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Questions and Answers
What is the primary purpose of using a calibration curve?
What is the primary purpose of using a calibration curve?
What distinguishes a fixed-time kinetic assay from a continuous monitoring assay?
What distinguishes a fixed-time kinetic assay from a continuous monitoring assay?
Which of the following is NOT a type of assay technique in clinical chemistry?
Which of the following is NOT a type of assay technique in clinical chemistry?
In comparative methods for analyte concentration calculations, what is typically used?
In comparative methods for analyte concentration calculations, what is typically used?
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What happens during the end-point assay?
What happens during the end-point assay?
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Which method relies on the known molar extinction coefficient?
Which method relies on the known molar extinction coefficient?
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What is a characteristic of the continuous monitoring kinetic assay?
What is a characteristic of the continuous monitoring kinetic assay?
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Which factor is common for both fixed-time and continuous monitoring assays?
Which factor is common for both fixed-time and continuous monitoring assays?
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What is the purpose of a blank solution in clinical chemistry measurements?
What is the purpose of a blank solution in clinical chemistry measurements?
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Which term refers to a pure solution with a known concentration of a substance?
Which term refers to a pure solution with a known concentration of a substance?
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What does molar absorptivity measure in spectrophotometry?
What does molar absorptivity measure in spectrophotometry?
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Which of the following is NOT a component of a reagent blank?
Which of the following is NOT a component of a reagent blank?
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What is the relationship between absorbance and transmittance?
What is the relationship between absorbance and transmittance?
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What is the purpose of a standard solution in clinical chemistry?
What is the purpose of a standard solution in clinical chemistry?
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Which statement best describes the function of a control solution?
Which statement best describes the function of a control solution?
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What adjustment is made when using a blank sample during calibration?
What adjustment is made when using a blank sample during calibration?
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Study Notes
Clinical Chemistry I - 0202304
- Course Instructor: Mohammad QABAJAH
- Email: [email protected]
Week 11: Measurement Procedures and Calculations
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Objectives:
- Define terminologies associated with measurements in clinical chemistry
- List fundamental solutions in spectrophotometric measurements
- Describe assay techniques in clinical chemistry measurements
- Discuss calibration curves
Definition of Terms
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Blank: A solution used to correct for background interferences, either from the sample or the reagent.
- Reagent blank: A solution used to eliminate interferences from reagents. It includes all solution components except the sample.
- Sample blank: A solution used to remove interferences from samples. It includes all solution components except the reagent.
- Standard: A pure solution with a precisely known concentration of the substance of interest. Used as a reference to compare unknown concentrations.
- Control: A solution with a known concentration (either normal, pathological, or both) of the substance of interest. Used to monitor the accuracy and precision of measurements.
Definition of Terms (cont.)
- Molar absorptivity: A constant value for a given compound at a specific wavelength and path length (1 cm) under defined conditions (solvent, temperature, pH).
- Transmittance: The ratio of transmitted radiant energy to incident radiant energy.
- Absorbance: The negative logarithm of transmittance.
Quantitative Measurements
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Standardizing the instrument: Essential step before measurements of intensity.
- Set the minimum and maximum transmission conditions.
- Adjust metering to obtain accurate readings.
- Maximum transmittance: Instrument adjusted using a blank sample to read 100% transmittance or 0 absorbance.
- Zero transmittance: All light blocked from reaching the detector, resulting in a 0% transmittance reading.
Methods for Calculations
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Comparative methods:
- Ratio of known standard to unknown
- Use of a standard calibration curve
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Absolute methods:
- Uses known molar extinction coefficient
Calibration Curve
- Prepared by plotting absorbance (y-axis) versus concentration (x-axis) of known standard solutions.
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Application:
- Analyzing concentration of analytes
- Verifying instrument function
Assay Techniques in Clinical Chemistry
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End-point Assay:
- Reagent mixed with sample, and absorbance (Abs) is measured after a specific incubation time.
- Reaction types include enzymatic and binding reactions.
- Absorbance is read at a specific time after incubation during result reading time.
- Analyte concentration calculated using appropriate method (absolute or competitive).
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Kinetic Assay: Measures changes in substrate consumption or product formation during the incubation-substrate depletion period.
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Types:
- Fixed-time kinetic: Absorbance measured at predetermined times after incubation.
- Continuous monitoring assay: Multiple absorbance readings recorded continuously over the entire reading interval using 3 or more data points.
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Types:
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Description
Test your knowledge on measurement procedures and calculations in clinical chemistry. This quiz covers essential terminologies, spectrophotometric measurements, assay techniques, and calibration curves. Enhance your understanding of the fundamental concepts presented in week 11 of Clinical Chemistry I.
