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19 Cards in this Set
- Front
- Back
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What is qualitative analysis? |
Identifying if an analyte is present in a sample |
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What is quantitative analysis? |
Determines the amount of analyte present in a sample |
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Quantitative analysis is represented by what 2 measurements |
1. The mass or volume of sample analysed. 2. Quantity of analyte in sample analysed. |
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Improving accuracy of an assay means what? |
Analysing more samples or increased time spent analysing |
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How do you assess the linearity of a calibration curve |
Visual inspection of curve. Also R squared value can be observed to check closeness to 1. |
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Assays that work for only one analyte are _____ |
Specific |
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Assays that work for several analytes are ______ |
Selective |
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What are the two sources of errors? |
Systematic and statistical (random) errors |
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What are systematic errors? |
Problem in preparation such as incorrect weighing. Errors occur in the same direction each time |
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How else is accuracy described? |
By trueness and bias |
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What is the definition of accuracy? |
The closeness of agreement of a test result and the accepted reference range. |
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What is the definition of trueness? |
The closeness of agreement between the average value obtained from a large set of test results and an accepted reference range. |
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What is trueness measured in? |
Bias |
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How do you calculate bias? |
The difference of the mean value of a set of measurements and the reference range. Average - ref = trueness |
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What is the definition of precision? |
The closeness of agreement between independent test results obtained under stipulated conditions. |
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What are the three levels of precision? |
Repeatability - replicates in interassay and intraassay settings. Reproducibility - same test different laboratories. Intermediate precision - some variation in test such as analysts or equipment |
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What is the limit of detection? |
The lowest amount of analyte that can be detected by an analytical method. |
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How do you prove the limit of detection is distinguished from background noise |
With sound to noise ratio (snr) Signal ÷ background noise = snr Snr of above 3 is acceptable
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How do you measure the limit of detection? |
Use the calibration curve y = mx + c |
