Research Topics
| John C ReepmeyerSummaryAffiliation: Food and Drug Administration Country: USA Publications
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Detail Information
Publications
Structure elucidation of a novel analogue of sildenafil detected as an adulterant in an herbal dietary supplementJohn C Reepmeyer
US Food and Drug Administration, Division of Pharmaceutical Analysis, St Louis, MO 63101, USA
J Pharm Biomed Anal 43:1615-21. 2007..The compound, named methisosildenafil, is a novel synthetic analogue of sildenafil in which the N-methylpiperazine moiety has been replaced with 2,6-dimethylpiperazine...
Analysis of crude heparin by (1)H NMR, capillary electrophoresis, and strong-anion-exchange-HPLC for contamination by over sulfated chondroitin sulfateDavid A Keire
Food and Drug Administration, Division of Pharmaceutical Analysis, 1114 Market St, Saint Louis, MO 63101, USA
J Pharm Biomed Anal 51:921-6. 2010..5M NaCl solution. This SAX-HPLC approach gave a weight percent LOD of 0.02% and a LOQ of 0.07% and had better performance characteristics than that of the protocol used for APIs...- Structure elucidation of thioketone analogues of sildenafil detected as adulterants in herbal aphrodisiacsJohn C Reepmeyer
US Food and Drug Administration, Division of Pharmaceutical Analysis, 1114 Market Street, Room 1002, St Louis, MO 63101, USA
J Pharm Biomed Anal 49:145-50. 2009..Ten herbal dietary supplements, each as a capsule dosage form, were found to contain 8-151 mg of thiomethisosildenafil per capsule, and one herbal dietary supplement was found to contain 35 mg of thiosildenafil per capsule... - Use of liquid chromatography-mass spectrometry and a chemical cleavage reaction for the structure elucidation of a new sildenafil analogue detected as an adulterant in an herbal dietary supplementJohn C Reepmeyer
U S Food and Drug Administration, Division of Pharmaceutical Analysis, St Louis, MO 63101, USA
J Pharm Biomed Anal 44:887-93. 2007..Since the new compound has one less CH(2) group than acetildenafil, it was named nor-acetildenafil... - Modifications and insights into a method for the analysis of the nitrogen mustard mechlorethamine by high-performance liquid chromatographyJohn C Reepmeyer
United States Food and Drug Administration, Center for Drug Evaluation and Research, Office of Phamaceutical Science, Division of Pharmaceutical Analysis, FDA, 1114 Market Street, Room 1002, St Louis, MO 63101, USA
Anal Chim Acta 616:78-84. 2008..The method has been extended to the analysis of mechlorethamine in aqueous solutions... - Detection of undeclared erectile dysfunction drugs and analogues in dietary supplements by ion mobility spectrometryConnie M Gryniewicz
FDA, Division of Pharmaceutical Analysis, 1114 Market St, St Louis, MO 63101, USA
J Pharm Biomed Anal 49:601-6. 2009..The results demonstrate that IMS is a viable method for screening herbal dietary supplements for the presence of ED drug or drug analogue adulterants... - Use of a hydrolytic procedure and spectrometric methods in the structure elucidation of a thiocarbonyl analogue of sildenafil detected as an adulterant in an over-the-counter herbal aphrodisiacJohn C Reepmeyer
U S Food and Drug Administration, Division of Pharmaceutical Analysis, St Louis, MO 63101, USA
J AOAC Int 92:1336-42. 2009..Another key product of hydrolysis was hydroxyhomosildenafil, generated by hydrolysis of the thiocarbonyl group to a carbonyl group (C = S --> C = O). Hydroxyhomosildenafil was detected as a minor component in the dietary supplement... - Use of liquid chromatography-mass spectrometry and a hydrolytic technique for the detection and structure elucidation of a novel synthetic vardenafil designer drug added illegally to a "natural" herbal dietary supplementJohn C Reepmeyer
US Food and Drug Administration, Division of Pharmaceutical Analysis, St Louis, MO 63101, USA
J Chromatogr A 1125:67-75. 2006..The dosage level of piperidenafil in the herbal product was 41 mg per capsule when calculated as the free base... - Analysis of heparin sodium by SAX/HPLC for contaminants and impuritiesMichael L Trehy
Food and Drug Administration, Division of Pharmaceutical Analysis, Saint Louis, MO 63101, USA
J Pharm Biomed Anal 49:670-3. 2009..1% and 0.8%, respectively. This manuscript is not a policy document and is not intended to replace either of the methods (capillary electrophoresis and NMR) currently required by the FDA... - Direct intramolecular gas-phase transfer reactions during fragmentation of sildenafil and thiosildenafil analogs in electrospray ionization mass spectrometryJohn C Reepmeyer
United States Food and Drug Administration, Center for Drug Evaluation and Research, Office of Pharmaceutical Science, Division of Pharmaceutical Analysis, FDA, 1114 Market Street, Room 1002, St Louis, MO 63101, USA
Rapid Commun Mass Spectrom 23:927-36. 2009..While methyl migration to the thiocarbonyl sulfur atom of thiosildenafil is dominant, methyl migration to the carbonyl oxygen atom of sildenafil may occur to a small extent... - Analysis of the nitrogen mustard mechlorethamine in topical pharmaceutical preparations by high-performance liquid chromatographyJohn C Reepmeyer
U S Food and Drug Administration, Division of Pharmaceutical Analysis, St Louis, MO 63101, USA
J Chromatogr A 1085:262-9. 2005..08 to 0.52% RSD (n = 6). Recoveries from ointments spiked with 0.02% mechlorethamine hydrochloride were 98.4-100.4%. The chromatograms were clean, showing minimal or no interference from ointment excipients or reagents... - Screening of heparin API by near infrared reflectance and Raman spectroscopyJohn A Spencer
Division of Pharmaceutical Analysis, Food and Drug Administration, Center for Drug Evaluation and Research, St Louis, Missouri 63101, USA
J Pharm Sci 98:3540-7. 2009..These technologies are meant for screening purposes and not meant to replace either of the methods (capillary electrophoresis and NMR) currently required by USP and FDA... - Separation and detection of the isomeric equine conjugated estrogens, equilin sulfate and delta8,9-dehydroestrone sulfate, by liquid chromatography--electrospray-mass spectrometry using carbon-coated zirconia and porous graphitic carbon stationary phasesJohn C Reepmeyer
US Food and Drug Administration, Division of Pharmaceutical Analysis, St Louis, MO 63101, USA
J Chromatogr A 1083:42-51. 2005..An examination of a selected few conjugated estrogens in the complex drug substance by LC-MS on Hypercarb is presented...