This paper presents electrospray mass spectrometric analysis of mixtures containing monoglyceride... more This paper presents electrospray mass spectrometric analysis of mixtures containing monoglycerides, diglycerides, and triglycerides. Sample compounds were dissolved in concentrations of 1-50 pmol/microL in chloroform:methanol (70:30, v:v), which was modified by the addition of alkall-metal or ammonium salts or by addition of formic acid to favor the addition of a cationic species to the sample molecules. Electrospray mass spectrometric analysis of acylglycerol standards yielded positive-ion current signals for (M + Na)+ or (M + NH4)+ of all the species that were present at low picomole per microliter concentrations with no fragmentation. For equimolar concentrations of these sample compounds, there was a general decrease in ion current response as the analyte polarity decreased. Therefore, acylglycerols that contained unsaturated fatty acid chains were observed to exhibit a response in the mass spectrum greater than those with saturated chains, and ion signals resulting from the molecular adduct ions of monoglycerides were more abundant than those of diglycerides, which were more abundant than those of triglycerides in the mass spectrum. Electrospray mass spectrometric analysis of an unknown lipid material recovered from a mammalian cell culture reactor revealed a mixture of triglycerides containing mostly C14, C16, and C18 fatty acids with varying degrees of unsaturation. The results obtained by electrospray mass spectrometry compared favorably to those obtained by gas chromatography after saponification and methylation of fatty acid components of the triglycerides. MS/MS fragmentation of sodiated acylglycerols required a dissociation energy significantly greater than that required for fragmentation of ammoniated acylglycerols, so MS/MS characterization of acylglycerols was generally performed on the ammoniated compounds.(ABSTRACT TRUNCATED AT 250 WORDS)
A commercial benchtop GC/MS ma88 spectrometer has been modlfled for liquid chromatography/mass sp... more A commercial benchtop GC/MS ma88 spectrometer has been modlfled for liquid chromatography/mass spectrometry (LWMS) applications. The modlflcations and concepts are straightforward, and the cost of the modlflcatlons Is minimal provlded approprlate pumplng is available. The system can sample Bagphase lons formed at atmospheric pressure etlher by pneumatlcally assisted electrospray (ion spray) or by atmospherlc pressure chemlcal lonlzatlon (APCI). A two-stage vacuun system allows transfer of lone fonned at atmospheric pressure through a heated ion-sampilng capillary and a conical sampling orlfice Into the analyzer vacuum chamber. An applled 50-140 V dc potentlal between the lon-sampling cawary comblned wtth a 2-15 V dc vOnage on the kmmnphg cone transfers podtlve analyte lons into the analyzer reglon where an rfonly quadrupole array tramnlts the Ion beem Into the mass analyzer. The length of the ion-sampling capillary Inside the flrst vacuum chamber Is heated to approxlmately 180 OC. On-line Ion spray LWMS analyses may be carried out wlth HPLC fkws from low mlcrdlter/mlnute to 1 mumin provlded a flow of 10-50 pUmln is dlrected to the Interface vla an appropriate postcolumn spllt. APCI condltlons using a corona discharge and a heated pneunatk nebulizer LC/MS interface can handle total HPLC effluent when the chromatographk flow ranges from 0.2 to 2.0 mUmln. Full-scan and selected-ion monltorlng (SIM) LC/MS analyses of samples contalnlng mixtures of sulfadrugs and of pestlcldes were carrled out on InJected sample sizes ranghg from 10 ng to 1.5 pg per component uslng APCI whHe sknllar experlments wlth samples contalnlng LSD, benzodlazeplnes, and selected pestlcldes were carried out under Ion spray micro and conventional LC/MS conditions uslng Injected sample levels ranging from 250 pg to 1 pg. When the potential dlfference between the ion-sampilng capillary and the conlcal ion-sampibtg orltice Is Increased, cdllslon-induced dlssoclatlon (CID) occurs, prodding structurally Informathre mass spectra. Examples are shown from CID LWMS experiments conducted under both Ion spray and APCI conditions. SIM CID ion spray micro LC/MS experiments demonstrated a forenslcaily valid detection ilmlt for LSD of 2.5 ng Injected on-column when four structurally s l g n b n t bns were monitored and250 pg when the protonated LSD molecule and lts most abundant fragment ion were monltored.
