Typical chromatograms of plasma extracts produced by HPLC-EC and LC-MS/MS are shown in Fig.
We compared the results obtained by the LC-MS/MS and the HPLC-EC methods for patient specimens routinely screened for pheochromocytoma (Fig.
50 nmol/L for MN, which were established with the HPLC-EC method from samples collected in an ambulatory position.
HPLC-EC has been the methodology of choice for estimation of NMN and MN in plasma of patients being screened for pheochromocytoma (1, 2).
Recently, the interference of acetaminophen in the HPLC-EC method was addressed by lengthening the chromatographic run time (20).
The LC-MS/MS method for urinary conjugated metanephrines has been validated and implemented in our clinical laboratory and has replaced the colorimetric and HPLC-EC methods.
22) also reported a rapid HPLC-EC procedure for the determination of Co[Q.
Yamashita and Yamamoto (23) reported a HPLC-EC procedure using single extraction with methanol-hexane (1:2 by volume; Table 1).
Lyophilized products from human blood, highly purified chemicals and biochemicals, and commonly prescribed drulys tested for potential interference with HPLC-EC.
The mean plasma concentration of SAM detected with the present HPLC-EC
method in women with normal tHcy was 156 nmol/L, which is considerably higher than previously published values of 26.