Cylinder plate assays (USP <81>)

Use Cylinder plate assay (USP <81>) documents to determine the potency of antibiotics according to the cylinder-plate method described in USP <81>. PLA 3.0 uses a linear regression model to fit the standard curve. This method allows you to correct for plate-to-plate variation.

To determine absolute potencies, 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.

About this document type

This document type lets you organize observation data, calculate potencies, and define statistical tests for individual microbial assays. It lets you closely follow the guidelines laid out in USP <81>, but also provides considerable flexibility. Moreover, it lets you document supplemental information on the setup of experiments.

Tip: You can identify assays of this document type by the icon in the upper right corner of the Content editor.

Document structure

Each Cylinder plate assay (USP <81>) document has three sections, that is, Setup, Analysis, and Documentation, plus one or more optional Comment sections.

Figure 1. Sections of a Cylinder plate assay (USP <81>) displayed in the Content editor
Section Description

Documentation

Provide supplemental information on the setup of experiments that is needed for documentary purposes, but is not required to calculate potencies or organize observation data.

Setup

  • Provide information on the setup of experiments that is required to calculate potencies.

  • Organize observation data.

For details on the available settings, see the Assay setup topic.

Analysis

  • Define how PLA 3.0 processes your response data before calculating potencies.

  • Select a logarithmic dose transformation where required.

  • Select a sample correction method where required.

  • Define the statistical tests you need for your microbial assay.

For details on the available settings, see the Assay analysis and Test system topics.

Comment

Provide more information on your assay.