Determination of 3[prime],4[prime],5[prime],5,7-pentamethoxyflavone in the plasma and intestinal mucosa of mice by HPLC with UV detection

In a preliminary experiment 3[prime],4[prime],5[prime],5,7-pentamethoxyflavone (PMF) inhibited adenoma development in ApcMin mice, a model of the human heritable condition familial adenomatous polyposis. An HPLC method for tricin was modified and validated to permit measurement of PMF in mouse plasma and intestinal mucosa. HPLC analysis was carried out on a Hypersil-BDS C18 column with detection at 324 nm and tricin as internal standard. The assay was linear in the range of 100-2000 ng/mL plasma and 1.0-40 µg/mL mucosa. PMF in plasma was efficiently extracted using solid-phase columns. In the case of mucosa organic solvent protein precipitation displayed satisfactory accuracy and precision. The assay recovery at low, medium and high concentrations was between 85 and 103% for both biomatrices, with a relative standard deviation of <15%. The lower limits of quantitation for plasma and mucosa were 100 ng/mL and 1.0 µg/mL, respectively. This method allowed measurement of PMF steady-state median concentrations in plasma (1.08 nmol/mL, n = 11; 10th and 90th percentiles: 0.633 and 2.385 nmol/mL) and mucosa (108.5 nmol/g, n = 9; 10th and 90th percentiles: 38.9 and 164.4 nmol/g) in mice which had received PMF (0.2%, w/w) with their diet. Copyright © 2008 John Wiley & Sons, Ltd.

In a preliminary experiment 3[prime],4[prime],5[prime],5,7-pentamethoxyflavone (PMF) inhibited adenoma development in ApcMin mice, a model of the human heritable condition familial adenomatous polyposis. An HPLC method for tricin was modified and validated to permit measurement of PMF in mouse plasma and intestinal mucosa. HPLC analysis was carried out on a Hypersil-BDS C18 column with detection at 324 nm and tricin as internal standard. The assay was linear in the range of 100-2000 ng/mL plasma and 1.0-40 µg/mL mucosa. PMF in plasma was efficiently extracted using solid-phase columns. In the case of mucosa organic solvent protein precipitation displayed satisfactory accuracy and precision. The assay recovery at low, medium and high concentrations was between 85 and 103% for both biomatrices, with a relative standard deviation of <15%. The lower limits of quantitation for plasma and mucosa were 100 ng/mL and 1.0 µg/mL, respectively. This method allowed measurement of PMF steady-state median concentrations in plasma (1.08 nmol/mL, n = 11; 10th and 90th percentiles: 0.633 and 2.385 nmol/mL) and mucosa (108.5 nmol/g, n = 9; 10th and 90th percentiles: 38.9 and 164.4 nmol/g) in mice which had received PMF (0.2%, w/w) with their diet. Copyright © 2008 John Wiley & Sons, Ltd.

Identification and quantification of two antihepatotoxic coumarinolignoids cleomiscosin A and cleomiscosin B in the seeds of Cleome viscosa using liquid chromatography-tandem mass spectrometry

A sensitive liquid chromatography/electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method was developed for the identification and quantification of two antihepatotoxic coumarinolignoids cleomiscosin A and cleomiscosin B in different extracts of the seeds of Cleome viscosa. The separation of cleomiscosin A and cleomiscosin B was achieved on an RP18 column using a solvent system consisting of a mixture of acetonitrile-methanol (1:2, v/v) and acetonitrile-water-formic acid (5:95:0.3, v/v) as a mobile phase in a gradient elution mode. A multiple-reaction monitoring (MRM) method was developed for quantification of cleomiscosin A and cleomiscosin B in the seed extracts of Cleome viscosa. On the basis of signal-to-noise ratio of 3, the limit of detection in MRM mode for cleomiscosin A and cleomiscosin B were 1.0 and 4.0 ng/mL respectively. The method was validated in terms of linearity, accuracy and precision for 6 days. The method developed was found to be useful for identification and quantification of cleomiscosin A and cleomiscosin B in the different extracts of the seeds of Cleome viscosa. Copyright © 2008 John Wiley & Sons, Ltd.

