Quantitative Analysis Chapter 5

What is sampling?

The process of collecting a representative sample for analysis

What is specificity?

Capability of an analytical method to distinguish an analyte from other species in the sample

What is sensitivity?

The magnitude of instrument response per unit change in the concentration of the analyte

What is robustness?

The ability of an analytical method to be unaffected by small changes in operating conditions

What is fortification?

Addition of a known compound (usually at a known concentration) to an unknown to find the concentration of the unknown.

What is calibration?

Process of relating the actual quantity (such as mass, volume, force, or electric current) to the quantity indicated on the scale of an instrument

What is a calibration check?

In a series of analytical measurements, a calibration check is an analysis of a solution formulated by the analyst to a certain known concentration of analyte. It’s the analyst’s own check that procedures and instruments are functioning correctly

What is a performance test?

In a series of analytical measurements, a performance test sample is inserted to see whether the procedure gives correct results when the analyst does not know the right answer; the performance test sample is formulated by someone other than the analyst to contain a known concentration of analyte

What is a method blank?

A sample without deliberately added analyte. The method blank is taken through all steps of a chemical analysis, including sample preparation.

What is a reagent blank?

A solution prepared from all the reagents except the analyte. The blank measures the response of the analytical method to impurities in the reagents ot any other effects caused by a component other than the analyte. A reagent blank is similar to a method blank, but it has not been subjected to all sample preparation procedures

What is a field blank?

A 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

What is a control chart?

a graph in which successive observations of a process are recorded to determine whether the process is within specified control limits

What are standard operating procedures (SOP)?

Set of step by step instuction that guides the analysist on how to preform a complex procedure the same way everytime.

What is method validation?

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

What is an assessment?

In quality assurance, the process of collecting data to show that analytical procedures are operating within specified limits and verifying that final results meet use objectives.

What is a linear range?

Concentration range over which the calibration curve is linear

Concentration and measured response have a 1-to-1 ratio

What is dynamic range?

Concentration range over which there is a measurable response

Must fit a curved line to get ratio/ equation

What is a detection limit?

The smallest quantity of analyte that is significantly different from a blank. The detection limit is often taken as the mean signal for blanks plus three times the standard deviation of a low-concentration sample

Whaat is the lower limit of quantitation?

Smallest amount of analyte that can be measured with reasonable accuracy, usually taken as 10 times the standard deviation of a low-concentration sample

What is the reporting limit?

concentration below which regulations dictate that an analyte is reported as not detected. The reporting limit is typically set 5 to 10 times higher than the detection limits

What is a standard addition?

a technique in which an analytical signal due to an unknown is first measured, then an unknown quantity of analyte is added, and the increased signal is recorded; from the response, it is possible to calculate what quantity of analyte was in the unknown

What is a internal calibration?

a known quantity of a compound other than the analyte is added to a solution containing an unknown quantity of analyte; the concentration of the analyte is then measured relative to that of the internal standard

What is a matrix?

The medium containing the analyte; everything in a sample other than the analyte. For many analyses, standards must be prepared in the same Matrix as the unknown

What is a matrix effect?

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