1、BRITISH STANDARD BS ISO 7981-2:2005 BS 6068-2.96:2005 Water quality Determination of polycyclic aromatic hydrocarbons (PAH) Part 2: Determination of six PAH by high-performance liquid chromatography with fluorescence detection after liquid-liquid extraction ICS 13.060.50 BS ISO 7981-2:2005 This Brit
2、ish Standard was published under the authority of the Standards Policy and Strategy Committee on 1 August 2005 BSI 1 August 2005 ISBN 0 580 46411 3 National foreword This British Standard reproduces verbatim ISO 7981-2:2005 and implements it as the UK national standard. The UK participation in its p
3、reparation was entrusted by Technical Committee EH/3, Water quality, to Subcommittee EH/3/2, Physical, chemical and biochemical methods, 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
4、 Standards which implement international 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 publi
5、cation does not purport to 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 internation
6、al/European committee any enquiries on the interpretation, or proposals for change, and keep 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 ISO title page
7、, pages ii to v, a blank page, pages 1 to 18, an inside 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 Comments Reference number ISO 7981-2:2005(E)INTERNATIONAL STANDARD I
8、SO 7981-2 First edition 2005-06-15 Water quality Determination of polycyclic aromatic hydrocarbons (PAH) Part 2: Determination of six PAH by high- performance liquid chromatography with fluorescence detection after liquid-liquid extraction Qualit de leau Dtermination des hydrocarbures aromatiques po
9、lycycliques (HAP) Partie 2: Dosage de six HAP par chromatographie de haute performance en phase liquide avec dtection fluorimtrique la suite dune extraction liquide-liquide BS ISO 7981-2:2005 ii iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Principle. 1 4 Inte
10、rferences . 2 5 Reagents 3 6 Apparatus 4 7 Sampling 5 8 Procedure 6 9 Calibration . 8 10 Measurement of samples. 9 11 Determination of the recovery. 9 12 Blank measurement 10 13 Calculation. 10 14 Expression of results . 10 15 Test report . 11 16 Accuracy 11 Annex A (informative) Examples of chromat
11、ographic conditions and columns. 12 Annex B (informative) Examples for the construction of special apparatus . 14 Annex C (informative) Accuracy . 17 Bibliography . 18 BS ISO 7981-2:2005 BS ISO 7981-2:2005 iv Foreword ISO (the International Organization for Standardization) is a worldwide federation
12、 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 committee.
13、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 accordance wit
14、h the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approv
15、al by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 7981-2 was prepared by Technical Committ
16、ee ISO/TC 147, Water quality, Subcommittee SC 2, Physical, chemical and biochemical methods. ISO 7981 consists of the following parts, under the general title Water quality Determination of polycyclic aromatic hydrocarbons (PAH): Part 1: Determination of six PAH by high-performance thin-layer chroma
17、tography with fluorescence detection after liquid-liquid extraction Part 2: Determination of six PAH by high-performance liquid chromatography with fluorescence detection after liquid-liquid extraction BS ISO 7981-2:2005 v Introduction Polycyclic aromatic hydrocarbons (PAH) are present in nearly all
18、 types of waters. These substances are adsorbed on solids (sediments, suspended matter) as well as dissolved in the liquid phase. Some PAH are known or suspected to cause cancer. The maximum acceptable levels of PAH in waters intended for human consumption are given in European Legislation 1 2 3 4 .
