Amine antioxidants, determination

Table 2.3 as a completely worked out example using quantitative solvent extraction, ash content determination, TGA, FTIR, XRF, GC-MS, HS-GC-MS, PyFTIR, ICP, and s-NMR. Information on the cure and antidegradant systems was obtained (assigned species/possible origin), as follows cyclohexane thiol/CBS accelerator benzothiazole/MBT, MBTS or CBS accelerators N, A-dimethylformamide/TMTD accelerator phthalim-ide/Santoguard PVI and IV-phenylbenzene amine/possi-bly a diphenyl/acetone amine antioxidant. 

GC is extensively used to determine phenolic and amine antioxidants, UV light absorbers, stabilisers and organic peroxide residues, in particular in polyolefins, polystyrene and rubbers (cf. Table 61 of Crompton [158]). Ostromow [159] has described the quantitative determination of stabilisers and AOs in acetone or methanol extracts of rubbers and elastomers by means of GC. The method is restricted to analytes which volatilise between 160 °C and 300 °C without decomposition. A selection of 47 reports on GC analysis of AOs in elastomers (period 1959-1982) has been published... 

Crompton [21] has reviewed the use of electrochemical methods in the determination of phenolic and amine antioxidants, organic peroxides, organotin heat stabilisers, metallic stearates and some inorganic anions (such as bromide, iodide and thiocyanate) in the 1950s/1960s (Table 8.75). The electrochemical detector is generally operated in tandem with a universal, nonselective detector, so that a more general sample analysis can be obtained than is possible with the electrochemical detector alone. 

Hilton [63] has reported an excellent procedure, described next, for the colorimetric determination of amine antioxidants. 

Hilton [82] described a colorimetric method B for determining amine antioxidants (p-phenylenediamine derivatives) based on the reaction of an ethanol extract of the polymer with cupric acetate in an hydrochloric acid/potassium chloride buffered medium. Kabota [83] made coloured derivatives of amines with benzothiazoline-2-one hydrazone hydrochloride and ferric chloride, and evaluated the colours obtained, spectroscopically. 

HPLC of polymer extracts has been used to determine dilauryl dithiopropionate, Irganox 1076 and distearyl-dithiopropionate in polyolefins [18], amine antioxidants and antiozonates in rubbers [16], Irganox 1076, Irganox 1010 and BHT in PE [19] and miscellaneous antioxidants, light stabilisers in polyolefins [20,21] and Santonox R, Ethanox 736, CAO-5, Irganox 1035, Irganox 259 and Topanol [22] in polyolefins and also the determination of antioxidants and accelerators in vulcanised rubber formulations [23-25]. 

TLC has been used extensively for the determination of phenolic and amine antioxidants and UV stabilisers in plastics and rubber [17, 32, 36-58]. 

Thin-layer liquid chromatography has been employed for the determination of alkylated cresols and amine antioxidants [102, 103] in polybutadiene, phenolic antioxidants in PE [104-106] and PP [106], dilauryl and distearyl thiodipropionate antioxidants in polyolefins, ethylene-vinyl acetate copolymer, acrylonitrile-styrene terpolymer and PS, UV absorbers and organotin stabilisers in polyolefins [102], and accelerators such as guanidines, thiazoles, thiurans, sulfenamides, diethiocarbamides, and morpholine disulfides in unvulcanised rubber compounds. 

The Hilton diazotization procedure has been used for the determination of amine antioxidants in polyolefins and other polymers (Method 14). 

The diazotized p-nitroaniline procedure has been applied to the determination of amine antioxidants in ethanol extracts of thin films of rubber. ... 

Solvent extraction gas chromatographic methods have been described for determining alkylated cresols (2,6-di-tert-butyl-p-cresol) and amine antioxidants (N-phenyl-2-naphthylamine, p-phenylene diamine type) and Santoflex (NN sec-heptyl phenyl-p-phenylene diamine) in polybutadiene. 

These relatively new techniques viz laser desorption/ionization Fourier transform mass spectrometry and fast atom bombardment and laser desorption Fourier transform ion cyclotron resonance mass spectrometry have been applied to the determination of non volatile polymer additives (thioester, phosphite, phosphonate and hindered amine antioxidant types) and antioxidants, ultraviolet absorbers and amide waxes. 

METHOD 11 - DETERMINATION OF PHENOLIC AND AMINE ANTIOXIDANTS, ULTRAVIOLET ABSORBERS AND ORGANOTIN STABILIZERS IN POLYALKENES AND OTHER POLYMERS. THIN LAYER CHROMATOGRAPHY. ... 

This thin-layer method is capable of determining a wide range of polymer additives, viz amine antioxidants, uv absorbers and organotin stabilizers in amounts down to 0.02% in polyalkenes. 

