I have some samples in 100% aqueous form and some in 0.05% acetic acid solution. I want to avoid any pre-sample preparation procedure and directly inject into LC/MSMS. Is it possible? Kindly attach some reference if possible as well. Thank you in advance.
Yes you can. The solvents used must be volatile and the tiny volume found within an injection cycle will present no problem at all. *To minimize extra signals, please make sure and use the freshest and highest purity acetic acid available as the MS will easily pick up many of the impurities found in it.
The short answer is Yes. Whether or not it is a good idea however is another question which depends a lot on what all else is in those aqueous samples besides water. If the samples are relatively clean to begin you should be fine. If the samples are very dirty however or have a high salt content or other contaminants at high levels then you could potentially plug up your column and contaminate your system after a few injections. It is important to know as much about the samples as possible ahead of time.
as with the others: yes you can. this is actually very easy. However, depending on you matrix and analytes you may have troubles with solubility in the water (very apolar compounds will show to stick to the glass of the vials) of matrix effect during ionisation as you avoid the cleanup. And thomas is correct: if you have a high salt concentration in the water: best to have a switch between the LC and the MS so the first eluens is going to wast, avoiding the salts to enter the MS.
By the way: even with GCMS it is possible to inject water. Only not so commen and it has some other disadvantages.
May I ask what your samples are and what are the goals of your analysis?
Respected Sir Schmitt
I have cyclodextrin linked biocomposite in aqueous form. I was thinking to check the thermal stability/daughter fragments of this complex.
Short answer is yes! As long as non-volatile salt content is low, because this can foul up your source. What is your injection volume?
There is no problem injecting water based samples into an LC-MS/MS system. Just do not overload the system (samples of 100 ug/ml are concentrated enough for most systems for tuning and optimisation of conditions).
You do not mention whether you are performing chromatography or direct infusion. If infusing you need some volatile buffer to aid in the ionisation process and for positive ionisation added formic or acetic acid would increase the sensitivity. For negative ionisation an ammonium formate or ammonium acetate buffer of a neutral to slightly alkaline pH would benefit the ionisation.
If performing reverse phas chromatography the same additives in the mobile phases would be required for the ionisation. These buffers are volatile so as not to accumulate in the mass spectrometer.
Yes you can directly inject it to MS/MS, no need to have even any reference for the same.
- Badges
- Science topic
- Similar topics
- Engineering
- Control Theory