A system is described which permits measurements, such as photometry, to be made on air-segmented streams, as in continuous-flow analysis. Elimination of the "debubbler" step before measurement provides two basic assets: (1) more rapid attainment of steady-state conditions (lower interaction between samples), and (2) maintenance of the integrity of the bubbled analysis stream, permitting subsequent handling and remeasurement. A device has been developed for detecting air bubbles. When placed across the light path of a photometer flow cell it inactivates the readout system when bubbles pass by. The resulting system measures the transmittance of each individual liquid segment of the analysis stream, while maintaining the integrity of the stream. Two examples of possible applications of this system are described. One is a simple total-protein determination with biuret, at three times the conventional sampling rate. The other is a continuous-flow, two-point, reaction-rate method for assay of alkaline phosphatase activity.
We describe a comprehensive gas chromatographic analysis for therapeutic concentrations of amitriptyline, nortriptyline, imipramine, desipramine, doxepin, and desmethyldoxepin in plasma, with use of a nitrogen detector. All these drugs are extracted and chromatographed under identical conditions. Each tertiary amine tricyclic is well resolved from its secondary amine metabolite on a mixed-phase column and the concentrations of both are determined simultaneously, without derivatization. The lower limit of sensitivity is 10 microgram/liter of plasma (2-ml sample). Analytical recoveries of the tertiary and secondary amines are 100 and 80%, respectively. Between-run CV's for all of the drugs ranged between 5 and 7%.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.