MS: ✗
BD: ✗

Interference Optics

Has a lower sample concetration limit (~0.1 mg/ml) but can allow for the use of much more concentrated samples.

Will observe the signal for all buffer components; requiring the subtration of buffer components using reference samples.

When to Use

Pros and Cons

Advantages Great for samples with high refractive indices.

Fast scanning speed, measuring every 5 seconds.

No temporal distortion. One snapshot for each hole. Good for fast sedimenting samples.

high radial resolution, low stochastic noise

no buffer interference, allowing for arbitrary buffers to be use.

Disadvantages

Sensite to refractive index artifacts such as wiener skewing and lens effect Use shorter path length or have lower concentrations to avoid wiener skewing.

Exact meniscus match required between buffer channel and sample channel to measure refractive index differences.

Sample must be dialyzed or column purified. Buffer components may sediment and change the concentration over time of the cell, and adds a singal.

Lower capacity: second channel cannot be used for a seperate sample. Only 3 cells for An-60, 7 cells for An-50. Needs counterbalance.