External Standard Calibration
External Standard Calibration - Related Videos
07:43
Calibration Curves
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2023
Source: Laboratory of Dr. B. Jill Venton - University of Virginia Calibration curves are used to understand the instrumental response to an analyte and predict the concentration in an unknown sample. Generally, a set of standard samples are made at various concentrations with a range than includes the unknown of interest and the instrumental response at each concentration is recorded. For more accuracy and to understand the error, the response at each concentration can be repeated so an error...
01:11
Glassware Calibration
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2024
Accurate calibration of glassware, such as volumetric flasks, pipettes, and burettes, is essential to ensure accurate measurements in the analytical laboratory. Calibration helps maintain consistency across measurements and prevents errors arising from inaccurate volumes. Volumetric flasks: Volumetric flasks are designed to prepare aqueous solutions of precise volumes accurately with a calibration line on the neck. To calibrate a volumetric flask, it is important to fill it with distilled...
01:20
Externalities
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2025
Externalities are unintended side effects of economic activities that impact third parties who are not directly involved in the market transaction. They can have positive or negative effects that can influence society and the environment in various ways. Positive Externalities Positive externalities occur when a market activity produces benefits for others without those beneficiaries having to pay for it. Examples include: Education: When individuals receive an education, society benefits...
08:43
Calibration Procedures for Orthogonal Superposition Rheology
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Cited by 4 •
2020
We present a detailed calibration protocol for a commercial orthogonal superposition rheology technique using Newtonian fluids including end-effect correction factor determination methods and recommendations for best practices to reduce experimental error.
08:12
Pressure Transducer: Calibration Using a Pitot-static Tube
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2023
Source: Shreyas Narsipur, Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC Fluid pressure is an important flow characteristic that is required to determine the aerodynamics of a system. One of the oldest and still existing pressure measurement systems is the manometer due to its accuracy and simplicity of operation. The manometer is generally a U-shaped glass tube that is partially filled with liquid, as shown in Figure 1. The U-tube manometer requires no...
FAQs
Linearity determines whether interpolation is dependable: over the working concentration range, signal should change predictably with concentration. If the calibration relationship departs from linear behavior, an unknown response may not correspond uniquely to a concentration, reducing quantitative accuracy. Checking the curve’s behavior therefore helps identify the range in which protein, metabolite, or enzyme measurements can be interpreted confidently.
Consistent measurement conditions are central because the unknown is interpreted through responses obtained from separately measured standards. Changes in instrument behavior, assay conditions, or sample matrix can alter absorbance, fluorescence, or chromatographic peak area without representing a true concentration difference. Controlling these sources of variation makes the standard curve relevant to the unknown and improves the reliability of the calculated result.
Linearity and precision protect against different errors in a biochemical measurement. Linearity indicates whether responses track concentration in a usable way across the calibration range, whereas precision concerns the consistency of the measurements supporting that relationship. Considering both helps distinguish a stable quantitative result from one that appears plausible but is poorly supported by the calibration data.
A practical workflow begins by preparing standards with known concentrations and measuring their responses separately from the unknown samples. The responses are then plotted against concentration to form the calibration curve. After the unknown is measured under consistent conditions, its signal is located on the curve and the corresponding concentration is interpolated. This sequence links raw instrument output to a biochemical quantity.
External Standard Calibration is useful when biochemists need quantitative values for proteins, metabolites, enzymes, or other biomolecules. It can accommodate different response types, including absorbance, fluorescence, and chromatographic peak area, as long as the response is related to concentration and measurement conditions remain consistent. The result is a concentration estimate rather than merely a qualitative indication of sample presence.
Matrix-related effects and instrument variation can shift the measured response independently of the biomolecule’s concentration. Because standards are measured separately, the calibration curve may not fully represent the sample if its matrix changes the signal or the instrument response changes between measurements. Recognizing and controlling these influences is essential for keeping interpolated concentrations accurate and comparable.