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Quantitation of valproic acid in pharmaceutical preparations using dispersive liquid‐liquid microextraction followed by gas chromatography‐flame ionization detection without prior derivatization
Author(s) -
Sobhi Hamid Reza,
Kashtiaray Amir,
Farahani Hadi,
Abrahimpour Farshad,
Esrafili Ali
Publication year - 2010
Publication title -
drug testing and analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.065
H-Index - 54
eISSN - 1942-7611
pISSN - 1942-7603
DOI - 10.1002/dta.131
Subject(s) - chromatography , chemistry , derivatization , disperser , flame ionization detector , detection limit , solvent , extraction (chemistry) , aqueous solution , acetone , gas chromatography , gas chromatography–mass spectrometry , analytical chemistry (journal) , high performance liquid chromatography , mass spectrometry , materials science , organic chemistry , composite material
Dispersive liquid‐liquid microextraction (DLLME), coupled with gas chromatography‐flame ionization detection (GC‐FID), has been successfully used for the extraction and determination of valproic acid (VPA) in pharmaceutical preparations. In the developed method, an appropriate mixture of extracting and disperser solvents was rapidly injected into an aqueous sample. Having formed a cloudy solution, the mixture was centrifuged and then the extracting solvent was sedimented at the bottom of a conical test tube. The extract was then injected into a GC system directly, without any further pretreatment. Initially, microextraction efficiency factors were optimized and the optimum experimental conditions found were as follows: tetrachloroethylene (9.0 µL) as extracting solvent; acetone (1.0 mL) as disperser solvent; 5 mL acidic aqueous sample (pH 1) without salt addition. Under the selected conditions, the calibration curve showed linearity in the range of 0.1–5.0 mg/L with regression coefficient corresponding to 0.9998. The limit of detection was found to be 0.05 mg/L. Finally, the method was applied for the determination of VPA in two different pharmaceutical preparations. A reasonable intra‐assay (3.9–10.8%, n = 3) and inter‐assay (5.6–11.4%, n = 3) precision illustrated the good performance of the analytical procedure. The protocol proved to be rapid and cost‐effective for screening purposes. Copyright © 2010 John Wiley & Sons, Ltd.