Patent Document ID: 5574215
Application ID: 08396378
Patent Flag: 1

Claim One:
1. A method for calculating the average molecular weight of individual molecules (MW.sub.0) in a sample, where the molecules in solution associate to form clusters, which method comprises, (a) heating a reference portion of a solvent at a reference temperature (T.sub.R) to form a saturated solvent vapor at vapor pressure (P.sub.R) above the reference portion, (b) dissolving a measured mass of the sample in a measured second portion of the solvent to provide a solution with a known concentration (C) of the sample in terms of mass per unit volume, and heating a sample portion of the solution to a sample temperature (T.sub.S) to form a saturated solvent vapor above the sample portion at vapor pressure (P.sub.S), (c) measuring the deviation of the sample temperature and vapor pressure (T.sub.S, P.sub.S) from the reference temperature and vapor pressure (T.sub.R, P.sub.R), and computing an apparent molar concentration (C.sub.M) in moles per unit volume by reference to the deviation, the apparent concentration being the molar concentration of the clusters of associated molecules and any unassociated molecules, (d) computing an apparent molecular weight (MW) from the equation; ##EQU16## the apparent molecular weight being the average molecular weight of clusters of associated molecules and any unassociated molecules, (e) repeating steps (a) through (d) for m repetitions with a different value of concentration (C) for each repetition, (f) solving for a.sub.1, a.sub.2,. .. a.sub.j, and MW.sub.0 from the MW and C data points from the following set of equations: a subset of equations for n=2 to m defined by ##EQU17## an equation defined by ##EQU18## an equation defined by ##EQU19## and a subset of equations that are relations between k.sub.n and n, for n=2 to m k.sub.n =f(n,a.sub.1,a.sub.2,. .. ,a.sub.j) where m is an integer greater than 2, k.sub.n are equilibrium constants of association between the monomers and the clusters, a.sub.1, a.sub.2,. .. a.sub.j are constants, and j is an integer greater than 0, the number of the apparent molecular weight (MW) versus concentration (C) data points produced by the repetitions in step (e) being an integer greater than j.