1、BRITISH STANDARD BS 6630:1985 ISO 4645:1984 Incorporating AmendmentNo.1 Method for Identification of antidegradants in rubber and rubber products by thin layer chromatography ISO title: Rubber and rubber products Guide to the identification of antidegradants Thin layer chromatographic methods UDC 67
2、8.06:543.544.062:678.041.2BS6630:1985 This British Standard, having been prepared under the directionof the Rubber StandardsCommittee, was published under the authority ofthe Board of BSI and comes into effect on 30August1985 BSI 12-1999 The following BSI references relate to the work on this standa
3、rd: Committee reference RUM/37 Draft for comment 78/52476 DC ISBN 0 580 14567 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Rubber Standards Committee (RUM/-) to Technical Committee RUM/37, upon which the following bodies were repres
4、ented: British Rubber Manufacturers Association Electric Cable Makers Confederation Institution of Water Engineers and Scientists Malaysian Rubber Producers Research Association Ministry of Defence National College of Rubber Technology Royal Society of Chemistry Rubber and Plastics Research Associat
5、ion of Great Britain Amendments issued since publication Amd. No. Date of issue Comments 6698 April 1991 Indicated by a sideline in the marginBS6630:1985 BSI 12-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and field of application 1 2 Reference 1 3 Prin
6、ciple 1 4 Reagents 1 5 Apparatus 2 6 Preparation of developing tank and plates 2 7 Preparation of test portion 3 8 Plate spotting 3 9 Plate development 4 10 Colour development on the plate 4 11 Standard chromatograms 5 12 Test report 5 Annex Preliminary spot tests 6 Publication referred to Inside ba
7、ck coverBS6630:1985 ii BSI 12-1999 National foreword This British Standard has been prepared under the direction of the Rubber Standards Committee. It is identical with ISO4645:1984 “Rubber and rubber products Guide to the identification of antidegradants Thin layer chromatographic methods”, publish
8、ed by the International Organization for Standardization (ISO). Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in Bri
9、tish Standards; attention is drawn especially to the following. Wherever the words “International Standard” appear, referring to this standard, they should be read as “British Standard”. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on t
10、he baseline as the decimal marker. Textual errors. The textual errors listed below have been discovered. They have been reported to ISO in a proposal to amend the text of the International Standard. A.2.2. The second sentence should read: Most phenolic compounds, except hindered phenols, give a red
11、colour. Phenolic resins give a red colour. A.2.5. The second and third sentences should read: Dialkylphenylenediamines give a pink colour, alkylarylphenylenediamines give a blue colour, and diarylphenylenediamines give a green colour. A British Standard does not purport to include all the necessary
12、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. Cross-reference International Standard Corresponding British Standard ISO 1407:1976 BS 1673 Methods for te
13、sting raw rubber and unvulcanized compounded rubber Part 2:1967 Chemical analysis of raw natural rubber (Technically equivalent) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 6, an inside back cover and a back cover. This standard has been u
14、pdated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6630:1985 BSI 12-1999 1 1 Scope and field of application 1.1 This International Standard describes two methods for the detection and identification, by thin
15、 layer chromatography, of antidegradants (antioxidants, antiozonants and stabilizers), which may be present in raw rubber, unvulcanized compounded rubber, or rubber products. Method A is a simplified method, based on a single solvent system, which provides for the identification of known materials a
16、nd may be used to check the presence or absence of a particular antidegradant which should be present. Method B is a more detailed method, using additional solvents and sprays, which enables a greater degree of separation of the spots to be obtained and therefore may be used to detect and identify a
17、n unknown antidegradant. 1.2 Antidegradants to which these methods are applicable include phosphited polyalkyl phenols, substituted bisphenols, secondary amines, substituted cresols and substituted p-phenylenediamines. Examination for other types of antidegradants is possible, provided that the requ
18、irement of11.1 is met. 2 Reference ISO 1407, Rubber Determination of solvent extract. 3 Principle Extraction of antidegradants from the rubber by means of a solvent. Evaporation of the original solvent, application of a solution of the dried extract as a spot on a thin layer chromatographic plate, e
