Randy Weintraub | Burlington County College (original) (raw)

Papers by Randy Weintraub

Research paper thumbnail of Some results on the ageing of wire chambers with dimethyl ether

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1988

... Research A273 (1988) 161-171 North-Holland, Amsterdam SOME RESULTS ON THE AGEING OF WIRE CHAM... more ... Research A273 (1988) 161-171 North-Holland, Amsterdam SOME RESULTS ON THE AGEING OF WIRE CHAMBERS WITH DIMETHYL ETHER Mohammed JIBALY, Peter ... First, it is a "cool" gas, with a very low electron diffusion constant [1]. Second, it is a very heavy quencher ...

Research paper thumbnail of Analytical Method and Interlaboratory Study for the Quantitation of Aminocyclopyrachlor Residues in Vegetation by Liquid Chromatography/Tandem Mass Spectrometry

Journal of AOAC International, 2013

The quick, easy, cheap, effective, rugged, and safe (QuEChERS) and the U.S. Food and Drug Adminis... more The quick, easy, cheap, effective, rugged, and safe (QuEChERS) and the U.S. Food and Drug Administration pesticide multiresidue methods were systematically tested for the analysis of aminocyclopyrachlor, a new synthetic auxin herbicide. Results revealed that these procedures are not suitable, highlighting the need for a publicly available residue method for this new active ingredient. Such a method has been developed and is reported herein for aminocyclopyrachlor residue analysis in vegetation, including white pine, Norway spruce, grass forage, and grass hay. Aminocyclopyrachlor residues were purified from plant tissue extracts by filtration through SPE cartridges with strong anion exchange stationary phases and analyzed using LC/MS/MS. This method was validated at five laboratories across the United States; their results were compared to evaluate reproducibility and ruggedness. The method LOQ was 0.01 mg/kg (ppm) and the LOD 0.003 mg/kg (ppm) for the matrixes tested. A qualitative procedure to confirm the molecular identity of residues based on retention time measurements and ion transition peak area ratios (m/z 214 --> 681m/z 214 --> 101) is also presented.

Research paper thumbnail of Trace Determination of Naringenin and Hesperitin by Tandem Mass Spectrometry

Research paper thumbnail of Simultaneous Esterification and Acylation of Pesticides for Analysis by Gas Chromatography. 1. Derivatization of Glyphosate and (Aminomethyl)-Phosphonic Acid with Fluorinated Alcohols-Perfluorinated Anhydrides

Research paper thumbnail of Flavanone absorption after naringin, hesperidin, and citrus administration*

Clinical Pharmacology & Therapeutics, 1996

Disposition of citrus flavonoids was evaluated after single oral doses of pure compounds (500 mg ... more Disposition of citrus flavonoids was evaluated after single oral doses of pure compounds (500 mg naringin and 500 mg hesperidin) and after multiple doses of combined grapefruit juice and orange juice and of once-daily grapefruit. Cumulative urinary recovery indicated low bioavailability ( < 25%) of naringin and hesperidin. The aglycones naringenin and hesperitin were detected in urine and plasma by positive chemical ionization-collisionally activated dissociation tandem mass spectrometry (PCI-CAD MS/MS). After juice administration, PCI-CAD MS/MS detected naringenin, hesperitin, and four related flavanones, tentatively identified as monomethoxy and dimethoxy derivatives. These methoxyflavanones appear to be absorbed from juice. Absorbed citrus flavanones may undergo glucuronidation before urinary excretion.

Research paper thumbnail of Variation in Anastrozole Metabolism and Pharmacodynamics in Women with Early Breast Cancer

Cancer Research, 2010

Aromatase inhibitors (AIs) play a prominent role in the management of postmenopausal women with e... more Aromatase inhibitors (AIs) play a prominent role in the management of postmenopausal women with endocrine sensitive breast cancer, but there is large variability in both efficacy and tolerability. The purpose of our study was to define inter-individual variation in anastrozole metabolism and pharmacodynamics among patients treated with the approved daily dose of one mg in a standard practice setting as adjuvant therapy for resected early breast cancer. This study was performed in 191 women in whom pre-treatment and during anastrozole plasma concentrations of estrone (E1), estradiol (E2), estrone conjugates, androstenedione and testosterone were determined and correlated with plasma concentrations of anastrozole and anastrozole metabolites. There were large inter-individual variations in plasma anastrozole and anastrozole metabolite concentrations as well as pre-treatment and post-drug plasma E1, E2, E1conjugate and estrogen precursor (androstenedione and testosterone) concentrations. E1 and E2 concentrations were below the lower limit of quantitation (LLQ) in most patients after anastrozole therapy (83% for both), but those with detectable concentrations had a broad range (1.58-45.2 pg/ ml and 0.635-97.0 pg/ml, respectively). E1-conjugates after anastrozole therapy were above the LLQ in most patients (93%), with wide interpatient variability (3.50-2990 pg/ml). Two patients appeared to extensively metabolize anastrozole and failed to display substantial decreases in estrogens. Acknowledging the potential factor of variable compliance, our results demonstrated large inter-individual variation in anastrozole metabolism and its effect on circulating estrogens in

