Abstract
The residual oxytetracycline analysis in cinnamon by dispersive solid-phase extraction using high-performance liquid
chromatography (HPLC) was developed and validated. Oxytetracycline was extracted using McIlvaine buffer containing
ethylenediaminetetraacetic acid (EDTA-2Na). The removal of matrix components derived from cinnamon was carried out using
hexane distribution, solid-phase column extraction, and dispersive solid-phase extraction with Z-sep (zirconia-coated silica gel). After
the removal of the solvent, the extract was dissolved in a potassium phosphate solution and analyzed by HPLC with a photodiode
array detector (PDA). An interfering peak was not observed in the cinnamon extract chromatograms, indicating the high selectivity
of this method. Method validation was performed by recovery tests at the maximum residue limit (MRL) concentration (0.1 µg/g) to
evaluate the trueness, repeatability (RSDr), and with-in laboratory reproducibility (RSDwr). The validation results exhibited sufficient
recovery (range, 79-81%) and precision (RSDr ≤ 5% and RSDwr ≤ 7%). These values fulfilled the criteria for the validation guidelines
for residual pesticide analysis in Japan. The limit of quantification (LOQ) of this method was 0.03 µg/g in Chinese and Ceylon
cinnamon. The time required for the preparation of eight test sample solutions was less than four hours. This method can help inspect
residual oxytetracycline in cinnamons.
