High-performance liquid chromatographic determination of m-iodobenzylguanidine in urine of cancer patients

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

A sensitive chromatographic assay has been developed for m-iodobenzylguanidine (MIBG) in human plasma based on the derivatization with benzoin. MIBG is first isolated from plasma using solid-phase extraction on a cyanopropyl-modified silica phase. After evaporation of the eluate, a fluorescent derivative is formed using benzoin. The derivative is analysed by reversed-phase liquid chromatography using a mixture 60% (v/v) acetonitrile, 30% (v/v) water and 10% (v/v) of the 0.5 M Tris buffer (pH 8.0) as the eluent and fluorescence detection at 320 nm for excitation and 435 nm for emission, respectively. In the evaluated concentration range (2-200 ng/ml) precisions < or = 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 benzylguanidine. The assay was successfully used to obtain a pharmacokinetic curve of MIBG.

High-performance liquid chromatographic determination of metaiodobenzylguanidine in whole blood and plasma of cancer patients

An accurate and simple high-performance liquid chromatographic (HPLC) assay is presented for the quantitative determination of metaiodobenzylguanidine (MIBG) in human whole blood and plasma. The sample pretreatment involves a solid-phase extraction on Bakerbond SPE cyano columns. The HPLC system comprises a microBondapak C18 column and ammonium phosphate (pH4.0; 25 mM)-acetonitrile (80:20, v/v) as the mobile phase. Detection is performed by UV absorbance measurements at 254 nm. Linear regression with weighting factor l/chi 2 yielded the smallest sum of per cent relative concentration residuals over the concentration range of the assay (0.1-10 micrograms ml-1). MIBG levels, at the end of a 3-h infusion, in whole blood and plasma of carcinoid patients were measured and compared with the results obtained with radiodetection after addition of iodine-131-labelled MIBG.