Flashcards
Chap 5 - Quantitative Chemical Analysis
Cards in this deck (34)
- 1Quality Assurancewhat we do to get the right answer for our purpose. The answer should have sufficient accuracy and precision to support subsequent decisions.
- 2External Standardssolutions of analyte that do not involve the unknown solution
- 3use objectiveswritten statement of how results will be used.
- 4Specificationswritten statements describing how good analytical results need to be and what precautions are required in an analytical method.
- 5selectivity / specificitycapability of an analytical method to distinguish analyte from other species in the sample.
- 6sensitivitycapability of responding reliably and measurably to changes in analyte concentration
- 7false positiveresults say concentration exceeds legal limit but it is actually below the limit
- 8false negativesays the concentration is below the limit but
- 9method blanksample containing all components except analyte and goes through all steps of the analytical procedure
- 10reagent blanksimilar to method blank but not subjected to all sample preparation procedures. complete estimate of the blank contribution to the analytical response
- 11field blanksimilar to method blank but it has been exposed to the site of sampling
- 12matrixeverything in the sample other than the analyte
- 13spike / fortificationknown 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.
- 14calibration checkanalysis 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
- 15performance test samples / quality control samples / blind samplesin 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.
- 16standard operating proceduresa written procedure that must be rigorously followed to ensure the quality of chemical analysis
- 17assessmentthe process of collecting data to show that analytical procedures are operating within specified limits and verifying that final results meet the use objective
- 18control charta visual representation of confidence intervals for a Gaussian distribution
- 19method validationthe process of proving that an analytical method is acceptable for its intended purpose
- 20linearitymeasures how well a calibration curve follows a straight line, showing response is proportional to the quantity of analyte
- 21repeatabilitydescribes 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
- 22reproducibilitydescribes 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
- 23precisionhow well replicate measurements agree with one another, usually expressed as a standard deviation or confidence interval
- 24rangethe concentration interval over with linearity, accuracy and precision are all acceptable
- 25linear rangeconcentration range over which calibration curve is linear
- 26dynamic rangeconcentration range over which there is measurable response
- 27detection limitthe concentration of analyte that gives a signal equal to three times the standard deviation of signal form a blank
- 28coefficient of variationthe standard deviation divided by the mean, usually expressed as a perentage
- 29lower limit of quantitationsmallest amount that can be measured with reasonable accuracy
- 30reporting limitthe concentration below which regulations say that a given analyte is reported as "not detected" which means analyte could be below prescribed level
- 31robustnessthe ability of an analytical method to be unaffected by small, deliberate changes in operating parameters
- 32standard additionknown quantities of analyte are added to the unknown
- 33matrix effecta change in the analytical signal caused by anything in the sample other than analyte
- 34standard uncertaintystandard deviation of the mean
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- College Chemistry Flashcards on Chap 5 - Quantitative Chemical Analysis, created by Raegan Ferro on 22/09/2019.
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- Raegan Ferro · Sep 2019
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- Sep 23, 2019
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