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Isocyanates and Amines – Sampling and Analytical Procedures
Stockholm University, Faculty of Science, Department of Analytical Chemistry.
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis covers sampling and analytical procedures for isocyanates (R-NCO) and amines (R-NH2), two kinds of chemicals frequently used in association with the polymeric material polyurethane (PUR). Exposure to isocyanates may result in respiratory disorders and dermal sensitisation, and they are one of the main causes of occupational asthma. Several of the aromatic diamines associated with PUR production are classified as suspected carcinogens. Hence, the presence of these chemicals in different exposure situations must be monitored.

In the context of determining isocyanates in air, the methodologies included derivatisation with the reagent di-n-butylamine (DBA) upon collection and subsequent determination using liquid chromatography (LC) and mass spectrometric detection (MS). A user-friendly solvent-free sampler for collection of airborne isocyanates was developed as an alternative to a more cumbersome impinger-filter sampling technique. The combination of the DBA reagent together with MS detection techniques revealed several new exposure situations for isocyanates, such as isocyanic acid during thermal degradation of PUR and urea-based resins. Further, a method for characterising isocyanates in technical products used in the production of PUR was developed. This enabled determination of isocyanates in air for which pure analytical standards are missing. Tandem MS (MS/MS) determination of isocyanates in air below 10-6 of the threshold limit values was achieved.

As for the determination of amines, the analytical methods included derivatisation into pentafluoropropionic amide or ethyl carbamate ester derivatives and subsequent MS analysis. Several amines in biological fluids, as markers of exposure for either the amines themselves or the corresponding isocyanates, were determined by LC-MS/MS at amol level. In aqueous extraction solutions of flexible PUR foam products, toluene diamine and related compounds were found.

In conclusion, this thesis demonstrates the usefulness of well characterised analytical procedures and techniques for determination of hazardous compounds. Without reliable and robust methodologies there is a risk that exposure levels will be underestimated or, even worse, that relevant compounds will be completely missed.

Place, publisher, year, edition, pages
Stockholm: Institutionen för analytisk kemi , 2004. , 65 p.
Keyword [en]
Isocyanates, Amines, Polyurethane, Air sampling, Industrial hygiene, Mass spectrometry, Liquid chromatography, Chemiluminescence
National Category
Analytical Chemistry
Identifiers
URN: urn:nbn:se:su:diva-204ISBN: 91-7265-917-3 (print)OAI: oai:DiVA.org:su-204DiVA: diva2:190909
Public defence
2004-09-10, Vita salongen, Hässleholms kulturhus, Järnvägsgatan 23, Hässleholm, 10:00
Opponent
Supervisors
Available from: 2004-08-20 Created: 2004-08-20Bibliographically approved
List of papers
1. Determination of isocyanic acid in air
Open this publication in new window or tab >>Determination of isocyanic acid in air
2004 (English)In: Journal of Environmental Monitoring, ISSN 1464-0325, Vol. 3, no 4, 432-436 p.Article in journal (Refereed) Published
Abstract [en]

A method is presented for the determination of isocyanic acid (ICA), HNCO, in air samples as a di-n-butylamine (DBA) derivative. The method is based on sampling in midget impinger flasks containing 10 ml of 0.01 mol l–1 DBA in toluene. Quantification was made using liquid chromatography (LC) and electrospray mass spectrometry (MS) monitoring positive ions. The instrumental detection limit for the LC-MS was 10 fmol of ICA-DBA. ICA was generated by thermal decomposition of urea. A standard solution containing the DBA derivatives of ICA was prepared by collecting the emitted ICA in an impinger flask containing DBA. ICA in the reference solution was characterised by LC and time-of-flight (TOF) MS and quantified by LC chemiluminescent nitrogen detection (LC-CLND). The instrumental detection limit for the LC-CLND was 1 ng of nitrogen. ICA was emitted during thermal degradation of PFU resins and polyurethane (PUR) lacquers, from car metal sheets. ICA was the most dominant isocyanate and in PUR coating up to 8% of the total weight was emitted as ICA and for PFU resins up to 14% was emitted as ICA. When air samples were collected in an iron foundry during casting in sand moulds with furan resins, concentrations of ICA in the range 50–700 µg m–3 were found in the working atmosphere

