1、BRITISH STANDARD BS 7164-32.1: 1998 ISO 10398: 1998 Chemical tests for raw and vulcanized rubber Part 32: Methods for determination of accelerators Section 32.1 Gas and thin layer chromatography ICS 83.040.10; 83.060BS7164-32.1:1998 This British Standard, having been prepared under the directionof t
2、he Sector Board for Materials and Chemicals, was published under the authority of the Standards Board and comes into effect on 15 October 1998 BSI 03-1999 ISBN 0 580 28063 2 National foreword This British Standard reproduces verbatim ISO 10398:1998 Rubber Identification of accelerators in cured and
3、uncured compounds, and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee PRI/23, Chemical testing of rubber, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European
4、committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-
5、references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic
6、Catalogue. 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 British Standard does not of itself confer immunity from legal obligations. Summary of pages This document
7、 comprises a front cover, an inside front cover, pages i and ii, theISO title page, page ii, pages 1 to 7 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendment
8、s issued since publication Amd. No. Date CommentsBS7164-32.1:1998 BSI 03-1999 i Contents Page National foreword Inside front cover Foreword ii 1 Scope 1 2 Principle 1 3 Method A Identification of amines via GC and thiazoles via TLC 2 4 Method B Identification of amines, guanidines, thiazoles and dit
9、hiocarbamates via TLC 5 5 Method C Identification of thiurams, thiazoles, sulfenamides and guanidines via TLC 6 6 Test report 7 Figure 1 Separation of trifluoroacetamides 3ii blankBS7164-32.1:1998 ii BSI 03-1999 Foreword ISO (the International Organization for Standardization) is a worldwide federat
10、ion 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 committe
11、e. International organizations, governmental 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 techn
12、ical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO10398 was prepared by Technical Committee ISO/TC45, Rubber and rubber products. Descriptors: Rubb
13、er, compounded rubber, ingredients, chemical analysis, determination of content, accelerators (chemical), gas phase chromatography.BS7164-32.1:1998 BSI 03-1999 1 WARNING Persons using this International Standard should be familiar with normal laboratory practice. This standard does not purport to ad
14、dress all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. 1 Scope 1.1 This International Standard specifies methods using gas chromatog
15、raphy (GC) and thin layer chromatography (TLC) for the separation and identification of the following classes of accelerators in vulcanized and unvulcanized compounds: thiazoles sulfenamides thiurams and dithiocarbamates guanidines dithiodimorpholine 1.2 When 2-mercaptobenzothiazole (MBT) is identif
16、ied and no sulfenamides are present, it is not possible to establish if the original accelerator was MBT and/or its salts or 2,2-dibenzothiazoledisulfide (MBTS) as each of these accelerators may be produced from the others during the vulcanization process. 1.3 When sulfenamides are identified, it is
17、 not possible to establish if MBT and/or its salts and MBTS are present as these accelerators may be produced from 2-mercaptobenzothiazole sulfenamides during the vulcanization process. 1.4 The methods do not distinguish thiurams and dithiocarbamates derived from the same amines. 1.5 From the morpho
18、line identification it is not possible to determine if the initial accelerator is 2-morpholinothiobenzothiazole (MBS) or dithiomorpholine as morpholine may be formed from MBS and dithiodimorpholine during the vulcanization process. 1.6 The separation of accelerator compounds from unvulcanized compou
19、nds is relatively straightforward whereas separation from vulcanized compounds is difficult due to the lesser ability of solvents to penetrate the vulcanized matrix. 1.7 Some compounding ingredients may interfere with method B. In such cases methods A or C shall be used. 2 Principle 2.1 Method A Ide
20、ntification of amines via GC and thiazoles via TLC 2.1.1 A portion of the sample compound is refluxed with hydrochloric acid (HCl) to hydrolyze sulfenamides, thiurams and dithiocarbamates. The resulting amine hydrochlorides are separated and purified. After purification, the amines are separated by
