ISO-6293-1-1996.pdf
《ISO-6293-1-1996.pdf》由会员分享,可在线阅读,更多相关《ISO-6293-1-1996.pdf(12页珍藏版)》请在三一文库上搜索。
1、INTERNATIONAL STANDARD IS0 6293-l First edition 1996-12-01 Petroleum products - Determination of saponification number - Part 1: Colour-indicator titration method Prod the mushroom-type condenser shall fit loosely to permit venting of the flask. All glasswa re shall be chemically cl ean. The flasks
2、should be cle cleanliness obtaine d by the use of chromosulfuric acid (see wa aned by nona ). For co Ikaline cle Impartson ani ng agents to match the of cleaning efficiency, the 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical
3、Standards 1/9972545001 Not for Resale, 04/23/2007 20:40:58 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 6293=1:1996(E) IS0 visual appearance and loss in mass on heating may be used. Detergent cleaning, or the use of other strong oxidizing agents, avoids the specific
4、hazards related to chromosulfuric acid, and is preferred for routine analysis. Flasks of borosilicate glass are preferred. New flasks may give high values, and old flasks that have become etched by long use should not be used. Blank tests should be run concurrently on both used and new flasks. WARNI
5、NG - Chromosulfuric acid is a health hazard. It is toxic, a recognized carcinogen as it contains Cr(VI) compounds, highly corrosive and potentially hazardous in contact with organic materials. When using chromosulfuric acid cleaning solution, eye protection and protective clothing are essential. Nev
6、er pipette the cleaning solution by mouth. After use, do not pour cleaning solution down the drain, but neutralize it with great care owing to the concentrated sulfuric acid present, and dispose of it in accordance with standard procedures for toxic laboratory waste (chromium is highly dangerous to
7、the environment). Non-chromium-containing, strongly oxidizing acid cleaning solutions are also highly corrosive and potentially hazardous in contact with organic materials, but do not contain chromium which has special disposal problems. 6.2 Hotplate, heated by either electricity or steam. 6.3 Titra
8、tion burette, of capacity 50 ml, graduated in 0,l ml subdivisions, or of capacity 10 ml, graduated in 0,05 ml subdivisions. 6.4 Balance, capable of weighing to the nearest 0,2 mg. 7 Blank run 7.1 Carry out one or more blank determinations concurrently with each set of samples in the manner described
9、 in 7.2 and 7.3. Blank determ nations should be run in dupl icate on samp les requiring t he high est act based on dup icate blank determinat ions. A single blank is su fficient for routine work. uracy. The precision data are 7.2 Measure from a burette or pipette into the conical flask (6.1) 25 ml +
10、 0,03 ml of the alcoholic potassium hydroxide solution (5.2) and 25 ml + 1 ml of the butan-Z-one (5.4). If a volumetric pipette is used, wait 30 s after delivery for complete drainage. Connect the condenser to the flask, and heat for 30 min after refluxing begins. NOTE 1 It is known that some fats a
11、re readily saponified and complete saponification takes place within 10 min after refluxing begins. On the other hand, some materials are saponifiable only with difficulty, and are known to require more than 2 h in some cases. Neither the shortened period nor the longer period should be used except
12、by mutual consent of the interested parties. The reflux time of the blank should be the same as that of the sample in all cases. Turn off the heat source and immediately add 50 ml of the petroleum spirit (5.5) by cautiously pouring it down the condenser (disconnect the condenser if a mushroom-type i
13、s used). NOTE 2 Pouring 50 ml of petroleum spirit down the condenser at the end of the saponification not only rinses the condenser but also cools the reaction mixture. However, in the case of insulating oils, the addition of petroleum spirit is not necessary. 7.3 Titrate the blank while hot, withou
14、t reheating, with the hydrochloric acid solution (5.3) using three drops of the phenolphthalein indicator solution (5.6). When the indicator colour has disappeared, add, drop by drop, more indicator solution. If this addition of indicator restores the colour, continue the titration, making further d
15、rop-by-drop additions of indicator, if necessary, until the 4 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 20:40:58 MDTNo reproduction or networking permitted without license
16、from IHS -,-,- IS0 IS0 6293=1:1996(E) end-point is reached. The end-point is reached when the indicator colour has completely disappeared and does not immediately reappear upon further drop-by-drop addition of the indicator solution. To avoid emulsification of the titration mixture, but assure phase
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- ISO 6293 1996
链接地址:https://www.31doc.com/p-3780554.html