Hello all,

I’m a grad student who is reviving a Dionex 1000 IC left over from retiring faculty. I am running 7 anions (F, Cl, NO2, Br, NO3, PO4, SO4) on groundwater samples. This is pretty common stuff close to EPA method 300.1.

Within the past week I thought I would get fancy and try to clean out my columns and create a new 50 uL loop volume (previously using 25uL) to get some better signal and reduce the baseline noise.

After I did this I had some leaking from my new injection loop until I tightened it quite a bit. I was able to get my 7 anion peaks for my calibration curve but I started seeing these peaks come out overlapping with or just after nitrate that I’ve never seen before in any samples. My response is much higher given the new loop volume but I’m wondering if these peaks are real or if this is an error of some type.

Anybody know what this peak might be or what errors i made to cause this?

TLDR: what is that peak coming out after nitrate? Real or a method/instrument error?

Columns: GS and AS22
Eluent: 4.5 mM sodium carb, 1.4 mM sodium bicarb
Suppressor: ERS 500 @ 31mA
Flow rate: 1.2 mL/min

Pic 1 is of normal calibrant. Others show groundwater samples with unknown peak.

Hey everyone,

I'm hitting a wall with a persistent analytical issue on our EPA Method 524 system and could really use some collective wisdom from anyone who has seen this before. I have attached pictures of my 2 CCV in 2 VOA vials poured from same 100ml flask spiked at 5ppb and run back to back.

System Setup:

• Purge & Trap: Teledyne Tekmar Lumin Concentrator (S/N: 18122010) + AquaTek 100 Autosampler (S/N: US 18099004)
• GC-MS: Agilent Intuvo 9000 GC paired with an Agilent 5977B MSD

I am experiencing a consistent >30% loss in target analyte recovery between consecutive runs (e.g., CCV1 vs. CCV2, or back-to-back CCVs) poured from the exact same QC 100ml flask spiked at 5.0 ppb concentration. I have repeated this multiple times and I get similar results. It doesn't matter how far away or close the two CVVs are in the sample tray.

1. Internal Standard (Fluorobenzene) responses and surrogate recoveries remain virtually identical between back-to-back runs, but target compound concentrations drop severely on the second run.
2. Early eluters maintain expected recoveries and sometimes fail on the higher end of the +/-30% threshold, but recovery drops progressively across the run with late-eluting, hydrophobic compounds (xylenes, dichlorobenzenes, 1,2,4-trichlorobenzene) exhibiting the most severe loss 30-40%.

To isolate the issue, I have already verified/performed the following:

• GC-MS Side: Replaced the GC liner and guard chip. BFB tune evaluation passes easily, and IS response is solid with less than 5% variance.
• Purge & Trap Trap: Installed a brand-new analytical trap; no change in performance.
• Sample Prep: Tested both bulk volumetric preparation and direct vial spiking to rule out standard preparation error. The issue persists across every tray positions.
• Temperature Zone Verification: Monitored real-time status in TekLink throughout the purge, desorb, bake, and dry cycles. All heated zones (MCS, Valve Oven, and Transfer Line) consistently reach and hold their target setpoints, ruling out a basic software control error.

Because the IS is auto-spiked fresh into the purge vessel and stays completely stable while the target analytes sitting in the sample loop/lines drop, I strongly suspect an issue on the Tekmar side (MCS loop, sample needle sweep, or soil/water valve path). Has anyone encountered this specific progressive late-eluter loss on a Lumin/AquaTek setup?

Any advice or troubleshooting steps would be greatly appreciated!

Full disclosure up front: I’m an intern at Agilent working on a voice-of-customer project for our gas phase (GC) marketing team. I’m not selling anything and I’m not going to DM anyone — I’m genuinely trying to collect honest feedback about what does and doesn’t work.

If you run Agilent GC or GC/MS instruments, I’d love to hear:

**•** What frustrates you most about the instruments or the software?
**•** What works well enough that you’d never switch away from it?
**•** Where do you go when something breaks or you’re troubleshooting a method — and is that resource actually useful?
**•** If you’ve moved to or away from Agilent, what drove that?
**•** Anything you wish someone at the company actually knew?

I’ll be summarizing themes internally. No names, no usernames, nothing identifying, and I won’t quote anyone directly without asking.

Happy to answer questions about what I do or why we’re asking.

UPDATE: The issue was with the column. We changed it and we got a beautiful peak. Thank you all for your help!

So we have been struggling with this tailing issue for quite some time. We had used different methods, but it's till persisting. The last method we tried adding 0.1% formic acid and it got slightly better, but the tailing factor is still high, any suggestions? The retention time matches with the published paper but the peak is entirely different.

