Reversed-phase degradation products

R Wessels, J. Ogorka, G. Schwinger and M. Ulmer, Elucidation of the structure of drug degradation products by on-line coupled reversed phase HPEC-GC-MS and on-line deiivatization , J. High Resolut. Chromatogr. 16 708-712 (1993). 

Tsuji and Goetz24 developed a quantitative high performance liquid chromatographic method for separating and measuring erythromycins A, B, and C, their epimers and degradation products. This method uses a /iBondapak Ci 8 reverse column with acetonitrile-methanol-O.2m ammonium acetate-water (45 10 10 25) as solvent. The pH and composition of the mobile phase may be adjusted to optimize resolution and elution volume. The authors utilized the procedure on USP reference standard and report a relative standard deviation of 0.64%. 

In order to study simultaneously the behaviour of parent priority surfactants and their degradation products, it is essential to have accurate and sensitive analytical methods that enable the determination of the low concentrations generally occurring in the aquatic environment. As a result of an exhaustive review of the analytical methods used for the quantification within the framework of the three-year research project Priority surfactants and their toxic metabolites in wastewater effluents An integrated study (PRISTINE), it is concluded that the most appropriate procedure for this purpose is high-performance (HP) LC in reversed phase (RP), associated with preliminary techniques of concentration and purification by solid phase extraction (SPE). However, the complex mixtures of metabolites and a lack of reference standards currently limit the applicability of HPLC with UV- or fluorescence (FL-) detection methods. 

Figure 4.12 Analysis of biosynthetic human growth hormone by isocratic reversed-phase chromatography. To generate all possible degradation products, a production lot of HGH was exposed to 40°C. The profile of the unstressed HGH is shown in the upper trace. (Reproduced from R.M. Riggin, G.K. Dorulla, and DJ. Miner, Anal. Biochem., 167 199 [1987]. With permission from Elsevier Science.)...

Kirchoff, C., Bitar, Y., Ebel, S., and Holzgrabe, U. (2004). Analysis of atropine, its degradation products and related substances of natural origin by means of reversed phase high performance liquid chromatography./. Chromatogr. A 1046, 115-120. 

The most commonly used stationary phase for the separation of aspartame from synthesis intermediates, stereoisomers, and degradation products is the reverse-phase Cl8 column. As can be seen on Table 2, the main type of the mobile phase used is a phosphate buffer at pH ranging from 2.5 to 5.0 associated with acetonitrile (14,55,80,83). Reverse-phase HPLC with gradient elution of acetonitrile in phosphate buffer has also been used (16,78). 

A reverse-phase column and a mobile phase of 12.5 mM KH2P04 (pH 3.5) acetonitrile (9 1, v/v) was used by Prodolliet and Bruelhart (33) for the separation of alitame from saccharin, acesul-fame-K, dulcin, aspartame and its degradation products, other food additives, and other constituents. 

Reverse-phase chromatography has been used for the determination of dulcin. Veerabhadrarao et al. (27) described a method for the separation of dulcin, acesulfame-K, and saccharin on pBondapak Cl8 using methanol acetic acid water (7 1 12, v/v). Prodolliet and Bruelhart (33) used the same column, but a mobile phase of 12.5 mM KH2P04 (pH 3.5) acetonitrile (9 1, v/v) for the separation of dulcin from saccharin, acesulfame-K, alitame, aspartame and its degradation products, other food additives, and natural constituents. Lawrence and Charbonneau (16) used a gradient of 0-100% mobile phase B (20 mM KH2P04, pH 3.5 acetonitrile, 8 2, v/v) in A (20 mM KH2P04, pH 5.0 acetonitrile, 97 3, v/v) on Supelcosil LC-18 for the separation of dulcin from saccharin, aspartame, acesulfame-K, cyclamate, sucralose, and alitame. 

Cadet J, Voituriez L, Berger M (1983) Separation of nucleic acid components and their radiation-induced degradation products on chemically bonded C12 reversed-phase thin-layer plates. J Chromatogr 259 111-119... 

El-Sherif et al. [79] developed and validated a reversed-phase HPLC method for the quantitative determination of omeprazole and two other proton pump inhibitors in the presence of their acid-induced degradation products. The drugs were monitored at 280 nm using Nova-Pak Ci8 column and mobile phase consisting of 0.05 M potassium dihydrogen phosphate-methanol-acetonitrile (5 3 2). Linearity range for omeprazole was 2-36 fig/ml. The recovery of omeprazole was 100.50 0.8%, and the minimum detection was 0.54 /zg/ml. The method was applied to the determination of pure, laboratory prepared mixtures, and pharmaceutical dosage forms. The results were compared with the official USP method for omeprazole. 

High selectivity, good DCs values Reversible can be cycled many times Commercial availability of components Robust to degradation Degradation products wash out Low solubility loss to the aqueous phase Resists effects of impurities... 

I. Beaumont and T. Deek, Determination of morphine, diamor-phine and their degradation products in pharmaceutical preparation by reversed-phase high-performance liquid chromatography, J. Chromatogr., 238 520(1982). 

E. Vidal, M. Guigues, G. Balansard, and R. Elias, Determination of ophthalmic therapeutic metipranolol and its degradation product by reversed-phase HPLC, J. Chromatogr., 348 304 (1985). 

R. Cross and Cunico, Reversed-phase chromatography of aspara-tame and its degradation products using uv and fluorescence, LC Mag., 2 678 (1984). 

A stability indicating HPLC method has been developed to measure etodolac in presence of three main degradants, 7-ethyl-2-( 1 -methylene-propyl)- 1 -//-indole-3 -ethanol, the decarboxylated product of etodolac, and 7-ethyltryptophol [23]. A reverse phase ODS column (15 cm x 0.41 cm i.d., 5 pm particles) was used to achieve separation. The mobile phase... 

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