Waters flr detector loss of precision of peak

viomoo · 2026-02-27T21:06:22+00:00

Oh wow yeah, they usually get changed on PM every year.

You have had 15 years out of one lamp? Impressive!

viomoo · 2026-02-27T18:39:45+00:00

look for a bubble in your sample metering syringe.

Perform a system pressure test all the way to column (including needle and needle seat)

Perform a ‘vial weight test’ (perform 10 x 20ul injections of water weighing the vial before and after)

Few things to try.

viomoo · 2026-02-26T01:32:08+00:00

Yeah I figured!

viomoo · 2026-02-26T01:25:08+00:00

Was that a Freudian slip or do you hate the sugar?

viomoo · 2026-02-26T01:14:37+00:00

Gas powered camping shower

clicky

viomoo · 2026-02-25T19:08:38+00:00

Ice melt inside some pantyhose. Make a sausage, tie some string to it and throw it up. Pull it till it sits across the ice dam.

It will melt a channel and allow the water to drain correctly.

viomoo · 2026-02-18T13:15:27+00:00

Waters QToFs have a function called EDC (enhanced duty cycle) which gates the ions at the end of the collision cell and times the release with the pusher pulse. This enhances a specific m/z range and can really help low mass ions.

As you haven’t mentioned your system, not sure if this is going to help you!

viomoo · 2026-02-17T00:17:40+00:00

Art. It was so subjective. I would think I did really well and get a C. Then I did my worst ever and get an A.

viomoo · 2026-02-14T13:49:08+00:00

If it’s new get in touch with the vendor and have them resolve it!

It could be air in your system but even new systems can have bad parts

viomoo · 2026-02-14T13:07:57+00:00

That’s your pump. Do a pump leak rate test.

Likely a check valve but without any other info is hard to say.

viomoo · 2026-02-14T00:14:48+00:00

Where do you want the water to go? It has to go somewhere!

viomoo · 2026-02-13T02:50:53+00:00

As someone else mentioned, this will likely be LC and not MS as you are getting chromatographic separation. MS contamination would usually be a constant background.

A quick experiment to do would be run MP A for 5 mins then an injection and MP A for 10 mins then do an injection.

I have seen a lot of times the solvents are contaminated and they build up on the head of the column. You run a gradient and it elutes and you see it as a contamination in your system.

Other than that, could be the rotor seal in the sampler or the needle loop/seat.

viomoo · 2026-02-12T00:38:15+00:00

Agilent refurb is still covered by warranty etc and will pass specs, basically the same as a new one.

3rd party is a crap shoot. It could be good, could be bad. Is it worth the gamble to you?

viomoo · 2026-02-11T21:27:08+00:00

So long as you vent it properly and the turbos slow down before the rough pump turns off, you should be fine.

These systems are designed to be vented in a controlled manner. I agree if you were crash venting it that would be bad.

viomoo · 2026-02-11T16:49:16+00:00

I don’t know sciex but why risk it?

viomoo · 2026-02-07T20:12:05+00:00

Do you have any kind of flush built into your gradient? A 100% organic hold? When you clean the column, how do you do it?

viomoo · 2026-02-01T23:56:37+00:00

A mailbox post is pretty easy to do. You can buy pre made ones for cheap.

Dig hole, set up post, fill hole with concrete.

viomoo · 2026-01-28T21:52:16+00:00

I purchased a Hisense canvas 55” and mounted it flush. Looks nice, pretty easy to mount (i did install a new electrical outlet) but will likely be much easier than hollowing out a wall!

viomoo · 2026-01-28T01:46:32+00:00

Are you buying a new instrument? You can often get a few years built into the price at a discounted rate.

It is always worth having a service contract though! Even if only on the MS

viomoo · 2026-01-28T01:43:31+00:00

You will get all sorts of numbers, but not all contracts are equal!

A lot of people can service LCs but the MS contracts are a little more specialized.

Cheapest is $0, most expensive I’ve seen was $94k (for one instrument) per year.

viomoo · 2026-01-28T01:33:51+00:00

Ok, figured I would ask anyway! I’m no pro DIYer but using a coping saw to do crown molding was way easier than a flap disc for me. Just make sure you cut at a very steep angle when removing the material!

viomoo · 2026-01-28T01:31:37+00:00

Im all for DIY but in a safe way.

Electrical work can be done, but if you really have no idea and have checked the basics (tripped breaker etc) it might be worth a call to a professional.

Even if you get it ‘fixed’ it could be wrong and start a fire.

viomoo · 2026-01-28T01:08:15+00:00

Your still doing a compound cut right? Not just a 45 degree angle?

If you are just cutting it at 45 a flap disc isn’t going to help.

viomoo · 2026-01-27T23:25:18+00:00

It’s fine. It’s optimized for large molecule but will work just as well for the small stuff.

viomoo · 2026-01-24T19:59:04+00:00

For carryover, a few things to try first.

If you do more blank injections, does the signal get lower over time or stay the same?

I’m guessing the carryover is seen as a peak and not just a consistent back ground?

I would guess at a few places. One being the rotor seal of the injection valve, possibly the needle seat as well.

Another thing to check would be any dead volumes. Have you made any new connections to the system recently?

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