A sensitive liquid chromatography/electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method was developed for the identification and quantification of two antihepatotoxic coumarinolignoids cleomiscosin A and cleomiscosin B in different extracts of the seeds of Cleome viscosa. The separation of cleomiscosin A and cleomiscosin B was achieved on an RP18 column using a solvent system consisting of a mixture of acetonitrile-methanol (1:2, v/v) and acetonitrile-water-formic acid (5:95:0.3, v/v) as a mobile phase in a gradient elution mode. A multiple-reaction monitoring (MRM) method was developed for quantification of cleomiscosin A and cleomiscosin B in the seed extracts of Cleome viscosa. On the basis of signal-to-noise ratio of 3, the limit of detection in MRM mode for cleomiscosin A and cleomiscosin B were 1.0 and 4.0 ng/mL respectively. The method was validated in terms of linearity, accuracy and precision for 6 days. The method developed was found to be useful for identification and quantification of cleomiscosin A and cleomiscosin B in the different extracts of the seeds of Cleome viscosa. Copyright © 2008 John Wiley & Sons, Ltd.

Strategies for characterizing sildenafil, vardenafil, tadalafil and their analogues in herbal dietary supplements, and detecting counterfeit products containing these drugs

Publication year: 2008
Saranjit, Singh , Vikrantsinh M., Gohil , Amandeep, Kaur , Bhagwat, Prasad , Akash, Savaliya , …

Publication year: 2008
Saranjit, Singh , Vikrantsinh M., Gohil , Amandeep, Kaur , Bhagwat, Prasad , Akash, Savaliya , ...

Sensitive and Selective Liquid Chromatography/Tandem Mass Spectrometry Methods for Quantitative Analysis of 1-Methyl-4-Phenyl Pyridinium (MPP+) in Mouse Striatal Tissue

Publication year: 2008
Mei-Yi, Zhang , Natasha, Kagan , Amy, Sung , Margaret M., Zaleska , Michael, Monaghan

Publication year: 2008
Mei-Yi, Zhang , Natasha, Kagan , Amy, Sung , Margaret M., Zaleska , Michael, Monaghan

Determination of short-chain branching content in polyethylene by pyrolysis comprehensive multidimensional gas chromatography using low thermal mass column technology

A research effort was undertaken to utilize the pyrolysis process to create fragments of polyethylene that could be indicative of branching, and allow quantitiation of said short-chain branches by pyrolysis comprehensive 2-D GC (Py-GC×GC). Several strategies for sample introduction and pyrolysis such as the in-column pyrolysis device and the programmed temperature vaporizer (PTV) were studied. The chromatographic separations were executed using low-thermal mass (LTM) comprehensive 2-D GC (GC×GC). A series of polyethylene-co-hexene samples were analyzed and a linear correlation of 1-hexene content with branching peak ratio was found. Correlation coefficients were determined as 0.97 for the measurements performed.

A research effort was undertaken to utilize the pyrolysis process to create fragments of polyethylene that could be indicative of branching, and allow quantitiation of said short-chain branches by pyrolysis comprehensive 2-D GC (Py-GC×GC). Several strategies for sample introduction and pyrolysis such as the in-column pyrolysis device and the programmed temperature vaporizer (PTV) were studied. The chromatographic separations were executed using low-thermal mass (LTM) comprehensive 2-D GC (GC×GC). A series of polyethylene-co-hexene samples were analyzed and a linear correlation of 1-hexene content with branching peak ratio was found. Correlation coefficients were determined as 0.97 for the measurements performed.