21、GC as their trifluoroacetamide derivatives. Identification may also be effected by comparison of GC retention times of sample and standard trifluoroacetamides, prepared and analyzed under the same analysis conditions. 2.1.2 The HCl reflux solubles and insolubles, remaining after amines are separated
22、 by distillation, are combined and refluxed with sodium hydroxide (NaOH). The resultant sodium salts of the thiazoles formed from free thiazoles and from MBT produced during the HCl reflux of sulfenamides and other MBT derivatives are separated by extraction and purified. After purification, the thi
23、azoles are separated by TLC and qualitatively detected by comparison of R fand colours of the sample TLC spots with R fand colours of standard thiazole spots prepared and analyzed under the same analysis conditions. 2.2 Method B Identification of amines, guanidines, thiazoles and dithiocarbamates vi
24、a TLC 2.2.1 Accelerators are extracted from the sample with suitable solvents. 2.2.2 A portion of the extract is hydrolyzed with HCl and the resultant amines separated and qualitatively detected by TLC through comparison of R fand colours of sample TLC spots with standard TLC spots prepared and anal
25、yzed under the same analysis conditions. 2.2.3 A second portion of the extract is hydrolyzed with ammonium hydroxide (NH 4 OH) and the ammonium salts of the thiazoles, dithiocarbamates and sulfenamides are separated and qualitatively detected by TLC through comparison of R fand colours of sample TLC
26、 spots with standard TLC spots prepared and analyzed under the same analysis conditions. 2.3 Method C Identification of thiurams, thiazoles, sulfenamides and guanidines via TLC 2.3.1 Accelerators are extracted from the sample with suitable solvents.BS7164-32.1:1998 2 BSI 03-1999 2.3.2 The extracted
27、accelerators are separated and qualitatively detected by TLC through comparison of R fand colours of sample TLC spots with standard TLC spots prepared and analyzed under the same analysis conditions. 3 Method A Identification of amines via GC and thiazoles via TLC 3.1 Apparatus Ordinary laboratory a
28、pparatus and 3.1.1 Several GC column types and operating conditions may be used providing column type and operating conditions are chosen which give good separation of the trifluoroacetamides from other eluting components. An example of trifluoroacetamide separation is given in Figure 1 together wit
29、h column type and GC operating conditions. 3.1.2 TLC plates covered with a silica gel layer. NOTETLC plates HPTLC Kieselgel 60, 10cm 10cm, supplied by Merck, have been found to be suitable. Other plates with similar qualities may be used. 3.1.3 Desiccator for storing activated TLC plates. 3.1.4 Deve
30、loping tanks for TLC. 3.1.5 Sprayers for spraying the spray reagents. 3.1.6 Microsyringe for GC, capacity 10mm 3(4l). 3.1.7 Microinjector or micropipettes for TLC, capacity 0,01cm 3 . 3.1.8 Filter paper, fast flowing. 3.2 Reagents 3.2.1 Mixture of isopropanol, hydrochloric acid and water, 50 : 25 :
31、25 (V/V/V). 3.2.2 Isopropanol. 3.2.3 Sodium hydroxide pellets. 3.2.4 Hydrochloric acid solution, prepared by diluting 1 volume of concentrated hydrochloric acid with 1 volume of water. 3.2.5 Trifluoracetic anhydride. 3.2.6 Methylene chloride. 3.2.7 Sodium sulfate, anhydrous. 3.2.8 Sodium hydroxide s
32、olution, 40g/dm 3 . 3.2.9 n-heptane. 3.2.10 Eluent A: mixture of 3.2.11 Spray reagent B: 1 % solution of 2,6-dichloroquinone-4-chlorimide in ethanol. 3.2.12 Toluene. 3.2.13 n-butanol. 3.2.14 Spray reagent F: 5 % bismuth nitrate solution in 0,5 mol/dm 3nitric acid. 3.3 Procedure 3.3.1 Identification
33、of the amines 3.3.1.1 Cut 2g to 10g of a representative sample into small pieces or thinly sheet about 10 g of a representative sample on a laboratory mill to about0,25mm to 0,5mm thickness. Maintain the sample at the lowest possible temperature during the milling in order to avoid thermal degradati
34、on of the accelerators. 3.3.1.2 Reflux the small pieces or thinly sheeted test portion for 2h with 100cm 3of the mixture of isopropanol, hydrochloric acid and water (3.2.1). 3.3.1.3 Filter the boiling solution through fast flowing filter paper (3.1.8) into a conical flask. Wash the reactor vessel an
35、d the insoluble portion in the filter with 20cm 3of boiling isopropanol (3.2.2) into the same conical flask. 3.3.1.4 Save the washed insoluble portion in the filter. 3.3.1.5 Adjust the solution to a volume of about10cm 3and cool at room temperature. 3.3.1.6 Make the solution strongly alkaline by add