Research paper thumbnail of Flavanone absorption after naringin, hesperidin, and citrus administration&ast

Clinical Pharmacology …, 1996

Disposition of citrus flavonoids was evaluated after single oral doses of pure compounds (500 mg ... more Disposition of citrus flavonoids was evaluated after single oral doses of pure compounds (500 mg naringin and 500 mg hesperidin) and after multiple doses of combined grapefruit juice and orange juice and of once-daily grapefruit. Cumulative urinary recovery indicated low bioavailability ( < 25%) of naringin and hesperidin. The aglycones naringenin and hesperitin were detected in urine and plasma by positive chemical ionization-collisionally activated dissociation tandem mass spectrometry (PCI-CAD MS/MS). After juice administration, PCI-CAD MS/MS detected naringenin, hesperitin, and four related flavanones, tentatively identified as monomethoxy and dimethoxy derivatives. These methoxyflavanones appear to be absorbed from juice. Absorbed citrus flavanones may undergo glucuronidation before urinary excretion.

Research paper thumbnail of Drug interactions with grapefruit juice

Research paper thumbnail of Trace Determination of Naringenin and Hesperitin by Tandem Mass Spectrometry

Journal of Agricultural and Food Chemistry, 1995

... system provided sufficiently selective analysis of trace flavanone com-ponents in the complex... more ... system provided sufficiently selective analysis of trace flavanone com-ponents in the complex matrix of extracted urine to permit the evaluation of flavanone absorption from orange and grapefruit. ... Randy A. Weintraub,* Barbara Ameer, Jodie V. Johnson, and Richard A. Yost ...

Research paper thumbnail of Simultaneous esterification and acylation of pesticides for analysis by gas chromatography. 1. Derivatization of glyphosate and (aminomethyl)phosphonic acid with fluorinated alcohols-perfluorinated anhydrides

Journal of Agricultural and Food Chemistry, 1985

ABSTRACT Glyphosate [N-(phosphonomethyl)glycine] and its major metabolite, (aminomethyl)phosphoni... more ABSTRACT Glyphosate [N-(phosphonomethyl)glycine] and its major metabolite, (aminomethyl)phosphonic acid, were fully functionalized for analysis by gas chromatography and mass spectrometry by reaction with mixtures of fluorinated alcohols and perfluorinated anhydrides. All phosphonic and carboxylic acid groups were esterified and all amino groups were acylated; derivatization was effected at 100°C for 1 h. Average recoveries from potable water samples were 95, 90, and 104% respectively for glyphosate at the 10, 50, and 100 ppb levels respectively; (aminomethyl)phosphonic acid recoveries averaged 106, 99, and 114% at the 10, 50, and 100 ppb levels, respectively.

Research paper thumbnail of Reaction products and rates of disappearance of simple bromoalkanes, 1, 2-dibromopropane, and 1, 2-dibromoethane in water. Reply to comments

rn The reactivities of 1,2-dibromoethane (EDB), 1,2-and 1,3-dibromopropane (1,2-DBP and 1,3-DBP),... more rn The reactivities of 1,2-dibromoethane (EDB), 1,2-and 1,3-dibromopropane (1,2-DBP and 1,3-DBP), l-bromoheptane (BH), and 1-bromo-3-phenylpropane (BPP) were studied in aqueous buffers in the pH range 7-11 and in the temperature range 45-90 "C. The half-lives at 25 O C were estimated by using the Arrhenius relationship: EDB (2.5 years); 1,2-DPB (320 days); BPP (290 days); 1,3-DBP (48 days); BH (=36 days). The dibromoalkanes with vicinal bromides, EDB and 1,2-DBP, eliminated HBr and yielded significant amounts of vinyl bromide and bromopropenes, respectively. The monobromo-and 1,3-dibromoalkanes (BH, BPP, and 1,3-DBP) hydrolyzed to alcohols with no elimination products detected. Reactivities of 16 bromoalkanes are correlated with Taft's polar substitution constant (r = 0.88).

Research paper thumbnail of Trace determination of naringenin and hesperitin by tandem mass spectrometry

Journal of Agricultural …, 1995

... system provided sufficiently selective analysis of trace flavanone com-ponents in the complex... more ... system provided sufficiently selective analysis of trace flavanone com-ponents in the complex matrix of extracted urine to permit the evaluation of flavanone absorption from orange and grapefruit. ... Randy A. Weintraub,* Barbara Ameer, Jodie V. Johnson, and Richard A. Yost ...

