Determination of catecholamines in urine and plasma by on-line sample pretreatment using an internal surface boronic acid gel

An automated method of analysis of catecholamines using a new packing material, internal surface boronic acid gel, was developed. The new support is designed with a carboxymethylcellulose-bonded external surface in order to be non-adsorptive to proteins and with a phenylboronic acid-bonded internal surface to retain only catecholamines. This packing support displayed an affinity for basic or neutral catecholic compounds with no protein adsorption and enabled on-line sample pretreatment of catecholamines in urine and deproteinized plasma. The catecholamines were selectively adsorbed on the new material and separated on a reversed-phase or a cation-exchange column. These compounds were then detected electrochemically. The limits of quantitation were 1.5-3.0 ng/ml in urine and 10-15 pg/ml in plasma, at a signal-to-noise ratio of 5.