Affordable Access

Publisher Website

Simple and reliable extraction and a validated high performance liquid chromatographic assay for quantification of amoxicillin from plasma.

  • Purohit, Trusha J1
  • Wu, Zimei1
  • Hanning, Sara M2
  • 1 School of Pharmacy, The University of Auckland, 85 Park Road, Grafton, Auckland 1010, New Zealand. , (New Zealand)
  • 2 School of Pharmacy, The University of Auckland, 85 Park Road, Grafton, Auckland 1010, New Zealand. Electronic address: [email protected] , (New Zealand)
Published Article
Journal of chromatography. A
Publication Date
Oct 09, 2019
DOI: 10.1016/j.chroma.2019.460611
PMID: 31627968


This study presents the development of an efficient extraction protocol for amoxicillin from plasma with improved solubility and stability using pH control. Solubility and stability of amoxicillin in commonly used extraction solvents were determined using a newly developed stability-indicating high-performance liquid chromatography (HPLC) method. Following this, protein precipitation (PP) mediated sample purification protocol was developed and validated along with the HPLC method for the extracted amoxicillin from rabbit plasma. The protocol was applied in a pharmacokinetic study in rabbits. A five-fold increase in solubility and two-fold increase in stability of amoxicillin was found by addition of acetate buffer (0.1 M, pH 5.0) in acetonitrile. PP mediated extraction protocol containing acetate buffer-acetonitrile (1:18 v/v) resulted in an extraction recovery of >80% for all the samples. The HPLC assay following extraction was found linear (R2 >0.9999) over the range of 0.2-20 µg/mL with a lower limit of quantification of 0.2 µg/mL. The accuracy of the quality control samples was found between 97-115% and the relative standard deviation (RSD) was found to be below 6% for all samples. The samples were stable in the mobile phase (pH 5.0) for 72 h post-extraction. Amoxicillin-spiked plasma samples were found stable for up to three freeze-and-thaw cycles but, nearly 50% samples had degraded following storage for two months at -20 °C. Pharmacokinetic analysis indicated a half-life of amoxicillin of nearly 1 h following intravenous injection in rabbits, which is similar to that in humans. Thus, a simple and repeatable, extraction protocol was developed using pH control for quantification of amoxicillin from plasma based on its physicochemical properties. Copyright © 2019. Published by Elsevier B.V.

Report this publication


Seen <100 times