I am getting lots of spikes in my RID signal and the RID says not ready. I am getting a message that the diodes are unbalanced and there is low light. Does anyone know what this means and if I can fix it?
I tried balancing the diode to change the optical balance level but when I did this then number didn’t change at all and was set to 1
Dear All,
I am using LabSolutions ver 6.129. I would like extend my knowledge on using control normalization, I am using "External Standard" as calculation for Assay calculation. However, Now I need to calculate the sample concentration normalized to control sample assay. Can an experience user help me explain, how can I perform this in LabSolutions. Sample batch is given in the pic.
Thank you for your help
Hello everyone,
I have an issue with my Perkin Elmer Clarus 580 GC. About a month ago, I replaced the column with the exact same model, and since then my baseline has looked quite strange.
In the attached image, I overlaid two chromatograms:
I have already replaced the septum and the liner, but the problem remains.
Does this baseline look normal, or is there likely something wrong with the system?
Hello!
We have decided to resurrect our ELSD that had been in storage since my predecessor. It works, and I’ve used ELSD once before, but that was many moons ago and I’d like to learn the tricks to optimizing it.
I know the gas flow controls the size of the aerosol/droplets, nebulizer temp is set to get as much of the aerosol as possible into the drift tube, and the drift tube is where the main evaporation happens. If I understand correctly, lower gas and thus larger droplets are better for sensitivity but are difficult to reproduce. Lastly, that you want the drift tube to be warm enough to evaporate the solvent but not vaporize the sample.
I guess my questions are:
Thanks to anyone who can provide insight!
Edit: THANKS! For all the answers, they're really helpful.
I’m a chemist currently working in analytical labs (ICP-MS, ion chromatography, some early UPLC experience) and I’ve been approached for a Technical Sales role for analytical instrumentation in an important company.
The role would involve customer interaction, demos, travel, technical consulting, and sales responsibilities across different industries.
I already explained them that I don't have background in the thing they're looking, but anywat they seem very interested in me. "You know the technic part, we form you in commercial". And also during the first months I would work among with previous person in that rol.
For people who made the transition from lab work to technical sales/application roles in analytical instrumentation:
Did you enjoy the change? Do you still feel technically connected to science/instrumentation? Any regrets or things you wish you knew beforehand?
I’m genuinely interested in the company and rol, but that would be a major career/life shift for me, so I’d appreciate honest opinions.
Hi all,
I’m troubleshooting an Agilent 7890B GC setup for CO2 reduction product analysis and I’m unsure how tight the microneedle/resistor valve that bypasses my molsieve column should be.
For reference, the current configuration is:
injector to PLOTQ to molsieve to TCD/FID
when the valve actuates, the flow is restricted to the PLOTQ and the molsieve is effectively cut off
I am using the PLOT/Q for CO2/large hydrocarbons and the molsieve for permanent gases. I understand that the idea is to balance the pressure and the flow when the molsieve is cut off by tightening the needle valve, but I don’t really know what “correct” looks like in practice. When I've actuated the valve that cuts off the molsieve, there seems to be no difference in the column pressures, flow rates, and velocities no matter how tight or loose the needle valve is (I have seen a slight drift in the baseline).
I was wondering if people had any experience with this. How tight do you normally tighten these resistor needle valves and are there any signs in the TCD/FID signal that I can use to tell if the valve is too tight vs too open?
Thanks!
Hi,
I'm developing an LC-MS assay for tenofovir diphosphate, which is structurally similar to ATP. I am new to chromatography and I've been having a lot of trouble with this compound. Today I discovered that peak shape and intensity significantly degrades at temperatures above 30 C, and actually improved at 20 C.
This is very counterintuitive to me; I would expect higher temperatures to result in a tighter peak and a lower retention time but I'm seeing a broader peak and HIGHER retention time. Does anyone have an explanation for this sort of behaviour? I considered thermal degradation, but I feel like these temperatures are quite low for that to occur especially when the compound is in the column for less than a minute.
My conditions are as follows
Mobile phase A: 15 mM ammonium bicarbonate in water, pH 9
Mobile phase B: 15 mM ammonium bicarbonate in 90% ACN, pH 9
Column: Premier Z-HILIC 2.1 x 50 mm 2.5 um.
Hi, I'm working on an assay for a triphosphated compound, and I'm trying to get down to an LLOQ of 0.1 ng/mL. Problem is that it's a pretty tricky analyte I'm hitting a wall at like 0.5-1 ng/mL.
