achem

Calibration curve (also called standard curve) A graph showing the value of some property versus concentration of analyte. When the corresponding property of an unknown is measured, its concentration can be determined from the graph.

Standard solutions A solution whose composition is known by virtue of the way that it was made from a reagent of known purity or by virtue of its reaction with a known quantity of a standard reagent.

Blank solution Solutions containing all reagents and solvents used in the analysis, but no deliberately added analyte. Blanks measure the response of the analytical procedure to impurities or interfering species in the reagents.

Linear range Concentration range over which the change in detector response is proportional to the change in analyte concentration. LOQ to limit of linearity (LOL)

Dynamic range Range of analyte concentration over which a change in concentration gives a change in detector response (LOQ to Upper LOQ)

Standard operating procedures (SOP) Statement of what steps will be taken and how they will be carried out

Accuracy Nearness to the "truth"

Precision How well replicate measurements agree with one another

Range The concentration interval over which linearity, accuracy, and precision are all acceptable

Selectivity Extent to which a method can distinguish an analyte from everything else in the sample

Matrix Everything in the unknown, other than the analyte

Matrix effects Interference of the matrix in analytical measurements

Sensitivity Capability of responding reliably and measurably to changes in analyte concentration (slope of the calibration curve, m)

Limit of detection (LOD) The smallest quantity of analyte that is "significantly different" from the blank: 3 times the standard deviation of y (blank signal), divided by the slope m

Limit of quantitation (LOQ) The smallest amount that can be measured with reasonable accuracy: 10 times the standard deviation of y (blank signal), divided by the slope m

Repeatability Describes how well one person can obtain the same results when analyzing the same sample by the same procedure with the same equipment in the same laboratory

Reproducibility Describes how well different people in different laboratories with different equipment can get the same results when analyzing equivalent samples by the same procedure

Robustness The ability of an analytical method to be unaffected by small, deliberate changes in operating parameter