High-performance liquid chromatographic determination of d-/l-epinephrine enantiomer ratio in lidocaine-epinephrine local anesthetics.
A procedure for the determination of the ratio of d- to l-epinephrine in lidocaine-epinephrine local anesthetics is described. Epinephrine was isolated via Sep-Pak cartridges and derivatized with 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate; the d- and l-chiral derivatives were separated and measured by high-performance liquid chromatography. About 70 samples of various dosage forms and concentrations from four manufacturers were successfully analyzed by the method.
Long-term stability study of L-adrenaline injections: Kinetics of sulfonation and racemization pathways of drug degradation.
Injectable formulations of L-adrenaline are commonly used in emergency medicine. Despite numerous studies, the comparative contribution and kinetics of the L-adrenaline inactivation pathways during storage have not been conclusively evaluated. We examined the kinetics of L-adrenaline degradation in a prospective study and determined the extent of drug inactivation by different pathways during and beyond the stipulated product shelf-life in 42 batches of adrenaline ampules stored under controlled conditions. The content of L-adrenaline and degradation products was determined with a chiral high-performance liquid chromatography (HPLC) assay, and the degradation products were identified by mass spectrometric detection as D-adrenaline and L- and D-adrenaline sulfonate. The kinetics of the content change with storage was analyzed simultaneously for L-adrenaline and the degradation products using kinetic modeling. The lower acceptable level of adrenaline content in the formulation stated by US Pharmacopoeia (90% as a sum of L- and D-isomers) was attained after 2.0 years of storage, at which time the content of the therapeutically active L-isomer amounted to as low as 85%. The modeling revealed significant differences in the degradation kinetics in the formulations produced before and after 1997, whose cause remained unidentified in this study.
Sensitive high-performance liquid chromatographic method for the determination of water in various samples
Water and phenyl isocyanate react to yield N,N′-diphenylurea, a very stable and highly UV-absorbing compound. The reaction is quatitative and is completed in half an hour. 
 
N,N′-dipenylurea can easily be chromatographed on a reversed-phase high-performance liquid chromatographic system. The smallest detectable amount, theoretically, is ca. 1 ng correspondign to <100 pg of water. 
 
Applications to both solid and liquid samples are given as well as examples of crystal water determinations. The results are compared to results obtained by the Karl Fischer method.