The instrument is old, I changed a lot of the other plumbing. The pressure is fine and steady when equilibrating, then when it goes to make the injection, it just starts flowing from the needle and not through the brand new needle seat...
Thanks, it ended up being the rheodyne valve, it was sticking so I had to take it apart, clean it and replace the stator.
I am running several matrices for sugar on the HPLC, and no matter how clear the sample looks, the pressure jumps when it gets to this particularly starchy sample. I suspect that the starch is...
02 March 2014 7,211 34 View
I have gotten the Vitamin C to stick to a C18 using methanol at 0.5 mL/min, but it always comes out in a blob when I run a food sample. I have set the UV to 243, 250 and 260 to try and phase out...
31 December 2013 8,750 26 View
At times, I have run into analytes that don't give particularly great peak shape, whether on GC, HPLC or MS. I have run methods where despite some tailing on the chromatography, we have...
09 October 2013 5,319 3 View
I have obviously gathered validation data such as linearity tests, matrix spikes, precision and even blind proficiency samples. So what would be the next step?
08 September 2013 7,134 10 View
My lab analyzes sugar in food samples using AOAC guidelines, and it doesn't take long for the chromatographic performance to decline, and there is a steady increase in backpressure with every run....
07 August 2013 6,889 5 View
I cleaned the inlet, changed the liner and septum, the flows are good, cleaned the detector, changed the jet, recut both ends and reinstalled the column. I could see a solvent peak after that, but...
07 August 2013 5,983 17 View
The work will not be for any educational purposes, this will be for my business institution. We are on a tight budget, but I also don't want to skimp too much on quality.
06 July 2013 10,029 8 View
A crude extract of fungal culture using EtOH was subjected to column and TLC and partially purified compound was obtained. UV vis spectrum of the compound/s has max absorbance at 218nm. The...
11 August 2024 9,801 2 View
Can anyone explain this method? Especially the last statement where it says only at 1.5 to 2.5mins was the MS/MS connected to the UPLC. How is that possible, is it a feature in this specific...
11 August 2024 8,141 3 View
Hello, Why do i see this baseline drift when i compare my blank (black) to the sample (blue)? Any suggestions as to why this happened? Thank you!
11 August 2024 3,770 4 View
Hello experts, Does anyone know any free software about retention index prediction ?
08 August 2024 7,403 2 View
I'm currently working on calculating the collision cross section (CCS) for various ions, and I'm facing challenges when dealing with sodiated and multiply charged ions. Most of the resources I’ve...
08 August 2024 8,329 0 View
I'm working on selecting antibodies against a recombinant protein that has a His-tag. My idea is to first bind the recombinant protein to a HisTRAP column and then use this column for an affinity...
07 August 2024 505 3 View
Are there any suggestions or insights you can provide to help address this problem
06 August 2024 1,443 2 View
Why is TLC not a form of partition chromatography and paper chromatography not a form of absorption chromatography?
03 August 2024 7,035 3 View
or we can collaborate
01 August 2024 6,705 2 View
I need something like Camag's VisionCat software for photodocumentation of TLCs. Could you recommend something?
31 July 2024 8,415 1 View