Traditional laboratory-based testing

Historically, plants and other living creatures have been used as medical treatments, and early chemically produced drugs were based on or identical to compounds extracted from natural sources. Nature continues to provide modern drugs, and searches stiU begin with systematic laboratory testing or by following clues from traditional folk healers. Modern chemical methods are used to improve upon what is foimd in nature. Some of these drugs, such as paclitaxel, provide major improvements in medical care. 

Monomer conversion has traditionally been determined gravitimetrically by drying emulsion samples to constant weight. The procedure is slow, requiring several hours for analysis, and precludes automated data acquisition. A new method has been developed based on the DMA-series digital densitometers manufactured by Anton Paar of Austria, and marketed in the United States by Mettier Instrument Corporation. (Very recently Dr. Kirk Abbey made us aware of his parallel work in these directions and of some initial data reported from his laboratory [1, 2]). This instrument is capable of immediate determination of the density of any test fluid, and, if equipped with a flow cell, can continuously monitor the density of a process stream. Results are displayed locally and can be transmitted digitally to a data acquisition computer. 

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