QA/QC Flashcards
define quality assurance
the guarantee that the quality of a product is actually what is claimed on the basis of the quality controll applied in creating that product
not meant to protect against failures of quality control
consists of all planned activities implemented within the quality system that can be demonstrated to provide confidence that a pdt will fulfill requirements
define quality control
maintenance and statement of the quality of a product specifically that it meets or exceeds some minimum standard based on known and testable criteria
consists of operational techniques to fulfill requirements for quality
for are sources of published or standardized methods for selecting an analytical procedure?
AOAC
ISO standards
IUPAC
what does AOAC stand for?
official methods of analysis
the use of a standard method is not a guarantee a lab generates quality assured data
T/F?
true.
a lab needs to prove initially and continuously its ability to analyze food chemicals
what are 2 methods of validation?
1) initial method validation
2) continuous method performance (routine analysis)
describe initial method validation
initial performances proving the capacity of the lab to analyze a specific set of chemicals in specific matrices
describe continuous method performance (routine analysis)
procedures and dataset demonstrating the capacity of the lab to continuously produce analyses with a high condense
what does ESI stand for?
electrospray ionization
what relationship between the analytical signal and concentration is preferred?
linear
what must be done if the response between analytical signal and concentration is non-linear?
assess linearity
residual = obs value - predicted value
when is linearity validated?
1) residuals (% of the value) do not exceed predefined criteria
2) residuals are randomly distributed in the plot residues vs calibration level
what is the equation of residue?
Residue = (observed value - predicted value)/predicted value x 100
what shape does a R=0.99 relationship have?
linear
define LOD
limit of detection
the smallest amount/conc of analyte in the test sample that can be reliably distinguished with significance from the background/blank
what is IDL?
what is MDL?
IDL = instrument detection limit
MDL: method detection limit
how can LOD be determined?
1) 3 x standard dev of the conc in a matrix blank
2) matrix blank fortiied with analyte close to this limit
if x < LOD, what does this mean? how do you report this?
signal not sig diff from background or blanks
report as below LOD
if LOD < x < LOQ, what does this mean? how do you report this?
signal is significantly higher than the background or blanks, but level not high enough to provide accuracy on the value
result repoted as below LOQ
if LOQ < x, what does this mean? how do you report this?
level is high enough to ensure some degree of accuracy on the value
exact value is reported
how can trueness be assessed?
1) analysis of certified reference material
2) use of a reference method with little or no systematic error
3) use of the method when participating in interlab tests
what is the equation of trueness?
equation of bias?
trueness % = measure conc / true conc x 100
bias % = (measured value - true value ) / true value x 100
how is the recovery of a method assessed?
from spiking of samples
recovery % = (Xspiked - Xunspiked) / amount of added analyte x 100
define repeatability
define reproducibility
repeatability: closeness of agreement between independent results obtained with the same method on identical test material under the SAME conditions
reproducibility: closeness of agreement between independent results obtained with the same method on identical test material but under DIFFERENT conditions
