1、International Standard INTERNATIONAL ORGANIZATION FOR STANDAROIZATION=MEWlYHAPOLLHAR OPAHHBAUHR fl0 CTAHAPTHJALWl-ORGANlSATlON INTERNATIONALE DE NORMALISATION Chemistry - Layouts for standards - Part 3: Standard for molecular absorption spectrometry Chimie - Plans de normes - Par-tie 3: Norme dlanal
2、yse par spectromitrie dabsorption mokkulaire First edition - 1983-10-01 s UDC 54X422.5/.6 Ref. No. IS0 78/3-1983 (E) 2 1 Descriptors : standards, chemical compounds, chemical analysis, molecular absorption spectrophotometry. 2 P 2 Price based on 6 pages Copyright International Organization for Stand
3、ardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of developing Int
4、ernational Standards is carried out through IS0 technical committees. Every member body interested in a subject for which a technical committee has been authorized has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO,
5、also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. International Standard IS0 78/3 was developed by Technical Committee ISO/TC 47, Chemis
6、try, and was circulated to the member bodies in March 1982. It has been approved by the member bodies of the following countries: Australia Germany, F. R. Austria Hungary Belgium India Brazil Italy China Korea, Rep. of Czechoslovakia Mexico Egypt, Arab Rep. of New Zealand France Poland Portugal Roma
7、nia South Africa, Rep. of Sri Lanka Switzerland Thailand USSR The member body of the following country expressed disapproval of the document on technical grounds: Netherlands 0 international Organization for Standardization, 1993 0 Printed in Switzerland Copyright International Organization for Stan
8、dardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-INTERNATIONAL STANDARD IS0 78/3-1983 (E) Chemistry - Layouts for standards - Part 3: Standard for molecular absorption spectrometry 0.1 Introduction Each member of the
9、 set: The products dissolved in a solution analysed by methods using molecular absorption spectrometry, the principles of the methods adopted and the operating conditions employed are extremely varied. Thus, the solutions on which the spectro- metric measurements are made vary greatly in composition
10、. The absorbance of any one of these solutions is generally equal to the sum of the characteristic absorbances of the various con- stituents. The principle of each method of analysis using molecular ab- sorption spectrometry consists of judiciously selecting the composition of solutions which will b
11、e measured so that the value of the characteristic absorbance due to each constituent to be determined can be obtained by difference. 0.2 Scope and field of application This part of IS0 78 establishes a layout for standard methods of analysis using molecular absorption spectrometry for exam- ining s
12、olutions in the visible and near ultra-violet regions, and gives some recommendations for their presentation and wording. The layout itself is preceded by a clause “Terminology and definitions”, which supplements the information given in IS0 6286. It is followed by a section “Notes on the applicatio
13、n of the layout for a standard method of analysis by molecular absorption spectrometry”, which deals with the wording of clauses and sub-clauses used in the layout. 0.3 References IS0 7812, Layouts for standards - Part 2: Standard for chemical analysis. IS0 6286, Molecular absorption spectrometry -
14、Vocabulary - General - Apparatus. 0.4 Terminology and definitions 0.4.1 set of calibration solutions : A set of reference solu- tions having different concentrations of the constituent to be determined. - is prepared without addition of the sample submitted for analysis; 1) - contains a known quanti
15、ty of the constituent to be determined ; - is prepared in such a way that the presence of the con- stituent to be determined is shown by a detectable absorp- tion and an absorption of the same magnitude as the sample solution. NOTE - The member of the set in which the quantity of the consti- tuent t
16、o be determined intentionally added is zero, is called the zero member. 0.4.2 test solution : A solution made up from a test portion of the sample submitted for analysis and prepared in such a way that the presence of the constituent to be determined is shown by an absorption. 0.4.3 blank test solut
17、ion : A solution prepared in the same way as the test solution, but so that it does not contain the con- stituent to be determined. With this intention, the test portion used for making up the test solution is - replaced by an equal quantity of sample which has been treated in such a way as to ensur
18、e that the constituent to be determined is totally absent from it, without its other characteristics being changed, or - replaced by an equal quantity of a substance, whose the composition is apart from the absence of the consti- tuent to be determined, identical or very similar to that of the sampl
19、e, or, - replaced by a substance which is inert under the condi- tions of the determination (water for example) and which does not contain the constituent to be determined, or - simply omitted. NOTE - The particular procedures must be based on a selection from these four possibilities. . 1) In metho
20、ds based on the addition technique however, each member of the set contains the sample submitted for analysis, and in this case the zero member corresponds to the sample solution. 1 Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reprod
21、uction or networking permitted without license from IHS-,-,-IS0 78/3-1983 (El 0.4.4 compensation solution : A solution designed to take into account the particular absorption of the reagents and, possibly, the absorption of the constituent to be determined in the sample. For this purpose, it is prep
22、ared in such a way that, if the constituent to be determined is present, it is not shown by an absorption. To do this, the procedures usually adopted consist either of seeing that the initial reaction producing the absorbing com- pound does not take place (omission of one of the reactants if it does
23、 not itself absorb at the wavelength used for measure- ment, modification of the order of reagent addition, etc.) or in destroying the absorbing compound formed (oxidation, reduc- tion, formation of a complex, etc.). Depending on circumstances, the procedure may include the following compensation so
24、lutions : a) calibration compensation solution ; b) zero member compensation solution; c) sample compensation solution ; d) blank test compensation solution. All the reagents which are used to make these solutions are found in those at the same concentration as in the corre- sponding solutions (memb
25、ers of the set of calibration solu- tions, zero member, sample solution, blank test solution). 0.4.5 Sample solution A solution made up from the test solution and prepared by dilu- tion in function of the sensitivity of the apparatus and of the calibration range selected, on which the measurement of
