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Measurand Particular quantity subject to measurement.
Method The overall, systematic procedure required to undertake an analysis. This includes all stages of the analysis - not just the (instrumental) end determination.
Microwave-assisted extraction (MAE) Method of extracting analytes from matrices using solvent at elevated temperatures (and pressures) based on microwave radiation. Can be carried out in either open or sealed vessels.
Microwave digestion Method of digesting an organic matrix to liberate metal content using acid at elevated temperatures (and pressures) based on microwave radiation. Can be carried out in either open or sealed vessels.
Organometallic An organic compound in which a metal is covalently bonded to carbon.
Outlier An observation in a set of data that appears to be inconsistent with the remainder of that set.
Pesticide Any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest. The latter can be insects, mice and other animals, unwanted plants (weeds), fungi, or microorganisms such as bacteria and viruses. Although often misunderstood to refer only to insecticides, the term ‘pesticide’ also applies to herbicides, fungicides, and various other substances used to control pests.
Polycyclic aromatic hydrocarbons (PAHs) These are a large group of organic compounds, comprising two or more aromatic rings, which are widely distributed in the environment.
Precision The closeness of agreement between independent test results obtained under stipulated conditions.
Glossary of Terms
Pressurized fluid extraction (PFE) Method of extracting analytes from matrices using solvent at elevated pressures and temperatures (see also Accelerated solvent extraction).
Qualitative analysis Chemical analysis designed to identify the components of a substance or mixture.
Quality assurance All of those planned and systematic actions necessary to provide adequate confidence that a product or services will satisfy given requirements for quality.
Quality control The operational techniques and activities that are used to fulfil requirements of quality.
Quality control chart A graphical record of the monitoring of control samples which helps to determine the reliability of the results.
Quantitative analysis Chemical analysis which is normally taken to mean the numerical measurement of one or more analytes to the required level of confidence.
Reagent A test substance which is added to a system in order to bring about a reaction or to see whether a reaction occurs (e.g. an analytical reagent).
Reagent blank A solution obtained by carrying out all of the steps of an analytical procedure in the absence of a sample.
Recovery The fraction of the total quantity of a substance recoverable following a chemical procedure.
Reference material Substance or material, one or more of whose property values are sufficiently homogeneous and well established to be used for the calibration of an apparatus, the assessment of a measurement method, or for assigning values to materials.
Repeatability Precision under repeatability conditions, i.e. conditions where independent test results are obtained with the same method on identical test items in the same laboratory, by the same operator, using the same equipment within short intervals of time.
Reproducibility Precision under reproducibility conditions, i.e. conditions where test results are obtained with the same method on identical test items in different laboratories, with different operators, using different equipment.
Robustness A measure of the capacity of an analytical procedure to remain unaffected by small, but deliberate variations in method parameters, and which provides an indication of its reliability during normal usage. Sometimes referred to as ruggedness.
Rotary evaporation Removal of solvents by distillation under vacuum.
Sample A portion of material selected from a larger quantity of material. The term needs to be qualified, e.g. representative sample, sub-sample, etc.
Selectivity (in analysis) (i) Qualitative - the extent to which other substances interfere with the determination of a substance according to a given procedure.
Methods for Environmental Trace Analysis
(ii) Quantitative - a term used in conjunction with another substantive (e.g. constant, coefficient, index, factor, number, etc.) for the quantitative characterization of interferences.
Sensitivity The change in the response of a measuring instrument divided by the corresponding change in stimulus.
Signal-to-noise ratio A measure of the relative influence of noise on a control signal. Usually taken as the magnitude of the signal divided by the standard deviation of the background signal.
Shake-flask extraction Method of extracting analytes from matrices using agitation or shaking in the presence of a solvent.
Solid-phase extraction (SPE) A sample preparation technique that uses a solidphase packing contained in a small plastic cartridge. The solid stationary phases are the same as HPLC packings; however, the principle is different from HPLC. The process, as most often practised, requires four steps: conditioning the sorbent, adding the sample, washing away the impurities, and eluting the sample in as small a volume as possible with a strong solvent.