松香PCA检验标准

小松鼠 · 发表于 2004-3-29 17:21:00

国际松树化学品协会制定的PCTM-27松香检验标准(此标准于2004年1月1日起开始执行):
4.2 Reagents and Materials
4.2.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise  indicated, it is intended  that all reagents shall conform to the specifications  of the Committee on  Analytical Reagents of the American Chemical Society, where  such specifications are available. Other grades may be  used, provided it is  first ascertained that the reagent is of sufficiently  high purity to permit  its use without lessening the accuracy of the determination.
4.2.2 Tetramethylammonium Hydroxide  Solution, 24 % in methanol, CAS No. 75-59-2.
4.2.3 Tetramethylammonium Hydroxide  Solution, 6 % (v/v) in methanol. Dilute 25 mL of the reagent  described in 4.2.2 with 75 mL of methanol.
4.2.4 Phenolphthalein Solution, 1 % (w/v) in methanol.
4.2.5 Diethyl Ether, anhydrous.
4.2.6 Methanol,  anhydrous.
4.2.7 Acetic Acid,  5 % volume/volume (v/v) in methanol.
4.2.8 Toluene, optional.
4.3 Procedure:
4.3.1 Dissolve the sample from 9.1 in 0.5 to 3.0 mL of a 50:50 ether/methanol mixture, add 2 to  3 drops of phenolphthalein indicator solution, and titrate to a pH of 7.8  to 8.1 or to the very first permanent pink color, with the 6 % solution  of TMAH. If the solution is overtitrated, it can be back titrated with the  acetic acid in methanol solution to the end point. When the solution is injected  into the heated injection port of the chromatograph, the tetramethylammonium  salts are pyrolyzed to methyl esters.

小松鼠 · 发表于 2004-3-29 17:22:00

8.1 Purity of Reagents—See 4.2.1
8.2 Rosin— Rosin should be sampled following the procedures described in publications such as the Chinese National Standard,GB 8145-87, ASTM Test Method D 509 or the Naval Stores Act of 1923 (42 Stat 1435.7 USC-91-99) as amended in 1951.

NOTE 3—Rosin samples need to be freshly broken from a larger mass to ensure the results are not affected by air oxidation of the rosin.

小松鼠 · 发表于 2004-3-29 17:22:00

10.1  Set the GC conditions so that they are approximately (see Note 4) as follows:

Column temperature; Isothermal 195°C
Injection port temperature 300°C
Injection port liner glass split
Detector temperature 280°C
Carrier gas Hydrogen or Helium
Linear gas velocity 40 cm/s
Split ratio 40 to 1
Detector FID
   Hydrogen 50 kPa
   Air 100 kPa

小松鼠 · 发表于 2004-3-29 17:23:00

Table 1 Typical Composition of Characteristic Resin Acids in Gum Rosins from some Pine Species
Resin Acid Pinus Pinus Pinus Relative Retention
Massoniana Merkusii Elliottii
(%) (%) (%)

Communic 0 0 5 0.588
Palustric 25 20 19 0.634

Isopimaric 2 15 17 0.664
Abietic 35 35 23 0.967

Dehydroabietic 4 5 5 1.000
Neoabietic 16 5 20 1.092
Mercusic 0 7 0 1.514

小松鼠 · 发表于 2004-3-29 17:30:00

中文版还没有,可惜可惜!

燕子 · 发表于 2004-3-30 09:22:00

采用标准的建议：
1、宣传、了解、掌握标准
2、对原料严加管理、区分、做好对应性生产记录和产品标识
3、注重生产企业实际控制与检测判定的对应性
4、杜决人为掺混、保持产品的均一性
5、增加经验掌握与GC分析对照的频次，保持合理的样品数量检验、监测，做到心中有数（修正偏差）
6、收集国外及用户的检测结果（GC图谱），以便对照分析。

燕子 · 发表于 2004-4-3 11:54:00

当初立此贴是非常希望大家重视松香的混合问题,但失望的是此贴几乎成了燕子呢喃,很感激小松鼠的参与.不知大家是否有此感觉:如果有人跟你的贴,你会感到高兴,心情好.如没有自然相反.所以再次谢谢小松鼠.
曹工有句话经常在我耳边反复响起:去年四月份,他在美国世界松香协会,面对协会的技术小组,说中国的混合问题已经得到有效控制,并且中国有能力做好.当时可是铮铮有声,一掷千金,相当是向全世界作了保证.可是九月份到年底,他走了很多松香厂,收集了很多样品,作了很多检验和分析,却发现情况比四月份时的还差,混合现状不容乐观,他说如果现在让他再次面对世界松香协会的技术小组,重复原来所说的话,已经不敢再说了,他说心情很沉重.
同样的我听了心情也很沉重,所以不管此贴是否有人跟,我都坚持发表,希望能起点作用.
(因作笔记的水平不高,引用曹工的话可能有所出入,请见谅)

[此贴子已经被作者于2004-04-03 12:21:28编辑过]

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