Trimethoprim analysis

We proposed using MLC for assay of azithromycin in tablets and capsules. As alternative conventional reversed-phase HPLC method MLC was used for analysis of Biseptol (sulfamethoxazole and trimethoprim) tablets and injection. The MLC was proposed to assay of triprolydine hydrochloride and pseudoephedrine hydrochloride in tablets as alternative normal-phase HPLC method described in USP phamiacopoeia. 

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. 

This sol-gel procedure is an elaboration on well established entrapment methods [29], but with the added advantage of stability and better flow properties. Interestingly, none of the examples presented thus far demonstrate competitive behavior between multiple ligands (i.e. displacement) in the FAC analysis of trimethoprim and pyrimethamine a reversed order of elution based on is described, but this could simply be due to the shift towards an on-rate limited situation for higher affinity compounds, as described earlier. Erosion of dynamic competition between ligands could occur if the sol-gel allows convective mixing of the entrapped protein however the bimodal pore structure of these materials would... 

For synthesis of the commercially available GFF-II version of the Pinkerton s internal surface reversed-phase, monofunctional instead of trifunctional silane has been used in order to prepare more homogenous surfaces (123). Compared with the first version, GFF-II shows significantly improved selectivity, retention capacity, and separation efficiency as demonstrated in the analysis of trimethoprim (124). 

A postchromatographic -glucuronidase procedure has been also used for the analysis of phenolic glucuronides, such as those produced from trimethoprim (274). The enzymatic analysis of these glucuronides provided the production of the corresponding phenolic compounds, which were measured by both UV and electrochemical detection. 

A preliminary investigation of SFC coupled to MS/MS for the analysis of trimethoprim, diethylstilbestrol, hexestrol, and dienestrol has demonstrated the considerable potential of this separation technique (81). Packed-column SFC has been also evaluated for the analysis of nine sulfonamides in swine kidney extracts... 

Before the extraction procedure may commence, the sample must be prepared in such a way that it is in a condition for extraction of the analyte(s). For analyzing sulfonamide residues in liquid samples such as milk, a pretreatment dilution step with water prior to direct fluorometric detection may be required (207). Dilution of milk with aqueous buffer (208) or sodium chloride solution (209) prior to sample cleanup has also been reported. For the analysis of honey a simple dissolution of the sample in water (210, 211) or aqueous buffer (212) is generally required. Semisolid samples such as muscle, kidney, and liver, require, however, more intensive sample pretreatment. The analyte(s) must be exposed to extracting solvents to ensure maximum extraction. The most popular approach for tissue break-up is through use of a mincing and/or homogenizing apparatus. Lyophilization (freeze-drying) of swine kidney has been carried out prior to supercritical-fluid extraction of trimethoprim residues (213). 

There is no clear preference for either methanol or acetonitrile as organic modifier in the mobile phase. Nevertheless, addition of alkylsulfonic acids in the mobile phase has been employed to alter the retention and improve the peak shape and separation of trimethoprim and sulfonamides ion pairs. Pentanesulfonic acid (216), hexanesulfonic acid (275), or octanesulfonic acid (238) are tire alkylsulfonic acids used in the analysis of these drugs. 

Diaminopyrimidines are used for antibacterial purposes. Although many of these compounds have some fluorescence, direct analysis is not useful because of the lack of sensitivity. The enhancement of the fluorescence of 2,4-diaminopyrimidines has been accomplished by treatment of the separated components with a solution of ammonium bisulfate [133], A fluorimetric method has also been developed for trimethoprim [2.4-diamino-5-(3,4, 5 -trimethoxybenzyl)pyrimidine] and its metabolites [134] which involves leaving the developed plates to stand for several days and then examining the increase in fluorescence. Amounts of ca. 10 ng could be detected after this time. 

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-... 

J. J. Bergh, J. C. Breytenbach, and J. L. Du Preez, High-performance liquid chromatographic analysis of trimethoprim in the presence of its degradation products, J. Chromatogr., 573 392 (1990). 

MarineUa MA. Trimethoprim-induced hyperkalemia An analysis of reported cases. Gerontology 1999 45(4) 209-12. 

Van der Steuijt, K. Sonneveld, P. Concurrent analysis of methotrexate, trimethoprim, sulfamethoxazole and their major metabolites in plasma by high-performance liquid chromatography. J.Chromatogr., 1987, 422, 328-333... 

Bonazzi, D. Andrisano, V. Di Pietra, A.M. Cavrini, V. Analysis of trimethoprim-sulfonamide drug combinations in dosage forms by UV spectroscopy and liquid chromatography (HPLC). Farmaco, 1994, 49, 381-386 [simultaneous sulfadiazine, sulfamethox3q>yridazine, trimethoprim]... 

Erdmann, G.R. Canafax, D.M. Giebink, G.S. Hi -performance liquid chromatographic analysis of trimethoprim and sulfamethoxeizole in microUter volumes of chinchilla middle ear effusion and serum. J.Chromatogr., 1988, 433, 187-195 [LOQ 500 ng/mL LOD 250 ng/mL cimetidine (IS) column temp 45° extracted trimethoprim pharmacokinetics]... 

Bergh, J.J. Breytenbach, J.C. Stability-indicating high-performance liquid chromatographic analysis of trimethoprim in pharmaceuticals. J.Chromatogr., 1987, 387, 528-531... 

In 2008, Carretero et al. described a multi-class method for the analysis of 31 antibacterials (including f)-lactams, macrolides, lincosamides, quinolones, sulfonamides, tetracyclines, nitroimidazoles, and trimethoprim) in meat samples by PLE-LC-MS/MS. Meat samples were homogenized and blended with EDTA-washed sand, then extracted with water by applying 1500 psi (Ib/in. ), at 70°C. One extraction cycle was 10 min. A drawback of the method is the large volumes of extracts (40 ml) obtained, which required evaporation to concentrate the extract volume prior to final analysis. This evaporation step considerably increases the time required for sample preparation. The proposed method has been applied to the analysis of 152 samples of cattle and pig tissues, with the presence of quinolones, tetracyclines, and sulfonamides detected in 15% of the samples, although at concentrations below the MRLs. 

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