Molecular weight of humic substances

Perminova, I. V., Frimmel, F. H., Kovalevskii, D. V., Abbt-Braun, G, Kudryavtsev, A. V., and Hesse, S. (1998). Development of predictive model for calculation of molecular weight of humic substances. Water Res. 32, 872-881. 

Aiken G. R. and Gillam A. H. (1989) Determination of molecular weights of humic substances by colligative property measurements. In Humic Substances II In Search of Structure, (eds. M. H. B. Hayes, P. MacCarthy, R. L. Malcolm, and R. S. Swift) Wiley, Chichester, pp. 515-544. 

GiUam A. H. and Riley J. P. (1981) Correction of osmometric number-average molecular weights of humic substances for dissociation. Chem. Geol. 33, 355—366. 

Reuter J. H. and Perdue E. M. (1981) Calculation of molecular weights of humic substances from colligative data application to aquatic humus and its molecular size fractions. Geochim. Cosmochim. Acta 45, 2017-2022. 

Effect of Molecular Weights of Humic Substances on Nitrogen Content... 

Measurement of the molecular weights of humic substances has been the subject of a considerable amount of work and this is dealt with in more detail by Wershaw and Aiken in Chapter 19 of this book. In this section the emphasis will be placed on the application of techniques that use molecular size as... 

In addition to methods that yield average molecular weights, there are a number of methods (gel filtration, ultrafiltration, small-angle X-ray scattering) that measure molecular size. In these methods, model compounds of known molecular weight and composition are used to estimate the molecular weight of humic substances. Problems can arise if the model compounds are not sufficiently similar to the humic substances of interest. Choice of appropriate model compounds is hampered by lack of detailed information about the chemical structures of humic substances. 

The molecular weight obtained by measurement of a colligative property is a number-average molecular weight. Two serious problems need to be addressed in determining number-average molecular weights of humic substances ... 

Gjessing, E. T. (1965). Use of Sephadex gel for the estimation of molecular weight of humic substances in natural water. Nature (London) 208, 1091-1092. 

O Loughlin, E. and Chin, Y. P., Effect of detector wavelength on the determination of the molecular weight of humic substances by high pressure size exclusion chromatography. Water Res., 35, 333-338, 2000. 

---