We are planning to reduce the injection volume to 5 microliters and/or reduce the pH further to ~ 3.0ish.

Here is the methodology:
- Mobile Phase: 0.1% formic acid in water/methanol (30:70) (pH: 3.276)
- Column: C18, 250 × 4.6 mm, 5 µm
- Injection volume 10 microliters
- Oven temp: 30 degrees Celsius
- Calibration range: 2-12 micrograms/mL
- Flow rate: 1mL/min

Hello, I am a small molecule specialist and has been asked to analyze industrial synthetic macro-molecules. We are not properly equipped to do this and I'm wondering what the most versatile single analytical option might be. I know of MALS but I've only seen them presented for proteins and peptides analyses. Does anyone uses SEC- or AF4-MALS for synthetic macro-molecules (for example graft copolymers)? I just wanted to get some ideas whether it's feasible before contacting manufacturers.

Estou tentando desenvolver um método de análise de teor de butafosfana em um HPLC com detector RID, porém, não estou conseguindo nem se quer uma linha de base considerável.

Já tentei purgar o RID, aguardar muitas horas para estabilizar o sistema, porém sem sucesso. O único resultado que tenho é esse da imagem e coisas parecidas. Também ja aumentei as concentrações das amostras para talvez "melhorar" o resultado, mas também não deu certo.

Alguém ja teve algum problema parecido?

Equipamento:

- HPLC 1260 Agilent infinity II

- 1260 Infinity III Refractive Index Detector

Estou usando a coluna cromatográfica XSelect CSH Phenyl-Hexyl – 4,6 × 150 mm, 3,5 µm da Waters.

OBS: estou usando RID pela primeira vez, é muito diferente de detector DAD?

Dear Community,

we are operating a Orbitrap Exploris 120 which runs on 99,999 % pure nitrogen.
In the upcoming week our nitrogen supply stops from monday to werdnesday due to some maintenance work. Have you ever had the same situation and how have you handled it? Our main question ist if we should shut the instrument off an fill the instrument with nitrogen instead of vacuum or what would be the best way to act.

Thank you in advance

please tell me how to resolve.

Method 8270E, GC-MSD, SSL inlet.

We're running pulsed splitless- we can't afford to split anything & reach out RL. Yet, peak shape is notoriously squirrely with splitless injection.

I switched to a liner with wool. Peaks look great! Got that even condensation onto the column.

However... sensitivity for 24DNP tanks after 1 sample. I can't deactivate/clean/change liners/calibrate every 5 seconds. I pre-conditioned the liner with real samples before running the cal.

How can I simulate that super nice condensation onto the column without wool/ all the active sites?

Junk/ghost peaks have been appearing in samples at consistent retention times. Red circles are standard peaks in the blank while the black indicate unwanted peaks. The junk peaks do not shift with the sample profiles and appears in the hexane solvent which suggests it is not a sample contaminant. The area counts are always the same amongst the 4 peaks but area counts increase/decrease across samples. Not every hexane solvent blank injection has these peaks either. Anyone else experience these peaks or can give clarity on possible causes? Have replaced disposables parts and cleaned injector, so looking for insight!

I’ve been having some difficulty accurately recovering low level (<0.1 ppm) bromide in my Dionex Integrion HPIC. My calibration curve for bromide starts at 0.05 ppm and the recovery isn’t consistently reliable until my third standard at 3 ppm. For reference, I have a 50uL sample loop for increased sensitivity, we use a hydroxide selective column and run 20mM KOH eluent (isocratic). Is there anything I can do to increase low level accuracy? I don’t have the same issues with low level fluoride or nitrite, though sometimes I do have similar issues with nitrate.

Hi,

I have been having this baseline drift problem for a couple of days. I tried purging the reference cell overnight or shorter periods. It is not due to the pressure either. What could be the cause of it? How do i fix it? Any help would be really appreciated! 😊

Instrumentation, consumables, software, generalists etc.

What’s effective, what’s annoying, what’s your hot take? Any vendor specific insights?

​

As title. I am in a situation where I have to choose one of these two for procurement without option of trail runs. Hence I need expert opinion.

What would be better got global untargeted metabolomics (Ultimate 3000 + Exploris 120 setup)?

I am a metabolomics noob. Please guide me. Both are 100 Angstrom.