The mass spectra of bicyclic ketones bicyclo[4.2.l]nonan-kone, bicyclo[5.2.l]decan-lO-one, bicycl... more The mass spectra of bicyclic ketones bicyclo[4.2.l]nonan-kone, bicyclo[5.2.l]decan-lO-one, bicyclo[4.3.l]decan-lO-one and bicyclo[5.3.llundec-ll-one specifically deuterated in positions both adjacent and nonadjacent to the carbonyl carbon have been investigated. The fragmentation and rearrangement processes predominating appear to be dictated by the inherent strain in the molecules. An unusual tendency for fragment ions to recyclize is supported by deuterium labeling results, high resolution mass measurements, metastable studies and comparison with model compounds. The mass spectra of the bicydic ketones under investigation are considerably more complex than those of acyclic ketones.
The generation of large numbers of samples during early drug discovery has increased the demand f... more The generation of large numbers of samples during early drug discovery has increased the demand for rapid and selective methods of analysis. Liquid chromatographytandem mass spectrometry (LC-MS-MS), because of its sensitivity, selectivity, and robustness, has emerged as a powerful tool in the pharmaceutical industry for many analytical needs. This work presents a high-throughput selected reaction monitoring LC-MS bioanalytical method for the determination of idoxifene, a selective estrogen receptor modulator, and its pyrrolidinone metabolite in clinical human plasma samples. The described method uses short, small-bore columns, high flow rates, and elevated HPLC column temperatures to perform LC separations of idoxifene and its metabolite within 10 s/sample. Sequential injections were accomplished with a 215/889 multiple probe liquid handler (Gilson, Inc.), which aspirates eight samples simultaneously and performs its rinse cycle parallel to sample injection, resulting in minimum lag time between injections. This highthroughput method was applied to the determination of idoxifene and its metabolite in clinical human plasma samples. Sample preparation employed liquid/liquid extraction in the 96-well format. Method validation included determination of intra-and interassay accuracy and precision values, recovery studies, autosampler stability, and freeze-thaw stability. The LOQ obtained was 10 ng/mL for idoxifene and 30 ng/mL for the metabolite. Using idoxifene-d 5 as an internal standard, idoxifene showed acceptable accuracy and precision values at QC level 1 (QC1, 15 ng/mL), level 2 (QC2, 100 ng/mL), and level 3 (QC3, 180 ng/mL) (85.0% accuracy (12.0% precision, 95.1 (4.9%, and 90.3 (4.7%, respectively). The pyrrolidinone metabolite also showed acceptable accuracy and precision values (using no internal standard for quantitation) at QC1 (60 ng/mL), QC2 (100 ng/mL), and QC3 (180 ng/mL) (104.9 (14.4%, 91.1 (13.0%, and 90.8 (12.2%, respectively). The validated method was applied to the analysis of 613 human clinical plasma samples. An average run time of 23 s/sample (∼37 min/ 96-well plate or over 3700 sample/day) was achieved. The successful validation presented indicates that rapid methods of analysis can efficiently and reliably contribute to the fast sample turnaround required for high sample number generating processes.
A method involving the semirobotic liquid-liquid extraction (LLE) in deep-well 96-well plates was... more A method involving the semirobotic liquid-liquid extraction (LLE) in deep-well 96-well plates was developed for the quantitation of the anti-cancer/antiinflammatory drug methotrexate (MTX) and its major metabolite, 7-hydroxymethotrexate (7OH-MTX) in human plasma. The extraction time for the sample preparation was relatively short with four 96-well plates (384 samples) prepared in approximately 90 min by one person. The sample extracts were each analyzed within 1.2 min using a positive ion turbo-ionspray selected reaction monitoring liquid chromatography/mass spectrometric (SRM LC/MS) method in which 768 samples were easily analyzed within 22 h (maximum of 820 samples in 24 h). Deuterated internal standards, MTX-d3 and 7OH-MTX-d3, were used. The calibration curves for MTX and 7OH-MTX were linear (R2 > 0.997) and ranged from 0.5 to 250 and 0.75 to 100 ng/mL, respectively. The limit of quantitation (LOQ) for MTX and 7OH-MTX was 0.5 and 0.75 ng/mL, respectively; persistent carryover from the autosampler limited the LOQ achievable. The limit of detection (LOD) was 0.05 ng/mL for MTX and 0.1 ng/mL for 7OH-MTX. The intra- and inter-assay precision and accuracy did not exceed 15% for both MTX and 7OH-MTX. The recoveries were 61% for MTX and 47% for 7OH-MTX. The method was validated and demonstrated to be robust with high precision and accuracy.
