1、BRITISH STANDARD BS ISO 78-2:1999 Chemistry Layoutfor standards Part 2: Methods of chemical analysis ICS 01.120; 71.040.40BSISO 78-2:1999 This British Standard, having been prepared under the directionof the Sector Committeefor Materials and Chemicals, waspublished under the authorityof the Standard
2、s Committee and comes into effect on 15June1999 BSI 03-2000 ISBN 0 580 32636 5 National foreword This British Standard reproduces verbatim ISO78-2:1999 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee CII/54, General test met
3、hods, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promu
4、lgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the se
5、ction entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct applicatio
6、n. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theISO title page, pages ii to iv, pages 1 to 14 and a back cover. This standard has been updated (see copyr
7、ight date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date CommentsBSISO 78-2:1999 BSI 03-2000 i Contents Page National foreword Inside front cover Foreword iii Text of ISO 78-2 1ii b
8、lankBSISO 78-2:1999 ii BSI 03-2000 Contents Page Foreword iii Introduction 1 1 Scope 1 2 Normative references 1 3 Terms and definitions 1 4 Quantities, units and symbols 2 5 Clause titles and clause order 3 Annex A (normative) Notes on the application of the layout forastandardmethodofchemicalanalys
9、is 4 Annex B (informative) Examples of formats for precision clauses 11 Annex C (informative) Statistical and other data derived from theresultsofinterlaboratorytests 12 Bibliography 14BSISO 78-2:1999 BSI 03-2000 iii Foreword ISO (the International Organization for Standardization) is a worldwide fe
10、deration of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that com
11、mittee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accord
12、ance with the rules given in the ISO/IEC Directives, Part3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least75% of the member bodies casting a vote. International S
13、tandard ISO78-2 was prepared by Technical Committee ISO/TC47, Chemistry, Subcommittee SC1, General methods. This second edition cancels and replaces the first edition (ISO78-2:1982), which has been revised to reflect changes in Part3 of the ISO/IEC Directives. ISO 78 consists of the following parts,
14、 under the general title Chemistry Layouts for standards: Part 2: Methods of chemical analysis; Part 3: Standard for molecular absorption spectrometry; Part 4: Standard for atomic absorption spectrometric analysis. NOTEPart1 was planned but never published. Annex A forms an integral part of this par
15、t of ISO78. Annex B andAnnex C are for information only.iv blankBSISO 78-2:1999 BSI 03-2000 1 Introduction It is recommended that standards for methods of chemical analysis are drawn up in accordance with Part3 of the ISO/IEC Directives for the technical work of ISO, which gives general guidance, an
16、d using the layout of which details are given on the following pages. It should always be remembered, in making use of this layout, that it is for guidance only. It should be adapted to suit any special requirements. There may be no need for all the subdivisions provided:those not required should be
17、 disregarded. With the object of helping to solve problems of drafting and layout which arise in drawing up standards for methods of chemical analysis, ISO/TC47 has established a series of standard layouts: layout for a standard method of chemical analysis, with notes on its application (ISO78-2); s
18、tandard layouts for instrumental analyses, with notes on their application (ISO78-3 and ISO78-4). A standard for a chemical product should form a consistent whole. In addition to specifying the characteristics required of the product, it should state how to determine these characteristics. A standar
19、d method of chemical analysis (test method) may be incorporated in the text of a standard for a chemical product. Test methods may be presented as separate clauses, as annexes or as separate parts. However, a test method will normally be issued as a separate standard if it is likely to be referred t
20、o in a number of other standards. This will shorten the text of the standard for the chemical product; and, if a general method of chemical analysis applicable to the product exists, the standard for the product may merely refer to it. The adoption of a standard form of layout and drafting ensures:
21、that no important point is overlooked in the preparation of the standard; that the various items of information to be included in the standard are always given in the same order; that any desired clause may be found rapidly, whatever the origin or scope of the standard (this is particularly importan
22、t if part of the text is being translated or two texts are being compared); simplification, rationalization and standardization of methods, reagents and equipment used in test laboratories; that each International Standard or other international document prepared in this field is drafted in terms wh
23、ich are as clear as possible. 1 Scope This part of ISO78 sets out a number of principles applicable to the layout and wording of methods of chemical analysis described in InternationalStandards. It may also be useful for other test methods. 2 Normative references The following normative documents co
24、ntain provisions which, through reference in this text, constitute provisions of this part of ISO78. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of ISO78 are encouraged to investigate the p
25、ossibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards ISO 31 (all parts), Quantities an
26、d units. ISO 1000, SI units and recommendations for the use of their multiples and of certain other units. ISO 5725 (all parts), Accuracy (trueness and precision) of measurement methods and results. 3 Terms and definitions For the purposes of this part of ISO78, the following definitions apply: 3.1
27、laboratory sample sample as prepared for sending to the laboratory and intended for inspection or testing Based on ISO 6206 3.2 test sample sample prepared from the laboratory sample and from which test portions will be taken Based on ISO 6206 3.3 test portion the quantity of material drawn from the
28、 test sample (or from the laboratory sample if both are the same) and on which the test or observation is actually carried out Based on ISO 6206 3.4 standard volumetric solution solution for titrimetric analysis, the concentration of which is known accuratelyBSISO 78-2:1999 2 BSI 03-2000 3.5 standar
