Quality Assurance in the Analytical Chemistry Laboratory Flashcards
Defined as the degree to which a set of inherent characteristics fulfill requirements
quality
does not only depend on the application of well-researched and/or developed and/or validated methods.
quality in chemical analysis
results have to be accompanied by concurrent proof that the measurements are really and truly correct
quality analytical results
is obtained by the application of a well-planned program of Quality Assurance(QA) to analytical measurements
proof
describes the overall measures that a laboratory uses to ensure the quality of its operations
quality assurance
Quality assurance includes
A quality systems
Suitable laboratory environment
Educated, Trained and skilled staff
Equipment suitably maintained and calibrated
Documented and validated methods.
Traceability and measurement uncertainty
Proficiency testing
Requirements for reagents, standards, reference materials
is an integrated system of management and technical activities within an organization that ensures overall activities meet the defined standard or quality
QA
is a definitive program for laboratory operation that specifies the measures required to produce defensible data of known precision and accuracy
QA in chemical analyses
Three of the most important components of laboratory QA are
QC
method validation
equipment maintenance
The QA program is defined in a documented laboratory quality system which consists of
QA manual
QC process
written management and technical procedures
work instructions
records
most widely recognized and used quality assurance protocols and standards in chemical testing
ISO/IEC 17025:2005 (International organization for standardization/ International Electrotechnical Commission
ISO 9001:2000
OECD Principles of Good Lab Practice (organization for economic cooperation and development)
An international standard which addresses the technical competence of laboratories to carry out specific tests and calibrations and is used by lab accreditation bodies worldwide
ISO/IEC 17025:2005
International standard that contains all the requirements that testing and calibration laboratories have to meet if they wish to operate a quality system
ISO/IEC 17025:2005
An international standard which relates primarily to quality management, for facilities carrying out production, or providing services, including chemical analysis
ISO 9001:2000
Guidelines concerned with the organizational processes and conditions under which laboratory studies related to certain regulatory work are carried out.
OECD Principles of GLP
ISO/ IEC 17025 : 2005 Management Requirements
- Organization
- Management system
- Document control
- review of requests, tenders and contracts
- Sub-contracting of tests and calibrations
- Purchasing services and supplies
- Service to the customer
- Complaints
- Control of non-conforming tests
- Improvement
- Corrective action
- Preventive Action
- Control of Records
- Internal audits
- Managements reviews
ISO/IEC 17025:2005 Technical Requirements
- General
- Personnel
- Accommodation and environmental condition
- Test and calibration method validation
- Equipment
- Measurement traceability
- Sampling
- Handling of test and calibration items
- Assuring the quality of test and calibration results
- Reporting of results
)- set of requirements covering the organization of test facilities and conditions to ensure the generation of high quality and reliable test data for specific objectives
GLP principles ( expanded sense
)- set of practice in the chemical laboratory that controls the laboratory activities and conditions that affect the accuracy of analytical data
GLP ( limited sense)
components of GLP
QA program
Laboratory Conditions
Test Samples
Test Measurements
Record Management
To ensure consistent quality of data
QA program
To ensure the laboratory conditions are optimized to obtain the desired performance of the test method
Laboratory conditions
To preserve the identity and integrity of the samples
test samples
To ensure that an acceptable test method will produce the expected performance
test measurements
to enable retrieval of undistorted information whenever required
record management
GLP includes
implementing standard operating procedures
Proper maintenance and calibration of equipment
Correct practices of laboratory personnel in performing analytical work
Efficient management of laboratory records
Method QA ensures that the defined characteristics of the method as required are met. The defined method characteristics are also known as
data quality objectives
are critical goals for accuracy, precision, sensitivity, and selectivity of analytical data to be satisfied so as to achieved analysis goals
data quality objectives (DQO)
– degree of agreement of measurements with an acceptable reference value or degree of acceptable method bias.
accuracy
bias is sometimes called what
recovery
) is the systematic error of the measuring system
bias
degree of spread of results ( degree of differences in individual test results, expressed as standard deviation, relative standard deviation or RSD).
Precision
Sensitivity is defined by detection limits such as
Method detection limit
Reliable detection limit
Limit of quantitation
the measured concentration at which there is a stated probability ( 95% or 99%) that an analyte is present. is defined as 3x standard deviation (of method blank runs)
Method detection limit (MDL)
the lowest concentration level that can be determined to be statistically different from the blank; the lowest analyte concentration required to be present to ensure an analytical response that will exceed the MDL
Reliable detection limit (RDL
the level above which quantitative results maybe obtained with a specified degree of confidence. Confidence in the apparent analyte concentration increases as the analyte signal increases above the MDL
Limit of quantitation (LOQ)
susceptibility of the method to interferences. This maybe determined by recovery of spiked samples.
Selectivity
are also defined to set Acceptance Criteria for QC
measurements
DQOs
Method of QA program covers
Method Selection
Method Validation
Sampling
Equipment
Quality Control
Traceability
Measurement Uncertainty
Proficiency Testing
Factors to consider when selecting a method
- Limit of detection
- precision
- Bias/Recovery
- Accuracy
- Selectivity
- Equipment required
- Sample size
- Time
- Cost
- Safety
Analytical procedures must be well-documented before validation is performed, which includes
- Title of test method
- Scope and application
- Sample matrices
- Method detection level
- Interferences
- Safety considerations
- Sample collection, preservation, transport, storage
- Apparatus, equipment, and supplies
- Reagents, standards, reference materials
- actual test procedure:
Calibration
Standardization
Sample preparation
Calculations- Specific QC practices
- Acceptance criteria
- Tables, flowcharts, validation data
- Estimation of measurement uncertainty
- References
ways of performing validation of an analytical method
collaborative validation
internal validation
- a method is validated in a laboratory before use to prove that the method performs adequately
- Whatever is the source of the method whether it is a standard method, a published method or a lab-developed method, the method must be internally validated before use in the lab.
-Validation can be done with the use of spiked samples, certified reference materials or comparing the performance of a method with a reference method whose performance has been well established.
internal validation
Components of internal validation methods
Characterization of instrument calibration and working range
Determination of sensitivity ( detection limits)
Determination of bias ( systematic error)
Determination of precision ( random error)
Assessment of ruggedness ( for lab-developed methods and non-standard methods
solutions with certified concentration of analytes used to verify the accuracy of the calibration curve
Lab Instrument Control Standard
to measure and control the instrument calibrations or instrument performance.
Laboratory instrument QC Samples
one of the standard solutions used in making the calibration curve that verifies the stability of a calibration curve over time
Verification Standard
solution to check for instrument contamination and background levels
instrument blank
to measure and control complete method performance
Lab method QC Samples
– measures method contamination background
methdo blank
assesses the precision of the test procedure
lab sample replicates
measures the recovery of a method
method analyte blank
analyte spiked on a method blank
bank spike
– analyte spiked on clean matrix to assess losses or contribution due to the matrix
matrix spike
– analyte spiked on samples – to assess the losses or contribution due to other components or characteristics of the sample
sample spike
Naturally- occurring materials or synthetic materials with known concentrations of analytes (obtained through collaborative studies) certified by recognized certifying bodies (such as NIST, IAEA) used to assess the bias of the method; comes with Certificate of Analysis
certified reference materials
Field QC smaples
field blank
field analyte spike
field replicate sample
measures contamination from sampling activities
field blank
measures recovery between time of sampling and time of analysis
field analyte spike
measures precision
field replicate sample