We present a study on the mass spectral as well as the binding properties of three triterpene gly... more We present a study on the mass spectral as well as the binding properties of three triterpene glycosides (cimicifugoside, cimiracemoside F, 27-deoxyactein) contained in black cohosh to the ligand binding domain of estrogen receptor beta (ER-beta). Using affinity ultrafiltration and LC/ MS detection, initial experiments using estradiol and the phytoestrogens daidzein and genistein (compounds known to bind ER-beta) were performed to serve as positive controls. The same affinity techniques and LC/MS procedures were then employed to show that neither the triterpene glycosides nor their enzymatically prepared aglycons bound significantly to ER-beta, except for 27-deoxyactein aglycon, which showed weak binding affinity (4%). Additionally, metabolites of the aglycons were prepared by incubation with female human liver microsomes and subjected to binding experiments with ER-beta. No significant binding of the metabolites to the receptor was observed. Further studies are needed to fully characterize whether these triterpene glycosides as well as other components of black cohosh in this plant extract bind to the estrogen receptor alpha (ER-alpha).
Digest of Papers. Microprocesses and Nanotechnology 2001. 2001 International Microprocesses and Nanotechnology Conference (IEEE Cat. No.01EX468)
We have used an embossed plastic microfluidic system for rapid electrophoretic separation of smal... more We have used an embossed plastic microfluidic system for rapid electrophoretic separation of small molecules and electrospray ionization. We have also visualized the separation of compounds by observation of dyes in microfluidic systems and electrospray from the edge of the device. We used a lithographically produced silicon master to emboss channels in ZEONOR 1020R plastic. An oxygen plasma or chromic
Compact mass spectrometry, in combination with suitable sample introduction techniques—such as th... more Compact mass spectrometry, in combination with suitable sample introduction techniques—such as the atmospheric solids analysis probe, thin-layer chromatography, and classical liquid chromatography techniques—can be used effectively for the detection and quantification of cannabinoids and pesticides in cannabis-related material and contraband.
Journal of the American Society for Mass Spectrometry, 2020
Recent advancements in immunocapture methods and mass spectrometer technology have 19 enabled int... more Recent advancements in immunocapture methods and mass spectrometer technology have 19 enabled intact protein mass spectrometry to be applied for the characterization of antibodies and 20 other large biotherapeutics from in-life studies. Protein molecules have not been traditionally studied by intact mass or screened for catabolites in the same manner as small molecules, but the 22 landscape has changed. Researchers have presented methods that can be applied to the drug 23 discovery and development stages, and others are exploring the possibilities of the new 24 approaches. However, a wide variety of options for assay development exist without clear 25 recommendation on best practice, and data processing workflows may have limitations depending 26 on the vendor. In this perspective, we share experiences and recommendations for current and 27 future application of mass spectrometry for biotherapeutic molecule monitoring from pre-clinical 28 and clinical studies.
