Collaborative study of a column chromatographic method for bendroflumethizide and cyclothiazide.

Bendroflumethiazide and cyclothiazide are eluted from a sodium carbonate column with chloroform-acetic acid (98+2) and are measured directly by ultraviolet spectrophotometry. The method was collaboratively studied by 8 analysts. The average per cent recovery and standard deviations for simulated mixes of bendroflumethiazide and cyclothiazide were 99.61+/-0.78 and 99.3+/-1.97. The method has been adopted as official first action for the determination of bendroflumethiazide.