SOLVENT EXTRACTION-FLOW INJECTION ANALYSIS FOR DETERMINATION OF TRIMETHOPRIM IN COMPOUND PREPARATIONS

Trimethoprim (TMP)in four pharmaceutical preparations (compound sulfamethoxazol tablets, compound tetracycline tablets, compound trimethoprim and sulfamethoxazol tablets, and compound berberine injection) is determined by solvent extraction- flow injection spectrophotometry. It can be extracted into chloroform directly,and the absorbance at a wavelength of 280 nm of the organic phase is measured after phase separation. The manifold comprises two streams. The sample is injected into a 0.2 mol/L NaOH carrier stream, and extracted with chloroform in a 200 cm coil (ID 0.7 mm) after a 50 cm reaction tube (ID 1.0 mm ). Calibration graph is linear in the range of 25～ 150μg/ml. The average recovery is 101.4 % with a relative standard deviation of 1.1%. The proposed system permits the analysis of about 50 samples per hour. Precise results in agreement with those obtained with officical methods are achieved.