Merck, Darmstadt, Germany) was BI 6727 used as the stationary phase. Sample application was done by using a Camag 100 ��l syringe and a Camag Linomat V applicator. The sample was sprayed in the form of narrow bands of 8 mm length at a constant rate 2 ��l/s. Linear ascending development was carried out in a 20 cm �� 10 cm twin trough glass chamber (Camag, Muttenz, Switzerland). The densitometric scanning was performed by using a Camag TLC scanner III supported by win CATS software (V1.4.2.8121 Camag). Chromatogram was evaluated by using a ratio of peak areas of drugs with an internal standard. Chemicals CEFPO (Blue Cross Laboratories Ltd., Ambad Nashik, India), AMBRO (Blue Cross Laboratories Ltd., Ambad Nashik, India), and paracetamol (Kirti Pharmachem Ltd., Sinner, Maharashtra, India) were received having 98.

80%, 98.70% and 100.1% purity, respectively. They were used as such without checking their purity. The HPLC grade methanol and Analytical reagent grade chloroform were purchased from S D Fine Chem. Ltd., Mumbai, India. Human plasma used for research work was supplied by Arpan Blood Bank, Nashik, Maharashtra, India. Preparation of stock solution and working standard solution Stock solutions 1.0 mg/ml each of CEFPO, AMBRO and paracetamol were prepared in methanol. Preparation of plasma sample In a 15 ml centrifuge tube 10, 20, 30, 40, 50, and 60 ��l of working stock solution of CEFPO were added to drug-free plasma to provide calibration standards of 500, 1000, 1500, 2000, 2500, and 3000 ng/ml and 2, 4, 6, 8, 10, and 12 ��l of working stock solution of AMBRO were added to drug-free plasma to provide calibration standards of 1000, 2000, 3000, 4000, 5000, 6000 ng/ml and 1000 ng/ml of paracetamol (internal standard) was kept constant.

The quality control (QC) samples were prepared in plasma in the concentration range 1000, 2000, 3000 ng and 2000, 4000, 6000 ng for CEFPO and AMBRO. Protein precipitation and extraction were carried out by using 3 ml of methanol and 0.1 ml of acetonitrile by vigorous vortex mixing using a remi mixer for 2 min and centrifuged at 5000 rpm at 10 min. The organic phase was recovered and evaporated to dryness on a hot plate. The residual mass was reconstituted with 1 ml of methanol. The analysis was carried on HPTLC. Chromatographic condition The mobile phase was selected as a mixture of chloroform and methanol (9.0:1.0 Brefeldin_A v/v) for the development of plates. Time for chamber saturation was optimized to 10 min. The length of the chromatographic development was 70 mm. The densitometric scanning was performed at 240 nm. Method validation The method was validated for sensitivity, selectivity, precision, accuracy, linearity, recovery, and stability.