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2004
Keyword
AIRBORNE ISOCYANATES; THERMAL-DEGRADATION; COMPLEX-MIXTURES; CHEMILUMINESCENT NITROGEN; LIQUID-CHROMATOGRAPHY; POLYURETHANE; AMINES; SURVEILLANCE; DIISOCYANATE; DETECTOR
National Category
Analytical Chemistry
Research subject
Analytical Chemistry
Identifiers
urn:nbn:se:su:diva-23246 (URN)10.1039/b103476f (DOI)
Note
Part of urn:nbn:se:su:diva-204Available from: 2004-08-20 Created: 2004-08-20 Last updated: 2010-01-05Bibliographically approved
2. Determination of technical grade isocyanates used in the production of polyurethane plastics
Open this publication in new window or tab >>Determination of technical grade isocyanates used in the production of polyurethane plastics
Show others...
2004 (English)In: Journal of Environmental Monitoring, Vol. 6, no 7, 606-614 p.Article in journal (Refereed) Published
Abstract [en]

A method for determination of technical grade isocyanates used in the production of polyurethane (PUR) is presented. The isocyanates in technical grade products were characterised as di-n-butylamine (DBA) derivatives using LC-MS and LC-chemiluminescent nitrogen detection (CLND) and the total isocyanate content was compared to a titration assay. For collection of isocyanates in air, an impinger–filter sampling technique with DBA as derivatisation reagent was used. Characterised DBA and nonadeuterium labelled DBA derivatives of isocyanates in technical products were used as calibration standards and internal standards, respectively, in the analysis of air samples. Three workplaces were studied where PUR products were produced either by spraying or by moulding. In both technical products and in air samples, a number of monomeric, oligomeric and prepolymeric isocyanates of e.g. methylenebisphenyl diisocyanate (MDI) and hexamethylene diisocyanate (HDI) were characterised. Several of these have not previously been described in workplace atmospheres. In the technical isocyanate products, between 69 and 102% of the NCO content determined by titration was accounted for by LC-CLND. Quantifications of a wide range of isocyanates in air samples were performed with correlation coefficients in the range 0.988–0.999 (n= 8) and the instrumental detection limits were 0.7–25 pg. At the two workplaces where MDI- and HDI isocyanurate-based products were sprayed, the isocyanate composition in the air reflected the composition in the technical product. At the workplace where a MDI-based product was used in a moulding process, only the monomeric isocyanates were found in the air. The advantage of using characterised technical grade isocyanates as analytical standards was clearly demonstrated and the possibility of using index compounds when monitoring isocyanate exposure is discussed.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2004
Identifiers
urn:nbn:se:su:diva-23247 (URN)10.1039/b402775b (DOI)
Note
Part of urn:nbn:se:su:diva-204Available from: 2004-08-20 Created: 2004-08-20 Last updated: 2010-01-05Bibliographically approved
3. Determination of airborne isocyanates as di-n-butylamine derivatives using liquid chromatography and tandem mass spectrometry
Open this publication in new window or tab >>Determination of airborne isocyanates as di-n-butylamine derivatives using liquid chromatography and tandem mass spectrometry
Show others...
Manuscript (Other academic)
Identifiers
urn:nbn:se:su:diva-23248 (URN)
Note
Part of urn:nbn:se:su:diva-204Available from: 2004-08-20 Created: 2004-08-20 Last updated: 2010-01-13Bibliographically approved
4. Solvent-free sampling with di-n-butylamine for monitoring of isocyanates in air
Open this publication in new window or tab >>Solvent-free sampling with di-n-butylamine for monitoring of isocyanates in air
Manuscript (Other academic)
Identifiers
urn:nbn:se:su:diva-23249 (URN)
Note
Part of urn:nbn:se:su:diva-204Available from: 2004-08-20 Created: 2004-08-20 Last updated: 2010-01-13Bibliographically approved
5. Extractable organic compounds in polyurethane foam with special reference to aromatic amines and derivatives thereof
Open this publication in new window or tab >>Extractable organic compounds in polyurethane foam with special reference to aromatic amines and derivatives thereof
2004 (English)In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 510, no 1, 109-119 p.Article in journal (Refereed) Published
Abstract [en]

