Determining the Level of Toxic Amines in Recycled Foams

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Cold-cure and flexible foams used for the manufacture of mattresses are made of polyurethane synthetics. Various intermediate products are formed during the synthesis of urethanes, which are the basis for polyurethanes.

TDA and DAPM are two of the products formed in the process, and these are classified as carcinogenic. Moreover, TDA is considered to be mutagenic and teratogenic. During the recycling of cold-cured and flexible foams, the concentration of these compounds needs to be determined prior to reusing the foams. Referring to OEKO-TEX® Standard 100, a limit value of 20 mg/kg for aryl amines is appointed [1].

Results

A calibration was made for the quantification. Hence, a mixed standard of TDA and DAPM at five different concentrations was used. A correlation coefficient of R2 = 0.999 was realized for both components.

One exemplary sample of flexible foam was chosen and spiked with standard to a concentration of 0.1 mg/mL. Sample measurement is shown in Figure 1, and an overlay of the sample (red) and spiked sample (blue) of flexible foam is shown in Figure 2. The limit of detection (LOD) was determined with 0.67 µg/mL for DAPM and 0.63 µg/mL for TDA.

Sample of flexible foam

Figure 1. Sample of flexible foam (18 mg/mL).

Overlay of sample of flexible foam

Figure 2. Overlay of sample (red) and spiked sample (blue) of flexible foam.

Materials and Method

For this application, an AZURA Analytical HPLC Plus system for a pressure range up to 700 bar was used. It included an autosampler 3950, an AZURA P 6.1L LPG pump, an AZURA MWD 2.1L multiwavelength detector, and an AZURA CT 2.1 column thermostat.

The analytical method was run with a step gradient at a flow rate of 1.0 mL/minute. The mobile phase was a mixture of acetonitrile and water, both with 0.1% triethylamine as mobile phase modifier. After setting the column thermostat to 25 °C, the detector was recorded at 290 nm. The column that was used was filled with ProntoSIL 120-3 C8 ace EPS silica.

Conclusion

Through the developed method and the AZURA HPLC Plus system, a rapid quantitative analysis of 2,4-diaminotoluene and 4,4-diaminodiphenylmethane was performed without any prolonged sample preparation.

With the specified method parameters, even a complex matrix such as the recycled cold-cured and flexible foams can be established to be robust and reproducible.

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References

[1] https://www.oeko-tex.com/de/business/certifications_and_services/ots_100/ots_100_limit_values/ots_100_limit_values.html

KNAUER

This information has been sourced, reviewed and adapted from materials provided by KNAUER Wissenschaftliche Geräte GmbH.

For more information on this source, please visit KNAUER Wissenschaftliche Geräte GmbH.

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