|Analysis Point||Analyte||Typ. Range||Suitable Analyzer|
|Polymerization Inhibitors||TBC||0-200 ppm||OMA Process Analyzer|
TBC is usually added as a polymerization inhibitor to monomers like butadiene and styrene. The concentration of TBC in the monomer needs to be regulated at approximately 100 ppm to avoid spontaneous polymerization as well as waste.
TBC has a distinct UV absorbance curve which allows the OMA system to easily monitor its real-time concentration. The full-spectrum analysis is critical for differentiating TBC absorbance from other absorbing impurities like toluene.
Since pure liquid butadeine is very difficult to prepare for system blanking purposes (i.e. at normal temperatures and pressures), pure isopropanol is used to zero the instrument. The full-spectrum analysis allows for normalization of the discrepancy between the butadeine spectrum and the isopropanol spectrum.
The OMA continuously outputs the TBC reading to the plant's main computer, providing a new measurement in 1 to 5 seconds — much faster than the traditional HPLC used for this application (15 minute interval). Response time is critical in order to respond quickly to sudden changes in TBC concentration.