Anion Exchange Gradient Method

At present the most used techniques for the separation and identification of organic and organophos-phorus compounds are HPLC and GLC. Procedures have been well developed for the introduction of chromatographically separated samples into mass spectrometers, and GLC/MS and HPLC/MS are well-established techniques. 

Phosphopeptides can be separated on an ion-exchange column. Mixtures of phosphoserine, phosphothreonine and phosphotyrosine, for example, and mixtures of other bio materials such as inositol phosphates can be successfully estimated. Casein components can be separated and estimated by liquid chromatography [46-50]. 

FIGURE 14.7 Chromatographic analysis of a nucleotide mixture. Anion exchange gradient method. 

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Brisbin, J.A., B Hymer, C., Caruso, J.A. A gradient anion exchange chromatographic method for the speciation of arsenic in lobster tissue extracts. Talanta 58, 133-145 (2002)... 

Purine nucleotides were determined by an anion-exchange gradient HPLC method (6). This method separates all major purine nucleotides as well as the ribonucleotide from the deoxyribo-nucleotide form. 

Initial Fractionation. The most effective method found for the initial fractionation of the complex enzyme mixtures present in wood-culture extracts was anion exchange chromato phy eluting with salt gradients (9,74,75). This permitted further sample concentration by functioning as a solid phase extractant during loading. It also showed higher sample capacity and better separations than other methods. 

Several HPLC methods have been reported for the determination of xanthine and hypoxanthine. Different RP-HPLC methods, using gradient elution and UV detection, have been described to determine these metabolites and other methylated purines.To improve xanthine determination in urine samples, analyses were carried out with two columns—reversed-phase column and anion exchange column—connected by a column switch. With this method, urinary hypoxanthine and xanthine can be measured without any sample preparation other than filtration. ... 

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