19、vaporation of the second solvent and development of the plate in an appropriate solvent. If extender oil is present, removal of the oil either by column chromatography of the extract prior to the completion of the evaporation of the original solvent or by development of the plate in light petroleum
20、prior to the normal development in an appropriate solvent. Identification of the unknown antidegradant by comparison of its chromatogram with standard chromatograms. 4 Reagents During the analysis, use only reagents of recognized analytical grade, and only distilled water or water of equivalent puri
21、ty. WARNING Use of fume hoods when handling volatile and toxic solvents is mandatory. Approved health and safety precautions shall be observed when using any solvent or chemical mentioned in this International Standard. 4.1 Plate adsorbent: silica gel, particle size2 to504m, with or without calcium
22、sulphate binder. 1) Silica gel containing a fluorescent indicator is useful in many cases to allow observation of spots, under ultra-violet radiation, before spraying. 4.2 Column adsorbent: silica gel, to pass a sieve of aperture200to6004m 1)activated by drying, either for at least2h at110 C, if the
23、 product is dry after that period, or overnight (approximately16h at110 C) for convenience. 4.3 Solvents: 4.3.1 Methanol 4.3.2 Acetone 4.3.3 Ethanol, anhydrous. 4.3.4 2-Propanol 4.3.5 Light petroleum, boiling range35to60 C. 4.3.6 Dichloromethane 4.3.7 Toluene 4.3.8 Ethyl acetate 4.3.9 n-Hexane 4.3.1
24、0 n-Heptane 4.3.11 Cyclohexane 4.3.12 Diethylamine 4.3.13 Ammonium hydroxide, 28 to30% (m/m) of NH 3 , solution ( = 0,9Mg/m 3 ). 4.3.14 Acetonitrile 4.4 Developing solvents: 4.4.1 For method A: 90 parts by volume of the n-heptane (4.3.10) and10 parts by volume of the ethyl acetate (4.3.8). 4.4.2 For
25、 method B: 4.4.2.1 Toluene 4.4.2.2 95 parts by volume of the toluene (4.3.7) and5 parts by volume of the ethyl acetate (4.3.8). 4.4.2.3 75 parts by volume of the cyclohexane(4.3.11) and25 parts by volume of the diethylamine (4.3.12). 4.4.2.4 50 parts by volume of the toluene (4.3.7) and50 parts by v
26、olume of the n-heptane (4.3.10). 4.4.3 Additional developing solvents which may prove useful for special problems: 1) Suitable material is available commercially. Details may be obtained from the Secretariat of ISO/TC45 (BSI) or ISO Central Secretariat.BS6630:1985 2 BSI 12-1999 4.4.3.1 100 parts by
27、volume of the toluene(4.3.7),10parts by volume of the acetone(4.3.2) and0,2parts by volume of the ammonium hydroxide solution (4.3.13). 4.5 Spray reagents: Most of the spray reagents below are equally suitable for colour development of both amines and phenols. The following suggestions give a base f
28、rom which analytical expertise may be developed: 4.5.1 For colour development of amines: 4.5.1.1 Diazotised sulphanilic acid Dissolve 1g of sulphanilic acid and1g of potassium nitrite in200cm 3of hydrochloric acid solution, c(HCI) = 1mol/dm 32) . Make fresh daily. 4.5.1.2 Benzoyl peroxide, 40g in1dm
29、 3of toluene. WARNING Benzoyl peroxide is a powerful oxidizer which may explode spontaneously. 4.5.1.3 Bismuth nitrate, solution. Dissolve 7,5g of anhydrous bismuth nitrate in a mixture of1cm 3of concentrated nitric acid and150cm 3of water. 4.5.1.4 Tetracyanoethylene (ethenetetracarbonitrile), satur
30、ated solution in dichloromethane. 4.5.2 For colour development of phenols: 4.5.2.1 Overspray, after the use of the reagent specified in4.5.1.1: with sodium hydroxide, c(NaOH) = 1mol/dm 3 . 4.5.2.2 p-nitrophenyldiazonium fluoborate,1%(m/m) solution in methanol containing0,5% (m/m) of hydrochloric aci
31、d. 4.5.2.3 Dichloroquinonechlorimide (Gibbs Reagent) or 2,6-dibromoquinonechlorimide, 0,1% solution in methanol. 4.5.2.4 Buffer spray for use with reagent4.5.2.3: dissolve23,4g of sodium tetraborate decahydrate, and3,3g of sodium hydroxide in1dm 3of water. 4.5.2.5 Tollens reagent Mix0,5cm 3of5% silv
32、er nitrate solution and2 drops of sodium hydroxide, c(NaOH) = 2mol/dm 3 . Dissolve the precipitate in as little2% (m/m) ammonium hydroxide solution as possible, and add an equal volume of96% (V/V) ethanol solution. WARNING Prepare this reagent immediately before use and dispose of within12h. 5 Appar
33、atus Ordinary laboratory apparatus and the following 5.1 Glass plates, of any convenient and adequate size, for example200mm 200mm. 5.2 Device for spreading a coating 250 to 3004m thick on the glass plates (5.1). 5.3 Pre-coated plates, covered with a layer of silica gel, 250 to3004m thick. These may
34、 be used as an alternative to preparing plates (see6.2). Pre-coated film-backed plates with thinner coatings may be used, provided that they give good separation of the mixtures listed in11.3. 5.4 Oven, capable of being controlled at100 5 C. 5.5 Desiccator or drying box, for storing plates at fixed
