BS-6920-4-2001.pdf

BRITISH STANDARD BS 6920-4:2001 Suitability of non-metallic products for use in contact with water intended for human consumption with regard to their effect on the quality of the water Part 4: Method for the GCMS identification of water leachable organic substances ICS 13.060.20; 13.060.50 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BS 6920-4:2001 This British Standard, having been prepared under the direction of the Health and Environment Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 July 2001 © BSI 07-2001 The following BSI references relate to the work on this standard: Committee reference EH/3/7 Draft for comment 00/561599 DC ISBN 0 580 33274 8 Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee EH/3, Water quality, to Subcommittee EH/3/7, Effects of materials on water quality, upon which the following bodies were represented: Association of Manufacturers of Domestic Electrical Appliances Automatic Vending Association of Britain British Bathroom Council British Cement Association British Coatings Federation Ltd. British Malleable Tube Fittings Association British Non-Ferrous Metals Federation British Plastics Federation British Plumbing Fittings Manufacturers Association British Precast Concrete Federation Ltd. British Rubber Manufacturers Association British Valve and Actuator Manufacturers Association British Water Department of the Environment for Northern Ireland The Drinking Water Inspectorate Galvanizers Association Laboratory of the Government Chemist Lead Development Association Pipeline Industries Guild UK Steel Association UK Water Byelaws Scheme Water Research Centre Water UK Zinc Development Association Amendments issued since publication Amd. No.DateComments BS 6920-4:2001 © BSI 07-2001 i Contents Page Committees responsibleInside front cover Forewordii Introduction1 1Scope1 2Terms and definitions1 3Principle3 4Reagents3 5Apparatus5 6Leachate6 7Method of analysis6 8Expression of results9 9Test report10 Annex A (informative) Procedure for preparing test leachates12 Annex B (informative) Methods for sealing the ends of pipe sections18 Annex C (informative) Suitable methods for preparing extracts from large diameter pipes20 Annex D (informative) Additional procedural details23 Bibliography27 Figure A.1 Test sequence Factory made13 Figure A.2 Test sequence Site applied products14 Figure B.1 Metal clamp to seal pipe sections18 Figure C.1 Test arrangement 121 Figure C.2 Test arrangement 222 Table D.1 Within-laboratory performance data for internal standards25 Table D.2 Summary of variation (% RSD) for internal standards in interlaboratory performance testing26 BS 6920-4:2001 ii© BSI 07-2001 Foreword This part of this British Standard has been prepared by Subcommittee EH/3/7, Effects of materials on water quality. It is a revision of BS 6920-4:1997, which is now withdrawn. This standard contains technical revisions to the test method, based upon experience of using this method. In addition, the main part of the (normative) text for leachate preparation (clause 8 in the 1997 edition) has been transferred to a new informative Annex A to allow variations in leachate preparation conditions to be specified by the National Regulator. BS 6920 is published in several other parts, namely: Part 1: Specification; Part 2: Methods of test; Part 3: High temperature tests. Part 2 is further sub-divided into a number of sections and subsections as follows: Annex A, Annex B, Annex C and Annex D are informative. This part of this British Standard describes methods of identification only, and should not be used or quoted as a specification. References to this standard should indicate that the methods of identification used are in accordance with BS 6920-4. This British Standard calls for the use of substances and/or procedures that may be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from legal obligations relating to health and safety at any stage. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Section 2.1Samples for testing; Section 2.2Odour and flavour of water; Subsection 2.2.1General method of test; Subsection 2.2.2Method of testing tastes imparted to water by hoses; Subsection 2.2.3Method of testing tastes imparted to water by hoses for conveying water for food and drink preparation; Section 2.3Appearance of water; Section 2.4Growth of aquatic micro-organisms; Section 2.5The extraction of substances that may be of concern to public health; Section 2.6The extraction of metals. