Isocyanates HPLC analysis

Analysis of Reagent Purity the enantiomeric purity of the reagent can be determined by either NMR or HPLC analysis of derivatives produced from a-methoxy-a-(trifluoromethyl)benzyl isocyanate, a-methoxy-a-(trifluoromethyl)benzyl acid chloride, or 2 -methoxy-l,l -binaphthyl-2-carboxylic acid chloride. ... 

Combination of a nonracemic isocyanate and a l,3-disul)sliluted distannoxane has provided a new method for determination of the optical purity of chiral alcohols (Scheme 12.174) [316]. When a chiral alcohol was reacted with commercially available (l )-l-(l-naphthyl)efhyl isocyanate in the presence of 1,3-disubstituted distannoxane, formation of the desired carbamates occurred rapidly, with acid-labile functional groups such as ester, THP and /Miydroxyketone remaining intact. Subsequent HPLC analysis of the resulting carbamate revealed a pair of well-separated peaks of diastereomers derived from both enantiomeric alcohols. 

Isocyanates are derivatised with tryptamine (27) and determined with a dual detection system based on fluorescence and amperometric oxidation Tryptamine and N-co-methyltryptamine (28) were found to be the most promising scavenging reagents for airborne organic isocyanates, before analysis by HPLC with reverse-phase columns and UV detection A personal sampler for airborne isocyanates in workplaces was developed based on 27. ... 

The HPLC analysis of the eleetrolysis carried out in DMF solvent showed the presence of both isoeyanate and earbammic acid, but no qualitative analysis was possible beeause earbammie aeid ean be also produced, by hydrolysis of isocyanate in the HPLC column. 

Used as fluorescent reagent for hplc analysis of isocyanates. Liq. Bpo3 90°, Bpoo2 71-81°. 

AEOs have been analysed by HPLC and UV or fluorescence detection after suitable derivatisation. The derivatising agents proposed so far are phenyl isocyanate [80,81], 1-anthroylnitrile [82], 3,5-dinitro-benzoyl chloride [83], naphthyl isocyanate [84] and naphthoyl chloride [84], However, the lack of fluorescence activity and the need for synthesis through a multistep reaction for some derivatising agents limits their application in a real-world analysis. In fact, only a few of them were applied in the determination of AEOs in environmental samples. Zanette et al. [84] developed derivatisation and separation... 

Isoouanates. Various isocyanates are employed in the polymer industry. These compounds are powerful irritants and they are highly toxic. Of particular interest are methylene-di-paraphenylene isocyanate (MDI) and toluene-2,4-diisocyanate (TDI). Various alkyl isocyanates (e.g., methyl, ethyl, propyl, butyl, and cyclohexyl) derivatives may also be of current interest with respect to potential occupational health hazards. Simultaneous analysis of MDI and TDI by HPLC has been accomplished by a modification of the method of Dunlap et al. (28). Air samples are collected in impingers containing p-nitrobenzyl-n-... 

Several unsuccessful attempts were made to analyze the fluorophor produced by the reaction of MIC with diacetylmonoxime using HPLC and a multiwavelength fluoroescence detector. Because of a series of analytical problems, a search was initiated for a method that would lend itself to liquid chromatographic analysis more readily. Since methyl isocyanate probably reacts with water according to the following equation ... 

Analysis of the enantiomeric ratios of several p-blocking drugs (l-aryloxy-3-isopropylamino-2-propanol derivatives) is carried out by HPLC with UV or fluorescence detection after derivatization with (R)-NEI or (i )-(+)-l-(l-phenyl)ethyl isocyanate (in a reversed-phase system), or (S)-NEI (on silica gel) only the amine function of the drugs reacts with the NEI the hydroxy group does not. Similar schemes for HPLC determination of enantiomeric purity of tetrahydrofolate derivatives and of fluoxetine are also reported. 

In this section the use of the integrated NESI-chip device is described to study the kinetics of the reaction of NBDPZ with isocyanates (Scheme 9.3) as a model system. This reaction has been introduced by Karst and co-workers99,100 for the derivatization of extremely reactive isocyanates101 in order to allow their analysis by means of HPLC. 

HPLC has also been applied to the analysis of trimethylolpropane and pentaerythritols in industrial synthesis solutions, 2-mercaptobenzothiazole in waste dump effluent, polythionates in mining waste water, isocyanates in working atmospheres, carcinogenic amines, aniline in waste water, polyethylene oxide fatty acid surfactants in industrial process waters and phthalate esters in river water. 

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