- by /u/Additional_Put_3088I am trying to optimize a method for analyzing methylated purines from DNA. I ran a method back in June and peaks looked beautiful: sharp, no tailing, great separation. Trying to rerun same analytes on the same column, same solvent system (but different solution for reconstituting samples: 0.1N HCl vs water) and although peaks still look sharp with no tailing, they are not separating well. They are eluting within 0.1 min of each other in pure water/0.1% FA??? A compound that eluted at 5 min previously is now eluting at 2 min? Is my column screwed? There’s no change in […]
- by /u/Unknown_LabsHi everyone. I am writing on behalf of the Unknown Labs. We're a start-up that provides spectrometry analysis solutions, hardware and software. We're exploring the Health & Safety applications of spectrometers. We wrote this white paper on portable XRFs' effectiveness in detecting lead based on our knowledge and on available research. Key findings are that: Spectrometry was considered to lack accuracy in previous years. When XRFs are calibrated with lab data, they can reach up to 4.4% lab accuracy. XRFs are a cheaper and faster alternative to screening but also reliably detecting lead. What are you thoughts on the effectiveness […]
- by /u/elnurgarHello everybody, We have a Synapt G2-Si from waters. Recently I started to get some regular intensity drops and found out that this problem is related to Triwave. https://preview.redd.it/hww5uynwxhzf1.png?width=1500&format=png&auto=webp&s=860a426139bc23863d53bdb7468c46276a6efbe8 Regularly, RF Amplitude, Amplifier Current and Rf Freq drop to 0. I think also that these drops occur when it is little bit more warm in the laboratory. Do you think it is possible to repair without replacing the whole board? Thanks submitted by /u/elnurgar [link] [comments]
- by /u/Itsme-TatiHas anyone ever encountered the contents of a microtube turning purple after the urine is added? My procedure starts as: 1. Enzyme 2. Buffer 3. Internal Standards 4. Urine —> (Contents of tube turns pink) 5. Vortex 6. Incubate —> (Contents of tube turns purple) This is the second time in 8 years that I’ve come across something like this. The first time, I just didn’t run the specimen and reported “NO TESTS PROCESSED – SPECIMEN INTEGRITY QUESTIONABLE”. I’ll probably do the same thing this time, but I want to understand why. Update: The specimen was positive for oxycodone and […]
- by /u/Glittering_Bunch6819We have a thermo Exploris 240 with Vanquish LC on an instrument with multiple users. Can anyone recommend a USB/Bluetooth/IOT scale or other method for monitoring solvent consumption? some of our uses use the acq machine remotely (via RDP) and we are hoping for something simple and cheap to just let people know "running low". submitted by /u/Glittering_Bunch6819 [link] [comments]
- by /u/alycatdabraWe have been having crazy issues with the Thermo flexmix showing impurities on the orbitrap fusion lumos. Sometimes I can fix the issue by baking the source while flushing with aqueous methanol but we've had to order two fresh bottles in the last six months because of impurities. The solution is so expensive at $350 for 10 mL and boss is worried about funding cuts as is. I almost want to aliquot it into 500µL vials to try and prevent contamination but I'm sure that changing the bottle it's in would be an issue too. Things we've done to prevent […]
- by /u/kbeastarHi all, I only have the final LC–MS feature Ă— sample table exported from Bruker (MetaboBASE / HMDB library) — I do not have the raw.d or full chromatograms. After alignment, I found that the same compound name / same formula / same adduct / same MS/MS library can appear at several different RTs. Right now I see three situations: MS/MS confirms it’s the same compound, but RT is far apart e.g. “4-Dodecylbenzenesulfonic acid” matched to the Bruker MetaboBASE library at RT 1.17, 6.52, and 14.37 min. MS/MS confirms it’s the same compound, and RT is extremely close (a few […]
- by /u/Big_Parsnip4209Hello, I want to ask how would career progression look like after working as an analytical specialist in a company. If you started as analytical specialist/laboratory specialist, what are you working as now? submitted by /u/Big_Parsnip4209 [link] [comments]
- by /u/Careful_Silver1045Hi everyone, this is a specific question and I understand that there is no straightforward answer, but any comment would be highly appreciated. We are considering buying an Agilent 6460 (in addition to our 1290 HPLC) and want to use it for quantification of plasma samples from pre-clinical trials. Basically, we administer peptide candidates (MW about 1 – 5 kDa) into different animal species, take blood samples, purify them via solid phase extraction and want to measure the peptide plasma concentration via LC/MS/MS. Assuming that there is no dilution effect during plasma purification, is it feasible to achieve a LOQ […]
- by /u/FreddieTheBiologistHi! I’m a biologist and we’re working with a collaborator on LCMS/MS. I understand the concept of MRM and how it works, but I was wondering what (monitored MRM: 218.1 -> 127, 218.1 -> 156) means for a given compound? Is the the m/z that’s you start -> the m/z you select for? submitted by /u/FreddieTheBiologist [link] [comments]
- by /u/mohgerTL/DR: A lightweight Python package for finding molecular formulae given a mass + error window. No databases required – generates all possible elemental compositions. I put this together and I'd like to share it with people who might find it useful. What find-mfs is a simple Python package for finding molecular formulae candidates which fit some given mass (+/- an error window). It uses Böcker & Lipták's algorithm for efficient formula finding, as implemented in SIRIUS. find-mfs also implements other methods for filtering the MF candidate lists: Octet rule Ring/double bond equivalents (RDBE's) Filtering by predicted isotope envelopes Note: This […]
- by /u/DryApplication4550Hello! I'm a beginner chromatographer and don't know much, but I'm looking for some advice on using my Vanquish Thermo chromatograph. I'm getting the same connection errors for the column compartment and the autosampler. I checked and replaced the USB cable, but it didn't help. The pump, however, is fine, connect. Has anyone else experienced this error? Thank you! https://preview.redd.it/dc9pi31z4nxf1.png?width=1915&format=png&auto=webp&s=436753b9ac490c13e9d7e63a9dc499f8ecf75d10 submitted by /u/DryApplication4550 [link] [comments]
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