Calculation

Cylinder plate assay (USP <81>) document calculations closely follow the guidelines laid out in USP <81>.

Tip: Standard reports let you output results in print and electronic form.

Calculation sequence

You can run calculations once you have completely set up an assay document. The results of calculations are added to and saved with the assay document.

Figure 1. Basic calculation steps performed for Cylinder plate assay (USP <81>) documents

Response data processing (optional)

Navigation: Analysis > Response data processing

Modifies response values prior to determining the standard curve line (where applicable) and calculating potencies. You can add a variety of response data processing steps and freely define the order in which they are to be executed.

The following types of response data processing are available:

  • Adjustment (optional): Subtracts a value you specify from the response values of the assay. You can adjust by a fixed value or by the response values of an assay element. You can add as many adjustment steps as you need.

  • Normalization (optional): Divides the response values of the assay by a value you specify. You can normalize by a fixed value or by the response values of an assay element. You can add as many normalization steps as you need.

  • Transformation (optional): Addresses issues related to heteroscedasticity in Cylinder plate assay (USP <81>) documents. If your response data is not homoscedastic and follows a trend, you have the following transformation options available: Logarithmic, Square, Square root.

Plate-to-plate variation correction of standard

Corrects for plate-to-plate variation of the reference standard in Cylinder plate assay (USP <81>) documents. Follows the method recommended by USP <81>.

Determination of standard curve line

Uses a linear regression model to fit the standard curve in Cylinder plate assay (USP <81>) documents.

Plate-to-plate variation correction of sample

Navigation: Analysis > Sample correction method

Corrects for plate-to-plate variation of the test sample(s) in Cylinder plate assay (USP <81>) documents. The following options recommended by USP <81> are available from the Sample correction method drop-down list:

  • Correction point (mean reference step response)

  • Estimated reference step response

Sample potency calculation

The main purpose of assay documents is to calculate potencies of test samples compared to a reference standard.

To determine absolute potencies for Cylinder plate assay (USP <81>) documents, PLA 3.0 interpolates the response values of the test samples on the standard curve. It calculates relative potencies based on the reference step of the standard.

This lets you closely follow the applicable guidelines laid out in the United States Pharmacopeia USP <81>.