Current Issues in Measurement of Airborne Isocyanates. Gunnar Skarping, Marianne Dalene, Daniel Karlsson, Daniel Gylestam

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1 Current Issues in Measurement of Airborne Isocyanates Gunnar Skarping, Marianne Dalene, Daniel Karlsson, Daniel Gylestam socyanates & Health, past present and future

3 Isocyanate exposure Physical state, particle/gas phase Reacting aerosol Thermal degradation products

4 The diols are typically esters or ethers. Aromatic amines such as MOCA and MDA are used in elastomers diol diol diol diol diol diol diol diol diol diol diol diol Additives: Catalysts, Fire retardants, Water, Solvents, Pigments Formic acid, Waxes Antistatic, Foaming and Crosslinking agents, Polyurethane is formed in an exoterm reaction between isocyanates and diols. Necessary properties are achieved with additives. diol diisocyanate diol diisocyanate diol diisocyanate diol diisocyanate diol diisocyanate diol diisocyanate diisocyanate diisocyanate diisocyanate diisocyanate diisocyanate diisocyanate diisocyanate diisocyanate diisocyanate diisocyanate diisocyanate diol diisocyanate diol diol diisocyanate diol diol diisocyanate diol diisocyanate diisocyanate diol diol diisocyanate diol diol diisocyanate diisocyanate diol diol + By-product By-product By-product 4

5 Aromatic / aliphatic amines e.g. TDA, MDA Amino isocyanat e Heat/Energy decompose PUR-polymers diol diisocyanate diol diisocyanate diol diisocyanate diol diisocyanate Carbonyl diol diisocyanate diol diisocyanate compounds Gas and particles are formed diisocyanate diol diisocyanate diol diisocyanate diol diisocyanate Monoisocyanates:, PIC, BIC PhI, ICA, MIC, EIC Biocides, Fireretardants, Pigments, etc. 5

6 Spraying applications In car repair shops

7 Spraying applications MDI based PUR

8 Spraying applications MS characterisation Identification of molecular ions [M+H] +, [MNa] + Identification of typical fragments [DBA+H] +, [MH-DBA] + Comparison with spectra from d 9 -DBA derivative

9 Thermal degradation In car repair shops

10 Thermal degradation Emission of amines and aminoisocyanates O O CH 3 O O O O C O R O C N H N H C O R O C N N H CH 3 H C O R O C CH 3 CH 3 OCN NCO H 2 N NH 2 OCN NCO H 2 N NH 2 CH CH 3 3 CH 3 CH 3 H 2 N NCO OCN NH 2 H 2 N CH 3 NCO

11 Isocyanate emission during fire - Small-scale combustion experiments in a Cone Calorimeter Total isocyanates in exhaust ducts (ppb) Glass wool Nitrile rubber Full-scale experiment Melamine PUR (rigid) PIR Particleboard Wool textile Mineral wool Room test-sofa PUR (flexible) FR4-laminate Optical cable Bitumen PVC Fluorocarbon-cable PVC-cable Plywood PVC+fluorocarbon-cable Wood Polyethylene-cable Polyethylene-pellets Average concentrations of total isocyanate measured in the exhaust duct in a small-scale tests and in a single full-scale Room test (logarithmic scale on y-axis).

12 Material Isocyanates Inorganic gases Glass wool 1.42 HCN = 0.04; NH 3 = 0.04; CO = 0.01 Nitrile rubber 0.72 HCl = 1.19; HCN = 0.12; SO 2 = 0.11; NH 3 = 0.06; CO = 0.05 Melamine 0.62 HCN = 0.12; SO 2 = 0.11; CO = 0.08; NO = 0.08; NH 3 = 0.01 PUR (rigid) 0.60 HCN = 0.44; HCl = 0.23; CO = 0.15; NO = 0.14 PIR 0.56 HCN = 0.12; HCl = 0.07; CO = 0.05 Particle board 0.45 NO = 0.16; CO = 0.02; NH 3 = 0.02 Wool textile 0.19 SO 2 = 0.21; NO = 0.10; (HCN < 0.04; CO < 0.01; NH 3 < 0.01) Mineral wool 0.18 (HCN < 0.04; NH 3 < 0.01; CO < 0.01) Polyethylene-pellets CO = 0.02 Sofa; full-scale experiment 0.17 CO = 0.30* Toxic hazard factors (quotient of measured average concentration and NIOSH IDLH-value) for total isocyanates compared to inorganic gas species for materials that produced isocyanates in the tests. Isocyanate emission during fire - Small-scale combustion experiments in a Cone Calorimeter