Research paper thumbnail of Some results on the ageing of wire chambers with dimethyl ether

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1988

... Research A273 (1988) 161-171 North-Holland, Amsterdam SOME RESULTS ON THE AGEING OF WIRE CHAM... more ... Research A273 (1988) 161-171 North-Holland, Amsterdam SOME RESULTS ON THE AGEING OF WIRE CHAMBERS WITH DIMETHYL ETHER Mohammed JIBALY, Peter ... First, it is a "cool" gas, with a very low electron diffusion constant [1]. Second, it is a very heavy quencher ...

Research paper thumbnail of Analytical Method and Interlaboratory Study for the Quantitation of Aminocyclopyrachlor Residues in Vegetation by Liquid Chromatography/Tandem Mass Spectrometry

Journal of AOAC International, 2013

The quick, easy, cheap, effective, rugged, and safe (QuEChERS) and the U.S. Food and Drug Adminis... more The quick, easy, cheap, effective, rugged, and safe (QuEChERS) and the U.S. Food and Drug Administration pesticide multiresidue methods were systematically tested for the analysis of aminocyclopyrachlor, a new synthetic auxin herbicide. Results revealed that these procedures are not suitable, highlighting the need for a publicly available residue method for this new active ingredient. Such a method has been developed and is reported herein for aminocyclopyrachlor residue analysis in vegetation, including white pine, Norway spruce, grass forage, and grass hay. Aminocyclopyrachlor residues were purified from plant tissue extracts by filtration through SPE cartridges with strong anion exchange stationary phases and analyzed using LC/MS/MS. This method was validated at five laboratories across the United States; their results were compared to evaluate reproducibility and ruggedness. The method LOQ was 0.01 mg/kg (ppm) and the LOD 0.003 mg/kg (ppm) for the matrixes tested. A qualitative procedure to confirm the molecular identity of residues based on retention time measurements and ion transition peak area ratios (m/z 214 --> 681m/z 214 --> 101) is also presented.

Research paper thumbnail of Trace Determination of Naringenin and Hesperitin by Tandem Mass Spectrometry

Research paper thumbnail of Simultaneous Esterification and Acylation of Pesticides for Analysis by Gas Chromatography. 1. Derivatization of Glyphosate and (Aminomethyl)-Phosphonic Acid with Fluorinated Alcohols-Perfluorinated Anhydrides

Research paper thumbnail of Flavanone absorption after naringin, hesperidin, and citrus administration*

Clinical Pharmacology & Therapeutics, 1996

Disposition of citrus flavonoids was evaluated after single oral doses of pure compounds (500 mg ... more Disposition of citrus flavonoids was evaluated after single oral doses of pure compounds (500 mg naringin and 500 mg hesperidin) and after multiple doses of combined grapefruit juice and orange juice and of once-daily grapefruit. Cumulative urinary recovery indicated low bioavailability ( < 25%) of naringin and hesperidin. The aglycones naringenin and hesperitin were detected in urine and plasma by positive chemical ionization-collisionally activated dissociation tandem mass spectrometry (PCI-CAD MS/MS). After juice administration, PCI-CAD MS/MS detected naringenin, hesperitin, and four related flavanones, tentatively identified as monomethoxy and dimethoxy derivatives. These methoxyflavanones appear to be absorbed from juice. Absorbed citrus flavanones may undergo glucuronidation before urinary excretion.

Research paper thumbnail of Variation in Anastrozole Metabolism and Pharmacodynamics in Women with Early Breast Cancer

Cancer Research, 2010

Aromatase inhibitors (AIs) play a prominent role in the management of postmenopausal women with e... more Aromatase inhibitors (AIs) play a prominent role in the management of postmenopausal women with endocrine sensitive breast cancer, but there is large variability in both efficacy and tolerability. The purpose of our study was to define inter-individual variation in anastrozole metabolism and pharmacodynamics among patients treated with the approved daily dose of one mg in a standard practice setting as adjuvant therapy for resected early breast cancer. This study was performed in 191 women in whom pre-treatment and during anastrozole plasma concentrations of estrone (E1), estradiol (E2), estrone conjugates, androstenedione and testosterone were determined and correlated with plasma concentrations of anastrozole and anastrozole metabolites. There were large inter-individual variations in plasma anastrozole and anastrozole metabolite concentrations as well as pre-treatment and post-drug plasma E1, E2, E1conjugate and estrogen precursor (androstenedione and testosterone) concentrations. E1 and E2 concentrations were below the lower limit of quantitation (LLQ) in most patients after anastrozole therapy (83% for both), but those with detectable concentrations had a broad range (1.58-45.2 pg/ ml and 0.635-97.0 pg/ml, respectively). E1-conjugates after anastrozole therapy were above the LLQ in most patients (93%), with wide interpatient variability (3.50-2990 pg/ml). Two patients appeared to extensively metabolize anastrozole and failed to display substantial decreases in estrogens. Acknowledging the potential factor of variable compliance, our results demonstrated large inter-individual variation in anastrozole metabolism and its effect on circulating estrogens in

