Research Of Measurement Method Of Isocyanate Compounds In The Air

Objectives Isocyanate compounds have been widely used in polyurethane industry, and the commonly isocyanate include toluene diisocyanate(TDI), with two isomers(2,4-TDI,2,6-TDI), diphenyl-methane-diisocyanate(MDI), hexamethylene diisocyanate(HDI),fisophorone diisocyanate(IPDI), etc. Chronically exposure to isocyanate compounds can lead to the damage like asthma, bronchitis and central nerve damage and other symptoms.Therefor, the objective of this study is to develop the methods to sampling and measure isocyanate compounds, including 2,4-DI, 2,6-TDI, HDI, IPDI, MDI, in order to provide technical support for the detection of isocyanate compounds.Methods 1 HPLC was used to the measurement method of 2,4-TDI, 2,6-TDI, MDI, HDI and IPDI. Different chromatogram, retention time were investigate to develop the optimum instrument application condition. 2 GC was used to the measurement method of 2,4-TDI,2,6-TDI and MDI. Different chromatogram, retention time were investigate to develop the optimum instrument application condition. 3 The index including linear range, detection limit, and the lowest detectable concentration were determined by evaluating the retention time, quantitative by peak area, calibration. 4 The different concentrations of isocyanate standard gas were prepared by dynamic volumetric. Imitating sampling was performed for sample collection test, in order to improve and optimize of sampling flow or sampling way of isocyanate in the air, as well as increase the sampling efficiency.Results 1 The sampling method is used 2000 ml/min, series impregnated filter and absorbing solution to collect air samples.The parameters for determination of 2,4-TDI, 2,6-TDI, MDI, HDI and IPDI by HPLC included, C18(5 μm, 4.6 mm×150 mm) column,moving phase(60% ACN/40% H2O), flow(1 ml/min), UV length(242 nm). Under the above condition, the linear ranges of 2,4-TDI, 2,6-TDI, MDI, HDI and IPDI were0.0005~42.12 μg/ml, r=0.9999~1.0. The detection limits were 0.00015~0.0088 μg/ml, the quantification limits were 0.0005~0.027 μg/ml. The lowest detectable concentrations of 15 L air sample were 0.0001~0.001 mg/m3, and the lowest quantification concentrations of 15 L air sample were 0.0003~0.036 mg/m3. The recovery were 95%~103.8%. 2 The samplingmethod is used 1000 ml/min, series absorbing solution to collect the air samples. The parameters of determination of 2,4-TDI, 2,6-TDI and MDI by GC included, DB-WAX(30m×0.25mm×0.25μm) column, inlet temperature(290 ℃), column temperature(initial value is 170℃, then 50℃/min to 220℃, maintain for 15min), ECD detector temperature(250 ℃), separate(20:1), flow of carrier gas(1.5ml/min). On this condition, the linear ranges of 2,4-TDI, 2,6-TDI and MDI were 0.003~31.46 μg/ml, r=0.9999. The detection limits were 0.0009~0.0034 μg/ml, the quantification limits were 0.003~0.011 μg/ml. The lowest detectable concentrations of 15 L air sample were 0.0006~0.0023 mg/m3, and the lowest quantification concentrations of 15 L air sample were 0.002~0.0075 mg/m3. The recovery were 95%~98%.Conclusions The detection methods of 2,4-TDI, 2,6-TDI, MDI, HDI and IPDI by HPLC and GC are successfully established. The methods can meet the demand of detection of isocyanate compounds. Meanwhile, sampling efficiency has been increased by optimizing and improving the sampling methods. Our data strong support that the established isocyanate compounds determination methods can provide the technical support for further establishing the national level of the sampling or determination methods.