Chap 5 - Quantitative Chemical Analysis

Frage	Antworten
Quality Assurance	what we do to get the right answer for our purpose. The answer should have sufficient accuracy and precision to support subsequent decisions.
External Standards	solutions of analyte that do not involve the unknown solution
use objectives	written statement of how results will be used.
Specifications	written statements describing how good analytical results need to be and what precautions are required in an analytical method.
selectivity / specificity	capability of an analytical method to distinguish analyte from other species in the sample.
sensitivity	capability of responding reliably and measurably to changes in analyte concentration
false positive	results say concentration exceeds legal limit but it is actually below the limit
false negative	says the concentration is below the limit but
method blank	sample containing all components except analyte and goes through all steps of the analytical procedure
reagent blank	similar to method blank but not subjected to all sample preparation procedures. complete estimate of the blank contribution to the analytical response
field blank	similar to method blank but it has been exposed to the site of sampling
matrix	everything in the sample other than the analyte
spike / fortification	known quantity of analyte added to a sample to test whether the response to the spike is the same as that expected from a calibration curve. They're analyzed in the same manner as unknowns.
calibration check	analysis of a solution formulated by the analyst to contain a known concentration of analyte. analyst own check to see that procedures and instruments are functioning correctly
performance test samples / quality control samples / blind samples	in a series of analytical measurements it is inserted to see whether the procedure gives correct results when the analyst does not know the right answer. Not formulated by analyst, to contain known concentration of analyte.
standard operating procedures	a written procedure that must be rigorously followed to ensure the quality of chemical analysis
assessment	the process of collecting data to show that analytical procedures are operating within specified limits and verifying that final results meet the use objective
control chart	a visual representation of confidence intervals for a Gaussian distribution
method validation	the process of proving that an analytical method is acceptable for its intended purpose
linearity	measures how well a calibration curve follows a straight line, showing response is proportional to the quantity of analyte
repeatability	describes the spread in results when one person uses one procedure to analyze the same sample by the same method with the same equipment multiple times
reproducibility	describes the spread in results when different people in different labs using different equipment each try to follow the same procedure with the same kind of sample
precision	how well replicate measurements agree with one another, usually expressed as a standard deviation or confidence interval
range	the concentration interval over with linearity, accuracy and precision are all acceptable
linear range	concentration range over which calibration curve is linear
dynamic range	concentration range over which there is measurable response
detection limit	the concentration of analyte that gives a signal equal to three times the standard deviation of signal form a blank
coefficient of variation	the standard deviation divided by the mean, usually expressed as a perentage
lower limit of quantitation	smallest amount that can be measured with reasonable accuracy
reporting limit	the concentration below which regulations say that a given analyte is reported as "not detected" which means analyte could be below prescribed level
robustness	the ability of an analytical method to be unaffected by small, deliberate changes in operating parameters
standard addition	known quantities of analyte are added to the unknown
matrix effect	a change in the analytical signal caused by anything in the sample other than analyte
standard uncertainty	standard deviation of the mean

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Chap 5 - Quantitative Chemical Analysis

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	Erstellt von Raegan Ferro vor etwa 5 Jahre