METHOD VALIDATION

PREPARED BY : SUBRATA SINHA

(SENIOR ANALYST) SIGMA TEST & RESEARCH CENTRE

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LINEARITYDefinition:- Linearity is a

mathematical relationship between two variable quantities (they may be of the same unit), which are directly proportional to each other.

Graphically it represents a straight line when plotted against each other.

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GRAPHICAL PRESENTATION OF LINEARITY

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f(x) = 10.1071428571429 x − 2.38095238095241R² = 0.999724965058912

Linearity Graph

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Y-ax

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NEEDNESS OF LINEARITYNON –LINEAR APPROCH LINEAR APPROCH

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NEEDNESS OF LINEARITYFrom the above graphical presentation of non-

linear and linear, We can definitely say that in the linear case we need only one variable value and the other variable value can be accurately determined. But in the case of non-linear we cannot accurately (definitely) determine the other variable’s value, even when one of the variable’s value is known.

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ROLE OF LINEARITY IN ANALYTICAL METHOD VALIDATION

The linearity of an analytical method is it’s ability to elicit test results that are directly proportional to the concentration of the analyte in samples within a given range.This is why to check the proportionality of result with concentrations, it is necessary to justify the linearity between LOWER Concentration & UPPER Concentration.

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DEFINITION OF SOME PARAMETERS RELATED TO LINEARITYLower Concentration:- LOQ is the lower concentration i.e.

starting point of the linearity in analytical method validation. Upper Concentration:- Cmax value is the upper concentration

of the linearity in analytical method validation. But it may be lower according to available quantity of the analyte in sample.

Cmax is a pharmacokinetics term. It is the maximum (or peak) serum concentration that an analyte achieves in a specified test area of the body after the analyte has been administrated.

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JUSTIFICATION OF LINEARITYThe strength & direction of the linear relationship

between two variable quantities is termed as correlation coefficient. It is denoted by r.

Mathematically it is expressed by r2, i.e. square of r, which is called coefficient of determination. The coefficient of determination (r2) ranges from 0 to 1. The range of r2 denotes how straight the line is.

Accepted value of r2 is NLT 0.95

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The End of Linearity Chapter

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