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Round Rock, TX, United States

Guo H.,University of Texas at Arlington | Dolzan M.D.,Federal University of Santa Catarina | Spudeit D.A.,Federal University of Santa Catarina | Xu C.,University of Texas at Arlington | And 3 more authors.
International Journal of Mass Spectrometry | Year: 2015

The detection window for drugs of abuse, including performance-enhancing drugs, is limited by the sensitivity of analytical methodologies. Herein, paired ion electrospray ionization mass spectrometry (PIESI-MS) was employed for sensitive analysis of performance-enhancing drugs and drugs of abuse by detecting their glucuronide and sulfate conjugates. The proposed approach provides enhanced sensitivity for these drug metabolites, and overcomes the drawbacks of the less sensitive negative ion mode ESI-MS by detecting the anionic metabolites in the positive ion mode at higher m/. z where the background noise is less. Absolute LODs down to sub-pg levels were obtained with the use of the optimal symmetrical or unsymmetrical ion pairing reagents. One to three orders of magnitude improvement were obtained compared to other reported methods performed in the negative ion mode. Structurally similar steroid conjugates were chromatographically separated and detected by HPLC coupled with PIESI-MS. Finally, an off-line solid phase extraction (SPE) protocol was successfully developed to eliminate any matrix effects in the analysis of human urine samples. © 2015 Elsevier B.V. Source


Guo H.,University of Texas at Arlington | Dolzan M.D.,University of Texas at Arlington | Dolzan M.D.,Federal University of Santa Catarina | Spudeit D.A.,University of Texas at Arlington | And 5 more authors.
International Journal of Mass Spectrometry | Year: 2015

The detection window for drugs of abuse, including performance-enhancing drugs, is limited by the sensitivity of analytical methodologies. Herein, paired ion electrospray ionization mass spectrometry (PIESI-MS) was employed for sensitive analysis of performance-enhancing drugs and drugs of abuse by detecting their glucuronide and sulfate conjugates. The proposed approach provides enhanced sensitivity for these drug metabolites, and overcomes the drawbacks of the less sensitive negative ion mode ESI-MS by detecting the anionic metabolites in the positive ion mode at higher m/z where the background noise is less. Absolute LODs down to sub-pg levels were obtained with the use of the optimal symmetrical or unsymmetrical ion pairing reagents. One to three orders of magnitude improvement were obtained compared to other reported methods performed in the negative ion mode. Structurally similar steroid conjugates were chromatographically separated and detected by HPLC coupled with PIESI-MS. Finally, an off-line solid phase extraction (SPE) protocol was successfully developed to eliminate any matrix effects in the analysis of human urine samples. © 2015 Elsevier B.V. Source


Trademark
Cerilliant Corporation | Date: 2006-07-18

Chemical preparations for use as standards and reference materials in research and analysis.


Trademark
Cerilliant Corporation | Date: 2010-05-25

chemical preparations for use as standards and reference materials in research and analysis.


Trademark
Cerilliant Corporation | Date: 2010-06-01

chemical preparations for use as standards and reference materials in research and analysis.

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