BS 6069-3 4-1991 Characterization of air quality - Workplace atmospheres - Method for the determination of vaporous aromatic hydrocarbons by charcoal tube solvent desorption gas ch.pdf

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1、BRITISH STANDARD BS 6069-3.4: 1991 ISO 9487:1991 Characterization of air quality Part 3: Workplace atmospheres Section 3.4 Method for the determination of vaporous aromatic hydrocarbons by charcoal tube/solvent desorption/gas chromatographyBS6069-3.4:1991 This British Standard, having been prepared

2、under the directionof the Environment andPollution Standards PolicyCommittee, was publishedunderthe authorityofthe Standards Boardand comes intoeffect on 20 December 1991 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference EPC/35 Draft for comment 88/527

3、66 DC ISBN 0 580 20410 3 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Environment and Pollution Standards Policy Committee (EPC/-) to Technical Committee EPC/35, upon which the following bodies were represented: Association of Consult

4、ing Scientists British Coal Corporation British Gas plc British Steel plc Department of Health Department of the Environment (Her Majestys Inspectorate of Pollution) Department of Trade and Industry (Laboratory of the Government Chemist) Department of Trade and Industry (Warren Spring Laboratory) El

5、ectricity Supply Industry in England and Wales European Resin Manufacturers Association GAMBICA (BEAMA Ltd.) Health and Safety Executive Institute of Occupational Hygienists Institute of Petroleum Institution of Environmental Health Officers Institution of Gas Engineers Lead Development Association

6、National Society for Clean Air Royal Society of Chemistry Society of Chemical Industry The following bodies were also represented in the drafting of the standard, through subcommittees and panels: Asbestos Information Centre Ltd. Asbestosis Research Council British Occupational Hygiene Society Chemi

7、cal Industries Association Council for Environmental Conservation Engineering Equipment and Materials Users Association Fibre Cement Manufacturers Association Limited Institute of Energy Institute of Occupational Medicine London Regional Transport Amendments issued since publication Amd. No. Date Co

8、mmentsBS6069-3.4:1991 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Principle 1 4 Reagents 1 5 Apparatus 2 6 Sampling 3 7 Procedure 4 8 Expression of results 5 9 Test report 6 Annex A (normative) Determination of break

9、through volume 7 Annex B (normative) Determination of desorption efficiency 7 Annex C (normative) Chromatographic columns suitable for use for the analysis of aromatic hydrocarbon solvent vapours 10 Annex D (informative) Bibliography 11 Table 1 Sample size and sampling rate 4 Table 2 Optimum samplin

10、g rate during8h as a function of the relative humidity and the presence of light hydrocarbons 4 Table B.1 Desorption efficiency data 8 Table C.1 Retention data for aromatic hydrocarbon solvents and carbon disulfide on SE30 and C 20 M relative to toluene 10 Publication(s) referred to Inside back cove

11、rBS6069-3.4:1991 ii BSI 10-1999 National foreword This Section of BS 6069, which has been prepared under the direction of the Environment and Pollution Standards Policy Committee, is identical with ISO9487:1991 “Workplace air Determination of vaporous aromatic hydrocarbons Charcoal tube/solvent deso

12、rption/gas chromatographic method”. The International Standard was prepared by Technical Committee146, Air quality, of the International Organization for Standardization (ISO) with the active participation and approval of the UK. BS6069 is being published in a series of Parts and Sections that will

13、generally correspond to particular International Standards arising from the UK participation in the work ofISO/TC146. This Section of BS6069 is one of several relating to workplace atmospheres that are being published as Sections of Part 3. Methods concerning stationary sources are being published a

14、s Sections of Part 4 of BS6069. Topics relating to other aspects of air quality characterization will be published as further Parts or Sections of BS6069. The following Parts of BS 6069 are being published. Part 1: Units of measurement (complete); Part 2: Glossary (complete); Part 3: Workplace atmos

15、pheres; Part 4: Stationary source emissions. Methods for the determination of particular constituents of ambient air are being published as Parts of BS1747 “Methods for measurement of air pollution”. A British Standard does not purport to include all the necessary provisions of a contract. Users of

16、British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard ISO 5725:1986 BS 5497 Precision of test methods Part 1:1987 Guide for

17、the determination of repeatabilityand reproducibility for a standard test method by inter-laboratory tests (Identical) BS 4559 Methods for preparation of calibration gas mixtures ISO 6145-1:1986 Section 5.1:1987 Review of methods of calibration (Identical) ISO 6349:1979 Part 7:1981 Permeation method

