Preface

The fourth edition of the Orange Book comes more than two decades after the third edition (Compendium of Analytical Nomenclature: Definitive Rules 1997).¹  Consideration of a revision started at the General Assembly held in Glasgow in 2009, and it soon became evident that a complete re-write would be necessary.

The first edition was published in 1977 edited by the legendary H. M. N. H. Irving, H. Freiser and T. S. West. It was a collection of 23 reports published by IUPAC between 1960 and 1976. The Compendium was updated as the second edition in 1987 by the 11 reports published between 1976 and 1984.

Although mostly keeping the structure of the original editions, the 1997 third edition, edited by János Inczédy, was a major revision. There were three new chapters: selections from the Green Book,²  a chapter on Quality Assurance, and a chapter on Applications.

A web edition of the Orange Book was prepared by David Moore (President, Division V 2002–2003) with each chapter sub-section being presented as a searchable pdf file (see https://media.iupac.org/publications/analytical_compendium/). Soon after, it was decided to create the Gold Book in XML format, which would be the on-line repository of IUPAC terminology and nomenclature. This appeared in 2006, with few additions since. In 2019 a new site (https://goldbook.iupac.org/) was launched to serve as the platform for a revision of all terms. Terms in this Orange Book, and its source recommendations, will be considered for inclusion in the revised Gold Book.³ 

The Orange Book is called a “Compendium of Terminology”. Since earlier editions, the way that concepts in science are termed and defined has been described and codified in ISO standards,^4,5  and while IUPAC is not mandated to follow these standards, they have informed the work of the Orange Book revision. Indeed “Compendium” is not defined by ISO, perhaps the nearest concept is “Vocabulary” or “Glossary”, but the title of the earlier editions is retained to cover what is to be found here.

The aim of the Orange Book is to bring together terms for, and definitions of, concepts that are used in analytical chemistry and present them to the reader collected under broad headings of methods and techniques commonly understood in the field. The Orange Book is therefore not a manual of how to do analytical chemistry; it is not a bibliography of learned publications in analytical chemistry, nor does it contain critical reviews of selected topics in analytical chemistry.

The Orange Book attempts to be a compilation of IUPAC-reviewed terms and definitions in analytical chemistry. Each term and definition are accompanied by appropriate notes, examples, and references. This layout with short paragraphs of comment and discussion should provide an intuitive navigation through the topics of interest to the analytical community.

Perhaps this edition of the Orange Book will be the last edition to appear in hard copy with the familiar orange cover. As new versions of the Gold Book, which is only to be found on the internet, are produced, there will be seamless synchronisation among the on-line Colour Books of IUPAC.

The nineteen chapters of the third edition have been replaced by thirteen chapters here. The first chapter (Fundamentals) while maintaining extracts from the Green Book has a major section devoted to metrology (the science of measurement) with concepts taken from the International Vocabulary of Measurement (VIM).⁶  Chapter 2 is new, with concepts from chemometrics and statistics applied to analytical chemistry. The use of computerised data analysis, as well as an increasing sophistication of statistical methods in interlaboratory comparisons and testing against regulatory limits, now require many concepts to be termed and defined. A chapter on extraction (including ‘sampling’) reflects the importance now placed on obtaining representative material capable of analysis. “Mass and volume” brings together and updates chapters in the third edition. Titration and gravimetry still represent some of the most used, and most accurate methods in chemical analysis and readers are reminded of concepts that are well known in the field. In the revision of the SI (International System of Units) in May 2019,⁷  the first two methods in the mise en practice for realising a mole (the unit of amount of substance) involve mass and volume. There follow chapters covering some of the most important instrumental techniques; separation (chromatography), aspects of spectroscopy (atomic, vibrational and nuclear magnetic resonance), mass spectrometry, electrochemical methods, radiochemistry, thermal methods and a new chapter on bioanalytical methods. The volume is completed with an updated review of the terminology of quality assurance as applied to analytical chemistry.

Limitations of space in the text and the enormous scope of the subject have prevented chapters on applications of analytical chemistry. The chapter on applications in the third edition could not do justice to the many areas in which analytical chemistry plays its role, and it was decided to limit the scope of the Orange Book to techniques and principles. Despite the wealth of material from the Subcommittee on Solubility and Equilibrium Data, contributions to terminology from this major subcommittee of our Division will be found in IUPAC Recommendations⁸  and in our on-line offerings.

