Assay: Maximum permitted %RSD check for system suitability

Estimate the maximum permitted %RSD for assay system suitability using the pharmacopoeial calculation described in USP <621> and Ph. Eur. 2.2.46

Enter your details and assay values to generate maximum %RSD critieria.

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In system suitability, %RSD is a measure of repeatability across replicate reference standard injections and is used to confirm that the chromatographic system is fit to perform the intended assay test.

%RSDmax = (K × B × √n) / t90%,n−1

Where:

• K = Constant, 0.349
• B = Upper assay limit - 100
• n = number of replicate injections of the reference solution (3 - 6)
• t = Student's t value at 90% probability with n - 1 degrees of freedom

Example: For an assay specification of 95.0 to 105.0%, enter 105.0 as the upper assay limit

Source: USP General Chapter <621> Chromatography and Ph. Eur. 2.2.46 Chromatographic separation techniques - Maximum permitted %RSD

The calculated values represent maximum permitted %RSD values only.

Where specific system suitability criteria are stated in the applicable monograph, those requirements take precedence.

Actual method performance and data trend should be considered in setting and justifying acceptance criteria.