Validation of high-performance liquid chromatography assay for quantification of formoterol in urine samples after inhalation using UV detection technique

Nadarassan, D.K., Chrystyn, Henry, Clark, Brian J. and Assi, K.H. (2007) Validation of high-performance liquid chromatography assay for quantification of formoterol in urine samples after inhalation using UV detection technique. Journal of Chromatography B, 850 (1-2). pp. 31-37. ISSN 15700232

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 × 4.6 mm × 5 μm) analytical column maintained at 30 °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

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