A rapid, accurate, and selective method was developed for the forensic determination of ionophore... more A rapid, accurate, and selective method was developed for the forensic determination of ionophore antibiotics in animal feeds. A simple extraction procedure and liquid chromatography/tandem mass spectrometry (LC/MS/MS) in the selected reaction monitoring (SRM) mode were used for rapid identification and confirmation of monensin and lasalocid in feed samples and for quantitation of monensin. Extracts from a homogenous portion of ground feeds were prepared using liquid–solid extraction and liquid–liquid extraction techniques. Feed extracts were further purified by a simple defatting and solvent wash step and then concentrated to dryness. Feed extract residues were reconstituted in 1 mL LC mobile phase and a 2 μL aliquot injected into the SRM LC/MS system. The latter system used a C18, 100 × 2.0 mm, LC column coupled to a PE-Sciex API 2000 tandem triple quadrupole mass spectrometer equipped with a TurboIonSpray LC/MS interface. Feed samples were extracted and analyzed for the determina...
Aim: The requirements for developing antibody biotherapeutics benefit from understanding the natu... more Aim: The requirements for developing antibody biotherapeutics benefit from understanding the nature and relevant aspects of the entire molecule. The method presented herein employs on-line multidimensional LC–quadrupole time-of-flight (QTOF)-MS for the quantitative determination of an antibody isolated from biological samples while maintaining the intact native biologically active conformation of the antibody. Results: Following method optimization for a model antibody, an incurred biotherapeutic in cynomologus monkey was quantified in its intact top-down native conformation. A partial method validation demonstrated acceptable precision and accuracy although improved sensitivity requires further studies. Conclusion: An on-line multidimensional LC–MS approach presents a proof-of-principle example for quantifying an intact, native antibody isolated from an incurred biological sample via immunoaffinity techniques coupled with top-down QTOF LC–MS bioanalysis.
Journal of Chromatography B: Biomedical Sciences and Applications, 1992
A method for rapid extraction and identification of drugs in urine is described. The system utili... more A method for rapid extraction and identification of drugs in urine is described. The system utilizes a high-performance protein G immunoaffinity column coupled to a reversed-phase analytical column by use of a trapping column and switching valve. A small amount of antibody (5 micrograms drug-specific) is used for each analysis to extract either propranolol or lysergic acid diethylamide (LSD) from human urine. Urine diluted with phosphate-buffered saline is pumped directly through the protein G column thus eliminating time- and solvent-consuming sample preparation procedures. On-line ultraviolet or mass spectral analysis provides the means of drug detection and identification. With ultraviolet detection propranolol may be detected in spiked urine at the 250 pg/ml level. A Hewlett-Packard mass spectrometer modified for atmospheric pressure ionization and equipped with an ion spray source allows detection of propranolol in urine at 2.5 ng/ml and LSD at 500 pg/ml using single ion monitoring. The potential applicability of the technique for drug confirmations is discussed.
Journal of Chromatography B: Biomedical Sciences and Applications, 1988
Identification and quantitation of trace amounts of trenbolone in bovine tissue by capillary gas ... more Identification and quantitation of trace amounts of trenbolone in bovine tissue by capillary gas chromatography-mass spectrometry-selected-ion monitoring (GC-MS-SIM) has been developed. Three-phase liquid-liquid extraction using a mixture of water-acetonitrile-dichloromethane-hexane was utilized for the sample extraction from tissue. Target compounds were extracted from the tissue into the acetonitrile layer. The residue from this extraction was then subjected to solid-phase extraction by C18 and silica gel disposable cartridges using methanol-water and benzene-acetone as eluents. To overcome extensive matrix interferences, preparative reversed-phase high-performance liquid chromatographic separation was used with an octadecyl-bonded column using methanol-water as mobile phase for sample clean-up prior to GC-MS analysis. A structural analogue of trenbolone, 19-nortestosterone, was chosen as the internal standard for quantitation by GC-MS. The sample was co-injected with N,O-bis (trimethylsilyl) trifluoroacetamide-1-(trimethylsilyl) imidazole (95:5, v/v) for flash heater derivation. Identification and quantitation were simultaneously carried out by SIM of characteristic ions of the trimethylsilyl derivatives of trenbolone and 19-nortestosterone. The limit of detection for trenbolone and epitrenbolone was 0.5 ppb in muscle and liver tissue. A comparison of sensitivity and specificity between GC-MS under electron ionization in addition to positive- and negative-ion chemical ionization conditions using methane reagent gas is also discussed.