METHOD 13 - DETERMINATION OF NONOX Cl AMINE ANTIOXIDANT IN POLYALKENES. ACID HYDROGEN PEROXIDE SPECTROPHOTOMETRIC METHOD. ... 

This spectrophotometric method is capable of determining down to 0.01% of Nonox Cl amine antioxidant in polyalkenes. 

Amine antioxidants which cannot be determined include ... 

The method is capable of determining down to 0.02 to 0.05% of amine antioxidants in polyalkenes with an accuracy of + 5%. The colour obtained with phenyl-fi-naphthylamine antioxidant fades too rapidly to enable it to be determined. 

METHOD 47 - DETERMINATION OF AMINE ANTIOXIDANTS AND ANTIDEGRADANTS IN RUBBER. GEL PERMEATION, CHROMATOGRAPHY. ... 

This gel permeation chromatographic method determines a range of amine antioxidants and antidegredants in rubbers in amounts down to 0.02%. 

Determination of phenolic and amine antioxidants, ultra-violet... 

Determination of amine antioxidants in polyalkenes and other polymers, p-nitro aniline coupling - spectrophotometric procedure... 

Determination of amine antioxidants and antidegradants in rubbers. Gel permeation chromatography... 

Plasticiser/oil in rubber is usually determined by solvent extraction (ISO 1407) and FTIR identification [57] TGA can usually provide good quantifications of plasticiser contents. Antidegradants in rubber compounds may be determined by HS-GC-MS for volatile species (e.g. BHT, IPPD), but usually solvent extraction is required, followed by GC-MS, HPLC, UV or DP-MS analysis. Since cross-linked rubbers are insoluble, more complex extraction procedures must be carried out. The determination of antioxidants in rubbers by means of HPLC and TLC has been reviewed [58], The TLC technique for antidegradants in rubbers is described in ASTM D 3156 and ISO 4645.2 (1984). Direct probe EIMS was also used to analyse antioxidants (hindered phenols and aromatic amines) in rubber extracts [59]. ISO 11089 (1997) deals with the determination of /V-phenyl-/9-naphthylamine and poly-2,2,4-trimethyl-1,2-dihydroquinoline (TMDQ) as well as other generic types of antiozonants such as IV-alkyl-AL-phenyl-p-phenylenediamines (e.g. IPPD and 6PPD) and A-aryl-AL-aryl-p-phenylenediamines (e.g. DPPD), by means of HPLC. 

Only few applications have been reported to determine antioxidants in rubbers or polymers by using electrochemical methods [927,928]. Sawada et al. [929] reported successful separations by coupling the antioxidants with p-diazobenzene sulfonic acid before electrophoresis. Amine AOs were coupled in acetic acid and phenolic AOs in NaOH-ethanol were analysed by CE methods. MEKC separation of the four major food grade antioxidants (PG, BHA, BHT, TBHQ) was completed within 6 min with pmole amount detection using UV absorption [930]. RPLC was not as efficient and required larger sample amounts and longer separation times. 

A method suitable for quantification of the functional class of bis(ethanol)amine antistatics, which lack UV chromophores, consists of reaction with methyl orange [53]. Atmer 163 (alkyl-diethanol amine) has been determined as a yellow complex at 415 nm after interaction with a bromophenol/cresole mixture [64]. Hilton [65] coupled extracted phenolic antioxidants with diazotised p-nitroaniline in strongly acidic medium and carried out identification on the basis of the visible absorption spectrum in alkaline solution. The antioxidant Nonox Cl in... 

Phenolic antioxidants in rubber extracts were determined indirectly photometrically after reaction with Fe(III) salts which form a red Fe(II)-dipyridyl compound. The method was applicable to Vulkanox BKF and Vulkanox KB [52]. Similarly, aromatic amines (Vulkanox PBN, 4020, DDA, 4010 NA) were determined photometrically after coupling with Echtrotsalz GG (4-nitrobenzdiazonium fluoroborate). For qualitative analysis of vulcanisation accelerators in extracts of rubbers and elastomers colour reactions with dithio-carbamates (for Vulkacit P, ZP, L, LDA, LDB, WL), thiuram derivatives (for Vulkacit I), zinc 2-mercaptobenzthiazol (for Vulkacit ZM, DM, F, AZ, CZ, MOZ, DZ) and hexamethylene tetramine (for Vulkacit H30), were mentioned as well as PC and TLC analyses (according to DIN 53622) followed by IR identification [52]. 8-Hydroquinoline extraction of interference ions and alizarin-La3+ complexation were utilised for the spectrophotometric determination of fluorine in silica used as an antistatic agent in PE [74], Also Polygard (trisnonylphenylphosphite) in styrene-butadienes has been determined by colorimetric methods [75,76], Most procedures are fairly dated for more detailed descriptions see references [25,42,44],... 

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