- by /u/LeonbimI am facing this issue where the TSQ vantage exhibits lower sensitivity than the TSQ ultra which is a previous gen model. At full scan Tyrosine standard is 10 times more sensitive on both Q1 and Q3 for the vantage than the ultra. When running standard through the HPLC the sensitivity is much less on the Vantage. At least 10 times lower. Any ideas on how to troubleshoot this. All Q2 relevant diagnostics and MS/MS diagnostics pass on the system evaluation etc. submitted by /u/Leonbim [link] [comments]
- by /u/Training-Resist-2745Dear community, Iāve been running a QE Orbitrap for several months now, and I still have some practical questions where Iād appreciate your advice: Background check: When doing ddMSĀ² runs for unknown identification, we aim for a low background. Is there a standard way (metric or tool) to evaluate whether background levels are acceptable, and to compare them day-to-day? Blank injections: We see some clear peaks in the TIC from blank runs. If a peak elutes as a chromatographic feature, does that necessarily mean it originates before the column (e.g., LC system/solvents), rather than from the source or MS? Are […]
- by /u/Purplegreen2019I am moving a method from an old Agilent QQQ to our new Xevo TQ ABs, but Waters software seems to be much more time demanding when developing methods, what would be the easiest way to create the quantitative targetlynx method for 200 or more pesticides? submitted by /u/Purplegreen2019 [link] [comments]
- by /u/UF_Chemistsubmitted by /u/UF_Chemist [link] [comments]
- by /u/Financial_Sand_8903Oi pessoal, comecei recentemente (faz tipo, 1 mĆŖs) a frequentar um lab de pesquisa sobre metabolĆ“mica e espectrometria de massas e estou escrevendo meu projeto para conseguir uma bolsa. Minha orientadora Ć© Ć³tima comigo porĆ©m as vezes me surgem algumas dĆŗvidas e me sinto burro demais pra perguntar. Minhas dĆŗvidas sĆ£o 1) o que seriam as transiƧƵes de MRM para os analitos em um estudo (precursor>fragmento)? e 2) minha orientadora pede para descrever os parĆ¢metros bĆ”sicos para detecĆ§Ć£o MS que geralmente usamos. Que tipo de informaĆ§Ć£o estaria inclusa nesses parĆ¢metros? AgradeƧo a gentileza em responder… submitted by /u/Financial_Sand_8903 [link] [comments]
- by /u/sweetmoonpie29Hi! Iām using a waters cyclic for HDX-MS at the moment. My HDMSonly runs are recorded for 10 minutes and 300-1200 m/z to capture the deuterated peptides, but yet the files are 3GB in size! I tried increasing the scan time from 0.3 s to 1 s, but this only reduced the file size to 2 GB. Iāve tried MSConvert to convert to mzml but it makes it unusable in PMI Byos software (I also asked their support team and they said it wonāt work for the deuterium quant part). Iāve also tried the Waters compression and noise reduction tool […]
- by /u/1lemonsliceThe high flow HESI probe has an issue. When placed into the housing, Tune software doesnāt recognise it and says āSource is openā. We have tried disassembling the probe, cleaning and reassembling it in case something was loose. The low flow probe doesnāt have this problem. Does anyone have any experience/idea what could be the reason and how to fix it? Could it be a simple part change or will we have to buy a brand new probe? (Latter seems more likely but wanted to see if something can be done before we order a new one) Update: thank you […]
- by /u/HGHS563Iām facing a problem with our GCMS shimadzu Pesticide residues calibration doesnāt last more than a three days we inject 15 samples/day we I inject QC itās out of the range even though itās within the range the day before We clean the ion source, replace septum, liner, column, matrix is free of pesticide, standard are new submitted by /u/HGHS563 [link] [comments]
- by /u/petrhap11Mathias Mann- for proteomics Zoltan takats- for Iknife more clinical applications Griffin- big untargeted studies Dorrestein- identifying uknown metabolites Fiehn- GC Suizdak- massive library submitted by /u/petrhap11 [link] [comments]
- by /u/YiningChuHi guys, I am doing mass spec with SQD2 with UPLC and would like to ask a few questions about the report. My compound(intended has a molecular mass of 464.65) In the first plot (MS ES+ extracted ion chromatogram), does the series of peaks represent the relative intensities of signals at different retention times, rather than proportions of compounds before smoothing? https://preview.redd.it/zq5id2qkgdlf1.png?width=2072&format=png&auto=webp&s=1d20fb3a4e15c328ba00e91626867f2381b3e190 In the second plot (MS ES+ TIC), the software has only integrated one peak (peak 31 at 1.14 min) and assigned it 100% of the area. Does this mean that my integration settings only recognized one peak, rather […]
- by /u/ajbzrsolĆ” a todos, alguĆ©m conhece alguns parĆ¢metros para limpeza da fonte APCI e HESI? Ficarei grato. submitted by /u/ajbzrs [link] [comments]
- by /u/Aggravating_Dream778Hi everyone, Iām a Masterās student currently working with a Thermo LTQ XL. Iāve been running UVPD experiments and expected to see Naāŗ at m/z 23 in my spectra. However, when I switch to PQD mode, I canāt seem to detect this signal ā neither when using UV irradiation nor when relying only on collisional activation. I also canāt use the standard CID mode here, since in that case the low-mass cutoff shifts to m/z 35, which excludes the ions Iām trying to look at. Has anyone here encountered similar issues with detecting very low-mass ions in PQD mode? Is […]
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