1、BRITISH STANDARD BS6648:1986 Incorporating Amendment No.1 Methods for Wet ashing of textile materials for subsequent determination of metal content UDC 677.074.014.27:543.832:5432:542.4BS6648:1986 This BritishStandard, having been prepared under the directionof the Textiles and Clothing Standards Co
2、mmittee, was published under the authorityof the Board of BSI andcomes into effect on 30April1986 BSI12-1999 The following BSI references relate to the work on this standard: Committee reference TCM/26 Draft for comment84/39977 DC ISBN 0 580 15099 2 Committees responsible for this British Standard T
3、he preparation of this BritishStandard was entrusted by the Textiles and Clothing Standards Committee (TCM/-) to Technical Committee TCM/26, upon which the following bodies were represented: British Carpet Manufacturers Association Ltd. Department of Trade and Industry (Laboratory of the Government
4、Chemist) International Wool Secretariat Man-made Fibres Producers Committee Manchester Testing House Ministry of Defence Textile Research Council Amendments issued since publication Amd. No. Date of issue Comments 7007 July1992 Indicated by a sideline in the marginBS6648:1986 BSI 12-1999 i Contents
5、Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Principle 1 3 Apparatus and reagents 1 4 Method A. General wet ashing 1 5 Method B. Wet ashing for the determination of mercury 1 Figure 1 Apparatus for wet ashing of textile material for the determination of mercury 2 Publicatio
6、ns referred to Inside back coverBS6648:1986 ii BSI 12-1999 Foreword This BritishStandard has been prepared under the direction of the Textiles and Clothing Standards Committee. A method for wet ashing of textile materials was included in the1974 edition of BS Handbook No.11 “Methods of test for text
7、iles” as a recommended method. However, due to the wide usage of this method it has been decided that it be revised and published as a BritishStandard. The revised method is similar to method3 of BS2087-2. The major changes from the method in Handbook No.11 are that perchloric acid is only used if t
8、reatment with sulphuric acid and nitric acid fails to oxidize the specimen completely. An additional method has been included for determination of mercury which involves a special apparatus to minimize losses of mercury. Where destruction of organic matter in a sample of textile material is required
9、, and the ash is not to be determined, wet combustion possesses many advantages over dry ashing. At the time of publication of this BritishStandard, no corresponding International Standard exists. NOTE 1 The wet ashing method for the determination of mercury is based on methodIV A published in Offic
10、ial, Standardised and Recommended Methods of Analysis second edition, 1973, edited by N.W.Hanson and published by the Society for Analytical Chemistry, and is included by permission of the Royal Society of Chemistry. Copies are available from the Royal Society of Chemistry, Burlington House, London
11、W1V0BN. This BritishStandard 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. NOTE 2See the
12、 Health and Safety at Work etc. Act1974 and the Control of Substances Hazardous to Health Regulations1988 (COSHH). 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 Br
13、itish Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments i
14、ncorporated. This will be indicated in the amendment table on the inside front cover.BS6648:1986 BSI 12-1999 1 1 Scope This BritishStandard describes two methods for wet ashing of textile materials for subsequent determination of metal content. Method A is a general method while method B is applicab
15、le for the determination of mercury. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. CAUTION. To avoid hazard it is essential that the conditions described be carefully followed and carried out only by trained operators. It is essential to wear sa
16、fety goggles and to carry out the procedures in a fume cupboard. 2 Principle The sample is heated under controlled conditions with a mixture of nitric acid and sulphuric acid and, if this fails to oxidize the specimen completely, perchloric acid. 3 Apparatus and reagents 3.1 Kjeldahl flasks, capacit
17、y200mL. 3.2 Means for heating Kjeldahl flasks 3.3 Safety glass screen 3.4 Fume cupboard 3.5 Balance, capable of weighing to an accuracy of0.1mg. 3.6 Digestion apparatus for the determination of mercury, as shown in Figure 1, comprising a flask of capacity250mL and a reservoir B having a capacity of1
18、50mL to200mL. The condenser is a double surface or spiral surface reflux type. The thermometer is calibrated for temperatures up to200 C. All the connections are made through standard ground glass joints. 3.7 Nitric acid, concentrated, relative density1.42. 3.8 Sulphuric acid, concentrated, relative
19、 density1.84. 3.9 Perchloric acid, 60%, relative density1.54. 3.10 Water, complying with BS3978. 4 Method A. General wet ashing Using the balance(3.5), weigh about2g of the textile and transfer it to a200mL Kjeldahl flask(3.1). Add10mL of sulphuric acid(3.8) followed by gradual addition of nitric ac
20、id(3.7) until there is no reaction on further addition of nitric acid (this volume can vary and may be as much as30mL). Apply heat gradually and digest with the further addition of nitric acid, if necessary, until the organic matter is completely destroyed. If the sample cannot be oxidized with nitr
21、ic acid, allow the flask and contents to cool. Add2mL of perchloric acid(3.9) and continue to apply heat gradually. Evaporate down to fuming, cool, then add5mL to10mL of distilled water and boil to remove nitric acid. Cool. The solution at this stage is ready for analysis. 5 Method B. Wet ashing for
22、 the determination of mercury Transfer an accurately weighed amount of the textile (see note1) to the flask of the digestion apparatus(3.6). Add a cooled mixture of20mL of water(3.10),5mL of concentrated sulphuric acid(3.8) and50mL of concentrated nitric acid(3.7) (see note2) and a few anti-bumping
23、granules or glass beads. Assemble the apparatus (see Figure 1) immediately and allow any initial reaction to subside. With tap A closed, heat the flask gently at first, collecting the distillate in reservoir B. When the temperature indicated by the thermometer reaches116 C (see note3), run off the d
24、istillate through the drain tube C and collect it in a500mL measuring cylinder. Close tap A again, and continue to heat the flask and collect the distillate in the reservoir; when the oxidation mixture darkens, run a little of the distillate from the reservoir into the flask. Continue this procedure
25、, maintaining a slight excess of nitric acid in the oxidation mixture, until the solution in the flask ceases to darken and fumes of sulphuric acid are evolved. Allow the solution in the flask to cool, run the distillate from the reservoir into the flask, then add the mixture to the reserved distill
26、ate in the measuring cylinder (see note4), rinsing in with a small volume of water, and mix. Cool. The solution at this stage is ready for analysis. NOTE 1The mass of sample taken should be such that it contains between0.54g and54g of mercury. NOTE 2Sample masses up to about10g of dry solid can be o
27、xidized by the procedure with50mL of nitric acid. NOTE 3The temperature of116 C is close to the boiling point of nitric acid. NOTE 4The volume of the mixed liquids is usually about80mL to90mL.BS6648:1986 2 BSI 12-1999 Figure 1 Apparatus for wet ashing of textile material for the determination of mer
28、curyBS6648:1986 BSI 12-1999 Publications referred to BS2087, Preservative treatments for textiles 1) . BS2087-2, Methods of test. BS3978, Water for laboratory use. 1) Referred to in the foreword only.BS6648:1986 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the indep
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