[RASMB] Detection limits

Tue Jun 10 18:22:43 PDT 2008

Hi Titus,

It is not as simple as stating a percentage. The minimum percent of
species you can detect depends on the total OD of your sample (or fringes)
and the noise in the data, and the reliability with which you want to
detect it, and the purity of the sample. For example, while you might be
able to detect the partial concentration of a contaminant, that doesn't
mean that you can determine both s and D of that contaminant reliably if
the signal is not sufficient.

When using UltraScan, you can get a better handle on this limit by
performing a 2DSA or GA Monte Carlo analysis which allows you to better
define the effect of stochastic noise on this limit and determine a
confidence interval for each fitted parameter. More information can be
found in:

Demeler, B. and E. Brookes. Monte Carlo analysis of sedimentation
experiments. Colloid Polym Sci (2008) 286(2) 129-137
(http://www.demeler.uthscsa.edu/ultrascan-publications/DemelerBrookes_ColloidPS-2007a.pdf)

Brookes, E. and B. Demeler. Parallel computational techniques for the
analysis of sedimentation velocity experiments in UltraScan. Colloid
Polym Sci (2008) 286(2) 138-148
(http://www.demeler.uthscsa.edu/ultrascan-publications/BrookesDemeler-Colloid-2007B.pdf)

Brookes, E and B. Demeler. Parsimonious Regularization using Genetic
Algorithms Applied to the Analysis of Analytical Ultracentrifugation
Experiments. GECCO ACM Proceedings 978-1-59593-697-4/07/0007 (2007)
(http://www.demeler.uthscsa.edu/ultrascan-publications/BrookesDemeler-GECCO-2007.pdf)

Good luck, -Borries

> 
> Hi everyone,
> 
> I was wondering if someone could tell me about the minimum detection
> limit of species using aUC SV?
> 
> 
> 
> If I had a pure sample (let's assume an absorbance =3D 0.5) that had =
> been
> contaminated with x% of the total signal with a different compound, what
> would be the minimum X% to be reliably detected this in SV experiment.
> For example, % dimers in a monomer-dimer equilibrium far below the Kd,
> or dimeric aggregates from non-reversibly associated monomers. Assuming
> that the machine is in OK shape and delivers RSMDs around 0.004 for
> absorbance experiments.
> 
> 
> 
> Cheers
> 
> Titus
> 
> 
> 
> 
> 
> 
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> <div class=3DSection1>
> 
> <p class=3DMsoNormal><span lang=3DEN-US>Hi everyone, =
> <o:p></o:p></span></p>
> 
> <p class=3DMsoNormal><span lang=3DEN-US><o:p> </o:p></span></p>
> 
> <p class=3DMsoNormal><span lang=3DEN-US>I was wondering if someone could =
> tell me
> about the minimum detection limit of species using aUC =
> SV?<o:p></o:p></span></p>
> 
> <p class=3DMsoNormal><span lang=3DEN-US><o:p> </o:p></span></p>
> 
> <p class=3DMsoNormal><span lang=3DEN-US>If I had a pure sample =
> (let’s assume an
> absorbance =3D 0.5) that had been contaminated with x% of the total =
> signal with a
> different compound, what would be the minimum X% to be reliably detected =
> this
> in SV experiment. For example, % dimers in a monomer-dimer equilibrium =
> far below
> the Kd, or dimeric aggregates from non-reversibly associated monomers. =
> Assuming
> that the machine is in OK shape and delivers RSMDs around 0.004 for =
> absorbance
> experiments.<o:p></o:p></span></p>
> 
> <p class=3DMsoNormal><span lang=3DEN-US><o:p> </o:p></span></p>
> 
> <p class=3DMsoNormal><span lang=3DEN-US>Cheers<o:p></o:p></span></p>
> 
> <p class=3DMsoNormal><span lang=3DEN-US>Titus<o:p></o:p></span></p>
> 
> <p class=3DMsoNormal><span lang=3DEN-US><o:p> </o:p></span></p>
> 
> <p class=3DMsoNormal><span lang=3DEN-US><o:p> </o:p></span></p>
> 
> </div>
> 
> </body>
> 
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