Characterization and utilization of a novel triflate ionic liquid stationary phase for use in comprehensive two-dimensional gas chromatography

A novel triflate (trifluoromethylsulfonate) ionic liquid (IL) thin film (0.08 [mu]m) stationary phase was implemented for use within the second column of a comprehensive GC×GC configuration. The first column in the configuration had a 5% phenyl/95% dimethyl polysiloxane (DMPS) stationary phase with a 0.4 [mu]m film. The DMPS×IL column configuration was used to separate a mixture of 32 compounds of various chemical functional classes. The GC×GC results for the IL column were compared with a commercially available polar column (with a 0.1 [mu]m PEG stationary phase film) used as the second column instead. Additional studies focused on the rapid and selective separation of four phosphorous-oxygen (P-O) containing compounds from the 32-compound matrix: dimethyl methylphosphonate (DMMP), diethyl methylphosphonate (DEMP), diisopropyl methylphosphonate (DIMP), and triethyl phosphate (TEP). van’t Hoff plots (plots of ln k vs. 1/T) demonstrated the difference in retention between the P-O containing compounds (with DMMP reported in detail) and other classes of compounds (i. e., 2-pentanol and n-dodecane as representative) using either the IL column or the commercial PEG column. The selectivity ([alpha]) of the triflate IL column and the commercially available PEG column were also compared. The IL column provided significantly larger selectivities between DMMP and the other two compounds (2-pentanol and n-dodecane) than the commercial PEG column. The [alpha] for DMMP relative to n-dodecane was 3.0-fold greater for the triflate IL column, and the [alpha] for DMMP relative to 2-pentanol was 1.7-fold greater for the triflate IL column than for the PEG column.

A novel triflate (trifluoromethylsulfonate) ionic liquid (IL) thin film (0.08 [mu]m) stationary phase was implemented for use within the second column of a comprehensive GC×GC configuration. The first column in the configuration had a 5% phenyl/95% dimethyl polysiloxane (DMPS) stationary phase with a 0.4 [mu]m film. The DMPS×IL column configuration was used to separate a mixture of 32 compounds of various chemical functional classes. The GC×GC results for the IL column were compared with a commercially available polar column (with a 0.1 [mu]m PEG stationary phase film) used as the second column instead. Additional studies focused on the rapid and selective separation of four phosphorous-oxygen (P-O) containing compounds from the 32-compound matrix: dimethyl methylphosphonate (DMMP), diethyl methylphosphonate (DEMP), diisopropyl methylphosphonate (DIMP), and triethyl phosphate (TEP). van't Hoff plots (plots of ln k vs. 1/T) demonstrated the difference in retention between the P-O containing compounds (with DMMP reported in detail) and other classes of compounds (i. e., 2-pentanol and n-dodecane as representative) using either the IL column or the commercial PEG column. The selectivity ([alpha]) of the triflate IL column and the commercially available PEG column were also compared. The IL column provided significantly larger selectivities between DMMP and the other two compounds (2-pentanol and n-dodecane) than the commercial PEG column. The [alpha] for DMMP relative to n-dodecane was 3.0-fold greater for the triflate IL column, and the [alpha] for DMMP relative to 2-pentanol was 1.7-fold greater for the triflate IL column than for the PEG column.

Stop-flow comprehensive two-dimensional gas chromatography with pneumatic switching

A new method for performing comprehensive GC×GC in the stop-flow mode is presented. A device was used to pneumatically stop the flow in the first dimension (1D) (by applying pressure pulses at the junction between the two columns), while flow was maintained in the second dimension (2D). This allowed for better preservation of resolution in the 1D of the GC×GC chromatograms, and the extension of the 2D’s separation space, reducing or eliminating the extent of wraparound. When increased flow rates in the 2D were used, sensitivity enhancements were also observed.

A new method for performing comprehensive GC×GC in the stop-flow mode is presented. A device was used to pneumatically stop the flow in the first dimension (1D) (by applying pressure pulses at the junction between the two columns), while flow was maintained in the second dimension (2D). This allowed for better preservation of resolution in the 1D of the GC×GC chromatograms, and the extension of the 2D's separation space, reducing or eliminating the extent of wraparound. When increased flow rates in the 2D were used, sensitivity enhancements were also observed.

