Parameters of Method Validation:

• Selectivity:

  • Degree to which a method can quantify the analyte accurately in the presence of interferences under the stated conditions of the assay for the sample matrix being studied
• Specificity:

  • Absolute absence of interference effects, equal to 100% selectivity
• Linearity:

  • Ability of the method to elicit test results directly proportional to analyte concentration within a given range
  • Established initially by visual examination of a plot of signals as a function of analyte concentration
  • Test results should be established by appropriate statistical methods if a linear relationship is observed
• Range (of an analytical method):

  • Interval between the upper and lower levels demonstrated to be determined with precision, accuracy, and linearity
  • Concentration range in which the linearity test is done
• Detection Limit:

  • Lowest concentration of an analyte in a sample that can be detected, not quantified
• Quantitation Limit:

  • Lowest concentration of an analyte in a sample that can be determined with acceptable precision and accuracy under the stated operational conditions of the analytical procedures
• Accuracy (of an analytical procedure):

  • Closeness of agreement between the accepted value and the found value
  • Sometimes termed as trueness
  • Should be established across the specified range of the analytical procedure
• Precision (of an analytical method):

  • Degree of agreement among individual test results when the method is repeated to multiple samplings of a homogenous sample
  • Usually expressed as the standard deviation or relative deviation (coefficient of variation) of a series of measurements
• Repeatability:

  • Use of the analytical procedure within a laboratory over a short period of time using the same analyst with the same equipment
  • Should be assessed using a minimum of nine determinations covering the specified range for the procedure
• Reproducibility:

  • Precision between laboratories, usually demonstrated by means of inter-laboratory trials
• Intermediate Precision:

  • Results from within laboratory variations due to random events such as different days, analysts, equipment, etc