2004632
| Questão | Responda |
| Data Domains | Modes of encoding information 1. Non-electrical: physical and chemical 2. Electrical: analog, digital, time |
| Detectors | A mechanical, electrical, or chemical device that IDs, records, or indicates a change in one of the variables in its environment |
| Transducer | Device that convert information in non-electrical domains to information in electrical domains |
| Sensor | Analytic devices capable of monitoring specific chemical species continuously and reversibly Consist of a transducer coupled with a chemically selective recognition phase |
| Readout Device | A transducer that converts information from an electrical domain to a form that is understandable by a human |
| Calibration | Determines the relationship between the analytical response and the analyte concentration |
| Comparison with Standards | "null comparison" Comparing a property of the analyte with standards such that the property being tested matches that of the standard (matching the color of a standard of known concentration with the color of a solution of unknown concentration) |
| External Standard | A series of external standards of known concentration is prepared and analyzed separate from the sample Graph of corrected analytical response vs. analyte concentration is prepared and a mathematical model developed Used when there are no interference effects from matrix components in the analyte |
| Standard Addition | Add one or more increments of a standard solution to sample aliquots contains identical volumes (spike the sample) and dilute to a fixed volume before measurement Measurements are made on the original sample plus the standard after each addition Used to analyze complex samples in which the matrix effects is substantial |
| Internal Standard | Substance is added in a constant amount to all the samples, blanks, and calibration standards Graph the ratio of analyte signal to internal standard signal vs. the analyte concentration of the standards compensates for both random and systematic errors should provide a signal similar to the analyte signal but distinguishable from it must be absent from the sample matrix so that only the source is the added amount |
| Choice of instrument | 1. Accuracy and precision 2. Amount of sample available 3. Concentration range of the analyte 4. Interfering sample components 5. Physical and chemical properties of the sample matrix 6. Number of samples to be analyzed |
| Precision (Reproducibility) | degree of mutual agreement among data that have been obtained in the same way |
| Accuracy | closeness of a measurement to its true or accepted value |
| Sensitivity | ability of an instrument to discriminate between small differences in analyte concentration limited by the slope of the calibration curve and the reproducibility of the instrument steeper calibration curve is more sensitive |
| Detection limit | the minimum concentration of analyte that can be detected at a known confidence level |
| Limit of quantitation (LOQ) | lowest concentration at which quantitative measurements can be made |
| Limit of linearity (LOL) | concentration at which the calibration curve departs from linearity |
| Dynamic range | range between LOQ and LOL |
| Selectivity | degree to which an analyte is free from interference by other species in the sample matrix |
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