Analysis of aldehydes via headspace SPME with on-fiber derivatization to their O-(2,3,4,5,6-pentafluorobenzyl)oxime derivatives and comprehensive 2D-GC-MS

A method for the analysis of the homologous series of alkanals, (E)-2-alkenals, and (E,E)-2,4-alkadienals is described utilizing a headspace solid-phase microextraction (HS-SPME) step and on-fiber derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) hydrochloride. Oxime derivatives formed on the fiber are desorbed in the gas chromatographic injector and analyzed by comprehensive 2-D GC coupled to quadrupole MS (GC×GC-qMS). Selecting specific fragment ions within the electron impact mass spectra of the oxime derivatives provides a suitable method for the target analysis of these aldehyde classes, which furthermore benefits from the increased separation efficiency by GC×GC. The analysis of higher molecular weight aldehydes is described in wine and grape seed oil as examples. Quantification of the aldehydes utilizes a stable isotope dilution analysis (SIDA) assay with octan-d16-al as isotopomeric internal standard. Besides the selectivity and sensitivity of aldehyde analysis using PFBHA derivatives, critical aspects on background level contamination and repeatability of the sample preparation method are discussed. Optimization of GC×GC-qMS parameters allowed a considerable saving of the cryogenic medium, involving additional (unmodulated) conditioning runs, rendering the method more amenable to routine analysis.

A method for the analysis of the homologous series of alkanals, (E)-2-alkenals, and (E,E)-2,4-alkadienals is described utilizing a headspace solid-phase microextraction (HS-SPME) step and on-fiber derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) hydrochloride. Oxime derivatives formed on the fiber are desorbed in the gas chromatographic injector and analyzed by comprehensive 2-D GC coupled to quadrupole MS (GC×GC-qMS). Selecting specific fragment ions within the electron impact mass spectra of the oxime derivatives provides a suitable method for the target analysis of these aldehyde classes, which furthermore benefits from the increased separation efficiency by GC×GC. The analysis of higher molecular weight aldehydes is described in wine and grape seed oil as examples. Quantification of the aldehydes utilizes a stable isotope dilution analysis (SIDA) assay with octan-d16-al as isotopomeric internal standard. Besides the selectivity and sensitivity of aldehyde analysis using PFBHA derivatives, critical aspects on background level contamination and repeatability of the sample preparation method are discussed. Optimization of GC×GC-qMS parameters allowed a considerable saving of the cryogenic medium, involving additional (unmodulated) conditioning runs, rendering the method more amenable to routine analysis.

Accumulating resampling (modulation) in comprehensive two-dimensional capillary GC (GC×GC)

During each sampling period, an accumulating resampler (modulator) in comprehensive 2-D chromatography accumulates all eluite from the first-dimension column and reinjects the whole or a portion of the accumulated material into the second-dimension column. The detrimental effect of the resampling on peak capacity of a 2-D separation comes from the broadening of the peaks along the first-dimension due to the resampling itself and due to the subsequent peak reconstruction. Sampling density ([rho]S) of resampling is the number of sampling periods per standard deviation of a peak at the outlet of the first-dimension column. It is shown that a simple formula describes the peak broadening as a function of [rho]S at any (even practically too low or too high) [rho]S, for the peaks of any (not necessarily Gaussian) shape, for a wide class of peak reconstruction techniques, and for any 2-D separation (GC×GC, LC×LC, etc.). In capillary GC×GC, optimal [rho]S ([rho]S,Opt) depends on the type of the peak reconstruction and on the degree of the gas decompression along the second-dimension column. When reconstructing using linear interpolation, [rho]S,Opt = 0.7 at large and [rho]S,Opt = 0.5 at small gas decompression. The choice of exact optimal conditions is not critical. Thus, two-fold departure of actual [rho]S from [rho]S,Opt in either direction (under- or oversampling) causes only 10% drop in the net peak capacity of GC×GC. The quantitative effect of a much greater undersampling is also evaluated.

