GCMS newbie and the questions to be solved...
Posted: Fri Feb 04, 2011 7:04 pm
Hi All,
I just start my career in chemistry field 3 months ago. I'm assigned by lab manager to incharge for the GC-MS instrument. Our lab have other instruments like FTIR, LPC, SEM, HPA and also IC. After 1 month been working there, i realized that it's quite difficult to handle the GC-MS instrument. It's because the GC-MS is quite sensitive, extra care is need either in samples preparation or instrument handling. For example, before run the samples, we have to auto tune / standard spectra tune the instrument, if air leak is detected, some services is needed (tighten/loosen the nut that connect column from GC to MS). After that, normally we will get a nice tune report.
Below i stated some questions.
1. Why each time after a sequence finished run, after heat the column for 2 hours (at ~300 Celsius), the standard spectra tune generated will showing the air leak problem ? (my lab manager didn't let me know the reason, he just said air leak will affect the sensitivity and help me to fixed it.)
(Company just bought that latest GC-MS from US, compared with another one old GC-MS, the design of autosampler is abit different).
2. Why the emVolt will increase ? I still remember that we started to use at the end of december, the emVolt at that time is 990, and now after 1 month the instrument being used, the emVolt raise to 1130. My lab manager told me that emVolt if higher than 2500, the instrument can consider as useless, he is not telling me the reason behind it. From my knowledge, i knew that adjusting the emVolt can make fake sensitivity. The height of spectrum for the compound detected can be adjusted if we increase the value of emVolt (but the height of noise actually is increased actually).
3. Basically, the results generated by the library can be trusted 100 % ? For example, compound Hydrocarbon C40 that having longer retention time will showing the peak at minutes 39 (based on the proper GC-MS parameters setting), when i manually analyze the peak, it's showing others compound. Why ? The concentration for C40 standard is quite high also (100 ppm).
4. Any advise from those who are experiences in chemistry/biology field ? I'm considered as newbie to handle GC-MS instrument since my job's tasks mainly on results interpretation. I have to gain more knowledge for better future.
Sorry for my English. I'm a Chinese from Malaysia. Hope i can improve myself through this forum
I just start my career in chemistry field 3 months ago. I'm assigned by lab manager to incharge for the GC-MS instrument. Our lab have other instruments like FTIR, LPC, SEM, HPA and also IC. After 1 month been working there, i realized that it's quite difficult to handle the GC-MS instrument. It's because the GC-MS is quite sensitive, extra care is need either in samples preparation or instrument handling. For example, before run the samples, we have to auto tune / standard spectra tune the instrument, if air leak is detected, some services is needed (tighten/loosen the nut that connect column from GC to MS). After that, normally we will get a nice tune report.
Below i stated some questions.1. Why each time after a sequence finished run, after heat the column for 2 hours (at ~300 Celsius), the standard spectra tune generated will showing the air leak problem ? (my lab manager didn't let me know the reason, he just said air leak will affect the sensitivity and help me to fixed it.)
(Company just bought that latest GC-MS from US, compared with another one old GC-MS, the design of autosampler is abit different).2. Why the emVolt will increase ? I still remember that we started to use at the end of december, the emVolt at that time is 990, and now after 1 month the instrument being used, the emVolt raise to 1130. My lab manager told me that emVolt if higher than 2500, the instrument can consider as useless, he is not telling me the reason behind it. From my knowledge, i knew that adjusting the emVolt can make fake sensitivity. The height of spectrum for the compound detected can be adjusted if we increase the value of emVolt (but the height of noise actually is increased actually).
3. Basically, the results generated by the library can be trusted 100 % ? For example, compound Hydrocarbon C40 that having longer retention time will showing the peak at minutes 39 (based on the proper GC-MS parameters setting), when i manually analyze the peak, it's showing others compound. Why ? The concentration for C40 standard is quite high also (100 ppm).
4. Any advise from those who are experiences in chemistry/biology field ? I'm considered as newbie to handle GC-MS instrument since my job's tasks mainly on results interpretation. I have to gain more knowledge for better future.
Sorry for my English. I'm a Chinese from Malaysia. Hope i can improve myself through this forum