36、ing sodium hydroxide pellets (3.2.3). 3.3.1.7 Distil the solution under a slow flow of nitrogen and recover the distillate by bubbling through a few cm 3of the hydrochloric acid solution(3.2.4) into a conical flask. 3.3.1.8 Stop the distillation when 2 cm 3to 3 cm 3of solution remains in the distill
37、ation flask. 3.3.1.9 Add to the distillation residue the washed insoluble portion (3.3.1.4) and save the mixture. 3.3.1.10 Concentrate the distilled solution to a volume of 2 cm 3to 3 cm 3 . 3.3.1.11 Transfer the concentrated solution into a10cm 3distillation vessel and heat in a sand bath until onl
38、y a few drops of solution remain in the vessel, then evaporate the solution to dryness by heating in an oven at 80 C overnight. 3.3.1.12 Cool the dry residue at room temperature, pour 2 cm 3of trifluoroacetic anhydride (3.2.5) into the vessel and immediately connect to a reflux condenser. In order t
39、o prevent moisture from entering the vessel, connect the upper end of the reflux condenser with a tube filled with calcium chloride. n-hexane 55 parts in volume methylene chloride 35 parts in volume ethyl ether 35 parts in volume methanol 15 parts in volume acetic acid 15 parts in volumeBS7164-32.1:
40、1998 BSI 03-1999 3 Figure 1 Separation of trifluoroacetamidesBS7164-32.1:1998 4 BSI 03-1999 3.3.1.13 Reflux for 1h in an oil bath at 80C to90C, disconnect the reflux condenser, concentrate the solution at a volume of about0,5cm 3and cool to room temperature. 3.3.1.14 Add drop by drop 10 cm 3of water
41、 and transfer the solution to a separating funnel. 3.3.1.15 Add 5 cm 3of methylene chloride (3.2.6), shake, allow the two layers to separate and recover the layer of methylene chloride. Repeat the extraction two times with methylene chloride. Discard the aqueous layer. 3.3.1.16 Wash the methylene ch
42、loride extract with water to pH7 to ensure that all the trifluoroacetic acid has been removed. 3.3.1.17 Add about 0,1 g of anhydrous sodium sulfate (3.2.7) to the methylene chloride extract and shake to eliminate any trace of water, filter through filter paper and concentrate the solution to a volum
43、e of about 0,5 cm 3 . 3.3.1.18 Inject a suitable amount of the solution into the injection port of the gas chromatograph (3.1.1) and record chromatogram. 3.3.1.19 Compare the retention times of the peaks obtained from the sample solution with the retention times of the peaks obtained from solutions
44、containing known amides under the same gas chromatographic operating conditions. NOTEIf the trifluoroacetamides of the amines to be identified are not available, it is possible to prepare them by carrying out the procedure described using the pure accelerators to produce the amines to be identified.
45、 These standard solutions can be stored at 5 C for at least 1 year. 3.3.2 Preparation of the TLC plates 3.3.2.1 Activate the TLC plates (3.1.2) by heating in an oven at 105 C for 2h or at 80 C overnight. 3.3.2.2 Cool the activated plates in the desiccator(3.1.3). NOTEThe activated plates can be stor
46、ed in the desiccator for10 days without further activation. 3.3.2.3 Just before use, inscribe a start line on the activated plate 15mm to 20mm from the edge of the plate. 3.3.2.4 Different solutions may be applied on the same plate, along the start line. The distance between the two spots shall be a
47、t least 25mm. 3.3.3 Procedure 3.3.3.1 Pour 50cm 3of isopropanol (3.2.2) and50cm 3of the sodium hydroxide solution (3.2.8) into the vessel containing the mixture 3.3.1.9 and reflux for 2h. 3.3.3.2 Filter the boiling solution through filter paper and wash the reaction vessel and the filter with a few
48、cm 3of boiling isopropanol. Quantitatively transfer the filtered solution and washings into a separating funnel. 3.3.3.3 Extract this solution two times with 2 portions of 25cm 3each of methylene chloride(3.2.6), discarding the methylene chloride extracts. 3.3.3.4 Make the solution strongly acidic b
49、y adding hydrochloric acid solution (3.2.4). 3.3.3.5 Add 25cm 3of methylene chloride, shake, allow the layers to separate and recover the methylene chloride extract. Repeat the extraction with another 25 cm 3portion of methylene chloride and combine the methylene chloride extracts. Discard the aqueous layer. 3.3.3.6 Concentrate the methylene chloride extract to a volume of 2 cm 3to 3 cm 3 . 3.3.4 Identification of the thiazoles 3.3.4.1 Apply a suitable amount of the methylene chloride extract from the test portion (3.3.3.6) to the
