SENSITIVE QUANTIFICATION OF DICLOFENAC AND IBUPROFEN USING THIN LAYER CHROMATOGRAPHY COUPLED WITH A VIBRIO FISHERI BIOLUMINESCENCE ASSAY

Abstract

We present a video-densitometric quantification method for the pain killer known as diclofenac and ibuprofen. These non-steroidal anti-inflammatory drugs were separated on cyanopropyl bonded plates using CH₂Cl₂, methanol, cyclohexane (95 + 5 + 40, v/v) as mobile phase. The quantification is based on a bio-effective-linked analysis using Vibrio fisheri bacteria. Within 10 min a CCD-camera registered the white light of the light-emitting bacteria. Diclofenac and ibuprofen effectively suppressed the bacterial light emission which can be used for quantification within a linear range of 10 to 2000 ng. The detection limit for ibuprofen is 20 ng and the limit of quantification 26 ng per zone. Measurements were carried out using a 16-bit ST-1603ME CCD camera with 1.56 megapixels (from Santa Barbara Instrument Group, Inc., Santa Barbara, USA). The range of linearity covers more than two magnitudes because the extended Kubelka-Munk expression is used for data transformation. The separation method is inexpensive, fast, and reliable.

Keywords:

• bioeffective-linked analysis
• diclofenac
• HPTLC
• ibuprofen
• Kubelka-Munk equation
• linear calibration range
• quantification
• TLC
• Vibrio fisheri
• video densitometry

ACKNOWLEDGMENTS

The authors express their appreciation to Merck-Company (Darmstadt, Germany), Machery & Nagel (Düren, Germany), DESAGA GmbH (Wiesloch, Germany) and the DFG (Deutsche Forschungsgemeinschaft) for support.