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 27 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. BS 6920-4:2001 © BSI 07-2001 1 Introduction Chemicals that leach from materials used in contact with public water supplies can cause health concerns for consumers. Potential health effects of these chemicals are assessed in three stages: 1) preparation of leachates by exposing a portion of the material to water under controlled conditions; 2) analysis of the leachates; 3) toxicological evaluation of the concentrations of substances identified. Analysis of organic substances present in the leachates usually involves two types of analytical method: a screening method which enables a qualitative and semi-quantitative assessment to be made of unspecified organic compounds; accurate quantitative methods for the determination of specific target compounds known to be present in the chemical formulations of the materials. This part of BS 6920 describes the analytical procedures based upon gas chromatography and mass spectrometry (GCMS) used to screen leachates for unspecified organic compounds derived from finished products such as pipes, protective coatings, membranes, etc. This method is suitable for leachates from all non-metallic materials that could be used in contact with water for human consumption, and which could be the subject of an application for approval by the National Regulator. In addition, Annex A gives general guidance on the preparation of test samples and their leachates. NOTE 1At the time of publication, products for use in contact with public water supply must be approved by the Secretary of State for the Environment under the provisions of regulation 25(1)(a) of the Water Supply (Water Quality) Regulations 1989 1, unless any of the subsections 25(1)(b), (c) or (d) applies. The methods described in this section of BS 6920 may form the basis of leaching test specifications issued by the committee that advises the Secretary of State on the approval of substances and products for use in contact with public water supplies. Equivalent provisions apply in Scotland and Northern Ireland. NOTE 2The results of these tests are assessed by reference to existing toxicological data concerning the chemicals identified. Where little or no information exists, it might be necessary for the substance itself or the material leachate to be submitted for toxicity testing. 1 Scope This part of BS 6920 describes a method for identifying organic chemicals that are amenable to GCMS analysis using the techniques described and which might leach from a product into water intended for human consumption. A method of calculating the concentrations of the organic substances identified is also provided. This part of this British Standard is not applicable to the toxicological evaluation of chemicals. NOTEThe method to be used for the preparation of leachates will be specified by the National Regulator. Annex A provides a suitable method for preparing these leachates. 2 Terms and definitions For the purposes of this British Standard, the following terms and definitions apply. 2.1 amu atomic mass unit defined as 1/12 of the mass of a single atom of carbon-12 in the gas phase (i.e. unbound), at rest and in its ground state BS 6920-4:2001 2© BSI 07-2001 2.2 asymmetry factor As measure of the adsorption of a compound during gas chromatographic analysis NOTE 1It can be derived from the equation: As= (a + b)/2b where NOTE 2Some manufacturers GCMS software packages allow the calculation of peak asymmetries to be produced automatically. 2.3 electron impact ionization ionization by a beam of electrons 2.4 GCMS analytical instrument comprising a gas chromatograph (GC) linked to a mass spectrometer (MS) 2.5 GCMS general survey analysis acquisition of a series of mass spectra (up to several thousand) during the course of a gas chromatographic run, by operating the mass spectrometer in a continuous cyclic scanning mode over a wide m/z range 2.6 internal standards organic compounds added to the leachate at a known concentration prior to the commencement of the analysis NOTEInternal standards are added: to demonstrate that the analysis has been undertaken successfully; and to provide a reference to allow other substances detected to be quantified. Ideally, the internal standards should not be present in the leachate; for this reason, isotopically labelled standards are preferred. 2.7 laboratory blank water sample known to contain negligible levels of contamination, to which internal standards have been added and which is then analysed in the same way as the leachate NOTELaboratory blanks are used to check for potential contamination of either leachates or solvent extracts which could occur within the laboratory during analysis. 