The aim of any good lexicon is to become an ontology where insight into the whole is obtained from the interrelations of the parts. We do not claim that entirely here, but the authors of the chapters are aware of some guiding principles that they hope to have followed.

1. Stability: any change of the vocabulary should have a cogent justification.

2. Internal consistency: definitions should be coherent, i.e., no pairwise contradiction should occur.

3. External consistency: the definitions should be coherent with the usage in relevant scientific and technical communities.

4. Philosophical agnosticism: definitions should, as far as possible, be formulated independently of any philosophy.

5. Closure: scope-related concepts referred to in one or more definitions should be defined in the vocabulary itself, except for primitive concepts that are considered self-evident.

6. Inclusion: a concept should only be included in the vocabulary if there is consensus on its relevance (i) to the scope or, less importantly, (ii) to the structure of the concept system.

7. Absence of circularity: two definitions should not mutually define each other.

1. A concept used to discriminate among subordinate concepts should be defined or, if it can be substituted, removed.

2. A new concept and term should not be introduced without necessity.

3. Negative forms in definitions should be avoided whenever possible.

4. Whenever two or more equivalent terms are possible, the simplest one in the context should be used when there is no possibility of ambiguity.

A concept in science is designated by one or more terms and can be defined by reference to other defined concepts and by so-called primitive concepts (ones that are sufficiently self-evident as to require no definition). For example the concepts ‘substance’ and ‘material’ are primitives and are used as such in the Gold Book.³  The major part of this Compendium is therefore the terms and definitions of over 3000 concepts in analytical chemistry (starting with ‘analytical chemistry’ itself). A definition should be concise, consistent and coherent with other definitions and should not stray into a discussion about the use of the concept, comparisons with other concepts, history, strengths and weaknesses and so on. Notes and examples to provide useful explanations are provided and cite important references. All definitions have been through the IUPAC review procedure by publication in Pure and Applied Chemistry (PAC) and through the review process of the Orange Book itself. Chapters and sections also have short introductions to put the material into context and highlight matters of importance to the subject.

The PAC conventions for definitions, namely starting with a capital letter and finishing with a period, are used.

Each concept is numbered by the chapter and a running number within the chapter. All terms and synonyms are to be found in the index. In the text a cross reference to a term in the Orange Book (not necessarily in the same chapter) is given in italics at its first mention in a subsection or term entry.

References are collected at the end of each chapter.

A specific format is required for entries in a glossary, or for definitions of terms in general. Adherence to this format will facilitate their eventual incorporation in the Gold Book and will also help to ensure that a term is explained accurately, logically and completely.

The general outline of the structure of a terminology entry is as follows. Annotations (which are not part of the terminology entry) are denoted as numbers in parentheses and are explained following the structure outline. The first five entries, as appropriate, are placed on one line, or continued on the following line, if necessary.

entry number (1.) preferred term (2.), (acronym) (3.), word class (4.), symbol (5.)

synonym (6.)

deprecated: deprecated term (6.)

obsolete: obsolete term (6.)

superseded: superseded term (6.)

definition of term (7.)....cross-referenced term (8.)....Ref. (9.)

Note 1: (10.)

Note 2: (10.)

......

Example: (11.)

See also: (12.)

Ref. and Source: (13.)

Explanation of Annotations:

1. Entry numbers in a glossary are assigned successively to terms arranged in alphabetical order. If the glossary contains more than one section, terms are arranged in alphabetical order within sections, but the numerical order is continuous throughout the document. The main use of entry numbers is in editing, in review, and to facilitate transfer to the Gold Book.

2. Use lower-case bold type, except when a proper name is part of the term.

   For entries in inverted order, e.g., tracer, generally labelled, add on the following line ‘See (entry in direct order)’, e.g., ‘See generally labelled tracer.’

   For homographic terms (those with the same spelling but different meanings), add an explanatory adjective in parentheses, and treat each term as a separate entry; e.g., ‘configuration (electronic)’, ‘configuration (stereochemical)’.

   Cross-references are listed alphabetically along with other terms.

3. Optional; printed in the same typeface as the preferred term.

4. Word class (or part of speech) is necessary only if the term can be used as more than one part of speech, in which case the particular part of speech is identified as an italicized abbreviation; e.g., n. (noun), v. (verb), adj. (adjective), adv. (adverb).

