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Good Laboratory Practices
GLP
An Introduction
GLP Objectives
• To (quantitatively) describe
instrument performance so that
analytical measurements of
unknowns can result in a
quantitative result.
• For example: Calibration of a
spectrofluorometer with
quinine, followed by the
analysis of unknown
concentrations of quinine in
tonic water.
Analytical Method
Considerations
COST
SPEED
NEEDS
• COST: Training, equipment...
• SPEED: When is it required...
• NEEDS: E.g., required detection limit...
• Overall: An equal balance among the three.
Basic Terms
Chapter 1 Page 11, Table 1-3
(Skoog Holler Nieman)
• Precision (Reproducibility): Absolute or
relative standard deviation, coefficient of
variation, variance
• Bias: Absolute or relative systematic error
• Sensitivity: Calibration or analytical...
• Response Factor: Response as a function
of analyte concentration
• Limit of Quantitation (LOQ): A numerical
value usually directly related to LOD (>)
• Detection Limit (LOD or MDL): Different
methods (statistical) to establish LOD
• Not Detected: Signal not discernible from
noise using the given analytical system
• Concentration Range: From LOQ to LOL
• Selectivity: Coefficient of selectivity (%)
t-Test - Comparison of Means
• Mean of TEST METHOD #1 (sample) X 1
• Mean of TEST METHOD #2 (sample) X 2
• Are the means equal? The t-test we use is
dependent on whether the variances of the two test
methods are the same or different. Again, assume
Gaussian Distributions. One-tailed t-test for equal
variances, and two-tailed for unequal variances.
The two-tailed presents more relaxed constraints on
establishing equivalence.