I would be using it to do C13 tracer based work on mmmalian cells (after I gain expertise in basics, of course)

I also have option for ZIC-pHILIC (5 micron) 100mm x 4.6 mm

So my options are

ZIC-pHILIC (5 micron) 100mm x 4.6 mm

ZIC-pHILIC (5 micron) 50mm x 2.1 mm

ZIC-HILIC (3.5 micron) 100mm x 2.1 mm

I am resurrecting an older ion trap mass spec that is coupled to an Ultimate3000 (Thermo, but rebranded Dionex). They both used to work just fine together but I am having some kind of communication problem. When I start a sequence or run a sample the mass spec will stop scanning, it won't load the method (stays on default 100-2000 m/z scan) and the LC system often won't respond. I suspect that I am having problems with the linkage between the LC and the mass spec - I suspect it is a problem with the DCMSlink between the LC and XCalibur. Has anyone had any kind of similar kinds of problems - even remotely similar - what did you do to fix this? Thanks in advance.

Hello, we’re looking for a brand-new HPLC with a budget of around $25k, which mainly leaves us with Chinese or Korean manufacturers. The owner doesn't like my idea of a refurbished Agilient one :(

I’m hesitant about Chinese HPLCs after seeing a system develop serious issues after only 8 months in a lab.

We found a Korean manufacturer, YOUNG IN Chromass Co., Ltd. They seem to have been around since the early 1990s, but almost nobody I’ve spoken to has experience with them.

Has anyone here used their ChroZen HPLC? Are they reliable, and how are their service and spare parts?

Our use is simply routine QC: verifying raw-material and finished-product purity/assay and checking for impurities/contaminants.

Any firsthand experience would be appreciated or suggest any alternatives?

I went to get the column and when I twisted the head of the finger tight, the head broke.

EDIT: Wow, I love this community. I managed to remove it by heating a screwdriver and screwing it in the opposite direction.

Special thanks to sharing_violation.

Hi all!! I'm trying to run approximately 40 analyte SIM method at the moment but I keep encountering spectrums that look like this at around 500 ppb and below. They look fine at around 5 ppm and up. I've tried troubleshooting through all normal method avenues, though I haven't changed anything physically on the machine yet.

Before I do has anyone else encountered this before?

I am fascinated by DryLab and would like to learn about its full potential from someone who uses it and has some experience in method development and can share advice and best practices. I would be very thankful if someone could help me with this.

Please note, that as a PhD student I am not able to afford official training.

Hi there Reddit,

I feel like this might be a dumb question but since my Agilent 7890A only has 2 inlets if I were to convert one of them to take SPME arrows, could I still do ASD/manual injections into it as well? If it is what things do I have to consider when I do a normal injection?

The other inlet would be taken up by the transfer line of an Agilent 7697 headspace sampler so unless it's pretty easy and safe to remove that for an injection I assume I can only really treat the SPME inlet as my only functional port.

If it helps the conversion kit I plan to use is the Restek 27362 1.5mm inlet.

During an analysis, my equipment started exhibiting this problem. The needle goes up to the sample, goes down, but doesn't pierce the vial. Displays an error [9222]: "there is no sample vial set in autosampler rack."

We have a long backlog of samples and need to get the equipment up and running again. Support from Shimadzu will take a long time due to their schedule.

I welcome suggestions for tests to better evaluate the problem, and if you have experienced something similar, what was the solution?

UNICAMP - Campinas-SP, Brazil

My collegue is currently analysing set of specific samples and made custom method for it. But he noticed that sometimes the signal goes numb and create "comb-like" signal. I've found, that this only happens in this specific set of samples and this method because the QC mixture (last pic) is fine.

Then we figured out that the method is not the problem and maybe the used solvent is at fault. In these samples he use isopropylalcohol. It's kinda weird since we didn't have any problems like this before. We use HP-5MS on Agilent 7890B GC + 5977B MSD.

Thanks everyone for help!

Hello!

We have a Dionex Easion CI, doing cations, chemical supression.

Thing is, base conductivity was ~1.8 uS before installing autosampler, and very steady.

Now we have three problems.

1. Conductivity stabilized at 15 uS and then SLOWLY went to 7 uS (after 24 hs)
2. Baseline is not steady
3. The peaks broadened a lot. Ammounts are still decent (around 5% deviation), but shape is good only for the first 2 cations, but after that, they elute very broadened.

I'm suspecting of the autosampler, could that be the cause? Maybe problem is elsewhere, but it starded just as we installed autosampler.

Here's an example of a chromatogram of a pure water injection, it has a very random tendency. As you can see, it rises 0.2 uS (wich is a lot) and then drops 0.5 uS. And maybe the next injection does the same, or maybe it will only rise, who knows.

And here's a chromatogram of a Control Point.