CHM 310 – Chemical Analysis Terminology

Vocabulary flashcards covering key terms and their definitions from the CHM 310 Chemical Analysis terminology notes.

Analyte

The substance being measured; the target of analysis; the species of interest that produces the analytical signal.

Interferent

A contaminant that alters the signal related to the analyte; can increase or decrease (attenuate) the signal.

Sample

A portion representative of the whole material to be analyzed.

Sampling

The process of obtaining a manageable, representative sample from the lot.

Lot

The total material from which samples are taken.

Bulk Sample

A portion taken from the lot for analysis; some is stored (archived) and some used for lab sample preparations.

Lab Sample

A smaller version of the bulk sample used for analysis; not yet small enough for final analysis; from which aliquots are drawn and prep may begin.

Aliquot

The portion of the lab sample that is actually analyzed.

Archiving

Storing a sample for potential future use.

Sample Preparation

Converting a bulk sample into a homogeneous lab sample ready for analysis, and removing or masking interferents.

Masking

Transforming an interferent into a species that is not detected.

Homogeneous

Same composition throughout.

Heterogeneous

Different composition from region to region within the sample.

Random Heterogeneous Material

Differences in the sample are random and occur on a small scale.

Random Sample

Portions taken from a desired number of randomly chosen regions.

Segregated Heterogeneous Material

Large regions of different composition within the lot.

Composite Sample

A representative sample prepared from heterogeneous material; composed of portions from each region in amounts proportional to region size.

Qualitative Analysis

Determines whether a substance is present or not.

Quantitative Analysis

Determines how much of a substance is present.

Specific

Describes one type of analyte targeted.

Selective

Works for a few analytes; not necessarily all.

Standard

A reagent with a known amount of analyte to a high degree of certainty.

Primary Standard

A reagent that is pure and stable enough to be used directly after massing; entire mass is pure; high formula mass; minimizes massing errors.

Secondary Standard

A reagent whose purity and/or concentration is verified by chemical analysis or established with a primary standard.

Internal Standard

Added to a sample containing the analyte; may or may not be the analyte itself; if equal to the analyte, it can enhance signal; if not equal, it helps correct for changes during analysis.

External Standard

A sample of analyte of known purity used for calibration.

Calibration

Relating the actual quantity to the instrument’s response; in wet chemistry, and in instrumentation, determining the response to a known amount of analyte.

Calibration Curve

Also called a Standard Curve; a graph of instrument response versus analyte concentration.

Matrix / Sample Matrix

All components in the sample other than the analyte; the matrix can be used to prepare standard solutions.

Reagent Blank

A sample with zero analyte used to account for response due to impurities; ideally matches the matrix.

Method Blank

A reagent blank that has undergone all sample prep procedures.

Control

A sample subjected to all prep and analysis steps to establish a known positive or negative result.

Accuracy

Closeness of a measured value to its accepted value.

Precision

Closeness of a series of measurements to one another.

Repeatability

The maximum acceptable difference between duplicate determinations on the same reference sample in the same lab by the same operator using the same equipment.

Reproducibility

The maximum acceptable difference between the means of duplicate determinations carried out in two different labs on the same reference sample.

Standard Deviation

A measure of the spread or uncertainty in a set of measurements; indicates variability or uncertainty in results.