18、 (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 12, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table

19、 on the inside front cover.BS6069-3.4:1991 BSI 10-1999 1 1 Scope This International Standard specifies a charcoal tube/gas chromatographic method for the determination of the concentration of vaporous aromatic hydrocarbons in workplace air. The method is valid for the measurement of the concentratio

20、ns of airborne vapours of any of the following compounds: a) benzene; b) toluene; c) ethylbenzene; d) m-xylene; e) o-xylene; f) p-xylene; g) styrene (vinylbenzene); h) cumene (isopropylbenzene); i) 1,2,3-trimethylbenzene; j) 1,2,4-trimethylbenzene; k) 1,3,5-trimethylbenzene; l) 4-tert-butyltoluene;

21、m) 3-methylstyrene; n) 4-methylstyrene; o) isopropenylbenzene. The method is valid for concentrations of airborne vapours of these compounds in the range from approximately 1mg/m 3to1000mg/m 3(about0,2ml/m 3to200ml/m 3 ; see8.1) when sampling10litres of air. NOTE 1The upper limit of the useful range

22、 is set by the adsorptive capacity of the first section of the charcoal tube (5.1) used. This capacity is measured as a breakthrough volume of air, which should not be exceeded during sampling (see clause6 andAnnex A). The lower limit is set by a number of parameters, including the noise level of th

23、e detector (5.9), blank concentrations due to the contamination of the charcoal and carbon disulfide by the substance analysed, desorption efficiency (seeAnnex B) and interference of the solvent peak in the gas chromatographic analysis. The method is also valid for the measurement of airborne concen

24、trations of mixtures of these compounds. In such cases, the unique properties of each compound have to be considered when determining the volume of air to be sampled and the gas chromatographic conditions to be used. The method may be applicable for other substituted monocyclic aromatic hydrocarbons

25、, but its validity has to be tested. NOTE 2When analysing aromatic hydrocarbon mixtures with very large differences in concentrations and in which several compounds are present, the reproducibility and repeatability of the compounds of minor importance might be influenced. The method has been valida

26、ted for a selection of typical aromatic hydrocarbons1. This procedure is compatible with low flow rate personal sampling equipment, and can be used for personal and fixed location sampling for obtaining time-weighted-average concentrations of aromatic hydrocarbon solvent vapours in air. It cannot be

27、 used to measure instantaneous or short-term fluctuations in concentrations. Alternative on-site procedures, such as gas chromatography or infrared spectrometry, shall be used to measure rapidly changing concentrations. Organic components which have the same or nearly the same retention time as the

28、substance analysed during the gas chromatographic analysis will interfere. Interferences can be minimized by proper selection of gas chromatographic columns and programme conditions. 2 Normative references The following standards contain provisions which, through reference in this text, constitute p

29、rovisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the sta

30、ndards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 5725:1986, Precision of test methods Determination of repeatability and reproducibility for a standard test method by inter-laboratory tests. ISO 6145-1:1986, Gas analysis Preparation of

31、 calibration gas mixtures Dynamic volumetric methods Part 1: Methods of calibration. ISO 6349:1979, Gas analysis Preparation of calibration gas mixtures Permeation method. 3 Principle A known volume of air sample is passed through a glass or metal tube packed with activated charcoal. The organic vap

32、ours are adsorbed onto the charcoal. The collected vapours are desorbed using a suitable solvent and analysed with a gas chromatograph equipped with a flame ionization detector or other suitable detector. 4 Reagents During the analysis, use only reagents of recognized analytical grade and only disti

33、lled water or water of equivalent purity. 4.1 Aromatic hydrocarbons, listed in clause 1, a) too). WARNING Benzene is a recognized human carcinogen.BS6069-3.4:1991 2 BSI 10-1999 Avoid any exposure by inhalation or skin contact. 4.2 Carbon disulfide (CS 2 ), chromatographic quality, previously checked

34、 for compounds coincident with the substance analysed of interest. If necessary, remove interfering compounds by percolation through silica gel (dried at180 C for8h under nitrogen) contained in a small glass column (600mm int. 20mm). This size of column will clean about 50ml of carbon disulfide. WAR

35、NING Carbon disulfide vapour is toxic and highly flammable. Avoid any exposure by inhalation or skin contact. Use only in a well-ventilated fume cupboard. A carbon-dioxide fire extinguisher should be available at all times. Dispose of small waste quantities of carbon disulfide in accordance with loc

36、al regulations and accepted practices. NOTE 3Other desorption solvents may be used if their blanks and desorption efficiencies are adequate. 4.3 Activated coconut shell charcoal, particle size between0,4mm and0,8mm. Before packing the tubes, the charcoal shall be heated in an inert atmosphere, e.g.

