Trimethoprim, separation from

The two examples of sample preparation for the analysis of trace material in liquid matrixes are typical of those met in the analytical laboratory. They are dealt with in two quite different ways one uses the now well established cartridge extraction technique which is the most common the other uses a unique type of stationary phase which separates simultaneously on two different principles. Firstly, due to its design it can exclude large molecules from the interacting surface secondly, small molecules that can penetrate to the retentive surface can be separated by dispersive interactions. The two examples given will be the determination of trimethoprim in blood serum and the determination of herbicides in pond water. 

Pulse polarography has also been used to measure dantrolene in plasma [181] and trimethoprim [192] and nitroimidazoles in blood [193,194]. The overall recovery of the trimethoprim assay was reported to be 81.7 6.3% (SD) with a detection limit of 0.5-0.75 fxg/mL of blood. There was no interference from the sulfamethoxazole, which is administered simultaneously. Glibomuride [195], phenobarbital, and diphenylhydantoin [97] have all been determined as their nitro derivatives after extraction from blood. The recovery of phenobarbital and diphenylhydantoin from blood was 72.3 6.5% (SD) and 76.6 2.3% (SD), respectively, with a detection limit of 1-2 fxg/mL. A modified assay [97] for the determination of both compounds in blood with TLC separation was also described. A differential pulse polarography determination of cephalosporin antibiotics in human serum samples has recently been described [196]. 

The SFC analysis of mercaptopurine, trimethoprim, triprolidine, pseudoephedrine, permethrin, zidovudine, and trifluridine was reported by Mulcahey and Taylor [9]. The mobile phase was carbon dioxide containing methanol and the packed column was a cyanopropyl (250 x 4.6 mm ID). Figures 7.11 and 7.12 show separations of the compounds of interest. In order to elute trimethoprim from the column without severe tailing, tetra-... 

Figure 7.12 Separation of three compounds using tetrabutylammonium hydroxide in the mobile phase. Elution order (1) permethrin, (2) zidovudine, (3) trimethoprim. Flow = 2 ml/min C02, 100 /d methanol-tetrabutyl-ammonium hydroxide for 2.0 min, 100-500 /d/min methanol-tetrabutyl-ammonium hydroxide for 2.0 min, 100-500 fd/min methanoI-TBAOH in 4.0 min, hold at 500 /d/min. Column Deltabond CN (250 x 4.6 mm ID). Oven temperature 60°C UV detection at 254 nm. (Reprinted from Ref. 9 with kind permission of Dr. Alfred Huthig Verlag GmbH, Heidelberg.)...

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