Bioanalysis of m-iodobenzylguanidine in plasma by high-performance liquid chromatography after derivatization with benzoin

A sensitive chromatographic assay has been developed for m-iodobenzylguanid ine (MIBG) in human plasma based on the derivatization with benzoin. MIBG i s first isolated from plasma using solid-phase extraction on a cyanopropyl- modified silica phase. After evaporation of the eluate, a fluorescent deriv ative is formed using benzoin. The derivative is analysed by reversed-phase liquid chromatography using a mixture 60% (v/v) acetonitrile, 30% (v/v) wa ter and 10% (v/v) of the 0.5 M Tris buffer (pH 8.0) as the eluent and fluor escence detection at 320 nm for excitation and 435 nm far emission, respect ively. In the evaluated concentration range (2-200 ng/ml) precisions less t han or equal to 10% and accuracies in between 90 and 100% have been found, with 2 ng/ml being the lower limit of quantification using a 0.5-ml plasma sample volume. The assay can also be used without the internal standard ben zylguanidine. The assay was successfully used to obtain a pharmacokinetic c urve of MIBG. (C) 1999 Elsevier Science B.V. All rights reserved.