This paper presents electrospray mass spectrometric analysis of mixtures containing monoglyceride... more This paper presents electrospray mass spectrometric analysis of mixtures containing monoglycerides, diglycerides, and triglycerides. Sample compounds were dissolved in concentrations of 1-50 pmol/microL in chloroform:methanol (70:30, v:v), which was modified by the addition of alkall-metal or ammonium salts or by addition of formic acid to favor the addition of a cationic species to the sample molecules. Electrospray mass spectrometric analysis of acylglycerol standards yielded positive-ion current signals for (M + Na)+ or (M + NH4)+ of all the species that were present at low picomole per microliter concentrations with no fragmentation. For equimolar concentrations of these sample compounds, there was a general decrease in ion current response as the analyte polarity decreased. Therefore, acylglycerols that contained unsaturated fatty acid chains were observed to exhibit a response in the mass spectrum greater than those with saturated chains, and ion signals resulting from the molecular adduct ions of monoglycerides were more abundant than those of diglycerides, which were more abundant than those of triglycerides in the mass spectrum. Electrospray mass spectrometric analysis of an unknown lipid material recovered from a mammalian cell culture reactor revealed a mixture of triglycerides containing mostly C14, C16, and C18 fatty acids with varying degrees of unsaturation. The results obtained by electrospray mass spectrometry compared favorably to those obtained by gas chromatography after saponification and methylation of fatty acid components of the triglycerides. MS/MS fragmentation of sodiated acylglycerols required a dissociation energy significantly greater than that required for fragmentation of ammoniated acylglycerols, so MS/MS characterization of acylglycerols was generally performed on the ammoniated compounds.(ABSTRACT TRUNCATED AT 250 WORDS)
A commercial benchtop GC/MS ma88 spectrometer has been modlfled for liquid chromatography/mass sp... more A commercial benchtop GC/MS ma88 spectrometer has been modlfled for liquid chromatography/mass spectrometry (LWMS) applications. The modlflcations and concepts are straightforward, and the cost of the modlflcatlons Is minimal provlded approprlate pumplng is available. The system can sample Bagphase lons formed at atmospheric pressure etlher by pneumatlcally assisted electrospray (ion spray) or by atmospherlc pressure chemlcal lonlzatlon (APCI). A two-stage vacuun system allows transfer of lone fonned at atmospheric pressure through a heated ion-sampilng capillary and a conical sampling orlfice Into the analyzer vacuum chamber. An applled 50-140 V dc potentlal between the lon-sampling cawary comblned wtth a 2-15 V dc vOnage on the kmmnphg cone transfers podtlve analyte lons into the analyzer reglon where an rfonly quadrupole array tramnlts the Ion beem Into the mass analyzer. The length of the ion-sampling capillary Inside the flrst vacuum chamber Is heated to approxlmately 180 OC. On-line Ion spray LWMS analyses may be carried out wlth HPLC fkws from low mlcrdlter/mlnute to 1 mumin provlded a flow of 10-50 pUmln is dlrected to the Interface vla an appropriate postcolumn spllt. APCI condltlons using a corona discharge and a heated pneunatk nebulizer LC/MS interface can handle total HPLC effluent when the chromatographk flow ranges from 0.2 to 2.0 mUmln. Full-scan and selected-ion monltorlng (SIM) LC/MS analyses of samples contalnlng mixtures of sulfadrugs and of pestlcldes were carrled out on InJected sample sizes ranghg from 10 ng to 1.5 pg per component uslng APCI whHe sknllar experlments wlth samples contalnlng LSD, benzodlazeplnes, and selected pestlcldes were carried out under Ion spray micro and conventional LC/MS conditions uslng Injected sample levels ranging from 250 pg to 1 pg. When the potential dlfference between the ion-sampilng capillary and the conlcal ion-sampibtg orltice Is Increased, cdllslon-induced dlssoclatlon (CID) occurs, prodding structurally Informathre mass spectra. Examples are shown from CID LWMS experiments conducted under both Ion spray and APCI conditions. SIM CID ion spray micro LC/MS experiments demonstrated a forenslcaily valid detection ilmlt for LSD of 2.5 ng Injected on-column when four structurally s l g n b n t bns were monitored and250 pg when the protonated LSD molecule and lts most abundant fragment ion were monltored.
