The Chromatogram Series: Sodium Hyaluronate / Hyaluronan
When Pete Townshend wrote “I hope I die before I get old” back in 1965’s “My Generation,” the Who guitarist was almost certainly taking an anti-establishment stance rather than fretting about future health issues.
Fortunately for music fans, Mr. Townshend has indeed gotten old. Luckily for people everywhere, medical technology has also advanced considerably over the past 48 years.
Nowadays, many medical procedures exist to help people cope with issues commonly associated with (but not limited to) age-related conditions, such as joint replacement, cataract removal and cosmetic surgeries. A shared component in these cures is the polysaccharide sodium hyaluronate, which is the water-soluble sodium salt of hyaluronan. Sodium hyaluronate forms a viscoelastic solution in water, which can be used to lubricate, protect and cushion, depending on the situation.
Here is an example of Hyaluronic acid, a high molecular weight of poly- glycosaminoglycans, i.e. a polysaccharide. The run conditions and some results are tabulated and shown below.
| Run Buffer | 0.1 Mol/L NaNO3 |
| Flow Rate [mL/min] | 0.700 |
| Column Set | A6000M + A2500 |
| Column Temp (°C) | 35.0 |
| Injection volume μL | 40.0 |
| Concentration [mg/mL] | 0.506 |
| Mw Weight Average [Da] | 415,044 |
| Sample dn/dc [mL/g] | 0.150 |
| Sample IV [dL/g] | 8.033 |
This ingredient for a cosmetic product has to be monitored closely as it has a big impact on the final product properties. Triple-detector GPC allows for comprehensive characterization of molecular mass, polydispersity and intrinsic viscosity. Sodium Hyaluronan is a polysaccharide that has viscoelastic properties even at low concentration, which supports its function as a tissue lubricant. Data were acquired with a Viscotek TDAmax system. The light scattering signal (strong dn/dc at high molecular weight, even with low injection loading) for both the 7º (LALS) and 90º (RALS) light scattering measurements overlay well. This sample shows a nice single peak, which is not necessarily easy to achieve for hyaluronic samples. The apparent shift of the RI peak indicates the polydisperse nature of the molecular weights that make up this sample.
Related publication: B Sabagh et al. “Investigating molecular weight and structure of linear and cross-linked Hyaluronic Acid by SEC–MALS and SEC–Triple Detection”