Residual monomer quantification

Polymer products or materials often contain unreacted monomers left over from synthesis. These residual monomers can be toxic, influence the mechanical/rheological properties of the material, or contribute to unwanted odors or tastes. To prevent these effects, their concentration must be carefully monitored. 

The analysis technique used for quantifying residual monomers greatly depends on the sample type. GC-FID, GC-MS, HPLC, and NMR are all techniques commonly used to determine the amount of residual monomers in polymer materials or solutions. 

It is important to know exactly what monomers are used in the synthesis so that the measurement is properly calibrated and the specific molecules can be quantified. In some cases, it may be necessary to provide a pure sample of the monomers along with the finished material.

Depending on the sample matrix and the monomers, our experts will choose the most appropriate analysis technique. Below are some considerations. 

• Gas chromatography (GC) methods require an extraction step to isolate the monomers from the polymer matrix. In cases of complex matrices, this preparation may result in the dilution of the sample and a corresponding increase in the limit of quantification (LoQ). 

• High-performance liquid chromatography (HPLC) methods can be used for materials containing non-volatile monomers or monomers with high molecular weights. 

• Nuclear magnetic resonance (NMR) spectroscopy allows for the quantification of monomers directly from a solution sample without the need for extraction. NMR is not as sensitive as GC methods, but can be used to monitor reaction kinetics or to provide additional information about the structure.

Viable matrices include solid polymers, aqueous/organic solutions, and dispersions. Other matrices may be accepted. Please contact our experts to receive a quotation tailored to your analysis needs.