35、humidity. 5.6 Micro-pipettes, of capacities 2, 5 and10mm 3 . 3) 5.7 Chromatographic developing tanks, large enough to hold the plates (5.1), for example of dimensions250mm 250mm 70mm or320mm 240mm 110mm. Small “sandwich type” tanks are not recommended, because they do not allow adequate solvent vapo
36、ur circulation between the tank wall and the sample plate. 5.8 Extraction apparatus, as described in ISO1407. 5.9 Rotary vacuum evaporator (optional, see7.3). 5.10 Short liquid-solid chromatographic column Those found to be satisfactory comprise: 5.10.1 5 cm 3hypodermic syringe barrel, fitted with a
37、 needle about35mm in length and1,25mm in diameter. 5.10.2 Glass tubes, 120mm in length and10to12mm in diameter, holding about5cm 3silica gel. 5.11 Spray apparatus 5.12 Mask for spraying portions of plates (optional, see8.5.1). 6 Preparation of developing tank and plates 6.1 Preparation of developing
38、 tank Add about200cm 3of the developing solvent (4.4.1 or 4.4.2) to a tank (5.7), swirl, cover and allow to stand for about15min before using. The tank may be re-used by repeating swirling and allowing to stand, provided that the composition of the solvent remains constant. 2) Hitherto expressed as
39、“1 M or 1 N solution”. 3) Hitherto expressed as “41”.BS6630:1985 BSI 12-1999 3 6.2 Preparation of plates 6.2.1 Prepare plates by making a slurry of2 parts of water and1 part of the silica gel (4.1). Allow to stand, with occasional gentle stirring, taking care to avoid the formation of air bubbles, u
40、ntil the mixture has thickened slightly. Spread the slurry evenly over the glass plates (5.1) using the spreading device (5.2). The thickness of the layer should be250 to3004m. Allow the plates to stand at room temperature until the silica gel sets. Dry completely and activate the silica gel, by pla
41、cing the plates for at least2h in the oven (5.4), controlled at100 5 C, or if more convenient, overnight (approximately16h). 6.2.2 The plates may be stored in a desiccator over silica gel. Unused plates shall be reactivated after4days. 6.2.3 Before use, “lanes” may be made on the plate, about20mm wi
42、de by scoring with a knife or scriber, but the procedure may be omitted if edge effects spoil the chromatogram. 6.2.4 Plates may be spotted while warm, if it has been proved that no decomposition of the antidegradant takes place. Spotting the plates while warm sometimes results in more compact spots
43、, but it has been observed that better duplication will result when plates are spotted at room temperature. 6.3 Preparation of pre-coated plates If pre-coated plates are used, follow the manufacturers instructions for conditioning. 7 Preparation of test portion 7.1 Sheet the test portion thinly usin
44、g a laboratory mill with a tight nip and running at even speed or cut it into very small pieces (length of edgesu 2mm) and place2 to5g between two filter papers. Transfer to the extraction apparatus (5.8) and extract with an appropriate solvent as specified in ISO1407 for4h with the test portion in
45、the extraction cup, or for1 to2h with the rubber immersed in the solvent. Alternative extraction procedures, such as shaking with dichloromethane (vulcanizates only) at room temperature for a short time, or standing overnight in2-propanol (4.3.4) or acetonitrile (4.3.14) are also satisfactory. 7.2 S
46、imultaneously with the extraction, carry out a preliminary screening, if necessary, as described in theAnnex. 7.3 Evaporate the extract (7.1) in a beaker on a hot plate, at not more than50 C, using a stream of nitrogen to aid evaporation in the final stages. The use of a vacuum rotary evaporator, if
47、 available, is helpful. When about1cm 3of solution remains, examine visually for the presence of extender oil. If extender oil is present, proceed as described in7.4 to7.7. If extender oil is absent, evaporate the extract to dryness using gentle heating (at a maximum of50 C) under a stream of nitrog
48、en. Dissolve the dried extract in0,5 to1,0cm 3of dichloromethane with gentle heating to obtain a clear solution and then proceed directly with spotting of the thin layer plate as described in clause8. NOTESmall amounts of residual alcohol may change mobilities of the spots (R fvalues). 7.4 Prepare a
49、 silica gel column from the activated silica gel (4.2) by placing a glass wool plug at the end of the column (5.10) and filling immediately. The column shall, preferably, be used when freshly prepared, but otherwise shall be used within2h of preparation and shall be stored in a desiccator during this period. 7.5 Dissolve the residue obtained as described in7.3 in about2cm 3of dichloromethane and pour this solution onto the dry silica gel column. Wash with the n-hexane (4.3.9) until the glass wool plug becomes colourless. Use no more than
