• Home
  • Search Results
  • Determination of glycine and threonine in topical dermatological preparations.

Determination of glycine and threonine in topical dermatological preparations.

Journal of pharmaceutical and biomedical analysis (2008-04-12)
G Marrubini, G Caccialanza, G Massolini
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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Phenyl isothiocyanate, reagent grade, 98%
Sigma-Aldrich
Phenyl isothiocyanate, for HPLC derivatization, the detection of alcohols and amines, ≥99.0%
Supelco
Glycine, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Phenyl isothiocyanate, 99%, for protein sequencing
Sigma-Aldrich
Phenyl isothiocyanate, Sigma Grade, 8.36 M, suitable for solid phase protein sequencing analysis, ≥99% (GC), liquid