The determination of free and sulfoconjugated catecholamines (CA) in serum and urine
with amperometric detection after HPLC separation is described. The reliability of
this method has been extensively investigated. Since in men 69-90% of the total CA
are sulfoconjugated, an enzymatic hydrolysis of these conjugates with arylsulfatase
VI has been elaborated and optimized for a routine assay. The reproducibility with
coefficients of variation between 1% and 3% for free and 5% and 10% for conjugated
CA and recovery rates of 65%-75% for both were found. The calibration plots were linear
between 10 and 5000 ng/1 and the smallest detectable amount of CA was 0.1 nmol/1.
The sample amount of 0.75 to 1.0 ml for free and 0.2 ml for conjugated CA was lower
than with the extraction method (18) which needs 3 ml of serum. Using an automatic
sampler, the sampling rate was 50-60 p.d. With the AI2O3 adsorption and the same buffer eluent system, L-dopa can also be detected at the
same voltage of 700 mV. The values obtained for the HPLCA described method correlated
well with those of the radio enzyme assays according to Da Prada et al. (7). The HPLCA
detection of free and sulfoconjugated CA in urine was carried out after an ion exchange
column procedure on Biorex 70. The validity of the urine assay was at least as reliable
as the determination of free and conjugated CA in plasma.
catecholamines - HPLC - amperometric detection - sulfoconjugates - deconjugation by
sulfatase - AV differences
