. Author manuscript; available in PMC: 2012 Dec 15.

Published in final edited form as: Anal Chem. 2011 Nov 28;83(24):9384–9390. doi: 10.1021/ac201973v

Table 1.

Determination of free phenytoin concentrations by ultrafiltration and RDIA

	Measured Free Phenytoin Conc. (µM)^a
Sample	Ultrafiltration	RDIA
550 µM HSA + 10 µM Phenytoin	2.4 (±0.3)	2.6 (±0.6)
550 µM HSA + 16 µM Phenytoin	3.7 (±0.2)	4.1 (±0.3)
Serum + 12 µM Phenytoin	2.5 (±0.1)	2.4 (±0.2)

All measurements were made in duplicate or triplicate at 37°C and in pH 7.4, 0.067 M potassium phosphate buffer. The values in parentheses represent ±1 standard error of the mean. The data for the drug/protein mixtures were obtained using labeled antibodies and the serum results were obtained using labeled F_ab fragments.