During each sampling period, an accumulating resampler (modulator) in comprehensive 2-D chromatography accumulates all eluite from the first-dimension column and reinjects the whole or a portion of the accumulated material into the second-dimension column. The detrimental effect of the resampling on peak capacity of a 2-D separation comes from the broadening of the peaks along the first-dimension due to the resampling itself and due to the subsequent peak reconstruction. Sampling density ([rho]S) of resampling is the number of sampling periods per standard deviation of a peak at the outlet of the first-dimension column. It is shown that a simple formula describes the peak broadening as a function of [rho]S at any (even practically too low or too high) [rho]S, for the peaks of any (not necessarily Gaussian) shape, for a wide class of peak reconstruction techniques, and for any 2-D separation (GC×GC, LC×LC, etc.). In capillary GC×GC, optimal [rho]S ([rho]S,Opt) depends on the type of the peak reconstruction and on the degree of the gas decompression along the second-dimension column. When reconstructing using linear interpolation, [rho]S,Opt = 0.7 at large and [rho]S,Opt = 0.5 at small gas decompression. The choice of exact optimal conditions is not critical. Thus, two-fold departure of actual [rho]S from [rho]S,Opt in either direction (under- or oversampling) causes only 10% drop in the net peak capacity of GC×GC. The quantitative effect of a much greater undersampling is also evaluated.

Use of partially porous column as second dimension in comprehensive two-dimensional system for analysis of polyphenolic antioxidants

In the present work, a comprehensive LC system using a microbore HPLC column in the first dimension and a partially porous column in the second dimension was developed and applied to the separation of polyphenolic components in a red wine sample. The performance of the partially porous short column (3.0 cm) was compared to that of a monolithic column, of comparable dimensions. The results obtained demonstrated the possibility to use partially porous columns to obtain fast analyses, using high flow rates, under repetitive gradient conditions and with very brief reconditioning times. A conventional HPLC system was used since the backpressure generated by the shell-packed column, even at very high flow rates, was well within the operational limits. The use of an increased column temperature (60°C) allowed a further pressure-drop decrease, with no stationary phase degradation, or loss in column performance.

In the present work, a comprehensive LC system using a microbore HPLC column in the first dimension and a partially porous column in the second dimension was developed and applied to the separation of polyphenolic components in a red wine sample. The performance of the partially porous short column (3.0 cm) was compared to that of a monolithic column, of comparable dimensions. The results obtained demonstrated the possibility to use partially porous columns to obtain fast analyses, using high flow rates, under repetitive gradient conditions and with very brief reconditioning times. A conventional HPLC system was used since the backpressure generated by the shell-packed column, even at very high flow rates, was well within the operational limits. The use of an increased column temperature (60°C) allowed a further pressure-drop decrease, with no stationary phase degradation, or loss in column performance.

Technology Forum: HPLC/ Ion Chromatography

This month, Chromatography Online’s Technology Forum looks at the topic of HPLC/ Ion Chromatography
and the trends and issues surrounding it. Joining us for this discussion is Chris Pohl of Dionex Corporation, Jody
Clark of Selerity Technologies, Scott Anderson and Laura Kaepplinger of Grace Davison Discovery Sciences, and Doug
McCabe of Waters Corporation.

This month, Chromatography Online's Technology Forum looks at the topic of HPLC/ Ion Chromatography and the trends and issues surrounding it. Joining us for this discussion is Chris Pohl of Dionex Corporation, Jody Clark of Selerity Technologies, Scott Anderson and Laura Kaepplinger of Grace Davison Discovery Sciences, and Doug McCabe of Waters Corporation.

Derivatization of Carbonyl Compounds for GC-MS Analysis

Scientists from various institutions in Taiwan collaborated on research to develop a derivatization
method for preparing carbonyl compounds for analysis by gas chromatography-mass spectrometry (GC-MS).

Scientists from various institutions in Taiwan collaborated on research to develop a derivatization method for preparing carbonyl compounds for analysis by gas chromatography-mass spectrometry (GC-MS).

