Substituent distribution along the cellulose backbone in O-methylcelluloses using GC and FAB-MS for monomer and oligomer analysis

Arisz, Peter W.; Kauw, Hendrikus J.J.; Boon, Jaap J.

doi:10.1016/0008-6215(95)00039-v

Cited by 130 publications

(126 citation statements)

References 9 publications

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“…For all methylated starches more non-and disubstituted monomers and less monosubstituted monomers were observed than expected on the basis of a statistically random distribution (de®ned as homogeneous [5]). This can be explained by assuming that some areas in a starch granule are better accessible during derivatisation than others, resulting in a heterogeneous substituent distribution along the polymer.…”

Section: Resultsmentioning

confidence: 67%

“…Using the monomer compositions of P4±P30 and A4±A30 (Table 2), statistical distributions of the methyl substituents over the eight theoretically possible monomers were calculated, assuming constant and independent reactivities of HO-2, HO-3 and HO-6 [5]. For all methylated starches more non-and disubstituted monomers and less monosubstituted monomers were observed than expected on the basis of a statistically random distribution (de®ned as homogeneous [5]).…”

Section: Resultsmentioning

confidence: 99%

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Distribution of methyl substituents over branched and linear regions in methylated starches

Burgt

Bergsma²,

Bleeker³

et al. 1998

Carbohydrate Research

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Granular potato starch and amylopectin potato starch were methylated in aqueous suspension to molar substitutions (MS) up to 0.29. A method was developed to determine the MS of both branched and linear regions. After exhaustive digestion of the methylated starches with -amylase, the highly branched fraction with a degree of polymerisation (DP) > 8 was separated from the linear oligomers by selective precipitation of the former in methanol. The substitution levels of branched and linear regions were determined. It was found that methylation takes place preferably at the branched regions of amylopectin and that amylose is higher substituted than linear regions of amylopectin. The distribution of methyl substituents in trimers and tetramers was determined by FABMS and compared to the outcome of a statistically random distribution. The results provided evidence for heterogeneous substituent distributions. Quanti®cation of the degree of heterogeneity of the branched and linear regions showed a much larger deviation from random distribution in the linear regions. #

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Section: Resultsmentioning

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Distribution of methyl substituents over branched and linear regions in methylated starches

Burgt

Bergsma²,

Bleeker³

et al. 1998

Carbohydrate Research

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“…Distribution of substituents in methylated amorphous domains and methylated crystalline domains.-The distribution of substituents in oligomer fragments represents the substitution pattern in the corresponding polymer backbone [27,28]. In order to prepare suitable derivatives for FAB mass spectrometric analysis, the amorphous fractions derived from P10, P30, A10 and A30, containing glucose and glucose-oligomers (DP mainly 2-4), were permethylated with CD 3 I [29].…”

Section: Resultsmentioning

confidence: 99%

“…However, substituents in crystalline [27]. c Trimers, m-p=trimers obtained after partial methanolysis of crystalline fractions followed by perdeuteriomethylation.…”

Section: Discussionmentioning

confidence: 99%

“…This is direct evidence for a more heterogeneous substitution of the crystalline domains during methylation of granular starch. In order to visualise these differences in a more quantitative way, the degree of heterogeneity is expressed in the parameter H n where n corresponds with the DP of the per(deuterio)methylated oligomers [27]. All heterogeneity values in Table 4 are normalised by dividing by the MS value of the corresponding trimers or tetramers.…”

Section: Molar Substitutions Of Amorphous and Crystalline Fractions Fmentioning

confidence: 99%

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Distribution of methyl substituents over crystalline and amorphous domains in methylated starches

Burgt

Bergsma²,

Bleeker³

et al. 1999

Carbohydrate Research

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Granular potato starch and amylopectin potato starch were methylated in aqueous suspension with dimethyl sulfate to molar substitution (MS) up to 0.29. The percentage of amorphous starch compared with crystalline domains increased with increasing MS. Prolonged treatment of these methylated starches with hydrochloric acid below the swelling temperature resulted in the release of D-glucose and small D-glucose-oligomers from the amorphous domains. The granular structure was maintained during the acidic treatment, indicating that the crystalline lamellae were less affected by acid. The amorphous domains contained on average about twice as many substituents per glucose unit as the remaining crystalline network. The distributions of methyl substituents in trimers and tetramers, released from amorphous domains and prepared from crystalline fractions, were determined by FABMS and compared to the outcome of a statistically random distribution. Quantification of the degree of heterogeneity of the thus-obtained trimers and tetramers showed a much larger deviation from random substitution in the crystalline fractions compared with the amorphous ones. These results are in agreement with our previous study that describes substitution patterns in branched and linear regions of methylated starch granules.

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Determination of the substitution pattern in the polymer chain of cellulose acetates

Heinrich

Mischnick

1999

J. Polym. Sci. A Polym. Chem.

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Substituent distribution along the cellulose backbone in O-methylcelluloses using GC and FAB-MS for monomer and oligomer analysis

Cited by 130 publications

References 9 publications

Distribution of methyl substituents over branched and linear regions in methylated starches

Distribution of methyl substituents over branched and linear regions in methylated starches

Distribution of methyl substituents over crystalline and amorphous domains in methylated starches

Determination of the substitution pattern in the polymer chain of cellulose acetates

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