19、 The sum of the mass concentrations of the six PAH specified in this part of ISO 7981 usually is about 0,01 g/l to 0,05 g/l in ground water, up to 1 g/l in surface water, and up to 1 000 g/l in waste water. blank1 Water quality Determination of polycyclic aromatic hydrocarbons (PAH) Part 2: Determin
20、ation of six PAH by high-performance liquid chromatography with fluorescence detection after liquid-liquid extraction WARNING Some compounds being measured are presumed to be carcinogenic. Acetonitrile and hexane are harmful. Persons using this part of ISO 7981 should be familiar with normal laborat
21、ory practise. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this part of ISO 7981 to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. IM
22、PORTANT It is absolutely essential that tests conducted according to this part of ISO 7981 be carried out by suitably trained staff. 1 Scope This part of ISO 7981 specifies the determination of six selected PAH in drinking, mineral and table waters and ground and surface waters in mass concentration
23、s above 0,005 g/l, by high-performance liquid chromatography with fluorescence detection after liquid-liquid extraction. The six PAH are: fluoranthene, benzobfluoranthene, benzoapyrene, benzokfluoranthene, indeno1,2,3-cdpyrene, and benzoghiperylene (see Table 1). With some modification, this method
24、is also applicable for the analysis of moderately polluted waste waters. 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 reference
25、d document (including any amendments) applies. ISO 8466-1, Water quality Calibration and evaluation of analytical methods and estimation of performance characteristics Part 1: Statistical evaluation of the linear calibration function 3 Principle Since PAH can to a large extent be adsorbed on particu
26、late matter, the whole sample is analysed. NOTE For the analysis of surface water, a differentiation between dissolved and undissolved PAH can be desirable, but this is not relevant for drinking water. BS ISO 7981-2:2005 2 PAH are extracted from the water sample by liquid-liquid extraction. The extr
27、act is evaporated to dryness and the residue is taken up in a solvent and analysed. Extracts of surface waters and other contaminated water samples should be cleaned on silica (8.4) prior to analysis. PAH are then separated by high performance liquid chromatography (HPLC) on suitable stationary phas
28、es under isocratic conditions, identified and quantified by means of fluorescence detection at a constant combination of excitation and emission wavelengths. Table 1 Polycyclic aromatic hydrocarbons determinable by this method Name Chemical formula Molar mass Carbon fraction CAS-number Structure g/m
29、ol Fluoranthene C 16 H 10202,26 95,0 206-44-0 Benzobfluoranthene C 20 H 12252,32 95,2 205-99-2 Benzoapyrene C 20 H 12252,32 95,2 50-32-8 Benzokfluoranthene C 20 H 12252,32 95,2 207-08-9 Indeno1,2,3-cdpyrene C 22 H 12276,34 95,6 193-39-5 Benzoghiperylene C 22 H 12276,34 95,6 191-24-2 4 Interferences
30、4.1 Interferences with sampling and extraction Use sampling containers made of materials (preferably of glass or steel) that do not affect the sample during the contact time. Avoid plastics and other organic materials during sampling, sample storage or extraction. If automatic samplers are used, avo
31、id the use of silicone or rubber material for the tubes. If present, make sure that the tubes are as short as possible. Rinse the sampling line with the water to be sampled before the test sample is taken. ISO 5667-2 and ISO 5667-3 can be used for guidance. BS ISO 7981-2:20053 Keep the samples from
32、direct sunlight and prolonged exposure to light. During storage of the test sample, losses of PAH can occur due to adsorption on the walls of the containers. The extent of the losses depends on the storage time. 4.2 Interferences with the HPLC Substances that show either fluorescence or quenching an
33、d co-elute with the PAH to be determined can interfere with the determination. These interferences can lead to incompletely resolved signals and can, depending on their magnitude, affect accuracy and precision of the analytical results. Peak overlaps will prevent the measurement of peak height and/o
34、r area. Unsymmetrical peaks and peaks broader than the respective peaks of the reference substance suggest interferences. 5 Reagents Use only reagents of recognized analytical grade (e.g. “for residue analysis” or “for HPLC analysis”) as far as available, and only distilled water or water of equival
