title: Determination of glycine and threonine in topical dermatological preparations.
abstract: In the present study, a single HPLC method was developed for the determination of glycine and threonine in cicatrizants. Two different preparations of a cream and an ointment, and the corresponding bandages, onto which the formulations were applied, were studied. The method involved matrix solubilisation with dichloromethane, liquid-liquid isolation of gly and thr with aqueous 1N NaOH, and derivatization with phenylisothiocyanate. Reversed-phase HPLC separation was carried out by gradient elution with 20mM aqueous NaClO4 and acetonitrile (from 90% to 30% aqueous NaClO4 in 10 min) on a LiChrospher 100 RP-18 cartridge (125 mm x 4.6 mm). Analytes were determined with a UV detector set at 245 nm. Quantitation was accomplished by internal standardization with methionine. Linearity was studied in the range 60-120% of the concentrations expected for gly and thr (viz. for gly from 200 to 400 microgml(-1), and for thr from 100 to 200 microgml(-1)). In reference aqueous samples, linear correlation (r) was better than 0.99 for gly and thr, while in spiked matrix samples r ranged from 0.97 to 0.98. Recoveries were in the 95-105% interval, and precision (CV%, N=6) was better than 5% for both analytes either in cream, ointment or bandages. The method was successfully used for the quality control of topical dermatological preparations.
authors.affiliation: Department of Pharmaceutical Chemistry, University of Pavia, Via Taramelli 12, 27100 Pavia, Italy. giorgio.marrubini@unipv.it
authors.forename: G
authors.initials: G
authors.lastname: Marrubini
authors.forename: G
authors.initials: G
authors.lastname: Caccialanza
authors.forename: G
authors.initials: G
authors.lastname: Massolini
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000287:Administration, Topical; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003879:Dermatologic Agents / Q000032:analysis*; D005079:Excipients / Q000737:chemistry; D005998:Glycine / Q000032:analysis*; D017879:Isothiocyanates / Q000737:chemistry; D008752:Methylene Chloride / Q000737:chemistry; D009824:Ointments; D010472:Perchlorates / Q000737:chemistry; D004364:Pharmaceutical Preparations / Q000032:analysis*; D011786:Quality Control; D012015:Reference Standards; D012680:Sensitivity and Specificity; D017670:Sodium Compounds / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013912:Threonine / Q000032:analysis*; D014867:Water / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D003879:Dermatologic Agents; D005079:Excipients; D017879:Isothiocyanates; D009824:Ointments; D010472:Perchlorates; D004364:Pharmaceutical Preparations; D017670:Sodium Compounds; D014867:Water; C005441:phenylisothiocyanate; D013912:Threonine; D008752:Methylene Chloride; C031068:sodium perchlorate; D005998:Glycine; C032159:acetonitrile