26、 ab- sorbance is carried out. Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IS0 78/3-1983 (El Preferred order-for the layout Title Warning and safety precautions Introd
27、uction Scope Field of application References Definitions Principle Reactions Reagents and materials Apparatus Sampling and samples Procedure Test portion Preparation of test solution Preparation of the blank test (or Blank test) Calibration Preparation of reference solutions and of the set of calibr
28、ation solutions Formation of the absorbing compound Calibration compensation solution Spectrometric measurements Analytical function (or Plotting calibration graph) Determination Formation of the absorbing compound Sample compensation solution Spectrometric measurements Blank test Expression of resu
29、lts Special cases Remarks Test report Schematic representation of procedure Bibliography Annexes For comments, see clause (or sub-clause) 2 3 4 5 6 6.1 6.2 6.3 6.4 6.4.1 6.4.2 6.4.3 6.4.4 6.4.5 6.5 6.5.1 6.5.2 6.5.3 6.5.4 7 NOTE - Clauses and sub-clauses should be numbered consecutively using arabic
30、 numbers and the point numbering system, 3 Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IS0 78/3-1983 (El Notes on the application of the layout for a standard method
31、of analysis by molecular absorption spectrometry 1 General The clauses included in the layout scheme (headings in capital letters) are strictly those given in IS0 78/2. The notes below concern only the clauses and sub-clauses whose content is directly related to analysis by molecular ab- sorption sp
32、ectrometry carried out in the visible range or the near ultra-violet; for the other clauses, see IS0 78/2. The aim in elaborating this part of IS0 78 has been to provide editors with a guide which can be used wherever possible. Where this standard layout cannot be followed exactly, it will be for ed
33、itors to modify the recommended layout, adapting it to analytical demands. In particular, the description of certain determinations will not require the inclusion of all the clauses or sub-clauses provided in the layout, while in other cases extra clauses or sub-clauses may occasionally be needed. C
34、onsequently, the only inflexible rules are the following : a) use the terminology given in this part of IS0 78 and in IS0 6286; b) where possible and justifiable, include the clauses and sub-clauses indicated in the layout, and arrange them in the sequence indicated (it is possible and even advisabl
35、e to re- arrange them where strictly following the plan would lead to sub-clauses having little meaning) ; c) only ignore instructions given in this part of IS0 78 if they are not applicable. 2 Principle This clause shall indicate concisely the essential steps of the method (preferably using substan
36、tive phrases), excluding details relating to the procedure. It shall thus, on the one hand contain the physical and chemical principles of preparations (e.g. ashing, solution preparation, extraction, separation, complexing) preceding the stage cor- responding to the molecular absorption spectrometry
37、 and, on the other, the characteristics of this step. With regard to this last statement, it shall - mention the nature and the details of formation of the absorbing compound ; - draw attention, where necessary, to the kinetics of the reaction in formation of this compound ; 4 - indicate the wavelen
38、gth at which the measurement should be made, stating whether it corresponds to the ab- sorption spectrum maximum and, if not, stating the reasons. 3 Reagents This clause, set out in accordance with the details given in IS0 78/2, shall indicate in particular how the standard solution for the members
39、of set of the calibration solutions shall be prepared. The quality of reagents should be precisely indicated and also, where necessary, the processes of checking and purification. 4 Apparatus It is not necessary to include in this list ordinary laboratory apparatus required to carry out the method.
40、On the other hand, it may be useful to indicate the minimum re- quirements with which the spectrometric equipment shall com- ply and, in particular, the maximum permissible spectral band- width for the wavelengths used and the permissible variation with regard to the nominal wavelength. If use of op
41、tical cells of particular thickness is required, it is necessary to specify it. Where necessary, include a reference to IS0 6286 with regard to the performances which may be required and for checking the condition of the equipment. 5 Sampling and samples It is recalled that, according to IS0 78/2, a
42、 sub-clause headed “Preparation of the test sample” shall be included if necessary in this clause, giving all the details regarding the preparation (from the laboratory sample) of the test sample from which the test portion shall be taken. 6 Procedure It should be remembered that the layout that is
43、the subject of this part of IS0 78 should not be regarded as universally ap- plicable. This is why, for example, certain procedures should be regarded as preliminary tests (designed, for example, to deter- mine how pH corrections should be made) or control tests (e.g. to check whether the quantities
44、 or nature of the reagents used are well adapted to the particular conditions of the medium), to be carried out on one or more solutions the preparation of which is the subject of this clause. It is then for the editor to decide how the corresponding sub-clauses should be inserted between the sub-cl
45、auses provided for in the layout, how to make the text understood and how best to carry out the method. Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IS0 78/3-1983 (El
46、The following is the only inflexible rule: as far as possible, include each time all the sub-clauses indicated in this clause and arrange them in the sequence given. 6.1 Test portion The recommendations to follow for editing the sub-clause concerning the amount of sample for analysis by mass or by v
47、olume are those which are given in the sub-clause 13.2 of IS0 78/2. 6.2 Preparation of test solution The mass or the volume of test portion is given as a guide; as it is a function of the sensitivity of the apparatus and of the calibration range selected, it may be reduced or increased. According to
48、 this hypothesis, the editor should indicate the maximum and minimum permissible concentrations of the sample in the sample solution and/or in the test solution. This sub-clause should indicate precisely all physical and chemical treatments which the test portion for analysis has to undergo prior to
49、 the development of the absorbing compound. The editor should not hesitate to describe the minor details capable of influencing the quality of the results. 6.3 Preparation of the blank test (or Blank test) The heading of this sub-clause depends on its contents : it will be “Preparation of the blank test” if the step corresponding to the formation of the absorbing compound is not included in it. Otherwise it will be “Blank test”. The contents of this sub-clause are also ess
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