in such guidance, “method development“ involves optimizing the procedures and

conditions involved with extracting and detecting the analyte. Method development

includes the optimization of the following bioanalytical parameters:

• Reference standards

• Critical reagents

• Calibration curve and linearity range

• Quality control samples (QCs)

• Selectivity and specificity, the ability to assess the analyte when it is in the

presence of other components, such as a matrix.

• Sensitivity, related to limit of detection and quantification

• Accuracy, the assessment of the difference between the measured value

and the real value. That could be quite difficult to evaluate if you have not

yet a reference standard.

• Precision, the measure of the agreement of multiple measurements on the

same sample

• Recovery, if you have sample pretreatment before the analysis

• Stability of the analyte in the matrix

Also, certain considerations should be envisioned upfront. The evaluation of the limits

of detection or quantification is not the same. The limit of detection is the lowest

amount of analyte that can be detected while the limit of quantification is the lowest

amount of analyte that could be determined accurately. Thus, an assay can give a result

at a very low level of analytes, but the precision of the test is not enough to reach proper

quantification. The linearity range is also important to determine. The linearity is the

range in which there is no saturation of the detection signal used for the assay. The

robustness of the assay regarding changes in the process is also of importance if a tool

is implemented in the development stages of the production process. As an assay could

be strongly impacted by the composition of the sample matrix, it is important to select

appropriate analytical methods if the process has been designed to modify this matrix.

Analytical tools can be affected by factors such as the manufacturing process, change in

formulation, or equipment used to synthesize the product. Overall, any test needs to be

validated; consequently, the way the assay is performed must be enough robust to allow

validation of the test.

8.2

ANALYSIS OF VIRAL PRODUCTS

Viral production processes are various, and consequently, the type of biological material

composition to characterize and quantify could involve a wide variety of quality attri-

butes. Indeed, depending on the end product, if the production process for example, aims

to produce viral vaccines or viral vectors, manufacturers will not target the same analytes.

8.2.1

BIOLOGICAL ATTRIBUTES OF VIRUS-BASED PRODUCTS

To start with definitions, biological activity is a critical quality attribute (CQA),

which means that biological activity is qualifying the viral product in terms of

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Bioprocessing of Viral Vaccines