Visit a chemical laboratory

1-2) HI and welcome to the LABORATORY for chemical chemistry. In this LAB we exploit all most advanced chromatography instruments coupled to mass spectrometry techniques. Our main job is to obtain precise and quantitative data on the chemicals present in food, drinks or any other material.

Usually each LAB is organized in two zones: the preparative room, used to set up the samples,…… and instruments room. SOME instrument, for proper working, do require a stable room temperature and controlled humidity, but since they heat a lot they need efficent climatisation. 4) the LAB is equipped with the state-of-the-art analytical instruments for every need. For example this Orbitrap Fusion is capable of super high resolution … that means it is capable to separate chemicals whose mass-to-charge ratio differs only of 0.00001 In case of trace and ultra-trace analysis, the best choice is an instrument called….”

the triple quadrupole mass spectrometer”, a complicated name for a complicated machine, which is capable of the highest sensitivity Cambio audio 2 the vast majority of samples is not compatible with the analysis in their native shape. So here we see Judy preparing the samples following a specific protocol, just like following a food recepy, In this case she is performing a liquid solubilization of a curcumin extract using ethanol. The bright yellow solution is however too concentrated for such high-sensitivity instruments. Thus the sample needs to be diluted to the optimal range.

Once the sample is ready, a calibration line with growing chemical concentration is also prepared Each vial containing the sample is inserted in the autosampler, a tool that is programmed to inject in the system a minimal volume, that is about 2 microliters Once the parameters are set up, we are ready to go. We push START and the autosampler will rotate to the selected vial and do the injection Cambio Audio 3 4) the sample is now flowing inside the separation system that you see here, in reality is a very expensive metal tube …that we call column. The column is where the separation actually happens.

The components of the sample are separated based on their affinity with the content of the column, that we name stationary phase. Molecules with more affinity need more time to exit, whereas the others flow faster and exit earlier. 1) Once a molecule has flown through the column, it arrives to the detection system at the end of the column, which is coupled to a new tool for the ionization of the chemical. A little complicated.. 2) But at the end of the process we obtain a plot …called chromatogram …which shows the generated ions versus their exit time; each ion represents a molecule and each peak is a population of ions with same properties, that means the same chemical.

3) Judy now can explore the results by clicking on each point of the chromatogram and note the mass-to-charge ratio of the ions in the peaks. 4) The Value that Judy uses for quantification is the peak area, which is then inserted in the calibration line to obtain a number which is then finally corrected for the dilution factor But what is the Calibration Line ? There is a bit of mathematics here… As you see briefly, the areas of the peaks are used to draw a diagram which reports on the x the standard’s concentration and, on the y the area value. Finally the sample concentration is calculated based on the interval.

Good, now you have seen how the chemical analyses are done in the Laboratory.