37、high purity nitrogen at600 C for1h. To prevent recontamination of the charcoal, it shall be kept in a clean atmosphere during its cooling to room temperature, storage and loading into the tubes. NOTE 4Suitable tubes containing pretreated coconut charcoal are commercially available (see5.1). 4.4 Arom

38、atic hydrocarbons, standard solutions for the preparation of the calibration graph (see7.1). Prepare standard solutions of aromatic hydrocarbons (4.1) gravimetrically and make serial dilutions from them to cover the range of the analysis. The concentration range of the analysis shall exceed the conc

39、entration range of the desorbed samples (see7.2). As an example, a typical procedure for toluene is described below. Prepare standard solutions in carbon disulfide (4.2). If the standard solution (4.4.1) has to be stored (for not longer than1 week), prepare it in n-heptane. 4.4.1 Toluene, standard s

40、olution, about50mg/ml. Accurately weigh approximately 500mg of toluene in a10ml one-mark volumetric flask. Dilute to the mark with carbon disulfide and mix well. 4.4.2 Toluene, standard solution, about5mg/ml. Pipette1ml of the standard solution (4.4.1) into a10ml one-mark volumetric flask. Dilute to

41、 the mark with carbon disulfide and mix well. 4.4.3 Toluene, standard solution, about5004g/ml. Pipette 1ml of the standard solution (4.4.2) into a10ml one-mark volumetric flask. Dilute to the mark with carbon disulfide and mix well. 4.4.4 Toluene, standard solution, about504g/ml. Pipette1ml of the s

42、tandard solution (4.4.3) into a10ml one-mark volumetric flask. Dilute to the mark with carbon disulfide and mix well. 4.4.5 Toluene, standard solution, about54g/ml. Pipette1ml of the standard solution (4.4.4)into a10ml one-mark volumetric flask. Dilute to the mark with carbon disulfide and mix well.

43、 4.5 Toluene, standard matching solutions for checking the calibration graph. If the standard solutions (4.5.1 and 4.5.2) have to be stored (for not longer than1week); prepare them in n-heptane. 4.5.1 Toluene, standard matching solution, about25mg/ml. Accurately weigh approximately250mg of toluene i

44、n a10ml one-mark volumetric flask. Dilute to the mark with carbon disulfide and mix well. 4.5.2 Toluene, standard matching solution, about5mg/ml. Accurately weigh approximately50mg of toluene in a10ml one-mark volumetric flask. Dilute to the mark with carbon disulfide and mix well. 5 Apparatus Ordin

45、ary laboratory apparatus, and the following. 5.1 Charcoal tube, made of a glass tube with both ends flame sealed,70mm long with an outside diameter of6mm and an inside diameter of4mm, containing two sections of0,4mm to 0,8mm of activated charcoal. The adsorbing section contains100mg of charcoal and

46、the back-up section, 50mg. The sections are separated and their contents are held in place with an inert material, e.g. glass wool plugs (preferably silanized). The pressure drop across the tube shall not exceed3kPa (25mmHg) at the maximum flow rate recommended for sampling (in this International St

47、andard,200ml/min). The glass tubes shall be held in suitable protective holders to prevent breakage. The desorption efficiency (D) for each batch of tubes shall be checked by one of the methods described inAnnex B. If the desorption efficiency is lower than0,75(75%), the tubes shall not be used. Cli

48、ps shall be provided to hold the charcoal tube and connecting tubing to the wearers lapel area. IMPORTANT Do not use charcoal tubes with any tubing upstream of the charcoal, as this may interfere with sampling and/or analysis. NOTE 5Instead of a commercial two-section tube, two single-section tubes

49、in series may be used. This arrangement has the advantage that it is not necessary to store tubes at sub-ambient temperatures after sampling, to prevent migration of the trapped compounds from one section to the other.BS6069-3.4:1991 BSI 10-1999 3 NOTE 6Tubes meeting these requirements are commercially available, however they may also be made by the user. 5.2 Polyethylene end caps, for capping charcoal tubes (5.1). The caps shall fit the tubes tightly to prevent leakage. 5.3 Pump, with adjustable flow rate, capable of being worn