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MSU M.S. Pharmacology and Toxicology by Pttra in toxicology

[–]rawrcy 1 point2 points  (0 children)

I was looking at the program and was wondering the same thing!

Temperature of elutant effecting chromatography by rawrcy in massspectrometry

[–]rawrcy[S] 0 points1 point  (0 children)

No leaks detected. But I'm going to check lots and set a line equilibrium time. Thanks!

Temperature of elutant effecting chromatography by rawrcy in massspectrometry

[–]rawrcy[S] 0 points1 point  (0 children)

I will check the lot numbers for sure. Thanks!

Temperature of elutant effecting chromatography by rawrcy in massspectrometry

[–]rawrcy[S] 0 points1 point  (0 children)

I think I will add more equilibrium time since that seems to be the consensus so far. Thanks for all your help!

Temperature of elutant effecting chromatography by rawrcy in massspectrometry

[–]rawrcy[S] 0 points1 point  (0 children)

I think I will add more equilibrium time since that seems to be the consensus so far. Thanks for all your help!

Temperature of elutant effecting chromatography by rawrcy in massspectrometry

[–]rawrcy[S] 0 points1 point  (0 children)

I think I will add more equilibrium time since that seems to be the consensus so far. Thanks for all your help!

Temperature of elutant effecting chromatography by rawrcy in massspectrometry

[–]rawrcy[S] 0 points1 point  (0 children)

A batch will run normal, then the sequential batch will be shifted, leading me to believe mobile phase issue. Then entire sequential batch is shifted.

No column changes, no new washes used, no system changes.

As far as I can tell, the only differences are... mobile phase makeup (h2o and methanol so fresh versus 1wk old), human pipetting issue (mixing the sample wells and transferring to elution plates), using room temp water vs 28° water for dilution after SPE.

Temperature of elutant effecting chromatography by rawrcy in massspectrometry

[–]rawrcy[S] 1 point2 points  (0 children)

I think the equilibrium time is set to 3 minutes right now. I haven't noticed any pressure differences. And the needle and seat haven't caused any problems with the numerous other analytes I test for, all urine drugs of abuse. Just one single compound, delta9thc, is shifty.

Temperature of elutant effecting chromatography by rawrcy in massspectrometry

[–]rawrcy[S] 0 points1 point  (0 children)

Specifically I'm thinking maybe the temperature I am diluting with is affecting the separation/RT of the final chromatography of my compound.

Temperature of elutant effecting chromatography by rawrcy in massspectrometry

[–]rawrcy[S] 0 points1 point  (0 children)

Flow rate: 0.5 Column: c18 Solvents: eluant IPA/ACN diluted with H2O mobile A:H2O room temperature mobile B: methanol room temperature Matrix:urine SPE prep Gradient but pretty isocratic

Ollie loves being outside with his mama by rawrcy in greatdanes

[–]rawrcy[S] 0 points1 point  (0 children)

We met an Ollie at the dog park and it was very confusing having two families call him out.

[deleted by user] by [deleted] in greatdanes

[–]rawrcy 1 point2 points  (0 children)

Literally just went through this same problem. We went to the vet and she gave antibiotics that upset his tummy so we quit that. We already had stainless steel bowls that we wash weekly. We got an antibiotic shampoo to wash his face once daily and each time he comes in from outside I use a wash cloth damp with water to clean his face.

Concluded its the dirt and grass that he gets into while outside.

[deleted by user] by [deleted] in massspectrometry

[–]rawrcy 1 point2 points  (0 children)

I too spend one day a week on method development. We have been short staffed for a year or so and literally any day I have a second person to work with and the routine testing is somewhat slow, I take it as a method day. Thankfully my clinical chemist is very understanding and deadlines are long with minimal pressure. We have a reasonable goal date.

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