The mass spectra of bicyclic ketones bicyclo[4.2.l]nonan-kone, bicyclo[5.2.l]decan-lO-one, bicycl... more The mass spectra of bicyclic ketones bicyclo[4.2.l]nonan-kone, bicyclo[5.2.l]decan-lO-one, bicyclo[4.3.l]decan-lO-one and bicyclo[5.3.llundec-ll-one specifically deuterated in positions both adjacent and nonadjacent to the carbonyl carbon have been investigated. The fragmentation and rearrangement processes predominating appear to be dictated by the inherent strain in the molecules. An unusual tendency for fragment ions to recyclize is supported by deuterium labeling results, high resolution mass measurements, metastable studies and comparison with model compounds. The mass spectra of the bicydic ketones under investigation are considerably more complex than those of acyclic ketones.
The generation of large numbers of samples during early drug discovery has increased the demand f... more The generation of large numbers of samples during early drug discovery has increased the demand for rapid and selective methods of analysis. Liquid chromatographytandem mass spectrometry (LC-MS-MS), because of its sensitivity, selectivity, and robustness, has emerged as a powerful tool in the pharmaceutical industry for many analytical needs. This work presents a high-throughput selected reaction monitoring LC-MS bioanalytical method for the determination of idoxifene, a selective estrogen receptor modulator, and its pyrrolidinone metabolite in clinical human plasma samples. The described method uses short, small-bore columns, high flow rates, and elevated HPLC column temperatures to perform LC separations of idoxifene and its metabolite within 10 s/sample. Sequential injections were accomplished with a 215/889 multiple probe liquid handler (Gilson, Inc.), which aspirates eight samples simultaneously and performs its rinse cycle parallel to sample injection, resulting in minimum lag time between injections. This highthroughput method was applied to the determination of idoxifene and its metabolite in clinical human plasma samples. Sample preparation employed liquid/liquid extraction in the 96-well format. Method validation included determination of intra-and interassay accuracy and precision values, recovery studies, autosampler stability, and freeze-thaw stability. The LOQ obtained was 10 ng/mL for idoxifene and 30 ng/mL for the metabolite. Using idoxifene-d 5 as an internal standard, idoxifene showed acceptable accuracy and precision values at QC level 1 (QC1, 15 ng/mL), level 2 (QC2, 100 ng/mL), and level 3 (QC3, 180 ng/mL) (85.0% accuracy (12.0% precision, 95.1 (4.9%, and 90.3 (4.7%, respectively). The pyrrolidinone metabolite also showed acceptable accuracy and precision values (using no internal standard for quantitation) at QC1 (60 ng/mL), QC2 (100 ng/mL), and QC3 (180 ng/mL) (104.9 (14.4%, 91.1 (13.0%, and 90.8 (12.2%, respectively). The validated method was applied to the analysis of 613 human clinical plasma samples. An average run time of 23 s/sample (∼37 min/ 96-well plate or over 3700 sample/day) was achieved. The successful validation presented indicates that rapid methods of analysis can efficiently and reliably contribute to the fast sample turnaround required for high sample number generating processes.
A method involving the semirobotic liquid-liquid extraction (LLE) in deep-well 96-well plates was... more A method involving the semirobotic liquid-liquid extraction (LLE) in deep-well 96-well plates was developed for the quantitation of the anti-cancer/antiinflammatory drug methotrexate (MTX) and its major metabolite, 7-hydroxymethotrexate (7OH-MTX) in human plasma. The extraction time for the sample preparation was relatively short with four 96-well plates (384 samples) prepared in approximately 90 min by one person. The sample extracts were each analyzed within 1.2 min using a positive ion turbo-ionspray selected reaction monitoring liquid chromatography/mass spectrometric (SRM LC/MS) method in which 768 samples were easily analyzed within 22 h (maximum of 820 samples in 24 h). Deuterated internal standards, MTX-d3 and 7OH-MTX-d3, were used. The calibration curves for MTX and 7OH-MTX were linear (R2 > 0.997) and ranged from 0.5 to 250 and 0.75 to 100 ng/mL, respectively. The limit of quantitation (LOQ) for MTX and 7OH-MTX was 0.5 and 0.75 ng/mL, respectively; persistent carryover from the autosampler limited the LOQ achievable. The limit of detection (LOD) was 0.05 ng/mL for MTX and 0.1 ng/mL for 7OH-MTX. The intra- and inter-assay precision and accuracy did not exceed 15% for both MTX and 7OH-MTX. The recoveries were 61% for MTX and 47% for 7OH-MTX. The method was validated and demonstrated to be robust with high precision and accuracy.
