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In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Bernd Wenclawiak
Glossary of Analytical Chemistry Terms (GAT)
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Glossary
Remark: Teaching and Learning terms is boring, but necessary!
Why is it necessary to know the meaning of a term?Because a lot of expressions are not common in everyday life or might be interpreted differently
In scientific and technical work it is necessary that all people use the same “language”.
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Glossary
Who defines a term? In chemistry there is IUPAC
IUPAC coordinates the international work of harmonization
In the field of metrology many different organizations work together: ISO, IEC , BIPM, OIML, IUPAC, IUPAP, IFCCThey jointly published the VIM
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Glossary - Vocabularies A Vocabulary contains general terms and definitions
International Vocabulary of Basic and General Terms in Metrology (VIM)
International Vocabulary of Terms in Legal Metrology (VIML).
Guide to the Expression of Uncertainty in Measurement (GUM)
ISO 3534-1:1993. “Statistics - Vocabulary and symbols - Part 1: Probability and general statistical terms”.
ISO 3534-2:1993. “Statistics - Vocabulary and symbols - Part 2: Statistical quality control”.
ISO 3534-3:1985. “Statistics - Vocabulary and symbols - Part 3: Design of experiments”.
ISO 8402:1994, “Quality - Vocabulary”.
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Glossary
The bibliography comprises four different types of documents: Guides Standards Books Articles (in scientific journals)
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Glossary - Standardization Organizations
International: ISO (www.iso.ch)
European: EN (www.cenorm.be)
German: DIN (www.din.de)
Great Britain: BS (www.bsi.org.uk)
United States: ASTM (www.astm.org)
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Glossary – SI System The International System of Units (SI)
differentiates two classes of units: Base Units and Derived Units.
The Base Units are: Unit QuantitySymbol
metre length m kilogram mass kg second time s ampere electric current A kelvin thermodynamic temperature K mole amount of substance mol Candela luminous intensity cd
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Glossary - Important Organisations
European EURACHEM - Co-operation for Analytical Chemistry in
Europe EUROLAB - Organization for Testing in Europe EA - European Co-Operation for Accreditation EUROMET - A European Collaboration in Measurement
Standards IRMM Institute for Reference Materials and Measurements
International CITAC - Co-Operation on International Traceability in
Analytical Chemistry NIST – (US) National Institute of Standards and Technology
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Glossary - Terms Related to:
General Statistics Validation Measurement Error Uncertainty
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Glossary of General Terms Accreditation Accuracy Accuracy of measurement Accuracy of a Measuring
Instrument Audit Bias Certification Fitness for Purpose Influence quantity Precision
Quality Quality Assurance Quality Control Internal Quality Control Standard Trueness True Value Conventional True
Value
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms - Accreditation
Procedure by which an authoritative body gives formal recognition that a body or person is competent to carry out specific tasks (ISO/CASCO 193 (Rev. 2), & ISO Guide 2:1996)
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms - Accuracy The closeness of agreement between the
result of a measurement and the true value of the measurand
Accuracy is a measure which combines precision and trueness (i.e. the effects of random and systematic factors)
Suppose the results produced by the application of a method show zero or very low bias (i.e. are "true"), their accuracy becomes equivalent to their precision If the precision is poor, any particular result will be inaccurate
If a method shows a high bias, even results with a high precision are inaccurate
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms – Accuracy of Measurement
The closeness of the agreement between the result of a measurement and a true value of the measurand [VIM]
"Accuracy" is a qualitative concept. The term "precision" should not be used for
"accuracy".
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms - Accuracy (of a Measuring Instrument)
Ability of a measuring instrument to give responses close to a true value.[IUPAC Orange Book]
In this context accuracy is a qualitative concept.
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms - Audit Quality Audit: ‘A systematic and independent
examination to determine whether quality activities and related results comply with planned arrangements and whether these arrangements are implemented effectively and are suitable to achieve objectives’ (ISO 8402 - 1994).
External Audit also known as assessment Internal
audit review
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms - Bias
The difference between the expectation of the test results and an accepted reference value.
Characterises the systematic error in a given analytical procedure and is the (positive or negative) deviation of the mean analytical result from the (known or assumed) true value. [IUPAC Compendium of Chemical Technology, 1985]
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms - Certification
Procedure by which a third party gives written assurance that a product, process or service conforms to specified requirements(ISO/CASCO 193 (Rev. 2), 4.1.2, & ISO Guide2:1996, 15.1.2)
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms – Fitness for Purpose
Degree to which data produced by a measurement process enables a user to make technically and administratively correct decisions for a stated purpose.[IUPAC Orange Book]
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms – Influence Quantity
A quantity that is not the measurand but that affects the result of the measurement [VIM].
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms - Precision The closeness of agreement between independent
test results obtained under stipulated conditions The precision statement can be made for any set of
measurements which have been performed under stated experimental conditions which can be chosen freely
The precision of a set of results of measurements can be quantified as a standard deviation
Precise results on the same analyte are characterized by small statistical variability
This would then result in a small standard deviation, range or interquartile distance, all being measures of precision
Precision is a characteristic of a set of data
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms - Quality
„ ...quality is the totality of features of a unit as regards its suitability to fulfill specified and expected requirements.“ (ISO 8402)
A very important remark:
“No data is better than poor data”
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms – Quality - What does that Mean?
