ISO INTERNATIONAL STANDARD 1576 Second edition 1988-07-15 INTERNATIONALORGANIZATIONFORSTANDARDIZATION ORGANISATIONINTERNATIONALEDENORMALISATION MEXKAYHAPOAHAR OPrAHM3ALMA NO CTAHAAPTV3AUWW Tea - Determination of water-soluble ash and water-insoluble ash The-DeterminationdescendressolublesetdescendresinsolublesdansIeau Referencenumber ISO 1576 : 1988 (E) for Standardizatic No reproduction or networking permitted without license from IHS Not for Resale ISO 1576 :1988 (E) 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, govern- mental 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. Draft International Standards adopted by the technical committees are circulated to thememberbodiesforapprovalbeforetheiracceptanceasInternationalStandardsby the ISo Council. They are approved in accordance with IsO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 1576 was prepared by Technical Committee ISO/TC 34, Agricultural food products. This second edition cancels and replaces the first edition (iS0: 1576 : 1975), of which it constitutes a minor revision. International Organization for Standardization, 1988 Printed in Switzerland CopyrightInternational Organization for Standardization No reproduction or networking permitted without license from IHS Not for Resale INTERNATIONALSTANDARD ISO1576:1988(E) Tea - Determination of water-soluble ash and water-insoluble ash 1 Scope 5 Apparatus This International Standard specifies a methodforthe deter- Usual laboratory apparatus and, in particular, the following. mination of the water-soluble ash and the water-insoluble ash of tea. 5.1 Dish, of 50 ml to 100 ml capacity, used for the deter- mination of total ash. 2 Normative references NOTE - It is considered that silica dishes are unsuitable for use with The following standards contain provisions which, through this test. reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated 5.2 Furnace, capable of being controlled at 525 oC ± 25 oC. were valid.All standards are subject to revision,and parties to agreements based on this International Standard are encouraged 5.3 Steam-bath. to investigate the possibility of applying the most recent editions of the standards listed below. Members of IEC and ISO 5.4 Filter paper, ashless. maintain registers of currently valid International Standards. ISo 1572 : 1980, Tea --.Preparation of ground sample of 5.5 Desiccator, containing an effective desiccant. knowndrymattercontent. 5.6 Analytical balance. ISO 1575 : 1987, Tea - Determination of total ash. Procedure 3 Definitions 6.1 Test portion For the purposes of this International Standard, the following definitions apply. Use the total ash obtained from the determination specified in IsO 1575. 3.1 water-soluble ash: The part of the total ash dissolved by water under the conditions specified in this International 6.2 Determination Standard. water-insoluble ash: The part of the total ash remain- equivalent purity) to the total ash in the dish (5.1), heat nearly 3.2 ing after treatment with water under the conditions specified in to boiling and filter through the filter paper (5.4). Vash the dish and the filter paper with hot distiled water (or water of at least this International Standard. equivalent purity) until the volume of the combined filtrate and washings is about 60 ml. Return the filter paper and contents to the dish (5.1), e