We describe a sensitive and specific liquid-chromatographic assay for pentoxifylline and three of its metabolites in human plasma and urine. Addition of hydrochloric acid to the sample before extraction, and incorporation of acetic acid in the chromatographic eluent, allow the simultaneous determination of the four compounds plus an internal standard in one chromatographic run. Unlike gas-chrom...

Inverse gas chromatography (IGC) represents a unique reRnement of a classic chromatographic method in which an unknown solid material such as a powder, Rbre or Rlm may be characterized. By reversing the traditional role of unknown mobile phases and known reference stationary phases, the gas}solid chromatographic retention processes may be used to characterize an unknown particulate sample by el...

This work describes a comparative qualitative and quantitative chemical analysis of Maytenus ilicifolia and Maytenus robusta (Celastraceae), extracts by high-resolution gas chromatography (HRGC), using external standards as the method of determination and thin layer chromatographic (TLC). The results show that both plants have a similar chromatographic profile. However, M. robusta exhibited abo...

Complete development of a gas chromatographic method often involves a significant amount of effort. Once a method is completed, retention time locking (RTL) can be used to implement the method and to obtain the same retention times on multiple systems. This application note describes how to use method translation combined with RTL to implement precise time-scaled versions of a method on multipl...

Complete development of a gas chromatographic method often involves a significant amount of effort. Once a method is completed, retention time locking (RTL) can be used to implement the method and to obtain the same retention times on multiple systems. This application note describes how to use method translation combined with RTL to implement precise time-scaled versions of a method on multipl...

A gas-liquid chromatographic method developed for the determination of putrescine and cadaverine in fishery products was modified for application to the determination of diamines in shrimp. Addition of potassium chloride and hydrochloric acid to the methanol-water extraction solvent resulted in increased recovery of the diamines and minimized gel formation. The recovery of putrescine increased ...

Verapamil is a newly marketed antiarrhythmic drug. It has a significant presystemic elimination when administered orally and, therefore, intravenous therapy is often recommended. Optimum therapeutic effect is obtained when verapamil plasma concentrations are between 100 and 400 ng/ml. Several chromatographic procedures for the determination of verapamil in biological fluids have been described ...