“Ta ~ No Worries”
檢測地溝油、大家唔洗愁
In collaboration with Prof. Yao Zhongping’s research group, on 28 Sep 2017, Year 2 students taking TECE1905 had joined the workshop facilitated by Dr. So Pui Kin from Mass Spectrometry Analysis Service of Hong Kong Polytechnic University.
Students listened to the instructions.
Students did the sample preparation and got hands-on experience in Direct Analysis by Electrospray Ionisation Mass Spectrometry (ESI-MS).
Students carefully prepared the Chinese herbal samples.
A costly Mass Spectrometer
The herbal samples for MS analysis
Neither hazardous solvent liquid-liquid extraction nor heating/digestion were carried out for selected herbal samples like Tianma （天麻）, Hunaglian （黃連）and Wuweizi （五味子）. No time-consuming chromatographic separation was required in order to get the ESI-MS test results.
Students only applied methanol at microliter scale onto the freshly cut samples and waited for few seconds before the mass spectra were shown onscreen.
The student was applying the test sample onto the sample inlet of MS.
Mass spectra were obtained.
They employed the very simple procedures but used very sophisticated instruments ESI-MS to analyse herbal samples. Based on the fragmentation patterns shown in individual mass spectra, students were able to differentiate the three herbs and to tell the origins of the herbs.
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On 1 Nov 2018, that was the second time for our year 2 testing and certification (TECE) students to try using the high-end analytical instruments. They learned some elementary knowledge in Matrix assisted laser desorption/ionisation - time of flight mass spectrometry (MALDI-TOF MS) from the lecture. With the facilitation of Dr. So from PolyU, we got a valuable opportunity in operating the analytical instrument (MALDI-TOF MS).
Dr So instructed the students to prepare the test samples.
TECE students spotted the test samples on the stainless steel plate.
One of TECE students was preparing the standard solutions and matrix.
This technique involves application of different organic matrix onto a steel board, followed by accurately spotting pure oils and gutter oil.
Test results were obtained from MALDI-TOP-MS
Students are able to interpret the test results and to differentiate edible oils from gutter oils.
Students learned how to find out those signals of triglycerides as found in common oil samples. Different oils give their own characteristics patterns of mass spectral peaks. Based on the experimental results, students are able to interpret and subsequently they can differentiate edible oils from gutter oil (地溝油) which is unhealthy.
This is really an experiential learning experience for the students.