13 Monitoring of isocyanates in air Many isocyanates with different physical properties Collection of both gas and particle phase isocyanates Reactive compounds Derivatisation upon collection into stable derivatives Low occupational exposure limits High demands on the analysis

14 Alternatives for air sampling Impinger flasks Gas and particles Dry samplers Gas and particles Diffusive sampling Gas phase - not common Direct reading instruments Gas phase

Alternatives for air sampling Impinger + filter backup Isocyanate-containing particles < 2 µm are poorly collected by impingers; however, they are efficiently

15 Alternatives for air sampling Impinger + filter backup Isocyanate-containing particles < 2 µm are poorly collected by impingers; however, they are efficiently collected by the filter. In situations where the physical/chemical nature of the atmosphere is unknown the impinger/filter combination is the most appropriate

Alternatives for air sampling Impregnated filters Incomplete derivatization with the reagent may occur due to the presence of other reactive species in the particle If

16 Alternatives for air sampling Impregnated filters Incomplete derivatization with the reagent may occur due to the presence of other reactive species in the particle If the physical/chemical composition of the air being sampled is unknown, samples should be collected using an impinger containing a derivatising agent with filter backup

17 Derivatisation reagents Di-n-butylamine (DBA) C 4 H 9 HN C 4 H 9 1-(2-methoxyphenyl)- piperazine (MP) H N 1-(9-antracenylmethyl)- piperazine (MAP) H N N CH 2 9-(N-methylaminomethyl)- antracene (MAMA) H CH 3 N CH 2 N OCH 3 1-(2-pyridyl)piperazine [PP}

18 The Double-Filter method H N N OCH 3 H CH 3 N CH 2 The sampler is a two stage filter sampler where the first stage is a polytetrafluoroethylene (PTFE) filter which physically traps airborne particles and is subsequently immersed in MP solution to derivatise (stabilize) any trapped isocyanate species immediately after sampling. The second stage consists of a glass fibre filter (GFF) impregnated with 9- (methylaminomethyl) anthracene (MAMA) positioned after the PTFE filter, where any isocyanate vapours present in the air sample are instantaneously derivatised. Similar to other filter methods, both gas and particle-borne isocyanates can be efficiently collected; however, because the first stage filter (PTFE) is devoid of any derivatising reagent (to stabilise the isocyanate) the sampler should not be used where there are possibilities of trapped isocyanate species reacting with other compounds, e.g., sampling reacting aerosols or sampling for prolonged periods.

19 The MAP-method H N N CH 2 Depending on the environment to be sampled, the sampler can consist of a MAP-impregnated filter, an impinger containing a solution of MAP in butyl benzoate, or a MAP impinger followed by a MAP-impregnated filter / Namn Namn, Institution eller liknande

20 The MP-method H N N OCH 3 The sampler consists of an impinger containing a toluene solution of 1-(2- methoxyphenyl)piperazine (MP) with a MP coated filter placed in series after the impinger. Solvent free sampling is performed with a glass fibre filter coated with MP / Namn Namn, Institution eller liknande

21 PP The following method is under preparation: ISO DIS 14382: Workplace Atmospheres - Determination of toluene diisocyanate vapours using 1-(2- pyridyl)piperazine-coated glass fibre filters and analysis by high performance liquid chromatography with ultraviolet and fluorescence detectors. The sampler is a glass fibre filter impregnated with 1-(2-pyridyl)piperazine (PP) / Namn Namn, Institution eller liknande

22 HN C 4 H 9 The DBA-method C 4 H 9 The sampler consists of an impinger containing a toluene solution of DBA with a glass fibre filter placed in series after the impinger. Solvent free sampling is performed using a sampler consisting of a tube with an inner wall coated with a filter, coupled in series with a filter. The filters are impregnated with equimolar amounts of DBA and acetic acid, which reduces evaporation of the volatile DBA.

