Author(s): Nadarassan DK, Chrystyn H, Clark BJ, Assi KH
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Abstract A novel high-performance liquid chromatography (HPLC) assay for the estimation of formoterol in urine samples was developed and validated. A solid phase extraction (SPE) using Oasis HLB was optimised to isolate formoterol from a urine matrix followed by HPLC with UV detection. This extraction procedure concentrated the final analyte forty times so that UV detection can be used to determine even a low concentration of formoterol in urine samples. The urinary assay was performed in accordance with FDA and ICH regulations for the validation of bioanalytical samples. The samples were injected onto a C18 Spherisorb (250 mm x 4.6 mm x 5 microm) analytical column maintained at 30 degrees C. The mobile phase consisted of 5 mM of potassium dihydrogen orthophosphate buffer (adjusted to pH 3 with ortho phosphoric acid):acetonitrile (ACN) (70:30, v/v), and the formoterol peak was detected at wavelength 214 nm. The extraction recovery of formoterol from the urine sample was >95\%. The calibration curve was linear (r2=0.99) over formoterol concentrations ranging from 1.5 to 25 ng/mL (n=6). The method had an accuracy of >92\% and intra and inter-day precision CV\% of <3.9\% and <2.2\%, respectively, at three different concentrations low, medium and high (10, 15, 20 ng/mL). The limit of quantification (LOQ) for formoterol was found to be 1.50 ng/mL. The accuracy and precision at the LOQ level were 95\% and \%CV <3.7\% (n=10), respectively. The method reported is simple, reliable, precise, and accurate and has the capacity to be used for determination of formoterol in urine samples.
This article was published in J Chromatogr B Analyt Technol Biomed Life Sci
and referenced in Pharmaceutica Analytica Acta