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19 Cards in this Set
- Front
- Back
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Name two 'types' of quantitation methods |
1. Classical methods 2. Instrumental methods |
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Name seven classical methods of quantitation |
1. Precipitation 2. Extraction 3. Distillation 4. Boiling Point 5. Melting point 6. Gravimetric 7. Volumetric |
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Name five analytical measurements that can be made using instruments in quantitation |
1. Conductivity 2. Electrode potential 3. Light absorption/emission 4. Mass-to-charge ratio 5. Fluorescence |
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What is external standard quantitation? |
1. An external standard is first used to construct a calibration curve 2. Sample of unknown concentration is analysed and concentration read off curve 3. Sample and external standrard MUST be analysed under the same conditions |
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What is internal standard quantitation? |
Standard is run at the same time as the sample. Response ratio vs amount ratio plotted. |
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Name three desirable properties of an internal standard |
1. Similar to analyte but chromatographically different 2. Unreactive 3. Pure |
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Name eight characteristics that should be considered in the validation of an analytical method |
1. Linearity 2. Accuracy 3. Range 4. Precision 5. Recovery 6. Specificity 7. Limit of Quantitation 8. Robustness |
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What is linearity? |
The ability to produce results that are directly proportional to the concentration of an analyte in the sample. |
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What is range? |
Range is an expression of the lowest and highest levels of analyte that has been demonstrated to be determinable for a product. Normally derived from the linearity study. |
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What is accuracy? |
Degree of agreement of test result with the true value, or closeness of result obtained by procedure to the true value. |
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What is precision? |
Degree of agreement among individual results |
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How is accuracy measured? |
% Error (actual-experimental/actual x 100). Three separate analysis on three days. |
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What value must the accuracy of a method meet? |
Must have a %Error of <15% |
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How is precision measured? |
Coefficient of variation (CV) = SD/mean * 100. Three separate analysis on three days. |
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What value must the precision of a method meet? |
%CV must be <15% |
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What is specificity / selectivity? |
Ability to measure unequivocally the desired analyte in the presence of impurities. |
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What is the detection limit? |
Smallest quantity of an analyte that can be detected, not necessarily in a quantitive manner. |
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What is the limit of quantitation? |
Lowest concentration of analyte in a sample that may be determined with acceptable accuracy and precision (15%). |
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Name three approaches for determining the detection limit and the limit of quantitation |
1. Visual evaluation 2. Signal-to-noise ratio 3. standard deviation of response and the slope |
