ISO 17736:2010 職場の空気の質—ダブルフィルターサンプリングデバイスを使用した空気中のイソシアネートの測定と高圧液体クロマトグラフィーによる分析 | ページ 2

Foreword

ISO (the International Organization for Standardization) is a worldwide federation 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. 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 with 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 approval 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 17736 was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 2, Workplace atmospheres.

Introduction

Isocyanates are commercially available chemicals used in the polyurethane industry. They are known to cause health problems, such as asthma, contact dermatitis and hypersensitivity pneumonitis, in workers even at very low levels in occupational environments.

Since isocyanates are highly reactive compounds and exposure limits are very low, the sampling and the analysis of these substances are critical.

This method is based on the standard method developed by the Institut de Recherche en Santé et en Sécurité du Travail [Occupational Health and Safety Research Institute] (IRSST) of Quebec. It has been in use for more than 18 years as the standard government method in that province of Canada. Since 1996, it has been introduced into the marketplace in the USA, Brazil, and the UK. After a year’s study (Reference [10]), the method was adopted in 1998-11 by the US Air Force as an acceptable alternative to NIOSH Method 5521 for monomeric isocyanates (now withdrawn).

The method is now routinely used in the Canadian provinces of Alberta, British Columbia, and Ontario, and in the US state of Washington, which has validated the method for TDI. Thirteen laboratories have been schooled in this analytical method, three in Canada, eight in the USA and Mexico, one in Brazil, and one in the UK. This method has been in use in several countries for many years and 13 laboratories participate in round robin testing on a regular basis in order to maintain their proficiency.

The double-filter method has been validated for different applications of isocyanates such as spray-painting (Reference [11]) and foam manufacturing. It has also been compared with other established methods and demonstrated equivalent results (Reference [10]).

Double-filter methods are also available in ASTM D6561 ^[7] and ASTM D6562 ^[8] for HDI, and ASTM D5932 ^[9] for TDI.

ISO draws attention to the fact that it is claimed that compliance with this document may involve the use of a patent concerning the double-filter sampling device for isocyanates.

1 Scope

This International Standard gives general guidelines for the sampling and analysis of airborne isocyanates in workplace air. This International Standard is appropriate for organic compounds containing free isocyanate functional groups and is specific for the quantification of monomers, polymers and prepolymers, vapours and aerosols. Differential air sampling is performed with a segregating device which can show the physical state of the isocyanates analysed as found in the field. This capacity, however, may show limitations for given situations, e.g. when aerosols collected on the first filter contain free monomer that migrates to the second filter and is then quantified as vapour phase isocyanate. The determination of aromatic monomers includes toluene diisocyanate (TDI) and 4,4'-diisocyanato-diphenylmethane (MDI). Aliphatic monomers include isophorone diisocyanate (IPDI), 4,4'-methylene bis-(cyclohexyl isocyanate) (HMDI) and 1,6-hexamethylene diisocyanate (HDI). Isocyanate oligomers and prepolymers can also be determined using this method.

The double-filter method is designed to determine short-term (15 min) exposure concentrations of organic isocyanates in a workplace environment by personal monitoring or by fixed location monitoring. However, if the exposure is expected to be in vapour form only, then sampling time can be extended to 8 h. Since the filter is derivatized in the field immediately after sampling, loss of isocyanate aerosol because of its reaction with other chemicals is negligible except for very fast-reacting isocyanate systems such as foam spraying of MDI in polyurethane applications. The method is suitable for the measurement of airborne organic isocyanates in the NCO equivalent concentration range of 0,01 µg/sample to 2,1 µg/sample, corresponding to approximately 0,67 µg/m³ to 140 µg/m³ for a 15 l sample volume. This range brackets about eight times the current established threshold limit value (TLV) of 5 ppb for monomers set by many national authorities.

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) applies.

Bibliography