Determination of Serum Free Valproic Acid by Ultrafiltration Method

Gas-chromatographic determination of valproic acid in serum without derivatization.

Valproic acid can be determined by gas-chromatography as the free acid after its extraction (1 ) or derivatization to form methyl, butyl, or phenacyl estars (2-4), the latter methods being more complicated for routine analyses. Other procedures, such as enzyme immunoassay (Syva Co., Palo Alto, CA 94304) or fluoroimmunoassay (Miles Inc., Elkhart, IN 46515), which do not require serum extraction,...

An improved ultrafiltration method for determining free testosterone in serum.

In this method, we use the Amicon MPS-1 centrifugal ultrafiltration device and the YMB membrane in measuring free testosterone in serum. Two independent assays are combined: total testosterone and the ultrafiltrable fraction of added [3H]testosterone. The unbound fraction is determined in 0.15-0.5 mL ultrafiltrates of 0.6 to 1 mL of variably diluted serum that has been equilibrated with [3H]tes...

Protein-free filtrates obtained by membrane ultrafiltration. Application to the determination of serum constituents.

Serum was ultrafiltered by centrifugation through size-selective membranes, and the ultrafiltrates were analyzed directly for glucose, urea nitrogen, creatmine, and uric acid. The concentrations obtained were equivalent to their concentration in conventional protein-free filtrates. This procedure eliminates the need for specific precipitating methods required in various analyses, and yields und...

Measurement of free desipramine in serum by ultrafiltration with immunoassay.

We developed an ultrafiltration method for assaying free desipramine (DMI) in serum. An ultrafiltrate of DMI-containing serum was prepared by centrifugation through an Amicon Centrifree micropartition filter. Syva DMI solid-phase extraction (SPE) columns were used to extract the DMI from the serum and ultrafiltrate. The Syva monoclonal EMIT assay was used to quantify the DMI in the extract. In ...

Determination of valproic acid in serum by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.