5. Required if appropriate; printed in the typeface as described below or in the Green Book.²  If used, the symbol should follow recommendations in the Green Book.

6. Add if necessary. Deprecated terms include those that have been in common use, but are not compatible with IUPAC Recommendations, e.g., ‘number of moles of X’ instead of the recommended ‘amount of X’. Obsolete terms include those that may be encountered in older literature, but are no longer in use; e.g., ‘gram-molecular weight’. Superseded terms include those that can still be found in the literature, but can be expressed more logically in newer terms; e.g., ‘specific gravity’ instead of the more logical ‘relative density’. The distinction between ‘obsolete' and ‘superseded’ terms is clearly somewhat arbitrary. It is not expected that many terms will appear in glossaries under these classifications.

7. For new definitions (those that have not appeared in previous IUPAC Recommendations), start the entry with a capital letter but do not use an article. The definition should be in the same word class (noun, adjective, verb, adverb) as the term itself.

   In defining terms involving a ratio of two quantities, do not use “ratio of” or “quotient of”. The phrase “divided by” is recommended. Phrases like “x per unit y” should never be used, as they confuse physical quantities and units, and can be ambiguous.

8. Cross-referenced terms are in italics.

9. References can be added here as “ref. number”, e.g., ref. 3. If desired, they can be placed in introductory text.

10. Explanatory notes can be added here, as many as necessary.

11. An example of use of the term can be given here.

12. Related terms can be added here.

13. References and sources may be added here.

This Compendium follows IUPAC practice as given in the Green Book.²  Section 10 of Chapter 1 gives rules for presenting quantities, values, and units in text, tables and graphics. Nomenclature of chemical compounds follows the Red and Blue Books.^10,11 

The Orange Book follows the convention given in the International Vocabulary of Metrology (VIM): “Single quotation marks (‘…’)surround the term representing a concept unless it is in italics. Double quotation marks (“…”)are used when only the term is considered, or for a quotation.”⁶ 

The majority of entries in this Orange Book have been published in an IUPAC Recommendation (Technical Report in the case of Chapter 3), mostly chapter by chapter. Therefore, at the beginning of each chapter the Recommendation in which terms will be found is referenced, and this becomes the definitive reference for all terms if a “Source:” is not otherwise given. Terms in italics without qualification are cross references to entries in the Orange Book, either the current chapter or elsewhere. Their chapter and entry numbers are given in the Index at the back of the book.

The twelve generating PAC publications (entries for Chapters 1 and 13 were published in one Recommendation) are:

Commonly used basic statistical terms are not referenced where they appear in individual entries. Most of these are defined in the first two parts of ISO 3534.^12,13 

• – population¹²  entry 1.1

• – probability (of an event)¹²  entry 2.5

• – statistic¹²  entry 1.8

• – standard deviation¹²  entry 2.37

• – variance¹²  entry 2.36

• – covariance¹²  entry 2.43

• – average (mean)¹²  entry 1.15

• – median¹²  entry 2.14

• – mode¹²  entry 2.27

• – correlation coefficient¹²  entry 2.44

• – standard error¹²  entry 1.24

• – characteristic¹³  entry 1.1.1

It is also noted that different fields of chemical science have preferred primitive expressions that are nearly synonyms: material, matter, and substance. We have not attempted to impose a common terminology.

This is a monumental work put together by many tens of dedicated scientists who are largely volunteers. The names of most are recorded in the front matter of the book.

As editor, starting in 2009, I have seen contributors come and go (four, alas, for ever), but always I have been excellently supported by my colleagues of the Analytical Division of IUPAC, and backed by the ever-helpful secretariat.

To name a few, Presidents of the Division Ján Labuda and Zoltán Mester have been carefully revising and advising. More recently, Derek Craston and Takae Takeuchi have taken up major chapters when all seemed lost, and many thanks to my metrology colleagues Heiner Korte and Ulf Örnemark who also took over chapters after the death of Paul de Bièvre and the retirement and death of René Dybkaer.

Thank you to my new chums at the Royal Society of Chemistry, led by my commissioning editor Janet Freshwater.

Finally, thanks to my partner in life Marian Kernahan who has put up with the Orange Book for decades and now hopes to resume a normal life.

Brynn Hibbert, Sydney