Correa COJ, Ruiz CAM, Restrepo GMM

Language: Spanish
References: 17
Page: 23-33
PDF size: 256.17 Kb.

ABSTRACT

Introduction: the diclofenac quantitation in small volume and low analyte concentration samples is complex and requires a simple, highly sensitive and reproducible analytical method.
Objective: to standardize a high performance liquid chromatography with precolumn photoderivatization to quantitate diclofenac in small volume and low analyte concentration samples.
Methods: diclofenac photoproducts were obtained by irradiating samples at λ = 254 nm in quartz polytetrafluoroethylene (PTFE) and polyvinyl chloride (PVC) cells placed in different positions of the irradiation area for 6, 24 and 60 minutes respectively. For the separation of photoproducts, a C-18 Agilent Eclipse Plus column (5 µm, 150 mm; 4.6 µm id.) was used, with a mobile phase containing a mixture of acetonitrile and water pH 3.0 adjusted with ortho-phosphoric acid, in different proportions until the optimal one was found; the flow rate of mobile phase was 1.0 mL/min with column temperature of 30 °C. The sample injection volume was 20 µL. Photoproducts were detected through fluorescence with excitation and emission wavelength at 286 and 360 nm respectively.
Results: diclofenac photodegradation in PTFE cells occurs within 6 minutes when solutions are irradiated at 254 nm in the central part of the irradiation area. The separation of the three major photoproducts was accomplished using a mobile phase of acetonitrile: water adjusted with ortho-phosphoric up to pH= 3.0;65:35. The photoproduct at 3.4 minutes was eluted at high stable concentrations, with a linear trend presented in an area graph versus diclofenac concentration in the range of 1.25-500 ng/mL.
Conclusions: a new HPLC-method for quantitation of diclofenac in small volume and low concentration samples was standardized; it may undergo validation process.

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