1、BRITISH STANDARD BS EN 14662-2:2005 Ambient air quality Standard method for measurement of benzene concentrations Part 2 : Pumped sampling followed by solvent desorption and gas chromatography The European Standard EN 14662-2:2005 has the status of a British Standard ICS 13.040.20 BS EN 14662-2:2005
2、 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 June 2005 BSI 30 June 2005 ISBN 0 580 46131 9 National foreword This British Standard is the official English language version of EN 14662-2:2005. The UK participation in its preparation was
3、 entrusted by Technical Committee EH/2, Air quality, to Subcommittee EH/2/3, Ambient atmospheres, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement internationa
4、l or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to
5、include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any e
6、nquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 30, an insi
7、de back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 14662-2 May 2005 ICS 13.040.20 English version Ambient air q
8、uality - Standard method for measurement of benzene concentrations - Part 2 : Pumped sampling followed by solvent desorption and gas chromatography Qualit de lair ambiant - Mthode pour le mesurage des concentrations en benzne - Partie 2 : Echantillonnage par pompage suivi dune dsorption au solvant e
9、t dune chromatographie en phase gazeuse Luftbeschaffenheit - Standardverfahren zur Messung von Benzolkonzentrationen - Teil 2: Probenahme mit einer Pumpe mit anschlieender Lsemitteldesorption und Gaschromatographie This European Standard was approved by CEN on 21 March 2005. CEN members are bound to
10、 comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Centra
11、l Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as th
12、e official versions. CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain
13、, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2005 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national M
14、embers. Ref. No. EN 14662-2:2005: EEN 14662-2:2005 (E) 2 Contents Foreword 3 1 Scope .4 2 Normative References 4 3 Terms and definitions.4 4 Method description.6 4.1 Principle.6 4.2 Reagents and Materials 6 4.3 Apparatus 9 4.4 Setting of sampling flow rate .10 4.5 Sampling10 4.6 Procedure 11 4.7 Cal
15、culation of mass concentration of benzene 12 4.8 Report 13 5 Determination of measurement uncertainty .13 5.1 Introduction.13 5.2 Parameters contributing to measurement uncertainty 14 6 Recommendations for use .15 Annex A (informative) Determination of breakthrough volume .16 Annex B (informative) A
16、ssessment of performance indicators and uncertainty contributions18 Annex C (informative) Performance characteristics28 Bibliography.30EN 14662-2:2005 (E) 3 Foreword This European Standard (EN 14662-2:2005) has been prepared by Technical Committee CEN/TC 264 “Air quality”, the secretariat of which i
17、s held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 2005, and conflicting national standards shall be withdrawn at the latest by November 2005. This document has been prepared
18、under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive 2000/69/EC and EU Directive 96/62 EC. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countrie
19、s are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland
20、 and United Kingdom. EN 14662-2:2005 (E) 4 1 Scope This part of EN 14662 is in accordance with the generic methodology for the determination of benzene in ambient air 1 for the purpose of comparison of measurement results with limit values with a one-year reference period. This part of EN 14662 give
21、s general guidance for the sampling and analysis of benzene in air by pumped sampling, solvent desorption and capillary gas chromatography. This part of EN 14662 is valid for the measurement of benzene in a concentration range of approximately 0,5 g/m 3 to 50 g/m 3in an air sample of 1 m 3volume, ty
22、pically collected over a period of 24 hours. The upper limit of the useful range is set by the sorptive capacity of the sorbent and by the linear dynamic range of the gas chromatograph column and detector or by the sample splitting capability of the analytical instrumentation used. The lower limit o
23、f the useful range depends on the noise level of the detector and on blank levels of benzene and/or interfering artefacts on the sorbent and in the desorption solvent. The method described here is based on sampling on sample tubes typically containing 100 mg of activated charcoal and desorption usin
24、g carbon disulphide. Alternative sorbents to activated charcoal may be used provided that the equivalence in performance characteristics of the procedure is demonstrated. Alternative desorption solvents to carbon disulphide may be used provided that the equivalence in performance characteristics of
25、the procedure is demonstrated. 2 Normative References The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) appl
26、ies. ENV 13005, Guide to the expression of uncertainty in measurement EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:1999) ISO 6144, Gas analysis Preparation of calibration gas mixtures Static volumetric method ISO 6145, Gas analysis
27、Preparation of calibration gas mixtures using dynamic volumetric methods 3 Terms and definitions For the purposes of this European standard the following terms and definitions apply. NOTE. Attention is drawn to the fact that the terms Ambient Air and Limit Value are defined in Directive 96/62/EC 2.
