- by /u/SenC1990Hi everyone, I need some help and maybe someone can give me a simple introduction to the following problem. For a university assignment I have to develop a method to identify different mint species and mixtures. I made a list of five Mentha species with their main essential‑oil components, and I also created a plan with the molecular weights where I expect peaks. The system I’m using is: Soft ionization with a Plasma Ion source (for essential oils / volatiles) Quadrupole Orbitrap for the final high‑resolution data I converted the .raw files to mzML Loaded everything into MZmine Now I […]
- by /u/orangepotatocatgeekOur UV detector is often acting up. For our method we don't really need it, since we go directly to the MS. However, the LC sequence doesn't run if the detector is offline, disconnected, or in an error status. Is it possible to bypass it? Maybe there is an option in the software that I don't know…. The software is EZChrom Elite v3.3 SP2. submitted by /u/orangepotatocatgeek [link] [comments]
- by /u/WucaleHey everyone, I’m running an LC–MS setup with a Q Exactive HF, and recently I’ve been seeing a significant increase in what looks like “noise,” especially when the proportion of eluent B is high. The pattern is present even during direct infusion of the eluents, so it doesn’t seem to be caused by the LC or the column. I already cleaned the MS front end (source housing, spray cone, ion transfer tube, S-lens), but that didn’t improve the situation. The “noise” isn’t random — it appears as clusters across the entire m/z range. The main clusters are separated by roughly […]
- by /u/TheProudCanadiansubmitted by /u/TheProudCanadian [link] [comments]
- by /u/Expensive-Painter-18Planning to establish a POC for aptamer/oligo analysis by ESI MS (Waters Xevo). Went through literature but most of it involves using ion pairing agents which we wish to avoid. Has any1 tried ammonium acetate based methods and hows the s/n ratio? Also, how challenging is the analysis? Please comment. Thanks MD submitted by /u/Expensive-Painter-18 [link] [comments]
- by /u/CantholditdownI am considering combining a Shimadzu with a Exploris 240 (mostly drug applications) using Xcalibur. Does anyone have experience using Shimadzu with Chromeleon to integrate the LC stack? I had a terrible experience with Chromeleon using PAL, but that was a very long time ago. It was a horrible combination. I am hoping that perhaps Shimadzu integrates better. submitted by /u/Cantholditdown [link] [comments]
- by /u/Turbulent-Mouse-4899Hello All, Does anyone have experience with using zHILIC columns for polar metabolomics? When attempting to follow several methods published online (that show great peak shape for these analytes), they seem to result in sub-optimal peak shape for two specific acids… Malate & Fumarate give poor peak shapes under almost all conditions I have tried so far. Below is an image of the peak shape & I have no idea what is going wrong / what to try to fix this issue. My mobile phase A is H2O + 20 mM Ammonium Acetate at pH 9.1, w/5 uM Medronic Acid […]
- by /u/Training_Pangolin177submitted by /u/Training_Pangolin177 [link] [comments]
- by /u/Responsible-Bat9984Hello Community, I got a Question regarding Masshunter Unknown Analysis. When I analyze a sample most peaks in the TIC show up as very "spiky"and some don´t. Does anybody know what could be the reason for this and how I could get rid of it? https://preview.redd.it/q3hd0oyzfawg1.png?width=975&format=png&auto=webp&s=d9326a69c783dae041b52675c73b9fd9fecd2054 Thank you! submitted by /u/Responsible-Bat9984 [link] [comments]
- by /u/Next_Coconut2027Shimadzu ICP-MS 2030 Autosampler Teledyne Glass expansion: Neb, humidifier, Trident Recent maintenance: New: Detector, neb, all sample introduction tubing. Cleaned: Cone and skimmer, torch, L pipe Run conditions: Quantification of As, Hg, Pb, Cd, solution is 5% nitric acid with L-Cysteine for stabilizing Hg. Samples done with microwave digestion then diluted to the 5% nitric. Internal standards: Bi, In, Sc Problem: Over the course of the run internal standards start failing. They are already smaller than normal Bi and In normally run around 200 and Sc is about 1000. They are currently running around 50 for Bi and In with […]
- by /u/Born_Finding_6872submitted by /u/Born_Finding_6872 [link] [comments]
- by /u/Born_Finding_6872Hello everyone, I would like to discuss something related to untargeted metabolomics(UTM) . I have not read in detail about this topic so i would like your opinion on this. I have heard that the annotation of metabolites based on their retention time and peak alignment could be merely prediction, there are chances that the metabolite annotated could be some other metabolite in reality. So, in that case, how do i validate my UTM results? Targeted metabolomics is mostly what people use for validating, but what about some other techniques? like how proteomics results could be validated by western blots. […]
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