2.8 leachate aqueous solution that results from leaving test water in contact with the test material under the specified test conditions NOTESee Annex A. 2.9 mass spectrometric resolution measure of the capability of the mass spectrometer to correctly distinguish two mass spectral peaks, having similar mass to charge m/z values, as separate peaks NOTE 1When z = 1 this is generally denoted by m2/(m2?m1) where m2 has the higher m/z value and m1 has the lower m/z value. NOTE 2A mass spectrometer set up so that the resolution is 650 will satisfactorily resolve and assign the correct masses to mass spectral peaks at m/z 649 and m/z 650. ais the distance from the leading edge of the peak at the point on the baseline at which a perpendicular dropped from the peak maximum crosses it; bis the corresponding distance from the trailing edge of the peak. BS 6920-4:2001 © BSI 07-2001 3 2.10 m/z mass-to-charge ratio of an ion NOTEAs most ions produced by electron impact ionization are singly charged, this ratio usually corresponds to the mass of an ion. However, exceptionally, ions can possess multiple charges. 2.11 solvent extract solution containing compounds partitioned from the leachate into the extraction solvent 2.12 total ion current TIC sum of all the separate ion currents carried by the individual ions contributing to a mass spectrum 2.13 TIC chromatogram graphical representation of the TIC versus time 3 Principle A mixture of internal standards is added to each of the test leachates prior to solvent extraction with dichloromethane. The solvent extract is concentrated and analysed by GCMS to determine the identity and approximate concentrations of organic chemicals that could be present. The mass spectrometer is used in a repetitive full-scan mode and the mass spectra produced are recorded by, and stored on, the GCMS data system. Wherever possible, each compound detected is identified and may be quantified by reference to the responses obtained for the internal standards. NOTE 1The number and duration of leaching (migration) periods, the nature of the test sample(s) and the test surface area to volume ratio are specified by the National Regulator based upon the nature of the product and its proposed use. Annex A provides a typical “model” for the preparation of leachates based upon the current requirements of the National Regulator. NOTE 2The methods used to identify organic compounds from their mass spectra do not form part of this method, but further information on this subject is given in Annex D. 4 Reagents 4.1 Only reagents of analytical grade shall be used, except where otherwise specified. All reagents shall be of sufficient purity to ensure that they do not give rise to interferences during the GCMS analysis. NOTEContamination can arise from various sources, e.g. plastics or rubber materials. The use of procedural blanks and laboratory blanks assists in detecting and identifying the source of any contamination. 4.2 Reagent water, having a conductivity of 5 % of that of the base peak (which by convention is assigned an intensity of 100 %) of the calibrant used. 7.2.4 Setting up the GCMS system Install the GC column according to the manufacturers instructions and verify its performance (e.g. in terms of separation number and adsorption) against the column performance data supplied by the manufacturer. NOTEProprietary standard solutions are available for this purpose (D.4). Provided the general performance of the column is satisfactory, use the internal standards GC column test solution (4.17) to establish the initial performance of the column for the internal standards. Use the same GC temperature program for this purpose as that used for the GCMS analysis of the concentrated solvent extracts (8.1). Ensure the temperature programming rate does not exceed 12?C/min at any time. Ensure that all of the internal standards are detected on the TIC chromatogram. Ensure the d6-benzene is separated from the solvent peak and ensure the retention time of d62-squalane is between 35 min and 45 min. Ionization mode:electron impact (EI); Electron energy:70 eV; Mass range:to include 20-650 amu; Scan speed:?1 scan per second; Scan mode:repetitive. BS 6920-4:2001 8© BSI 07-2001 Ensure that the asymmetry factors, As, (2.2) for the peaks obtained for d5-phenol and d8-naphthalene are within the range 0.67 to 2.0. If this requirement is not met, investigate the cause and correct before continuing with the analysis. If necessary, install a new GC column. Adjust the sensitivity of the mass spectrometer so that the mass spectra obtained for the internal standards present at the highest level (16 ng/?l) in the internal standards GC column test solution are not saturated. Inspect the mass spectra obtained from the GCMS system performance test to ensure that they correspond closely to mass spectra previously acquired for these internal standards on the same GCMS system under identical operating conditions. Ensure that the m/z value of the base peak is consistent, and that the intensities of all peaks having an intensity 10 % of the base peak do not vary by mor