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A calibration curve plot showing limit of detection (LOD), limit of quantification (LOQ), dynamic range, and limit of linearity (LOL).. In analytical chemistry, a calibration curve, also known as a standard curve, is a general method for determining the concentration of a substance in an unknown sample by comparing the unknown to a set of standard samples of known concentration. [1]
A calibration curve is obtained by measuring a series of standard solutions with known concentrations, which can be used to determine the concentration of an unknown sample using linear regression analysis. [10] For example, by comparing the absorbance values of a solution with an unknown concentration to a series of standard solutions with ...
The calibration curve that does not use the internal standard method ignores the uncertainty between measurements. The coefficient of determination (R 2 ) for this plot is 0.9985. In the calibration curve that uses the internal standard, the y-axis is the ratio of the nickel signal to the yttrium signal.
In comparison to the calibration curve method, the standard addition method has the advantage of the matrices of the unknown and standards being nearly identical. [1] This minimizes the potential bias arising from the matrix effect when determining the concentration.
Instead, they rely on building a calibration curve from mixtures of the natural primary standard (A*) and the isotopically enriched standard (the spike, B). Calibration curves are obtained by plotting measured isotope ratios in the prepared blends against the known ratio of the sample mass to the mass of the spike solution in each blend.
The analytical (total) concentration of a reactant R at the i th titration point is given by = + [] + where R 0 is the initial amount of R in the titration vessel, v 0 is the initial volume, [R] is the concentration of R in the burette and v i is the volume added. The burette concentration of a reactant not present in the burette is taken to be ...
The concentration of analyte in both standards should be the same. A matrix effect value close to 100 indicates absence of matrix influence. A matrix effect value of less than 100 indicates suppression, while a value larger than 100 is a sign of matrix enhancement. An alternative definition of matrix effect utilizes the formula:
depending on whether the electrode is calibrated in millivolts or pH. For convenience the concentration, [H +], is used in place of activity. In a titration of strong acid with strong alkali, the analytical concentration of the hydrogen ion is obtained from the initial concentration of acid, C i and the amount of alkali added during titration.