This package determines the molecular-weight distribution of alginate using size-exclusion chromatography coupled with refractive-index detection (SEC-RI). During the analysis, alginate molecules are separated according to their hydrodynamic size, allowing the molecular-weight profile of the polymer to be characterised. The SEC system is calibrated over a molecular-weight range of approximately 1 kDa to 7,000 kDa.

 

The molecular weight and distribution of alginate can have an important influence on properties such as solution viscosity, gel formation, mechanical strength, processability and stability. Molecular-weight analysis can therefore support the comparison of alginates from different seaweed species, extraction conditions or processing methods. It is also useful for assessing batch consistency and identifying polymer degradation caused by heat, chemical treatment, storage or other processing conditions.

 

Where more than one molecular-weight population is resolved, statistics are reported separately for each identified chromatographic peak. The reported parameters include peak retention time, weight-average molecular weight (Mw), number-average molecular weight (Mn), Z-average molecular weight (Mz), Z+1 average molecular weight (Mz+1), polydispersity index (PDI) and the relative area of each peak.

 

The polydispersity index, calculated as Mw divided by Mn, provides an indication of the breadth of the molecular-weight distribution. A value approaching 1 represents a relatively narrow distribution, while higher values indicate a broader and more heterogeneous population of polymer chains. The relative peak area provides an estimate of the proportion of the detected alginate material associated with each molecular-weight population.

Constituents Determined

For every constituent determined via wet-chemical analysis each sample is analysed in duplicate and we provide the compositional data for each replicate along with the average value and the standard deviation between the duplicates. Our analytical protocols typically provide results with a high level of precision, as detailed here.

Examples of the data reports generated can be viewed on the Celignis Database. Please log on to the guest account using email "test@celignis.com" and password "celignis".

Click here to place an order for determining Alginate Molecular Weight Analysis.

Sample Weight Requirements

Under nornal conditions there is a minimum requirement of 1g of sample for this analysis package with a recommended weight of 1+g of sample.

However, it may be possible for us to undertake the anaysis with lower quantities than the minimum specified above. Please email us at info@celignis.com to find out.