In paper chromatography

Acid hydrolysis of the basic hexasaccharide yielded the disaccharide 31. Its mobility in paper chromatography lay between those of the corresponding (1 — 3)-linked (from S10A) and /3-(l — 6)-linked (from S29) isomers, which is why it was assumed to be (1 — 4)-linked. The (1 — 2)-linked isomer was excluded, as the D-galactose residue that is part of 31 carries a D-galactopyranosyl group linked to 0-2 in the original polysaccharide, as will be discussed. 

In each chromatographic technique, one of the four mechanisms predominates, but it should be emphasized that two or more may be involved simultaneously. Partition and adsorption frequently occur together and in paper chromatography, for example, ion-exchange and exclusion certainly play minor roles also. 

The transmethylation hypothesis depended on the psychosis of mescaline as an example of how methylated compounds similar in structure to the monoamine neurotransmitters could be psychotogenic, and demonstrated how methionine, the precursor of the methyl donor S-adenosylmethionine, could exacerbate the psychotic symptoms of schizophrenia in patients. This theory was fed by studies of the now notorious pink spot, an amine found in paper chromatography of urine extracts from schizophrenics and thought to be 3,4-dimethoxyphenylethylamine (i.e., O-methylated dopamine). Subsequent studies eventually identified this as another compound or compounds, primarily of dietary origin. Another methylated derivative erroneously proposed to be found in higher quantities in schizophrenia was dimethyltryptamine. This compound is similar in structure to LSD, the hallucinogenic nature of which was the key to the serotonin deficiency hypothesis, which proposed that the known antagonism of serotonin (5-HT) by LSD indicated that psychotic disorders such as schizophrenia may result from a hypofunction of 5-HT. 

In this section the group of polyphosphates with a chain length of n > 4 which undergo definite migration in paper chromatography is considered. They include compounds with (P 03,l+i)( +2) anions having chain length up to n 9. 

When cellulose is used as a stationary phase, with water or aqueous organic solvents as eluents, the separation of substances is by partition between the eluting mixture and the water adsorbed on the column. This is similar to the cellulose in paper chromatography. 

A sheet of high-quality filter paper containing adsorbed water serves as the stationary phase in paper chromatography. However, thin-layer chromatography, which employs a layer of silica gel or other material spread on a glass or plastic plate, has often supplanted paper chromatography because of its rapidity and sharp separations (Fig. 3-5).16/96a 98-10°... 

Because of the similarities in the theory and practice of these two procedures, they will be considered together. Both are examples of partition chromatography. In paper chromatography, the cellulose support is extensively hydrated, so distribution of the solutes occurs between the immobilized water (stationary phase) and the mobile developing solvent. The initial stationary liquid phase in thin-layer chromatography (TLC) is the solvent used to prepare the thin layer of adsorbent. However, as developing solvent molecules move through the stationary phase, polar solvent molecules may bind to the immobilized support and become the stationary phase. 

Purified substances can be isolated from developed chromatograms however, only tiny amounts are present. In paper chromatography, the spot... 

One of the classical approaches of liquid chromatography, paper chromatography, was used for chiral resolution about 50 years ago but is not part of modem practice. In paper chromatography, the stationary phase is water bonded to cellulose (paper material), which is of course chiral and hence provides a chiral surface for the enantiomers. However, some workers used chiral mobile phase additives also in paper chromatography [73,74]. In 1951 some research groups independently [73,75-77] resolved the enantiomers of amino acids. Simultaneously, numerous interesting publications on chiral resolution by paper chromatography appeared [70]. 

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