.2 μg kg-1, respectively. Fish samples from cyanobacteria-contaminated lakes were analyzed, and concentrations ranging from 2.9 to 13.2 μg kg-1 were reported. © 2015 American Chemical Society. Source


Roy-Lachapelle A.,University of Montreal | Solliec M.,University of Montreal | Sinotte M.,Direction du Suivi de Letat de Lenvironnement DSEE | Deblois C.,Center Dexpertise en Analyse Environnementale | Sauve S.,University of Montreal
Talanta | Year: 2014

A new innovative analytical method combining ultra-fast analysis time with high resolution/accurate mass detection was developed to eliminate the misidentification of anatoxin-a (ANA-a), a cyanobacterial toxin, from the natural amino acid phenylalanine (PHE). This was achieved by using the laser diode thermal desorption-atmospheric pressure chemical ionization (LDTD-APCI) coupled to the Q-Exactive, a high resolution/accurate mass spectrometer (HRMS). This novel combination, the LDTD-APCI-HRMS, allowed for an ultra-fast analysis time (<15 s/sample). A comparison of two different acquisition modes (full scan and targeted ion fragmentation) was made to determine the most rigorous analytical method using the LDTD-APCI interface. Method development focused toward selectivity and sensitivity improvement to reduce the possibility of false positives and to lower detection limits. The Q-Exactive mass spectrometer operates with resolving powers between 17 500 and 140 000 FWHM (m/z 200). Nevertheless, a resolution of 17 500 FWHM is enough to dissociate ANA-a and PHE signals. Mass accuracy was satisfactory with values below 1 ppm reaching precision to the fourth decimal. Internal calibration with standard addition was achieved with the isotopically-labeled (D5) phenylalanine with good linearity (R2>0.999). Enhancement of signal to noise ratios relative to a standard triple-quadrupole method was demonstrated with lower detection and quantification limit values of 0.2 and 0.6 μg/L using the Q-Exactive. Accuracy and interday/intraday relative standard deviations were below 15%. The new method was applied to 8 different lake water samples with signs of cyanobacterial blooms. This work demonstrates the possibility of using an ultra-fast LDTD-APCI sample introduction system with an HRMS hybrid instrument for quantitative purposes with high selectivity in complex environmental matrices. © 2014 Elsevier B.V. Source


Roy-Lachapelle A.,University of Montreal | Fayad P.B.,University of Montreal | Sinotte M.,Direction du Suivi de Letat de Lenvironnement DSEE | Deblois C.,Center Dexpertise en Analyse Environnementale | Sauve S.,University of Montreal
Analytica Chimica Acta | Year: 2014

A new approach for the analysis of the cyanobacterial microcystins (MCs) in environmental water matrices has been developed. It offers a cost efficient alternative method for the fast quantification of total MCs using mass spectrometry. This approach permits the quantification of total MCs concentrations without requiring any derivatization or the use of a suite of MCs standards. The oxidation product 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) was formed through a Lemieux oxidation and represented the total concentration of free and bound MCs in water samples. MMPB was analyzed using laser diode thermal desorption-atmospheric pressure chemical ionization coupled to tandem mass spectrometry (LDTD-APCI-MS/MS). LDTD is a robust and reliable sample introduction method with ultra-fast analysis time (<15ssample-1). Several oxidation and LDTD parameters were optimized to improve recoveries and signal intensity. MCs oxidation recovery yield was 103%, showing a complete reaction. Internal calibration with standard addition was achieved with the use of 4-phenylbutyric acid (4-PB) as internal standard and showed good linearity (R2>0.999). Limits of detection and quantification were 0.2 and 0.9μgL-1, respectively. These values are comparable with the WHO (World Health Organization) guideline of 1μgL-1 for total microcystin-LR congener in drinking water. Accuracy and interday/intraday variation coefficients were below 15%. Matrix effect was determined with a recovery of 91%, showing no significant signal suppression. This work demonstrates the use of the LDTD-APCI-MS/MS interface for the screening, detection and quantification of total MCs in complex environmental matrices. © 2014 Elsevier B.V. Source


Rosberg A.K.,Swedish University of Agricultural Sciences | Gruyer N.,Center Dexpertise en Analyse Environnementale | Hultberg M.,Swedish University of Agricultural Sciences | Wohanka W.,Geisenheim University | Alsanius B.W.,Swedish University of Agricultural Sciences
Scientia Horticulturae | Year: 2014

Closed hydroponic growing systems are commonly used for greenhouse production of vegetables. One of the main problems associated with these systems is the potential spread of plant root pathogens. The purpose of this study was to investigate whether Community Level Physiological Profiling (CLPP) can be used as a method to monitor changes in the rhizosphere microbial communities inflicted by a pathogen. We studied the microbial communities of the roots from three different physiological stages of Pythium ultimum inoculated and non-inoculated tomato plants, with culture-dependent (CLPP and viable counts) and culture-independent methods (PCR-DGGE). The results showed that the presence of P. ultimum changed the utilization of carbon sources by the root microbiota, and significant differences were found between inoculated and non-inoculated plants. However, the differences in utilization patterns were larger between plant physiological stages than between treatments. Also with the results from PCR-DGGE it was confirmed that plant age was a stronger driver of the community structure than the introduction of a pathogen. CLPP is hence a good method for examining changes in microbial communities related to plant development, but regarding changes caused by the presence of a pathogen the method shows less potential. © 2014 Elsevier B.V. Source


Bastien C.,Center Dexpertise en Analyse Environnementale | Cardin R.,Center Dexpertise en Analyse Environnementale | Veilleux E.,Center Dexpertise en Analyse Environnementale | Deblois C.,Center Dexpertise en Analyse Environnementale | And 2 more authors.
Journal of Environmental Monitoring | Year: 2011

The performance of two field probes (YSI 6600 and TriOS), used for the measurement of in vivo phycocyanin fluorescence, was compared and validated in the laboratory in 2008 and 2009 with cultures of Microcystis aeruginosa and field samples. The background noise of the two probes was low and the detection limits were estimated at 1500 cells mL -1 for the YSI and 0.69 g PC L -1 for the TriOS. The linearity and repeatability of both probes have been excellent. Strong relationships were observed between the in vivo fluorescence and the total cyanobacterial biovolume (R 2 = 0.82 YSI; 0.83 TriOS) or the abundance (R 2 = 0.71 YSI; 0.75 TriOS) of cyanobacteria. However, the difference between cell densities determined by microscopy and measured by the YSI can be very large and has been associated to the variability of cell volume among cyanobacteria. This last observation makes the YSI a qualitative tool if a post-calibration is not done. The analysis of filtrated samples showed that dissolved phycocyanin (extracellular) may represent a significant fluorescence signal. No relationship could be established between the abundance, the total cyanobacterial biovolume or the in vivo fluorescence of phycocyanin and the concentrations of cyanotoxins (R 2 ≤ 0.22). © 2011 The Royal Society of Chemistry. Source

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