Currently I'm using an atlantis premier BEH Z-HILIC 2.1 x 50 mm 2.5 um column. There is a 1.7 um version available, and I was wondering what one might expect with a smaller particle size? There is only one compound, so separation is not one of my concerns. Would the smaller particle size be expected to have any effect on the intensity of my peak if I scale my gradient accordingly? Trying to figure out if it's worth looking into.
Hello chromatographers!
I'm working with a Thermo Dionex ICS2100 IC system and I feel like I've been arm wrestling this system for the past 3 months with different problems popping up.
On my last run, the pressure started fluctuating like crazy in a cyclical pattern. This pointed to a pump issue, so I cleaned out both the primary and secondary pumps with milli-Q waterand wiped off all salty residue. Easy enough!
However, after reassembling the primary and secondary pump heads, the bottom drain on the spacer for the secondary pump head started dripping water!
A couple of questions for the chromatography community: (1) is this normal for the drain on the secondary spacer to be dripping liquid? I've not seen this happen on this instrument before, but I know I can attach drain tubing to it so maybe this isn't a big deal? (2) What is causing the drip from the secondary pump drain?
Thank you for your time! Y'all rock!
How often do you perform maintenance on your HPLC? And what do you include under the scope of regular maintenance? How often do you run samples, and which mobile phase do you use? Furthermore, it would be interesting to know what types of samples you run through your HPLC.
Solved. Sampler got connected succesfully. Now i'm doing tests. I wish i wasn't that underpayed :(
Hi there! Hope you are doing well. Last week i asked about advice changing the gripper arm in an Agilent G1313A autosampler. Unfortunately my boss said it was better to change all the autosampler (G1329A) instead of the gripper arm.
But, as soon they connected it, OpenLabCDS doesn't recognize it.
Here is an example of what appears in the layout:
I'm not an expert of software development, but LabAdvisor shows me sampler and system firmware isn't the same.
Is this the reason why OpenLab doesn't detect it? Sampler is on, and connected.
Thanks in advance! :)
Hi everyone,
We’re looking for advice from anyone experienced with the Agilent 6460A LC-MS or similar 6400-series systems.
We’ve been troubleshooting this instrument for about 2 months and still can’t get it running, even with help from an “expert” over WhatsApp.
Initial symptom: when plugged in, only the turbo controller showed power: two green lights. Pressing the front power button produced no normal startup: no other lights, no fan, no rough pump, no obvious relay click.
What we’ve tried:
Replaced the AC board with a new one.
Bought and installed a third AC board.
Replaced fuses.
Tested wall power.
Used a power conditioner set to 230 V.
Tried a UPS/battery backup.
Tested the roughing pump power outlet with the system “on”: no voltage.
Checked the front power-button connection.
Checked wiring/connectors as best we can.
Odd recent behavior: one time, a fan briefly kicked on when powered up. After turning the system off and back on, the fan did not come on again.
Questions:
If the turbo controller has green lights but the rest of the MS seems dead, what would you check next?
Should the rough pump outlet receive voltage immediately, or only after an internal startup condition?
Are there common interlocks, relays, low-voltage supplies, or enable signals that prevent startup?
Has anyone seen this exact failure mode?
We’re not trying to bypass safety systems. We’re trying to understand where the power chain is stopping.
Any advice would be appreciated.
As the title suggests, these are the same standards ran 2 days apart on a GC/MS Agilent 7890 gc connected to a 5975C MS. DB5ms column, brand new septum and liner. I get good linearity, just not good repeatability.
EDIT: This trend shows the response factor growing over time, previous studies have shown it also shrinks. Slope increases over time then decreases over time repeating.
Hello, does anyone have any experience as a freelancer consultant for chromatography for GMP QC/R&D through platforms like Upwork? I would like to hear your experience, it might save my money and time not to invest in such stuff.
I want to use my years of experience, troubleshooting and development skills to make an extra buck and lay the groundwork for a full time freelancing career if possible, if you have an alternative platform or path please suggest.
Thank you in advance!
Everything else looks fine, already tried to restart again but nothing changes
I'm running samples of 0.1 N sulfuric acid solutions on a dionex system.
Eluent is carbonate/bicarbonate 10 mM.
I'm screening for trace anions but I get a big peak at around where the chloride peak should elute. The chloride peak appears as a small peak riding on the big peak which looks like a shark fin.
Any insight would be extremely appreciated.
Would anyone in the Kendall Square / Cambridge MA area want two of these Agilent benchtop HPLC stand/bench/rack things? I have two that are kind of just taking up space that I don't need. Unfortunately don't have any of the shelves that go on them, but I figured I'd ask!
If you want them and are able to swing by and grab them just shoot me a message!
