Series 5 - Research Insights

5# The findings

After a month of research, I successfully obtained the ideal method set-up for separating eight amines and the Active Pharmaceutical Ingredient (Ibuprofen) compound. All mass spectrum I obtained has more than a 50% probability of similarity with the standard, according to the National Institute of Standards and Technology (NIST) Library software.

Figure 1. Peak Chromatogram of Dibutylamine (generated with Thermo Xcalibur™ 2.2 SP1.48)

Figure 2. Mass Spectrum of Dibutylamine (generated with Thermo Xcalibur™ 2.2 SP1.48)

Figure 3. NIST Mass Spectrum Search 2.0 Library Similarity Result for Dibutylamine

Even though I still have a long way to run, the progress I have achieved so far may allow me to deliver some insights and findings:

1) Difference in boiling point is the key to enhancing the separation. After identifying each analyte's boiling point, we will be able to optimise the oven temperature appropriately.

Figure 4. Oven Temperature Set-up in Thermo Xcalibur Gas Chromatography Instrument

As shown in the above picture, I started my method setting with a very low temperature (35°C) to accommodate better separation in my mixture sample.

2) The inlet temperature is critical and must be set according to the analyte’s highest boiling point to ensure all the analytes evaporate and turn into gas phases. Diethanolamine has the highest boiling point (268.8°C); therefore, I set my inlet temperature to 270°C.

Figure 5. Split/Splitless Set-Up in Thermo Xcalibur Gas Chromatography Instrument

3) Knowing the compound's structure, formula, exact mass, molecular weight, and m/z is an excellent way to start! This information will help us set the mass range scans (in amu units) when using the Mass Spectrometry detector.

Figure 6. ISQ General Acquisition Method Setup in Thermo Xcalibur Gas Chromatography Instrument

Future Study

Another consideration is that amines in drug products are likely to be in low concentrations. Due to the heavy matrix of drug samples, extraction or sample clean-up methods must be applied to reduce matrix interferences, which I’ll do very soon!