Methods for determination of aromatic amines and related compounds in flexible toluene diisocyanate (TDI)-based polyurethane (PUR) foam were investigated. The foam was extracted using 0.1% (w/v) aqueous acetic acid (HAc). Extraction solutions were analysed and aromatic amines were determined as ethyl chloroformate (Et) and pentafluoropropionic acid anhydride (PFPA) derivatives. The determinations were performed using liquid chromatography (LC) and mass spectrometry (MS) detection with electrospray ionisation (ESI) or gas chromatography (GC)-MS with chemical ionisation monitoring negative ions (NCI). The Et derivatives were determined using LC-ESI+-MS with detection limit of 2 pg of toluenediamine (TDA). The PFPA derivatives were determined using LC-ESI--MS or GC-NCI-MS with detection limits of 0.1 and 0.02 pg of TDA, respectively. Using trideuterium labelled TDA as internal standard, linear calibration curves were obtained in the range of 0.01-0.50 mug ml(-1) (n = 7), with correlation coefficients >0.999. When plotting calibration curves for TDA-PFPA derivatives determined using LC-MS against TDA-PFPA using GC-MS and TDA-Et using LC-MS, linear curves were obtained. The relative standard deviation (R.S.D.) for determination of TDA in foam extraction solutions were 13%. LC-MS determination of PFPA derivatives was more selective, as compared to LC-MS of Et derivatives.

In foam extraction solutions, 2,4- and 2,6-TDA, several isomers of methylenedianiline (MDA) and dimers of TDA/TDI were observed. 2,4-TDA and 4,4'-MDA are possible human carcinogens. Hydrolysis of the extraction solution revealed a large pool of TDA/TDI compounds and oligomers. The concentration of TDA in foam was affected by the extraction media, temperature and duration. The choice of derivatisation procedure also affected the determination of TDA. In extraction solutions from six different commercially available flexible foam qualities 2,4- and 2,6-TDA were found in the range of 0-7 and 0-6 mug g(-1) foam, respectively. When flexible foam was heated, considerable higher concentrations of TDA were observed.

Keyword
polyurethane; PUR; toluenediamine; TDA; LC-MS
National Category
Analytical Chemistry
Research subject
Analytical Chemistry
Identifiers
urn:nbn:se:su:diva-23250 (URN)10.1016/j.aca.2003.12.063 (DOI)
Available from: 2004-08-20 Created: 2004-08-20 Last updated: 2013-06-19Bibliographically approved
6. Determination of amines as pentafluoropropionic acid anhydride derivatives in biological samples using liquid chromatography and tandem mass spectrometry
Open this publication in new window or tab >>Determination of amines as pentafluoropropionic acid anhydride derivatives in biological samples using liquid chromatography and tandem mass spectrometry
2004 (English)In: The Analyst, ISSN 0003-2654, Vol. 129, no 6, 522-528 p.Article in journal (Refereed) Published
Abstract [en]

Determination of amines in biological samples as markers of exposure to the amines or the corresponding isocyanates is an important tool for industrial exposure assessment. In this study, a liquid chromatography and tandem mass spectrometry (LC- MS/ MS) method for determination of amines in biological samples as perfluorofatty amides derivatives is presented. The method enables determination of diamines such as methylene diamine (MDA), toluene diamine (TDA), naphthalene diamine (NDA), hexamethylene diamine (HDA), isophorone diamine (IPDA), methylenedi( cyclohexylamine) (HMDA) and 4,4'-methylene-(2-chloroaniline) (MOCA) in human urine and plasma. The work-up procedure included hydrolysis of the biological samples with 3 M H2SO4 at 100degreesC for 16 h and extraction of the amines into toluene, where derivatisation of the amines with perfluorofatty acid anhydride was performed. Following removal of excess reagent and the acid formed and an exchange of solvent, the derivatives were analysed using gradient elution with an acetonitrile/water mobile phase composition and electrospray ionisation (ESI) with multiple reaction monitoring (MRM) of [M - H](-) --> [M - H - 120](-) or [119](-). Several perfluorofatty acid anhydrides were evaluated as derivatisation reagents, but the LC chromatographic properties of the pentafluoropropionic acid anhydride (PFPA) derivatives were favourable. Quantification of amine - PFPA derivatives was performed using deuterium labelled amine - PFPA derivatives as internals standards with good precision and linearity in the investigated range of 0 - 20 ng ml(-1) urine. The instrumental detection limits for the amine - PFPA derivatives were 0.2 - 3 fmol for MRM of [M - H](-) --> [119](-) and 0.3 - 8 fmol for [M - H](-) --> [M - H - 120](-). In 10 urine and 6 plasma samples from workers exposed to isocyanates, determination of TDA and MDA as PFPA derivatives was performed using LC- MS/ MS and a reference GC-MS method. No significant difference between the two methods was observed.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2004
National Category
Analytical Chemistry
Research subject
Analytical Chemistry
Identifiers
urn:nbn:se:su:diva-23251 (URN)10.1039/b403439b (DOI)
Note
Part of urn:nbn:se:su:diva-204Available from: 2004-08-20 Created: 2004-08-20 Last updated: 2010-01-05Bibliographically approved

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