OSI) International Standard 1573 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEKAYHAPOAHAA OPIAHW3ALMA HO CTAHAAPTW3AUWMORGANISATION INTE RNATIONALE DE NORMALISATION Tea - Determination of loss in mass at 103 °C The--Déterminationde la pertedemassea103C Second edition - 1980-08-15 D 1573-1980 (E) UDC663.95:543.81 Ref.No.ISO1573-1980 (E) Descriptors : agricultural products, tea, tests, determination, mass losses, mass losses by heating. Foreword Iso (the International Organization for Standardization) is a worldwide federation of national standards institutes (Iso member bodies). The work of developing Inter- national Standards is carried out through Iso technical committees. Every mermber body interested in a subject for which a technical committee has been set up has the and non-governmental, in liaison with iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the Iso Council. International Standard ISO 1573 was developed by Technical Committee ISO/TC 34, Agricultural food products. This second edition was submitted directly to the ISo Council, in accordance with clause 5.10.1 of part 1 of the Directives for the technical work of ISo. It cancels and replaces the first cdition (i.e. ISo 1573-1975), which had been approved by the member bodies of the following countries : Australia Hungary Romania Brazil India South Africa, Rep. of Canada Iran Spain Chile Israel Sri Lanka Colombia Korea, Rep. of Thailand Czechoslovakia Netherlands Turkey Egypt, Arab Rep. of Poland United Kingdom France Portugal USSR The member body of the following country had expressed disapproval of the docu- ment on technical grounds : USA C InternationalOrganizationforStandardization,1980 Printed in Switzerland ISO 1573-1980 (E) INTERNATIONALSTANDARD Tea - Determination of loss in mass at 103 oC 0 Introduction 5 Sampling The loss in mass when tea is heated in air at a temperature near Sample the tea in accordance with IS0 1839. 100 °c is conventionally designated as moisture, the contribu- tion made by small amounts of other volatile constituents being regarded as negligible for practical purposes. In some other In- ternational Standards for oven-drying methods, the expression Procedure moisture and volatile matter has been used, to take account of the fact that the loss in mass may not be wholly due to 6.1 Preparationof weighingbottle moisture. There is an objection to the use of this expression in the case of tea, however, since tea contains volatile com- Remove the lid from the weighing bottle (4.1) and heat both for pounds which do not contribute appreciably to the loss in mass 1 h in the oven (4.2) at 103 ± 2 °C. Cool in the desiccator on heating in air at a temperature near 100 oc but may be (4.3). After cooling, fit the lid and weigh to the nearest 0,001 g. removed by other means, for example steam distillation. To avoid possible confusion, the expression loss in mass sat 6.2 Preparation of test sample 103 c has been adopted in this International Standard. Thoroughly mix the sample of tea as received. Scope and field of application 6.3 Test portion This International Standard specifies a method for the deter- mination of the loss in mass when tea is heated in air at Weigh, to the nearest 0,001 g, about 5 g of the test sample into 103°C. the prepared weighing bottle (6.1). 6.4 Determination Reference Heat the weighing bottle and contents, with the lid removed ISO 1839, Tea - Sampling. but alongside the bottle, in the oven (4.2) at 103 ± 2 C for 6 h. Cool in the desiccator (4.3), fit the lid and weigh. Return the bottle and its lid to the oven and heat again for 1 h, cool in Principle the desiccator, fit the lid, and weigh; repeat these operations, if necessary, until the difference between two successive Heating a test portion of the tea in an oven at 103 ± 2 °C, to weighings does not exceed 0,005 g. c