A combination of isocratic and gradient elution modes in HPLC with the aid of time-overlapping process for rapid determination of methyldopa in human urine
Emara S.; Masujima T.; Zarad W.; Kamal M.; Fouad M.; El-Bagary R.
Date issued:
2015
Publisher:
Taylor and Francis Inc.
Series Info:
Journal of Liquid Chromatography and Related Technologies
38
Type:
Article
Keywords:
October University for Modern Sciences and Arts
,
جامعة أكتوبر للعلوم الحديثة والآداب
,
University of Modern Sciences and Arts
,
MSA University
,
coupled-column
,
double injection
,
fluorescence detection
,
HPLC
,
methyldopa
,
mixed elution modes
,
Coupled-column
,
Elution modes
,
Fluorescence detection
,
HPLC
,
Methyldopa
,
acetic acid
,
acetonitrile
,
buffer
,
methyldopa
,
Article
,
calibration
,
elution
,
fluorescence
,
high performance liquid chromatography
,
human
,
pH
,
quality control
,
time
,
urinalysis
,
urinary excretion
,
validation study
Abstract:
A new rapid time-overlapping high-performance liquid chromatography method using coupled-column double-injection technique with fluorescence detection has been developed and validated to determine methyldopa (MTD) in human urine. The method was based on injecting a new sample onto the second column before finalizing the cleanup and the re-equilibration of the first column for the former sample. A combination of isocratic and gradient elution was employed according to a pre-set program. At the beginning, isocratic step of acetate buffer solution (0.1 M, pH 2.4) was set until 7 min. Subsequently, a gradient elution step using acetate buffer (0.1 M, pH 2.4) as mobile phase A and acetonitrile as mobile phase B was employed. After the end of each gradient step, the column was re-equilibrated with 4 mL of the starting isocratic elution system before the next analysis. The overall cycle time was 7 min per each sample. The calibration curve was linear over the concentration range of 0.1-40 ?g/mL MTD. The overall mean recoveries were in the range of 98.29-101.39%. The applicability of the method was successfully evaluated by monitoring the incremental urinary excretion of MTD in human urine over 12 hr after a single oral administration of 250 mg. � 2015 Taylor & Francis Group, LLC.
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