We present a study on the mass spectral as well as the binding properties of three triterpene gly... more We present a study on the mass spectral as well as the binding properties of three triterpene glycosides (cimicifugoside, cimiracemoside F, 27-deoxyactein) contained in black cohosh to the ligand binding domain of estrogen receptor beta (ER-beta). Using affinity ultrafiltration and LC/ MS detection, initial experiments using estradiol and the phytoestrogens daidzein and genistein (compounds known to bind ER-beta) were performed to serve as positive controls. The same affinity techniques and LC/MS procedures were then employed to show that neither the triterpene glycosides nor their enzymatically prepared aglycons bound significantly to ER-beta, except for 27-deoxyactein aglycon, which showed weak binding affinity (4%). Additionally, metabolites of the aglycons were prepared by incubation with female human liver microsomes and subjected to binding experiments with ER-beta. No significant binding of the metabolites to the receptor was observed. Further studies are needed to fully characterize whether these triterpene glycosides as well as other components of black cohosh in this plant extract bind to the estrogen receptor alpha (ER-alpha).
Digest of Papers. Microprocesses and Nanotechnology 2001. 2001 International Microprocesses and Nanotechnology Conference (IEEE Cat. No.01EX468)
We have used an embossed plastic microfluidic system for rapid electrophoretic separation of smal... more We have used an embossed plastic microfluidic system for rapid electrophoretic separation of small molecules and electrospray ionization. We have also visualized the separation of compounds by observation of dyes in microfluidic systems and electrospray from the edge of the device. We used a lithographically produced silicon master to emboss channels in ZEONOR 1020R plastic. An oxygen plasma or chromic
Compact mass spectrometry, in combination with suitable sample introduction techniques—such as th... more Compact mass spectrometry, in combination with suitable sample introduction techniques—such as the atmospheric solids analysis probe, thin-layer chromatography, and classical liquid chromatography techniques—can be used effectively for the detection and quantification of cannabinoids and pesticides in cannabis-related material and contraband.
Journal of the American Society for Mass Spectrometry, 2020
Recent advancements in immunocapture methods and mass spectrometer technology have 19 enabled int... more Recent advancements in immunocapture methods and mass spectrometer technology have 19 enabled intact protein mass spectrometry to be applied for the characterization of antibodies and 20 other large biotherapeutics from in-life studies. Protein molecules have not been traditionally studied by intact mass or screened for catabolites in the same manner as small molecules, but the 22 landscape has changed. Researchers have presented methods that can be applied to the drug 23 discovery and development stages, and others are exploring the possibilities of the new 24 approaches. However, a wide variety of options for assay development exist without clear 25 recommendation on best practice, and data processing workflows may have limitations depending 26 on the vendor. In this perspective, we share experiences and recommendations for current and 27 future application of mass spectrometry for biotherapeutic molecule monitoring from pre-clinical 28 and clinical studies.
