- by /u/Designer-Profit8333Hello! I'm wondering if the formation of white deposits on the ESI nozzle a normal phenomenon? I don't use any buffers though… I use ultrapure water and so far the samples analyzed are organic extracts of either plant or MRS broth… SPE is not done prior to analysis since we don't yet have SPE cartridges in our lab… Also, I'm currently having trouble with the autotuning of our equipment… Is this one of the possible causes? Thus, I can't proceed with my analysis .. submitted by /u/Designer-Profit8333 [link] [comments]
- by /u/Ojayy33Hey everyone, I’m looking for some guidance before I go down the peptide route. I’d rather ask people who have experience instead of just jumping into something blindly. For context, I’m in my mid-20s, pretty active, and I train consistently. I lift regularly and stay fairly active day to day. My goal isn’t anything crazy — I’m mainly trying to lean out a bit for summer while keeping muscle and maybe help recovery since I still deal with some shoulder issues from surgery. Diet isn’t terrible. I eat a lot of chicken and tortillas, and I stay active. I run […]
- by /u/foolish_athenaI have a really badly clogged HESI source needle from the source not being rinsed after repeated use. Solvent can get through it, but it takes a lot more force than it should and turning the flow rate up too high just forces solvent to leak out of junctions/the syringe instead. Typically, I've been able to save the needle with sonication in water, then methanol:water, then methanol, 30 min each. Sonicating the thing overnight isn't saving it. Is there anything else I can try before I give up and bin this needle? submitted by /u/foolish_athena [link] [comments]
- by /u/jeromepainHi friends! Yesterday one of the rough pumps on my quantum ultra died and the instrument vented. After replacing the pump the fore pump pressure goes down to submitted by
- by /u/icondaI’m looking at Merck (Millex PTFE 0.2 um) and Agilent (Captiva PES 0.2 um) and even with uni pricing, it’s £200 for a 100 pack. That’s £2 per injection just for the syringe filter. I see "standard" HPLC ones for 10x cheaper. Am I just paying a massive "MS tax" for the certificate, or do the "only HPLC" ones actually bleed and ruin the signal + the instrument (HRMS)? I'm dealing with sometimes very dirty mostly food samples. submitted by /u/iconda [link] [comments]
- by /u/PlasticFern971I have been using LC-QTOF for the past year to analyze leached plastic additives, but I am getting annoyed with the kind of meh fragmentation I am getting. So I am switching to GCMS and EI. With the instruments we have, I know the GC has much lower limits of detection than the LC QTOF I have been using, but so far, it doesn't seem like that at all. I have tried 5 different methods with published success, but haven't been able to resolve a standard mix of 6 phthalates at lower than 100ug/mL, and even though I am getting […]
- by /u/Miserable_Win3414Hello, 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 […]
- by /u/SrongHandsubmitted by /u/SrongHand [link] [comments]
- by /u/nintendochemist1I’m curious how you all would handle this. We are a university lab and I am the manager of the instruments. Our LC-MS is my baby (I rebuilt it). We have one research group whose focus, not to be rude, I consider setting themselves up for failure with mass spec. They are trying to eliminate the need of organic solvents. The love their ammonium bicarbonate buffer, and every time I come check the system after they use it, it looks like the attached image. Now, I cannot get hardly any whereas I was using it minutes before their calendar time […]
- by /u/fifedawg11https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2022.995590/full Does anyone have experience with protocols which reliably enrich C-terminal peptides from mammalian cell proteomes?. This is the most recent paper I could find in the topic which used HEK293T cells as a model, which is the cell line I am going to be working with, but I haven't seen this paper cited by any other research groups. Just curious if anyone on this sub has tried this method, or others similar to it, and have any recommendations, warnings, or tweaks to established protocols. Thanks for your help! submitted by /u/fifedawg11 [link] [comments]
- by /u/Adept_Extent6117Does anyone know the IDL of Sciex 7500+? I am trying to choose between this and the Xevo TQ Absolute XR. Any parameters that are different between the two? submitted by /u/Adept_Extent6117 [link] [comments]
- by /u/csenye22Hey everyone! A little while ago, I shared the first version of Chromascope, a fast and lightweight open-source GUI for inspecting mzML mass spectrometry data. The feedback was really helpful, so I kept building it and I’m excited to announce the release of v0.2! What's new: Multi-file support — open and compare multiple mzML files Peak integration — integrate peaks directly from the chromatogram view Advanced filtering — filter by MS level (MS1/MS2), polarity, precursor m/z, and m/z ranges Much better performance — files now load in a background thread so the UI stays responsive, and XIC extraction is parallelized […]
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