Chemical Analysis Measurement Techniques

These flashcards summarize key terms and concepts from the lecture notes on chemical analysis measurements, including the purpose of replicate measurement, types of errors, and evaluation methods.

Replicate Measurement

Samples conducted in close similarity to improve reliability in analysis.

Accuracy

Closeness of a measurement to the true or accepted value.

Precision

Reproducibility of a measurement across multiple trials.

Mean

The average value obtained from a set of measurements.

Median

The middle value when a data set is arranged in numerical order.

Outlier

A measurement that differs significantly from the others in a dataset.

Systematic Error

Errors that consistently shift measurements in one direction away from the true value.

Random Error

Errors that lead to variability in measurements without a defined pattern.

Gross Error

Significant mistakes often due to human error or misconceptions in measurement.

Standard Deviation

A measure of the amount of variation or dispersion of a set of values.

Coefficient of Variation

A normalized measure of dispersion expressed as the ratio of the standard deviation to the mean.

Instrumental Errors

Errors due to non-ideal instrument behavior or faulty calibrations.

Method Errors

Errors related to the non-ideal behavior of reagents during a measurement process.

Personal Errors

Errors arising from the carelessness or limitations of the experimenter.

Detection Limit

The lowest concentration of a substance that can be reliably detected.

Dynamic Range

The range over which an instrument can accurately measure a particular variable.

Bias

A systematic deviation of the measurement from the true value.

Control Determination

Using a standard material under the same conditions to minimize errors.

Dilution Method

A technique to reduce interference errors by diluting the sample.

Standard Addition

Adding a known quantity of analyte to a sample to measure changes in response.

Internal Standard Method

Adding a reference species to samples and comparing the analyte signal.

Parallel Determination

Repeating measurements in duplicates or triplicates to minimize errors.

Absolute Error

The difference between a measured value and the true value.

Relative Error

The absolute error expressed as a percentage of the true value.

Bias Significance

Negative bias indicates results are low; positive bias indicates results are high.

Statistical Test

A method used to evaluate differences in results from different analytical methods.

Performance Characteristics

Criteria used to evaluate the performance of analytical techniques.

Figures of Merit

Measurements that assess the capability and reliability of an analytical instrument.

Experimental Uncertainty

The degree of doubt in measurements that always exists.

Replicate Data Variability

Variations observed when repeating the same measurement procedure.

Calculation Errors

Errors resulting from incorrect calculations or data recording.

Laboratory Discipline

Systematic, careful work approach in laboratory experiments to minimize personal errors.