Dimethylformamide spectrophotometry

TLC spectrophotometry is used to determine zirconium in Mg-Al alloy. For this purpose, the alloy sample (2 g) is dissolved in HNO3 (20 ml, 6 M), and zirconium is extracted in 6 ml of 0.02-M diantipyrilmethane (DAM) solution in chloroform. The extract was concentrated to 0.4 ml and an aliquot (10 p,l) was chromatographed on silica gel LS plate using 4-M HCl -f dimethylformamide (1 2) as the mobile phase. After development, the portion of the sorbent layer containing the zirconium-DAM complex was removed, and the metal was extracted with 6-M HCl. The zirconium present in this solution was determined in the form of a xylenol orange complex (Amax, 540 nm) by spectrophotometry [22]. 

Das and Haider described a simultaneous spectrophotometrie method for the analysis of binary dosage form mixtures of diloxanide furoate with metronidazole or with tinidazole [19], Powdered tablets or suspension, equivalent to 50 mg of the drug substances, were dissolved in 50 mL of dimethylformamide with shaking. After 15 minutes, the solution was diluted to 100 mL with water and filtered. A 1 mL portion of the filtrate was diluted to 50 mL with water, and the absorbance of the resulting solution measured at 320 and 262 nm for metronidazole and diloxanide furoate simultaneously. Alternatively, readings were taken at 318 and 262 nm for the simultaneous determination of tinidazole and diloxanide furoate. Recoveries were reported to be quantitative. 

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