„Quality means that the customer comes back, and not the product.“
Quality and Liability are tightly connected
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms – Quality Assurance
All those planned and systematic activities implemented within the quality system, and demonstrated as needed, to provide adequate confidence that an entity will fulfil requirements for quality.[ISO 8402:1994]
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms – Quality Control
The operational techniques and activities that are used to fulfil requirements of quality. [ISO 8402:1994]
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms – Internal Quality Control
Set of procedures undertaken by laboratory staff for the continuous monitoring of operations and the results of measurements in order to decide whether results are reliable enough to be released.[IUPAC Orange Book]
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms – Standard
was used for widely adopted procedures, specifications, technical recommandations etc.
and also to chemical or physical standards, which are used for calibration purposes.
standard is used here only in the sense of writtenstandard
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms – Trueness The closeness of agreement between the average
value obtained from a large series of test results and the conventional true value
A true result is a result with little (or ideally no) systematical error without respect to the statistics of the series of results
Perfect trueness cannot be achieved, so trueness in its analytical meaning is always trueness within certain limits
These limits may be narrow at a high concentration level and wide at the trace level
It is important to note the difference between accuracy and trueness.
The lack of trueness is called bias
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms – True Value
Value which charcterizes a quantity perfectly defined in the conditions which exist when that quantity is considered.
The true value is a theoretical concept and, in general, cannot be known exactly
It is a value that would be obtained by a perfect measurement
True values are by nature indeterminate
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
General Terms – Conventional True Value Value attributed to a particular quantity and
accepted, sometimes by convention, as having an uncertainty appropriate for a given purpose
A result obtained by using several independent methods in several expert laboratories on one measurand is regarded as conventional true value of a quantity even if it is not the "true" value
A conventional true value is in general, regarded as sufficiently close to the true value for the difference to be insignificant for the given purpose.
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Glossary on Statistical Terms
Arithmetic mean Distribution functions Normal distribution Rectangular distribution Triangular distribution Poisson distribution Binomial distribution Estimate
Probabilty Standard Deviation Sample Standard
Deviation Standard deviation of
the mean Relative Standard
Deviation (RSD)
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Statistical Terms – Distribution Functions
Normal distribution continuous distribution Rectangular distribution Triangular distribution
Poisson distribution discrete function Binomial distribution discrete function
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Glossary on Validation Terms Calibration Curve linear least squares calibration
Cross Reactivity Discrimination Discrimination Threshold Limiting Mean Limit of Detection Minimum Detectable Net
Concentration Limit of Decision Limit of Determination Limit of Quantitation Limit of Reporting Linearity Proficiency Testing Range - Measuring and working
Recovery
Reference Material Certified Reference Material Repeatability Repeatability of Results of Measurements Repeatability of a Measuring Instrument Repeatability Standard Deviation Repeatability Limit r Reproducibility Reproducibility Standard Deviation Reproducibility Limit R Ruggedness Test Selectivity Selectivity in Analysis Sensitivity Specificity Validation Method Validation Verification
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Validation Method Validation Instrument Validation Verification Proficiency Testing
Limiting Mean Limit of Detection Minimum Detectable
Net Concentration Limit of Quantitation
Validation Terms
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Validation Terms
Calibration Curve Graphical representation of measuring
signal as a function of quantity of analyte. [AOAC]
Linear least squares calibration calibration with the method of minimizing
the least squares
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Validation Terms
Linearity Defines the ability of the method to obtain
test results proportional to the concentration of analyte.
The Linear Range is by inference the range of analyte concentrations over which the method gives test results proportional to the concentration of the analyte. [AOAC]
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Measurement Terms
Measurand Measurement Measurement Procedure Method of Measurement Response Time Result of a Measurement
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Measurement Terms - Measurement Standard
measurement standard is used to describe chemical or physical standards used for calibration purposes such as: chemicals of established purity and their corresponding solutions of known concentration, UV filter, weights, etc. They are also called: reference material
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Error Terms
Error of Measurement Random Error Systematic Error False Negatives/Positives
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Error Terms - Error (of a Result)
The test result minus the conventional true value
error is the sum of random and systematic errors
If a measurement is repeated, each individual result will have its own associated error
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Error Terms– False Negatives / Positives
For qualitative methods the false positives/negatives rate may be determined.
Data from a confirmatory method comparison should be provided if such method(s) is applicable to the same matrix(es) and concentration range(s).
In the absence of a method comparison, populations of negative and positive fortified samples must be analysed.
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Uncertainty Terms
Uncertainty (of Measurement) Standard Uncertainty Combined Standard Uncertainty Expanded Uncertainty Coverage Factor Type A evaluation (of uncertainty) Type B evaluation (of uncertainty)
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Uncertainty Terms - Measurement Uncertainty
Parameter, associated with the result of a measurement, that characterizes the dispersion of the values that could reasonably be attributed to the measurand
Uncertainty sets the limits within which a result is regarded accurate, I.e. precise and true
Uncertainty of measurement comprises, in general, many components. Some of these components may be evaluated from the statistical distribution of the results of series of measurements and can be characterized by experimental standard deviations
The other components, which can also be characterized by standard deviations, are evaluated from assumed probability distributions based on experience or other information.
In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching
Wenclawiak, B.: Glossary of Analytical Chemistry Terms © Springer-Verlag Berlin Heidelberg 2003
Uncertainty Terms – Traceability
Property of the result of a measurement or the value of a standard whereby it can be related with: a stated uncertainty, to stated references (usually national or
international standards)
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