  Home Contact Sitemap                # How can I calculate the concentrations of my unknowns using standards data measured in a previous assay?

Document ID: DQ153
Relevant to following products: WorkOut 2.0/Manta
Document description: How To: Use archived standards data? It is possible to calculate the concentration of your unknowns from standards data measured in a different assay (this currently cannot be achieved with polynomial regression or cubic spline fits)

This can be achieved by identifying the determined coefficients of the fit and using this model on your future assays.
1. Open the results file which contains the standards curve fit which you want to reuse.
2. Select the Report tab and find the Fit Results table, within this table identify and make a note of the determined coefficients of the fit:

Linear Regression, this is: m, c
Four Parameter Fit, this is: a, b, c, d
Five Parameter Fit, this is: a, b, c, d, m
Michaelis-Menten: Vmax, Km
3. Next open the results file which contains your unknowns that you want to calculate the concentration of.
4. Select Edit Transforms, press Create and select Matrix Expression.
5. Under the Input Matrix select the raw data (this corresponds to the Y axis of the fit), under the Output Matrix tab enter “Conc.” and under the Expression tab enter the relevant expression:

Linear Regression: (x-c)/m
Four Parameter Fit: c*pow((d-x)/(x-a), 1/b)
Five Parameter Fit: c * pow( pow( (d - a) / (x - a), (1/m)) - 1, (1/b))
Michaelis Menten: Km * x / (Vmax - x)

Substitute the letters with the coefficients noted above (the x variable will remain as x). Also replace any double negatives with a positive, (i.e. - - 1.2 = +1.2) Related articles:
DQ308: Can I back fit or evaluate a point on a standard curve fit?
Can I back fit or evaluate a point on a standard curve fit? DQ054: Can I use a standard curve from one plate on other plates read in the same batch?
Application Example: RIA on Multiple plates. DQ119: I want to run a Quantitative assay with the standards measured on every plate, but each time I run the assay I change the number of samples and hence the number of plates required.
How To: Create a Quantitative assay which will use a variable number of samples and plates with the concentrations calculated using each plates own standards.  Search again  Download software now: WorkOut 2.5 Manta Stingray  Search Knowledge Base Browse Knowledge Base Submit a query

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