28、3.1 Certified reference material A reference material 3.5, accompanied by a certificate, one or more of whose property values are certified by a procedure which establishes its traceability to an accurate realisation of the unit in which the property values are expressed, and for which each certifie
29、d value is accompanied by an uncertainty at a stated level of confidence. ISO Guide 30:1992 EN 14662-2:2005 (E) 5 3.2 Combined standard uncertainty Standard uncertainty of the result of a measurement when that result is obtained from the values of a number of other quantities, equal to the positive
30、square root of a sum of terms, the terms being the variances or covariances of these other quantities weighted according to how the measurement result varies with changes in these quantities. ENV 13005:1999 3.3 Desorption efficiency Ratio of the mass of analyte desorbed from a sampling device to tha
31、t applied. EN 1076:1997 3.4 Expanded uncertainty Quantity defining an interval about the result of a measurement that may be expected to encompass a large fraction of the distribution of values that could reasonably be attributed to the measurand. ENV 13005:1999 NOTE 1 The fraction may be viewed as
32、the coverage probability or level of confidence of the interval. NOTE 2 To associate a specific level of confidence with the interval defined by the expanded uncertainty requires explicit of implicit assumptions regarding the probability distribution characterised by the measurement result and its c
33、ombined standard uncertainty. The level of confidence that can be attributed to the interval can be known only to the extent to which such assumptions may be justified. NOTE 3 Expanded uncertainty is termed overall uncertainty in ENV 13005:1999. 3.5 Reference material A material or substance, one or
34、 more of whose property values are sufficiently homogeneous and well established to be used for the callibration of an apparatus, the assessment of a measurement method, or for assigning values to materials. ISO Guide 30:1992 3.6 Repeatability conditions Conditions where independent test results are
35、 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. ISO 3534-1:1993 3.7 Sampling efficiency Ratio of the mass of analyte collected by a sampling device to that applied. 3.8 Standard uncertainty Un
36、certainty of the result of a measurement expressed as a standard deviation. ENV 13005:1999 3.9 Uncertainty (of measurement) Parameter, associated with the results of a measurement, that characterises the dispersion of values that could reasonably be attributed to the measurand EN 14662-2:2005 (E) 6
37、NOTE 1 The parameter may be, for example, a standard deviation (or given multiple of it), or the half width of an interval having a stated level of confidence. NOTE 2 Uncertainty of measurement comprises, in general, many components. Some of these components may be evaluated from the statistical dis
38、tribution of the results of a series of measurements and can be characterised by experimental standard deviations. The other components, which can also be characterised by standard deviations, are evaluated from assumed probability distributions based on experience or other information. NOTE 3 It is
39、 understood that the result of a measurement is the best estimate of the value of a measurand, and that all components of uncertainty, including those arising from systematic effects, such as components associated with corrections and reference standards, contribute to this dispersion. ENV 13005:199
40、9. 4 Method description 4.1 Principle A measured volume of sample air is drawn through an activated charcoal sorbent tube. Provided suitable sampling conditions are chosen, benzene is retained by the sorbent and thus is removed from the flowing air stream. The collected vapour is desorbed using carb
41、on disulphide and is analyzed on a gas chromatograph equipped with a capillary column and a flame ionisation detector or other suitable detector. The analysis is calibrated by means of charcoal tube calibration standards or calibration solutions of known amounts of benzene in carbon disulphide. 4.2
42、Reagents and Materials During the analysis, use only reagents of known purity appropriate to the application. Use only volumetric glassware and syringes that are calibrated to ensure traceability of volume to primary standards. 4.2.1 Benzene Benzene is required as a reagent for calibration purposes
43、and for the determination of desorption efficiency.The benzene used shall be of a minimum established purity of 99,5%. 4.2.2 Carbon disulphide The carbon disulphide used for the desorption of benzene from the charcoal shall be free from compounds interfering with the analysis of the benzene sampled.
44、 Grades of carbon disulphide used shall contain benzene in concentrations less than 0,1 g/ml. 4.2.3 Internal standard An internal standard may be used to correct for small variations in the volume of carbon disulphide injected. It shall not interfere with benzene and it shall not be removed from the
45、 elution solvent by the charcoal. The internal standard shall contain less than 0,1 % benzene. The internal standard is added to the carbon disulphide before the preparation of calibration solutions (4.2.8) or the desorption of samples (4.6) or calibration standards (4.2.5). Internal standards used
46、in practice include 2-fluorotoluene (flame-ionization detection; photo-ionization detection) and benzene-d6 and toluene-d8 (mass-spectrometric detection). 4.2.4 Activated charcoal A particle size of 0,35 mm to 0,85 mm is recommended. Before use, the charcoal shall be heated in an inert atmosphere, e
47、.g. high-purity nitrogen, at approximately 600 C for 1 hour. To prevent recontamination of the charcoal, it shall be kept in a clean atmosphere during cooling to room temperature, storage, and loading into the EN 14662-2:2005 (E) 7 tubes. Tubes prepacked by manufacturers with pre-conditioned charcoa
48、l are also available and require no further conditioning. NOTE The sorptive capacity and desorption efficiency of different batches of activated charcoal may vary. Commercial tubes, if used, should be purchased from the same batch and in sufficient number to provide consistent performance for a defi
49、nite period of time. 4.2.5 Calibration standards Calibration standards can be prepared by loading the required amounts of benzene from standard atmospheres (4.2.6) on charcoal tubes of the same batch as those used for sampling as this procedure most closely resembles the practical sampling situation. The concentrations of the desorbed solutions of the sample tubes may then be compared directly with the solutions resulting from desorption of these tube standards, i
