Quantitative Chemistry Ch 5

Front 1

Quality Assurance

Back 1

Quantitative indications that indicate whether data requirements have been met. Also refers to the broader process that includes quality control, quality assessment, and documentation os procedures and results designed to ensure adequate data quality.

Front 2

Use Objective

Back 2

States the purpose for which results will be used

Front 3

Specifications

Back 3

describes how good analytical results need to be and what precautions are required in an analytical method

Front 4

False Positive

Back 4

conclusion that a concentration of analyte exceeds a certain limit when, in fact, the concentration is below the limit

Front 5

False Negative

Back 5

conclusion that a concentration of analyte is below a certain limit when, in fact, the concentration is above the limit

Front 6

Selectivity

Back 6

being able to distinguish analyte from other species in the sample

Front 7

Sensitivity

Back 7

the capability of responding reliably and measurably to changes in analyte concentration (slope of the calibration curve)

Front 8

Method Blank

Back 8

a sample containing all components except analyte and is taken through all steps of the analytical process (response is subtracted from samples response)

Front 9

Reagent Blank

Back 9

a solution prepared from all of the reagents, but with no analyte (measures the response of the analytical method to impurities in the reagents and other effects caused by any component other than analyte)

Front 10

Field Blank

Back 10

blank sample exposed to the environment at the sample collection site and transported in the same manner as other samples between the lab and the field

Front 11

Matrix

Back 11

everything in the sample other than analyte

Front 12

Spike

Back 12

addition of a known compound (usually with known concentration) to an unknown

Front 13

Calibration Check

Back 13

the analysis of a solution formulated by the analyst to contain a known concentration of analyte

Front 14

Performance Test Samples

Back 14

it is inserted in a series of measurements to see if a procedure gives correct results when the analyst does not know the right answer

Front 15

Standard Operating Procedures

Back 15

a written procedure that must be rigorously followed to ensure the quality of a chemical analysis

Front 16

Control Chart

Back 16

a visual representation of a confidence interval for a Gaussian distribution

Front 17

Assessment

Back 17

the process of (1) collecting data to show that analytical procedures are operating within specified limits and (2) verifying that final results meet use objectives

Front 18

Method Validation

Back 18

the process of proving that an analytical process is acceptable for its intended purpose

Front 19

Specificity

Back 19

the ability of an analytical method to distinguish the analyte from everything else that might be in the sample

Front 20

Linearity

Back 20

measures how well a calibration curve follows a straight line

Front 21

Square of the Correlation Coefficient

Back 21

measure of goodness of fit of data points to a straight line (R^2)

Front 22

Accuracy

Back 22

nearness of a measured value to the "true" value

Front 23

Precision

Back 23

the reproducibility of a result

Front 24

Range

Back 24

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

Front 25

Detection Limit

Back 25

the smallest quantity of analyte that is "significantly different" from the blank
Signal DL = Ydl = Yblank + 3s
DL (conc) = 3s/m

Front 26

Quantitation Limit

Back 26

the smallest amount of analyte that can be measured with reasonable accuracy
QL = 10s/m

Front 27

Reporting Limit

Back 27

the concentration below which regulatory rules say that a given analyte is reported as "not detected"

Front 28

Robustness

Back 28

the ability of an analytical method to be unaffected by small, deliberate changes in operating parameters

Front 29

Standard Addition

Back 29

known quantities of analyte are added to the unknown and the responses are recorded (keeps matrix effect constant)

Front 30

Matrix Effect

Back 30

a change in the analytical signal caused by anything in the sample other that the analyte

Front 31

Internal Standards

Back 31

a known amount of a compound, different from analyte, that is added to the unknown

Front 32

Response Factor

Back 32

(F) the relative response of a detector to analyte and internal standard