9th Csaba Horváth Medal Award Symposium Announces Call for Papers

The 9th Csaba Horv&aacute;th Medal Award Symposium, to be held on April 28-29, 2009 at the
Hartford Convention Center (Hartford, Connecticut), announced they are accepting papers for oral and poster
presentations on the topics of Advances in Separation Technologies, Multidimensional Separations, UPLC, LC-MS,
Biomarkers, and Separation of Enantiomers.

The 9th Csaba Horv&aacute;th Medal Award Symposium, to be held on April 28-29, 2009 at the Hartford Convention Center (Hartford, Connecticut), announced they are accepting papers for oral and poster presentations on the topics of Advances in Separation Technologies, Multidimensional Separations, UPLC, LC-MS, Biomarkers, and Separation of Enantiomers.

Chromatide Partners with Kromasil

Chromatide (Runcorn, Cheshire, UK), which develops polymer technologies to improve pharmaceutical and
chemical production, and Separation Product’s Kromasil, a brand of Akzo Nobel (Amsterdam, The Netherlands), have
set up a research collaboration to develop and market improved silica-based high performance liquid chromatography
(HPLC) media.

Chromatide (Runcorn, Cheshire, UK), which develops polymer technologies to improve pharmaceutical and chemical production, and Separation Product's Kromasil, a brand of Akzo Nobel (Amsterdam, The Netherlands), have set up a research collaboration to develop and market improved silica-based high performance liquid chromatography (HPLC) media.

Princeton University Selects Thermo Fisher Scientific Mass Spectrometer

Thermo Fisher Scientific (San Jose, California) announced that Princeton University (Princeton, New
Jersey) will be using the company’s MALDI LTQ Orbitrap XL mass spectrometer for research on virus-host protein
interactions in the laboratory of Ileana Cristea.

Thermo Fisher Scientific (San Jose, California) announced that Princeton University (Princeton, New Jersey) will be using the company's MALDI LTQ Orbitrap XL mass spectrometer for research on virus-host protein interactions in the laboratory of Ileana Cristea.

Derivatization of Carbonyl Compounds for GC–MS Analysis

Scientists from various institutions in Taiwan collaborated on research to develop a derivatization
method for preparing carbonyl compounds for analysis by gas chromatography-mass spectrometry (GC-MS).

Scientists from various institutions in Taiwan collaborated on research to develop a derivatization method for preparing carbonyl compounds for analysis by gas chromatography-mass spectrometry (GC-MS).

PerkinElmer and M. D. Anderson Cancer Center Collaborate

PerkinElmer, Inc. (Waltham, Massachusetts) announced an arrangement with the University of Texas M. D.
Anderson Cancer Center (Houston, Texas) that will bring the company’s Array Comparative Genomic Hybridization
technique to the cancer center.

PerkinElmer, Inc. (Waltham, Massachusetts) announced an arrangement with the University of Texas M. D. Anderson Cancer Center (Houston, Texas) that will bring the company's Array Comparative Genomic Hybridization technique to the cancer center.

Ask the Editor: GPC-SEC

The following question and answer appeared in an article by Daniela Held in the June 2008 issue of The
Column, LCGC Europe&acirc;&euro;&trade;s e-zine. Why does
GPC&acirc;&euro;&ldquo;SEC require a calibration?

The following question and answer appeared in an article by Daniela Held in the June 2008 issue of The Column, LCGC Europe&acirc;&euro;&trade;s e-zine. Why does GPC&acirc;&euro;&ldquo;SEC require a calibration?

Pittcon Announces ACS-DAC Coprogramming

Pittcon (Pittsburgh, Pennsylvania) announced that 12 sessions at Pittcon 2009 at McCormick Place South
in Chicago, March 8-13, will be coprogrammed with the ACS Division of Analytical Chemistry (ACS-DAC).

Pittcon (Pittsburgh, Pennsylvania) announced that 12 sessions at Pittcon 2009 at McCormick Place South in Chicago, March 8-13, will be coprogrammed with the ACS Division of Analytical Chemistry (ACS-DAC).