We tested the reproducibility of ambulatory blood pressure monitoring (ABPM) by the use of agreement plots. Thirty-two normotensive volunteers underwent ABPM on four separate days (interval 28 days), on the same typical weekday. Sleeping time was restricted to the ABPM nighttime subperiod from 11:00 PM to 7:00 AM. Twenty-four-hour average values-both systolic and diastolic-daytime average values, and nighttime average values, as well as standard deviation (SD) values, were analyzed for differences (analysis of variance). Adaptation occurred from the first to the fourth ABPM, ie, average 24 h, daytime, and nighttime values were lower (-1 to -3 mm Hg) during the fourth recording than the first (P < .05 to P < .01). The agreement analysis showed a surprisingly high agreement among the four data sets (ie, differences from +/-2.54 to +/-5.92 mm Hg; +/-2 SD of the distribution). We concluded that reproducibility of ABPM seems excellent, but adaptation may occur, even in normotensive volunteers under research conditions. Caution must be paid before labeling a patient as hypertensive, because initial ABPM may yield higher values than later monitorings.

We present a method involving minor modifications of previous techniques, in which we use an ion-pair reversed-phase HPLC separation with three-electrode coulometry. Isocratic baseline separations can be obtained in 5 min. The sample preparation procedure, involving extraction with alumina at low temperature, allows good reproducibility (within-run and between-run CVs less than 10%) and improved sensitivity (less than 5 pg of each catecholamine per extract). This method allows approximately 70 low-cost plasma catecholamine analyses to be done in a working day.

Epinine is the active moiety of ibopamine, a cardiovascular prodrug used in congestive heart failure. This catecholic compound shows dopaminergic and adrenergic properties. Moreover the drug seems to affect plasma catecholamine levels in patients with heart failure. Here we present a method developed for the simultaneous determination of epinine and catecholamine plasma levels. Free epinine and catecholamines were extracted from human venous plasma via an alumina adsorption procedure. The extracts underwent an ion-pair reversed-phase HPLC separation with three-electrode coulometry. Quantitation was made by an internal standard method. Coefficients of variation were < 9%. The validity was assessed as the peak height—picograms correlation (r >0.997). The detection limits were ≤ 5 pg of each catechol after extraction. This method allows about 50 low cost determination to be done in a working day.