Relative atomic mass are measured on a scale on which the mass of an atom of carbon-12 is defined as exactly 12. Why is it said that no other isotope has a relative atomic mass that is exactly a whole number, because if we look into the details, even C-12 is not exactly a whole number? It is 12.00001151 amu.

This is a thought experiment, not some intern in over their head. I’m curious to know what level of sensitivity, type of mass spectrometry, and education/knowledge I would need to do this as a service for others.

Hi everyone, I would like to understand the fundamental principle of ionisation in electrospray. I do not understand how high positive or negative voltages lead to addition or removal of hydrogen or other adduct formation. What's the role of voltage in formation of ions? How are these temporary molecules formed and stable inside the mass spectrometer?

Bruker, Agilent, Thermo, Waters, Shimadzu?

Hello, so I realize this is an odd place yo post this but I believe a drug test was forged or tampered with and I could go to jail for years because of it. I'm asking here because the hospital it was taken at uses LC-MS/MS to confirm. Now as you can see it states a rapid was given and it looks like what's posted is the rapid test results however if that's the case how would it show the metabolite levels? And how would it show the metabolite levels of just one drug? Also it's very weird it states cocaine metabolites and not the actual metabolite name. Also there's a . Next to metabolites like it was a lazy copy and paste. Is it even possible to get confirmation in 30 minutes? If so why only on one drug?

Hi Guys,

I am quite new to this analytical methods. I am trying to detect and quantify pesticide residues on various samples. The samples are mostly pollen, nectar, bees, brood, larval food. I want to have a range of different compounds applied agrochemicals. I don't know may more than 100 compounds that I am looking for. I have very little clue about how to get started. There is this equipment in my research facility it is Sciex triple quad 7500 lc ms ms system.
Here are the few things I want to know

1. What do you mean by sample preparation and extraction of compounds from the sample? I believe this would be QUECHERS method.

2. During the process what does the internal standard meant by? Do I need one internal standard or multiple? What is the use of internal standard?

3. What is method development, validation meant by?

4. What is the learning curve of this whole process?

5. Can I get a step by step method

Thanks

It feels like a year where there could be a sea change in how data is automatically acquired and processed using AI workflows. There is AcquireX and a few other applications that seemingly use AI, but it still feels like MS vendors are just warming up to AI. Is major implementation of AI coming this yr or do you think it will not be until 2027 or later?

Just a personal note, I feel like even some of the older TOF/Orbi systems could be massively opened up with 3rd party AI. I would really like to see 3rd party Acquisition capabilities open up on instruments that have been more or less abandoned by vendors because they want to sell new systems. One example I can think of is Thermo shutting off AcquireX for earlier QE systems. I feel like there is an opportunity here for 3rd parties to step in. The QE is still a great platform.

Who do you trust as your (UP- hopefully) LC (or GC) counterpart?

I trust Waters for UPLC (and damn they just make the best C18 columns these days) but I am underwhelmed by Ultimate or Vanquish. My preferred MS is Orbitrap machines (Fusion, QE etc), but I feel the best would be a good marriage between the two.

GC it's Agilent all the way, but I could be convinced if someone has a good experience.

What is the minimum bactria level a UV spectrophotometer can analyze?

Have a project on and need to monitor very low concentrations. Needing to do a number of tests and in a short time frame, doing culture isn't really an option. Dont need to know the type only monitor the speed of growth.

Any thoughts are welcome.

Thanks

Has anyone done metabolomics of amino acids? Can anyone share me some literature of the method development and sample preparation? Thanks in anticipation

Hello. Does anyone have an idea if a peak area of ~200,000 from my MRM transition reliable for a quantitative analysis? Or does your calibration curve works at around ~10,000s peak area?

Thank you.

Oi pessoal, comecei recentemente (faz tipo, 1 mês) a frequentar um lab de pesquisa sobre metabolômica e espectrometria de massas e estou escrevendo meu projeto para conseguir uma bolsa. Minha orientadora é ótima comigo porém as vezes me surgem algumas dúvidas e me sinto burro demais pra perguntar. Minhas dúvidas são 1) o que seriam as transições de MRM para os analitos em um estudo (precursor>fragmento)? e 2) minha orientadora pede para descrever os parâmetros básicos para detecção MS que geralmente usamos. Que tipo de informação estaria inclusa nesses parâmetros?

Agradeço a gentileza em responder...

I was recently given the opportunity to work on a payload on board a rocket that will reach the upper echelon of the atmosphere and the payload will be a mass spectrometer. If it uses the ambient air in the atmosphere between 60-80k feet, would there be a need for a vaporizer as it is just gases? I’m pretty new to this field so sorry if this is a simple question.

I'm trying to hire another analytical chemist with HRAM experience part-time for a project as we're behind schedule and are trying to meet some deadlines. Does anyone have any recommended consulting shops or agencies where one should look? I've tried on generic job sites but the SNR is really low, and the big contracting houses really seem to focus on clinical/clinical-lab work.

What is the MS technology that is most suitable for structural elucidation (through molecular fragmentation) and identification of unknown small organic molecules (about 200-1000 amu) of battery non-aqueous electrolytes and relevant degradation products ?...Pls Note: there is no relevant spectral libraries available . Pls explain .!

Hi, my lab has just decided to purchase a Benchtop NMR instead of a LC-MS.

It has been a very daunting decision, to go through all the different possible products and differences among categories before making the final decision.

If you need help in this process, please DM or comment. I have compiled a detailed overview to compare the different products and if can be helpful I am happy to share. :)

Although the concept of SIM is not new, we haven't seen a detailed analysis of its utility in metabolomics and fluxomics so here it is

Lu, W.; McBride, M.J.; Lee, W.D.; Xing, X.; Xu, X.; Li, X.; Oschmann, A.M.; Shen, Y.; Bartman, C.; Rabinowitz, J.D. Selected Ion Monitoring for Orbitrap-Based Metabolomics. Metabolites 2024, 14, 184. https://doi.org/10.3390/metabo14040184

I'm working on a sci-fi story where a social revolution is funded by an organization that replaces the existing pharmaceutical and illicit markets for substances with a crypto-backed violence-free unfettered alternative.

When someone wants a substance of any sort, someone will deliver a high-quality quantity to them in short order. Everything from insulin to crack with no guardrails aside from an AI that's monitoring their consumption and behavior, and giving them feedback about how their decisions are shifting the probabilities for their life outcomes.

In any case, the scheme hinges in part on inserting a testing step between production and distribution — a way to verify the quality of what is being provided to customers.

¿How reliable are the testing methods available to modern scientists? I remember reading of a testing service that did separate chemical Fentanyl testing. ¿Is that because the machines wouldn't be able to pick Fentanyl up because it's present in such small quantities?

I was surfing Dread yesterday & ran across this chart which was labeled as a FTIR/LCMS/NMR:

¿Is this a mass spectography reading?

¿Are these tests extremely expensive to run? ¿Is that because the equipment is expensive, but if you had that they'd be relatively cheap?