front 1 What is the definition of an assessment? | back 1 In quality assurance, the process of (1) collecting data to show that analytical procedures are operating within specified limits and (2) verifying that final results meet use objectives. |
front 2 What is the definition of a calibration check? | back 2 In a series of analytical measurements, a calibration check is an analysis of a solution formulated by the analyst to contain a known concentration of analyte. It is the analyst’s own check that procedures and instruments are functioning correctly |
front 3 What is the definition of a control chart? | back 3 A graph in which successive observations of a process are recorded to determine whether the process is within specified control limits. |
front 4 What is the definition of a detection limit? | back 4 The smallest quantity of analyte that is “significantly different” from a blank. The detection limit is often taken as the mean signal for blanks plus three times the standard deviation of a low- concentration sample. Also called lower limit of detection |
front 5 What is the definition of a dynamic range? | back 5 The range of analyte concentration over which a change in concentration gives a change in detector response. ie oncentration range over which there is measurable response |
front 6 What is the definition of a field blank ? | back 6 A blank sample exposed to the environment at the sample collection site and transported in the same manner as other samples between the lab and the field |
front 7 What is the definition of an internal standard? | back 7 A known quantity of a compound other than analyte added to a solution containing an unknown quantity of analyte. The concentration of analyte is then measured relative to that of the internal standard. |
front 8 What is the definition of a linear range? | back 8 The concentration range over which the change in detector response is proportional to the change in analyte concentration. ie concentration range over which calibration curve is linear |
front 9 What is the definition of a lower limit of quantitation? | back 9 Smallest amount of analyte that can be measured with reasonable accuracy. Usually taken as 10 times the standard deviation of a low-concentration sample. |
front 10 What is the definition of a matrix? | back 10 The medium containing analyte (that is, everything in a sample other than the analyte). For many analyses, it is important that standards be prepared in the same matrix as the unknown |
front 11 What is the definition of a matrix effect? | back 11 A change in analytical signal caused by anything in the sample other than analyte. |
front 12 What is the definition of a method blank? | back 12 A sample without deliberately added analyte. The method blank is taken through all steps of a chemical analysis, including sample preparation. See also reagent blank |
front 13 What is the definition of a method validation? | back 13 The process of proving that an analytical method is acceptable for its intended purpose |
front 14 What is the definition of a performance test sample? | back 14 In a series of analytical measurements, a performance test sample is inserted to see whether the procedure gives correct results when the analyst does not know the right answer. The performance test sample is formulated by someone other than the analyst to contain a known concentration of analyte. Also called a quality control sample or blind sample |
front 15 What is the definition of a quality assurance? | back 15 Practices that demonstrate the reliability of analytical data. |
front 16 What is the definition of a range? | back 16 The difference between the highest and lowest values in a set of data. Also called spread. With respect to an analytical method, range is the concentration interval over which linearity, accuracy, and precision are all acceptable. |
front 17 What is the definition of a reagent blank? | back 17 A solution prepared from all of the reagents except analyte. The blank measures the response of the analytical method to impurities in the reagents or any other effects caused by any component other than the analyte. A reagent blank is similar to a method blank, but it has not been subjected to all sample preparation procedures. |
front 18 What is the definition of a reporting limit? | back 18 Concentration below which regulations dictate that an analyte is reported as “not detected.” The reporting limit is typically set 5 to 10 times higher than the detection limit |
front 19 What is the definition of a response factor, F? | back 19 The relative response of a detector to analyte (X) and internal standard (S): (signal from X)/[X] = F(signal from S)/[S]. Once you have measured F with a standard mixture, you can use it to find [X] in an unknown if you know [S] and the quotient (signal from X)/ (signal from S |
front 20 What is the definition of a robustness? | back 20 The ability of an analytical method to be unaffected by small changes in operating conditions. |
front 21 What is the definition of a selectivity? | back 21 The capability of an analytical method to distinguish analyte from other species in the sample. Also called specificity. |
front 22 What is the definition of a sensitivity? | back 22 The magnitude of instrument response per unit change in concentration of analyte |
front 23 What is the definition of a specifications? | back 23 In quality assurance, specifications are written statements describing how good analytical results need to be and what precautions are required in an analytical method |
front 24 What is the definition of a spike? | back 24 Addition of a known compound (usually at a known concentration) to an unknown. In isotope dilution mass spectrometry, the spike is the added, unusual isotope. Spike is a noun and a verb. Also called a fortification. |
front 25 What is the definition of a standard addition? | back 25 A technique in which an analytical signal due to an unknown is first measured. Then a known quantity of analyte is added, and the increase in signal is recorded. From the response, it is possible to calculate what quantity of analyte was in the unknown. |
front 26 What is the definition of an use objectives? | back 26 In quality assurance, use objectives are a written statement of how results will be used. Use objectives are required before specifications can be written for the method |
front 27 What is raw data? | back 27 are individual measurements, such as peak areas from a chromatogram or volumes from a buret. ie individual measurements. |
front 28 What is treated data? | back 28 are concentrations or amounts found by applying a calibration procedure to the raw data. |