29、d reference solution solution used as a reference solution for calibrating other solutions NOTE 1It is either prepared from a primary standard or calibrated by some other means. NOTE 2Many standard reference solutions which can be used to prepare standard solutions are commercially available. 3.6 st
30、andard solution solution of accurately known concentration of an element, an ion, a compound or a group derived from the substance used for its preparation 3.7 standard matching solution solution of which the relevant characteristic is known or defined (for example colour, turbidity) and is used to
31、assess the test solution in relation to that characteristic NOTE 1The English term standard matching solution is used solely as a generic term for these solutions, and each solution is normally defined more precisely by the appropriate adjective (for example, “standard colorimetric solution”, “stand
32、ard turbidimetric solution”). NOTE 2It may be prepared from solutions mentioned above or other solutions having the required characteristic. NOTE 3The method of preparation of standard matching solutions is normally given in the subclause “Calibration” (seeA.13.7). 3.8 precision the closeness of agr
33、eement between independent test results obtained under stipulated conditions Based on ISO5725-1 3.9 accuracy closeness of agreement between a test result and an accepted reference value NOTEThe term accuracy, when applied to a set of test results, involves a combination of random components and a co
34、mmon systematic error or bias component. Based on ISO5725-1 3.10 repeatability precision under repeatability conditions Based on ISO5725-1 3.11 repeatability conditions conditions where independent test results are obtained with the same method on identical test items in the same laboratory by the s
35、ame operator using the same equipment within short intervals of time Based on ISO5725-1 3.12 repeatability limit value less than or equal to which the absolute difference between two test results obtained under repeatability conditions may be expected to be with a probability of95% NOTEThe symbol us
36、ed is r. Based on ISO5725-1 3.13 reproducibility precision under reproducibility conditions Based on ISO5725-1 3.14 reproducibility conditions conditions where test results are obtained with the same method on identical test items in different laboratories with different operators using different eq
37、uipment Based on ISO5725-1 3.15 reproducibility limit the value less than or equal to which the absolute difference between two test results obtained under reproducibility conditions may be expected to be with a probability of95% NOTEThe symbol used is R. Based on ISO5725-1 4 Quantities, units and s
38、ymbols 4.1 General The quantities, units, mathematical signs and symbols for quantities laid down in ISO31 (allparts) and ISO1000 shall be used wherever possible. The symbols for units of measurement shall be used if they are preceded by a number expressed in figures. In other cases, these units sho
39、uld preferably be written out in full, except where used in drawings, graphs and in column headings in tables. NOTEIn some countries, the symbol (“per mill” or “perthousand”) is used for the number0,001. This symbol should preferably be avoided. Since per cent and per mill are numbers, it is in prin
40、ciple meaningless to speak about percentage by mass or percentage by volume. Additional information, such as% (m/m) or% (V/V) should preferably not be attached to the unit symbol therefore. The preferred way of expressing a mass or volume fraction is: “the mass (or volume) fraction is0,75” or “the m
41、ass (or volume) fraction is75%”. Mass and volume fractions can also be expressed in the form54g/g and4,2 ml/m 3respectively. Abbreviations such as ppm, pphm and ppb shall not be used.BSISO 78-2:1999 BSI 03-2000 3 4.2 Choice of test methods As far as possible, the same test methods for a given proper
42、ty or characteristic of related chemical products shall be adopted in all ISO documents, and their wording shall be as similar as possible. This does not apply to certain industries if, in a particular industry, this rule would be contrary to justified and well established practice which it is desir
43、able to retain. 4.3 Chemical nomenclature The recommendations prepared by the International Union of Pure and Applied Chemistry (IUPAC) on the nomenclature of chemicals of high purity and the way of spelling and printing their names should preferably be applied, e.g. the IUPAC nomenclature for organ
44、ic compounds. If they exist, Chemical Abstract Registry Service Numbers (CASnumbers) should be given (seeclauseA.10). It is advisable to put the trivial name of the reagent in parentheses after the IUPAC name when it first occurs. In the remainder of the text, either the IUPAC name or the trivial na
45、me may be used, but the same name shall be used consistently throughout the remainder of the text. The use of trade/proprietary names shall be avoided as far as possible, even if they are in common use. For commercial chemicals (basic chemicals for industrial use), the trivial name should be given i
46、n the title of the standard and in the “Scope” clause of the standard; the corresponding IUPAC name for the pure product should be given in parentheses after the trivial name, but thereafter only the trivial name need be used. The use of symbols for chemical products shall be restricted to chemical
47、formulae and to symbols used to indicate quantities, e.g. c(H 2 SO 4 ). In running text, the full names shall be used. 4.4 Numerical values and tolerances Whenever a quantity, for example a temperature or a period of time, is expressed, a tolerance on its value shall be specified where it is critica
48、l. 5 Clause titles and clause order The preferred titles of the clauses (and other elements) in methods of chemical analysis, and the preferred order of the clauses, are given below. Any clause or subclause which is unnecessary in a particular case may be omitted, and others, if required, may be add
49、ed in the most appropriate places. The clauses and subclauses shall be numbered consecutively from the beginning to the end of each document, using arabic numerals. Clear distinction shall be made between normative and informative parts of the standard, such as annexes. For further details, see the relevant clause in Annex A. For comments see Foreword A.1 Introduction A.2 Title A.3 Warnings A.4 Scope A.5 Normative references A.6 Definitions A.7 Principle A.8 Reactions A.9 Reagents and materials A.10 Apparatus A.11 Sampling A
