Diode laser induced fluorescence detection for the far-red analysis of pharmaceutical compounds by capillary electrophoresis and capillary electrochromatography

Capillary Electrophoresis (CE) and Capillary Electrochromatography (CEC) are powerful analytical separation techniques with favorable figures of merit. Both CE and CEC have decreased concentration sensitivity, however, when compared to HPLC. Capillary techniques in combination with visible diode laser induced fluorescence (VDLIF) detection (620–700 nm) can provide increased concentration sensitivity and selectivity.; Doxorubicin, an anti-cancer drug containing a primary amine was chosen as a model analyte for the purpose of CEC-VDLIF detection. A method was developed for the derivatization of doxorubicin with Cy5.29.OSu. The LOD of the assay in plasma calculated as 3 s_b/m was determined to be 1.7 ng/ml. The calibration curve was linear from 16.7 to 671 ng/ml. The precision of the assay determined at a concentration of 167.7 ng/ml was found to be within 7.04% RSD.; An alternate VDLIF detector that used a collinear design was constructed and evaluated in comparison with the earlier system. A LOD (3 s _b/m) of 1.2 × 10–12 M for Cy5.29 carboxylic acid was achieved. The collinear system was found to be more sensitive than the orthogonal design by greater than one order of magnitude. The increased sensitivity of the collinear system can be attributed to the fluorescence microscope. The collinear design therefore has the potential to further decrease the detection limits obtained for amantadine and doxorubicin in plasma.; An orthogonal VDLIF detection system was constructed in our laboratory for capillary electrophoresis/electrochromatography. The limit of detection (LOD) of the VDLIF system for Cy5.29 carboxylic acid, calculated as 3 s_b/m was determined to be 7.4 × 10–11M.; Amantadine, a low molecular wt. primary amine was chosen as a model analyte for CE-VDLIF detection. A method was developed for the derivatization of amantadine with Cy5.29.OSu, a far-red label. Baseline resolution of the derivative from other reaction products was achieved by investigation of the complex interactions involved between the analyte, the physical and electrical properties of the mobile phase and the charged double layer that exists on the capillary wall. Baseline resolution was achieved by employment of a partition mechanism through addition of micelles to the run buffer. The precision and accuracy of the assay (n = 6) were determined to be within 17% RSD and 15% difference from the nominal concentration respectively. The LOQ of the assay was determined to be 1.8 ng/ml. (Abstract shortened by UMI.)...