Preparation schemes

Preparation schemes are your central tool for efficiently assigning settings to assay elements. Define doses and dimensions of your treatments once and use the setup for as many assay elements as you require. Entering redundant information is not necessary.

Assignment to assay elements

All assay elements must have a preparation scheme assigned. Assay elements inherit the following settings from their assigned scheme:

Number of replicates: How many replicates an assay element requires for each dose step.
Absolute potency: Details on how to back-calculate the absolute potency.
Predilution factor: How much of the original stock solution is present in the total solution.
Dilution sequence: If the dilution sequence is defined as a sequence (by manually defining dose values), or as a stepwise dilution sequence (by manually defining dilution factors).

By default, Quantitative response documents created from scratch contain one preparation scheme, a Standard sample, and a Test sample. The preparation scheme is assigned to both assay elements:

Figure 1. Default assignment of preparation scheme to assay elements

You can add more schemes and assign them to assay elements as you require. For example, you can add a Control line to your assay. As this type of assay element requires a one-step sequence, you then create a second preparation with a defined sequence of one step, give it a meaningful name, and assign this scheme to the Control line assay element.

Absolute potency calculation

The primary goal of quantitative response assays is to calculate relative potencies of Test samples compared to a Standard sample. You can also calculate absolute potencies if you provide information on stock solutions or raw materials. In this case, assays still calculate relative potencies first and then perform calculations to determine absolute potencies.

The dilution model follows the path depicted in the following figure:

Figure 2. Dilution model applied to a Quantitative response assay document

Note: To correctly calculate stock solutions, you have to provide the dilution factors of all assay elements.

Defining raw materials and stock solutions is optional. To derive absolute potency, PLA 3.0 can perform various calculations. The type of calculation PLA 3.0 uses depends on the potency information you provide. The following tables show the most common use cases.

No absolute potency calculation

No absolute potencies are calculated if you provide one of the following combinations:


Standard sample		Test sample
Raw material potency	Stock solution potency	Raw material potency	Stock solution potency
-	-	-	-
-	-	yes	-

Calculation of absolute potency for stock solution

PLA 3.0 calculates absolute potencies for stock solutions if you provide one of the following combinations:


Standard sample		Test sample
Raw material potency	Stock solution potency	Raw material potency	Stock solution potency
-	-	-	yes^*
-	yes	-	^**
-	yes	-	yes
-	yes	yes	-
yes	-	-	^**
yes	-	-	yes

^* If you provide potency information on the stock solution of the Test sample only, the calculation assumes equipotency of Standard sample and Test sample.

^** If you provide potency information on the raw material or stock solution of the Standard sample and do not provide any potency information on the raw material or stock solution of the Test sample, the stock solution potency of the Test sample is assumed to be 1.

Calculation of absolute potency for raw material

PLA 3.0 calculates absolute potencies for raw materials if you provide the following combination:


Standard sample		Test sample
Raw material potency	Stock solution potency	Raw material potency	Stock solution potency
yes	-	yes	-