Research paper thumbnail of Flavanone absorption after naringin, hesperidin, and citrus administration&ast

Clinical Pharmacology …, 1996

Disposition of citrus flavonoids was evaluated after single oral doses of pure compounds (500 mg ... more Disposition of citrus flavonoids was evaluated after single oral doses of pure compounds (500 mg naringin and 500 mg hesperidin) and after multiple doses of combined grapefruit juice and orange juice and of once-daily grapefruit. Cumulative urinary recovery indicated low bioavailability ( < 25%) of naringin and hesperidin. The aglycones naringenin and hesperitin were detected in urine and plasma by positive chemical ionization-collisionally activated dissociation tandem mass spectrometry (PCI-CAD MS/MS). After juice administration, PCI-CAD MS/MS detected naringenin, hesperitin, and four related flavanones, tentatively identified as monomethoxy and dimethoxy derivatives. These methoxyflavanones appear to be absorbed from juice. Absorbed citrus flavanones may undergo glucuronidation before urinary excretion.

Research paper thumbnail of Drug interactions with grapefruit juice

Research paper thumbnail of Trace Determination of Naringenin and Hesperitin by Tandem Mass Spectrometry

Journal of Agricultural and Food Chemistry, 1995

... system provided sufficiently selective analysis of trace flavanone com-ponents in the complex... more ... system provided sufficiently selective analysis of trace flavanone com-ponents in the complex matrix of extracted urine to permit the evaluation of flavanone absorption from orange and grapefruit. ... Randy A. Weintraub,* Barbara Ameer, Jodie V. Johnson, and Richard A. Yost ...

Research paper thumbnail of Simultaneous esterification and acylation of pesticides for analysis by gas chromatography. 1. Derivatization of glyphosate and (aminomethyl)phosphonic acid with fluorinated alcohols-perfluorinated anhydrides

Journal of Agricultural and Food Chemistry, 1985

ABSTRACT Glyphosate [N-(phosphonomethyl)glycine] and its major metabolite, (aminomethyl)phosphoni... more ABSTRACT Glyphosate [N-(phosphonomethyl)glycine] and its major metabolite, (aminomethyl)phosphonic acid, were fully functionalized for analysis by gas chromatography and mass spectrometry by reaction with mixtures of fluorinated alcohols and perfluorinated anhydrides. All phosphonic and carboxylic acid groups were esterified and all amino groups were acylated; derivatization was effected at 100°C for 1 h. Average recoveries from potable water samples were 95, 90, and 104% respectively for glyphosate at the 10, 50, and 100 ppb levels respectively; (aminomethyl)phosphonic acid recoveries averaged 106, 99, and 114% at the 10, 50, and 100 ppb levels, respectively.

Research paper thumbnail of Reaction products and rates of disappearance of simple bromoalkanes, 1, 2-dibromopropane, and 1, 2-dibromoethane in water. Reply to comments

rn The reactivities of 1,2-dibromoethane (EDB), 1,2-and 1,3-dibromopropane (1,2-DBP and 1,3-DBP),... more rn The reactivities of 1,2-dibromoethane (EDB), 1,2-and 1,3-dibromopropane (1,2-DBP and 1,3-DBP), l-bromoheptane (BH), and 1-bromo-3-phenylpropane (BPP) were studied in aqueous buffers in the pH range 7-11 and in the temperature range 45-90 "C. The half-lives at 25 O C were estimated by using the Arrhenius relationship: EDB (2.5 years); 1,2-DPB (320 days); BPP (290 days); 1,3-DBP (48 days); BH (=36 days). The dibromoalkanes with vicinal bromides, EDB and 1,2-DBP, eliminated HBr and yielded significant amounts of vinyl bromide and bromopropenes, respectively. The monobromo-and 1,3-dibromoalkanes (BH, BPP, and 1,3-DBP) hydrolyzed to alcohols with no elimination products detected. Reactivities of 16 bromoalkanes are correlated with Taft's polar substitution constant (r = 0.88).

Research paper thumbnail of Trace determination of naringenin and hesperitin by tandem mass spectrometry

Journal of Agricultural …, 1995

... system provided sufficiently selective analysis of trace flavanone com-ponents in the complex... more ... system provided sufficiently selective analysis of trace flavanone com-ponents in the complex matrix of extracted urine to permit the evaluation of flavanone absorption from orange and grapefruit. ... Randy A. Weintraub,* Barbara Ameer, Jodie V. Johnson, and Richard A. Yost ...