A rapid, accurate, and selective method was developed for the forensic determination of ionophore... more A rapid, accurate, and selective method was developed for the forensic determination of ionophore antibiotics in animal feeds. A simple extraction procedure and liquid chromatography/tandem mass spectrometry (LC/MS/MS) in the selected reaction monitoring (SRM) mode were used for rapid identification and confirmation of monensin and lasalocid in feed samples and for quantitation of monensin. Extracts from a homogenous portion of ground feeds were prepared using liquid–solid extraction and liquid–liquid extraction techniques. Feed extracts were further purified by a simple defatting and solvent wash step and then concentrated to dryness. Feed extract residues were reconstituted in 1 mL LC mobile phase and a 2 μL aliquot injected into the SRM LC/MS system. The latter system used a C18, 100 × 2.0 mm, LC column coupled to a PE-Sciex API 2000 tandem triple quadrupole mass spectrometer equipped with a TurboIonSpray LC/MS interface. Feed samples were extracted and analyzed for the determina...
Aim: The requirements for developing antibody biotherapeutics benefit from understanding the natu... more Aim: The requirements for developing antibody biotherapeutics benefit from understanding the nature and relevant aspects of the entire molecule. The method presented herein employs on-line multidimensional LC–quadrupole time-of-flight (QTOF)-MS for the quantitative determination of an antibody isolated from biological samples while maintaining the intact native biologically active conformation of the antibody. Results: Following method optimization for a model antibody, an incurred biotherapeutic in cynomologus monkey was quantified in its intact top-down native conformation. A partial method validation demonstrated acceptable precision and accuracy although improved sensitivity requires further studies. Conclusion: An on-line multidimensional LC–MS approach presents a proof-of-principle example for quantifying an intact, native antibody isolated from an incurred biological sample via immunoaffinity techniques coupled with top-down QTOF LC–MS bioanalysis.
Journal of Chromatography B: Biomedical Sciences and Applications, 1992
A method for rapid extraction and identification of drugs in urine is described. The system utili... more A method for rapid extraction and identification of drugs in urine is described. The system utilizes a high-performance protein G immunoaffinity column coupled to a reversed-phase analytical column by use of a trapping column and switching valve. A small amount of antibody (5 micrograms drug-specific) is used for each analysis to extract either propranolol or lysergic acid diethylamide (LSD) from human urine. Urine diluted with phosphate-buffered saline is pumped directly through the protein G column thus eliminating time- and solvent-consuming sample preparation procedures. On-line ultraviolet or mass spectral analysis provides the means of drug detection and identification. With ultraviolet detection propranolol may be detected in spiked urine at the 250 pg/ml level. A Hewlett-Packard mass spectrometer modified for atmospheric pressure ionization and equipped with an ion spray source allows detection of propranolol in urine at 2.5 ng/ml and LSD at 500 pg/ml using single ion monitoring. The potential applicability of the technique for drug confirmations is discussed.
Journal of Chromatography B: Biomedical Sciences and Applications, 1988
Identification and quantitation of trace amounts of trenbolone in bovine tissue by capillary gas ... more Identification and quantitation of trace amounts of trenbolone in bovine tissue by capillary gas chromatography-mass spectrometry-selected-ion monitoring (GC-MS-SIM) has been developed. Three-phase liquid-liquid extraction using a mixture of water-acetonitrile-dichloromethane-hexane was utilized for the sample extraction from tissue. Target compounds were extracted from the tissue into the acetonitrile layer. The residue from this extraction was then subjected to solid-phase extraction by C18 and silica gel disposable cartridges using methanol-water and benzene-acetone as eluents. To overcome extensive matrix interferences, preparative reversed-phase high-performance liquid chromatographic separation was used with an octadecyl-bonded column using methanol-water as mobile phase for sample clean-up prior to GC-MS analysis. A structural analogue of trenbolone, 19-nortestosterone, was chosen as the internal standard for quantitation by GC-MS. The sample was co-injected with N,O-bis (trimethylsilyl) trifluoroacetamide-1-(trimethylsilyl) imidazole (95:5, v/v) for flash heater derivation. Identification and quantitation were simultaneously carried out by SIM of characteristic ions of the trimethylsilyl derivatives of trenbolone and 19-nortestosterone. The limit of detection for trenbolone and epitrenbolone was 0.5 ppb in muscle and liver tissue. A comparison of sensitivity and specificity between GC-MS under electron ionization in addition to positive- and negative-ion chemical ionization conditions using methane reagent gas is also discussed.
Uploads
Papers by Jack Henion