Quality assurance 5

Question 1

VAM principles of best analytical practice

Answer 1

Measurements should be made to satisfy an agreed requirement, and should be made using methods and equipment which have been tested to ensure they are fit for purpose
Staff should be qualified and competent
There should be a regular independent assessment
Organisations making analytical measurements should have well defined quality control and quality assurance procedures

Question 2

Equipment qualification

Answer 2

Provides documented evidence that the instrument is fit for intended purpose, and kept in state of maintenance and calibration

Question 3

Four stages of equipment qualification

Answer 3

Design qualification
Installation qualification
Operational qualification
Performance qualification

Question 4

Design qualification

Answer 4

Usually performed by the manufacturer
Design of user requirement specification for intended application
Defines the functional and operational specification of the instrument

Question 5

Installation qualification

Answer 5

Covers installation of the instrument up to and including initial turn on

Question 6

Operational qualification

Answer 6

Initially follows installation qualification

Repeated: following relocation of instrument, following maintenance of instrument, periodically at defined intervals

Question 7

Performance qualification

Answer 7

Undertaken regularly during routine use

Provides evidence that performance remains consistent and within required limits over time

Question 8

General considerations

Answer 8

What is its intended use?
Instrument set up and control
Module compatibility/software
Data acquisition, processing and software
In built diagnostics
Sample introduction and throughput
Sample preparation, clean up or pre-treatment

Question 9

Initial performance qualification

Answer 9

Holistic performance test to verify correct functioning and performance of entire system
Analyse test mix on a test column under defined operating conditions
Allows performance to be compared to other instruments and throughout life

Question 10

Accuracy vs precision

Answer 10

Accuracy: how close measured value is to true value
Precision: how close the measured values are to each other

Question 11

Injection volume precision

Answer 11

Important for accuracy and precision of results
Test by determining relative standard deviation in detector response (peak area/height) to repeated injections of same volume of standard solution
Should be <1% RSD
Shape of the peak should be reproducible

Question 12

Injection volume linearity

Answer 12

Important where various volumes are injected
Test by determining detector response (peak area/height) to injections of different volumes of standard solution
Should be linear i.e. double volume = double response

Question 13

Injection carry over

Answer 13

Important for accuracy and precision of results and reproducibility of peak area/height
Determined by measuring detector response to blank injection immediately following standard solution

Question 14

Other injection considerations

Answer 14

Flow rate precision
Proportioning precision
Column oven thermostatting precision

Question 15

Linearity of detector response

Answer 15

Important for accuracy of results
Determined by producing calibration curve of detector response (peak area/height) against standard solution concentration

Question 16

Signal to noise ratio

Answer 16

Important for sensitivity and limit of detection
Determined by measuring detector response to blank injection compared to diluted standard solution
S:N ratio=height of dilute analyte peak/ height of largest baseline fluctuation

Question 17

Method validation

Answer 17

Doing a thorough method validation can be tedious, but the consequences of not doing it right are wasted time, money and resources

Question 18

Analysis in discovery, development and manufacture of pharmaceuticals

Answer 18

Screening of potential drug candidates
Aid in development of drug synthesis
Support formulation studies
Monitor stability of bulk pharmaceuticals and formulated products
Testing of final products

Question 19

Prior to analysis

Answer 19

You need to establish minimum criteria and set minimum requirements
Agree a complete list of criteria between analyst and end users before method is developed so that expectations are clear
Precision and accuracy both important

Question 20

Performance characteristics assessed in method validation include:

Answer 20

Specificity (how method is specific for the compound)
Range (between LofD and LofQ)
Linearity (calibration)
Limit of detection (how low you get)
Limit of quantitation (how high you get)
Ruggedness (signal to noise ratio)
Uncertainty (precision and bias)

Question 21

Specificity

Answer 21

Ability to accurately measure analyte in the presence of al potential sample components
Compare the response to analyte alone with response to analyte in test mixtures containing analyte and all other components
Subject sample to extreme conditions to monitor degradation: heat, light, acid, base, oxidant and humidity

Question 22

Linearity

Answer 22

Verify that sample solution is within concentration range where analyte response is linearly proportional to concentration
Test standard solutions at five different concentrations over a range of 50 to 150% of target analyte concentration

Question 23

Precision

Answer 23

Scatter in results obtained from multiple analyses of homogenous sample
Instrument precision can be determined by repeatedly injecting the same sample
repeatability, or intra-assay precision, can be determined by repeatedly analysing aliquots of same sample in same lab on same day

Question 24

Accuracy

Answer 24

Can be determined by:
Analysing sample of known concentration and compare measured value to true value
Determining the recovery of known amounts of analyte spiked into blank sample matrix
Comparing results from new method with results from existing alternative method known to be accurate

Question 25

Range

Answer 25

Concentration range over which acceptable accuracy, linearity and precision obtained
Determined using data from linearity and accuracy studies
Precision calculated from replicate analyses of spiked samples in accuracy study

Question 26

Limits of detection and quantitation

Answer 26

LOD: lowest analyte concentration that produces a response that is detectable above noise
LOQ: lowest level of analyte that can be accurately and precisely measured

Question 27

Ruggedness

Answer 27

The degree of reproducibility of results obtained by the analysis of the same sample under a variety of normal test conditions
Different analysts, different laboratories etc.

Question 28

Stability

Answer 28

Stability of product
Stability of reagents, mobile phases and standard solutions
Essential that solutions are stable enough to allow for delays

Question 29

Uncertainty

Answer 29

Measurement depends on system, method, operator and environment
Repeat measurements performed under the same conditions should provide results with a small degree of error
Acceptable level of uncertainty depends on reason for analysis and application of reesults

Question 30

Typical problems that can be avoided

Answer 30

Impurities co-elute with peak- need to know sample composition
Degradation of analyte of interest- information on stability and properties of analyte
QA audit of validation report finds no documentation on how method was performed- must keep comprehensive records of analysis