Sampler description ASSET-NCO sampler (Supelco, Bellefonte, PA,

23 Sampler description ASSET-NCO sampler (Supelco, Bellefonte, PA, US) In the denuder, gaseous substances are collected by diffusion and collection on the sampler walls. The diffusion of particles is too slow for collection on the denuder walls. The particles pass through the denuder and are collected on a reagent impregnated glass fibre filter connected in series with the denuder Denuder End filter

24 Samplers - Transportation / Storage Storage Shelf life Storage of exposed samplers Transportation Unexposed samplers Exposed samplers

25 Direct reading instruments

26 Direct reading instruments

27 Direct reading instruments

28 Summary of isocyanate sampling /analytical methods (ISO/TR17737, Workplace air Guidelines for selecting analytical methods for sampling and analysing isocyanates in air) Sampling: Method DBA Double-filter MAP MP PP Phase separation (vapour/particle) +/- +a Efficient collection (small particle) + +b +b +b +b Non-impinger version available c Maximum sampling time (hours) 0,25-8 d 0, ,25-8 d 0,25-4 Accurate analysis of: Unknown species (identification) e + + / + / + / e Low-molecular mass species (e.g. methyl NCO) f + + / + / + / Unstable species + +g Volatile species + +a Large particles + +h l Amino isocyanates + Pre-polymers NCO group (direct measure) +i e + j +k

29 TRIG The sampling of the Total Reactive Isocyanate Group (TRIG) has been performed using 2-MP, MAMA and MAP as isocyanate derivativatising agents. TRIG analysis demands equal signal strengths from a detector for all isocyanate compounds. The isocyanate group can be quantified without using isocyanate standards. TRIG can work as an indicator of the presence of isocyanate groups but does not give any molecule structural information.

30 Losses due to interfering reactions Moisture Interfering compound Method I Method II Method III 2,4-TDI 2,6-TDI 2,4-TDI 2,6-TDI 2,4-TDI 2,6-TDI Diethylamine Dimethylethylamine N-methylmorpholine ,4-Diazabicyklot(2,2,2)- octane (DABCO) 1,4-Diazabicyklot(2,2,2)- octane (DABCO) from a Concentration (ppm) Losses due to interfering substances (%) solution of 33% in polyol Aniline Phenol Ethanol Method I: Sampling in 0.4 M HCl. Method II: Sampling in toluen with 2x10-4 M MP reagent. Method III: Sampling in toluen with 1x10-4 M MAMA reagent. Brorson T., Sangö C., Skarping G., Renman L., Evaluation of chromatographic methods for the determination of isocyanates in air., Intern. J. Environ. Anal. Chem., 1990, 38,

31 Derivatisation reagents Chromatograms from different air sampling methods LC-MS/MS (MRM) chromatograms of different dibutylamine (DBA) and D 9 -DBA (Internal standards) derivatives

32 Dry sampler - Results sampling times in the range of 0.5 h 32 h The amount of isocyanates was plotted against the duration of the sampling in the chamber. Correlation of sampling time with amount of sampled isocyanate. HDI( ):y = x , R² = 0.999; IPDI 1 ( ):y = x , R² = 0.999; IPDI 2 ( ):y = x , R² = 0.999; 2,4-TDI ( ):y = x , R² = 0.998; 2,6-TDI ( ):y = x , R² =

33 Isocyanate standards Toxic compounds - paper work to ship Many different isocyanates Many not commercially available Dilute standards solutions are not stable / Namn Namn, Institution eller liknande

34 Isocyanate derivative standards Many not commercially available With the exception for the DBA derivatives several of the different derivatives are not stable Standards may be necessary to freshly be prepared / Namn Namn, Institution eller liknande

35 Internal standards There are different approaches for external internal standards. Sometime the standards are not isocyanate related compounds. Deuterium labelled internal standards are available for many of the isocyanate derivatives Unstable internal standards is a problem.

36 Interpretation of results Representative sampling, number of samples The uncertainty associated with the method Method bias

37 Uncertainty estimates Combined uncertainty: 12% Expanded uncertainty: 24%

38 Climate chamber studies Controlled studies with regards to: Temperature Humidity Interferences Wind speed conditions / ventilation Necessary for method comparisons and method validation

39 Future The use of isocyanates is increasing Millions are exposed Satisfactory PPE is necessary Biggest need is to reduce exposure Monitoring with this purpose is urgent Degradation products of TDI, TDA, etc Differentiation between gas and particles. Speciation of different isocyanates. More reliable results. (Increased general use of LC-MS). Methods for total isocyanates

Quantification of isocyanates and amines in polyurethane foams and coated products by liquid chromatography tandem mass spectrometry

ORIGINAL RESEARCH Quantification of isocyanates and amines in polyurethane foams and coated products by liquid chromatography tandem mass spectrometry Motoh Mutsuga, Miku Yamaguchi & Yoko Kawamura National