QA vs QC Flashcards
Quality Assurance
- encompasses a set of procedures designed to ensure the reliability of laboratory analysis
- process-oriented and focuses on defect prevention
Quality Control
- encompasses a set of procedures designed to
validate measurement quality - product oriented and focuses on defect identification
Raw data
individual values of a measured
quantity
Treated data
concentrations found by
applying a calibration procedure to the raw data
Results
what is ultimately report such as
mean, standard deviation and confidence interval after applying statistics to treated data
True or false: QA begins with sampling
true
False positive
says that the concentration
exceeds the legal limit when in fact the concentration is below the limit
False negative
says that the concentration is
below the limit when it is actually above the limit
Method blank
sample containing all components
except analyte
Reagent blank
similar to method blank but it has not
been subjected to all sample preparation procedure
Field blank
similar to method blank but it has been
exposed to the site of sampling
Calibration blank
used in establishing the analytical
curve
Rinse blank
is used to flush the instrument uptake
system and nebulizer between standards, check
solutions and samples to reduce memory
interferences
Matrix
refer to everything else in the sample
other than analyte
Spike (fortification)
known quantity of analyte
added to a sample to test whether the
response to a sample is the same as that
expected from a calibration curve.
Performance test samples
quality control
measure to help eliminate bias introduced by
the analyst knowing the concentration of the
calibration check sample
Standard Operating Procedures
states what
steps will be taken and how they will be carried
out are the bulwark of quality assurance
Assessment
process of collecting data to show that
analytical procedures are operating
within specified limits and verifying that
final results meet use objectives
Method Validation
process of proving that an analytical method is
acceptable for its intended purpose
Repeatability (spread of measurements
established
through the standard deviation and/or the relative
standard deviation
Ruggedness
ssessment of precision or variation
by different analysts using different instruments on
different days but within the same laboratory
Reproducibility
refers to the variation obtained by
different analysts utilizing different instruments in
different laboratories using the same analytical
method with similar samples (Precision)
Selectivity
ability of a method to distinguish the
response of different analytes from each other
means being able to distinguish analyte from other species in
the sample (avoiding interference)
Specificity
ability of a method to provide a response
to a single analyte only
ability of an analytical method to distinguish the analyte from
everything else that might be in the sample
Linearity
measures how well a calibration curve
follows a straight line
Sensitivity
capability of responding reliably and
measurably to changes in analyte concentration
Accuracy
nearness to the truth
spiking
most common method to evaluate accuracy
Range
concentration interval over which linearity, accuracy
and precision are all acceptable (linear vs dynamic)
Limit of Quantitation
smallest amount that can be
measured with reasonable accuracy
Limit of Detection
smallest quantity of analyte that is
“significantly different” from the blank
Robustness
measure of the capability of an analytical method to
remain unaffected by small (but intentional) changes to parameters
in the method
Recovery
the fraction of analyte added to a
blank matrix before analysis that is actually
measured by the method
Matrix effect
change in the analytical
signal caused by anything in the
samples other than analyte
Internal Standard
Known amount of a compound different
from analyte that is added to the
unknown