35、ent purity showing the lowest possible fluorescence. Monitor the blank to guarantee that the reagents do not contain PAH in detectable concentrations (see Clause 12). 5.1 Solvents 5.1.1 Solvents for extraction and clean-up of the extract 5.1.1.1 Cyclohexane, C 6 H 125.1.1.2 Hexane, C 6 H 145.1.1.3 D
36、ichloromethane, CH 2 Cl 2Other volatile solvents may be used as well, if it is proved that the recovery is equivalent or better. NOTE Dichloromethane often contains stabilizers, e.g. ethanol or amylene. Stabilizers can influence the elution strength of the eluent. Without stabilizer, free radicals m
37、ight develop. This can lead to degradation of PAH. The presence of hydrogen chloride indicates the presence of radicals. Hydrogen chloride can be determined by extracting dichloromethane with water and measuring the pH value. 5.1.2 HPLC solvents 5.1.2.1 Methanol, CH 3 OH 5.1.2.2 Acetonitrile, CH 3 C
38、N 5.1.2.3 Tetrahydrofuran, C 4 H 8 O, without stabilizer NOTE Tetrahydrofuran can contain peroxides. Although peroxides have not yet shown to cause any interference with the HPLC determination, it is preferred to use batches with low peroxide content (regularly checked using test rods). It is of adv
39、antage to use small packages. 5.2 Sodium thiosulfate pentahydrate, Na 2 S 2 O 3 5H 2 O 5.3 Sodium chloride, NaCl 5.4 Sodium sulfate, Na 2 SO 4 , anhydrous, precleaned by heating to 500 C. 5.5 Nitrogen, having a purity (volume fraction) of at least 99,999 %. BS ISO 7981-2:2005 4 5.6 Helium, having a
40、purity (volume fraction) of at least 99,999 %. 5.7 Silica, with an average particle size approximately 40 m and stored in a desiccator to ensure maximum activity. NOTE Prepacked silica cartridges are commercially available. 5.8 Molecular sieve beads, pore size 0,4 nm. 5.9 Reference substances (see T
41、able 1) Because of the dangerous nature of the substances to be used, it is highly recommended to use commercially available, preferably certified, standard solutions. Avoid skin contact. 5.10 Single-substance stock solutions, of those listed in Table 1, diluted in acetonitrile (5.1.2.2) to a mass c
42、oncentration of, for example, 10 g/ml. 5.11 Multiple-substance stock solution, preferably certified, diluted in acetonitrile (5.1.2.2) to a mass concentration of, for example, 10 g/ml for each individual compound. 5.12 Calibration solutions Prepare at least five calibration solutions by appropriate
43、dilution of the stock solution (5.11), using methanol (5.1.2.1) or acetonitrile (5.1.2.2) as solvent. The choice of solvent depends on the composition of the mobile phase. For example, using 50 l of the stock solution (5.11) in a graduated 10 ml flask (6.16), make up to volume with acetonitrile (5.1
44、.2.2) or methanol (5.1.2.1). 1 l of this reference solution contains 50 pg of the respective individual substance. NOTE The solutions 5.10 to 5.12 are stable for at least one year when stored in the dark at room temperature and protected from evaporation. 6 Apparatus Standard laboratory equipment cl
45、eaned to eliminate all interferences. Clean all glassware, for example, by rinsing with detergent and hot water, and drying for about 15 min to 30 min at about 120 C. After cooling, rinse with acetone, seal the glassware and store in a clean environment. Glassware that has been in contact with waste
46、 water samples or samples with high PAH concentrations shall not be re-used for drinking water analysis. 6.1 Brown glass bottles, narrow-necked, flat-bottomed, nominal capacity 1 000 ml, with solid glass stopper. 6.2 Magnetic stirrer with stirring rods, PTFE coated, kept under cyclohexane, with a ma
47、ximal rotational frequency of 1 000 min 1 . 6.3 Measuring cylinder, nominal capacity 10 ml, 25 ml and 1 000 ml. 6.4 Separating funnel, nominal capacity 1 000 ml, with PTFE stopcock, kept under cyclohexane, and glass stopper, e.g. a Squibb funnel. 6.5 Conical flask, nominal capacity 100 ml, with glas
48、s stopper. 6.6 Reduction flask, nominal capacity 100 ml (see Figure B.1). BS ISO 7981-2:20055 6.7 Centrifuge with rotor, with a rotational frequency of about 3 000 min 1and with centrifuge tubes with tapered bottom, nominal capacity 50 ml (see Figure B.2). 6.8 Pasteur pipettes 6.9 Evaporation assemb
49、ly, such as a rotary evaporator with vacuum stabilizer and water bath. 6.10 Shaking apparatus, with adjustable rotational speed, suitable for test tubes. 6.11 Blow-down assembly, nitrogen pressure cylinder with pressure-reducing valve and needle valve for fine adjustment. 6.12 Microfilter, with solvent-resistant membrane, pore size 0,45 m. 6.13 Autosampler vials, capacity approximately 2 ml, with inert filler cap,
