Troubleshooting - vivianlu9/EMAX_VOA_sandbox GitHub Wiki

Table of Contents:

DCC is failing

Compounds failing low

When this happens, the easiest solution to try first is to change your standards. If all of the compounds are trending high, change your IS/SS. If specific compounds are trending low but the rest are fine, you may need to make other adjustments.

If these compounds are low, change your KET-AA or raise the preheat temperature on the autosampler.

  • acrolein
  • acrylonitrile
  • acetone
  • 2-butanone
  • 4-methyl-2-pentanone
  • 2-hexanone
  • oxygenates (MTBE, ETBE, DIPE, TAME), 2-butanol & 1,4-dioxane - part of 8260 mix, but they're temperature-sensitive so raising the preheat temperature also increases the recoveries for these compounds

If these compounds are low, change your GAS.

  • dichlorodifluoromethane
  • chloromethane
  • vinyl chloride
  • bromomethane
  • chloroethane
  • trichlorofluoromethane
  • vinyl acetate

If this compound is low, change your CS2.

  • carbon disulfide

If these compounds are low, change your 4 ADD.

  • methyl acetate
  • cyclohexane
  • methylcyclohexane
  • 2-butanol

If these compounds are low even after changing standards:

  • acrolein
  • 2-chloroethyl vinyl ether (2-cleve)
  • ethyl methacrylate
  • trans-1,4-dichloro-2-butene
  • napthalene
  1. Change the trap (use a new trap)
  2. Change the water management
  3. Change the transfer line (need to ask Diem or Robert to help you with this)

Compounds failing high

If these compounds are failing high, lower the preheat temperature on the autosampler.

  • acrolein
  • acetone
  • acrylonitrile
  • 2-butanone
  • 4-methyl-2-pentanone
  • 2-hexanone
  • oxygenates (MTBE, ETBE, DIPE, TAME)
  • 1,4-dioxane
  • 2-butanol

If these compounds fail high, try lowering the ion focus.

  • dichlorodifluoromethane
  • chloromethane
  • vinyl chloride
  • bromomethane
  • chloroethane
  • trichlorofluoromethane
  • dibromofluoromethane
  • 1,2-dichloroethane-d4

If all compounds are trending high, change the IS/SS.

Other Adjustments

I don't like doing this because doing this makes it harder for other people to prep QC for your instrument, but if all of the above doesn't work, it is possible to adjust the spiking ratios of your standards to make the DCC pass.

Ex: Vinyl chloride is failing low, so instead of spiking 1.0μL of GAS std, you can try spiking 1.1μL and vice versa.

Blank Contamination

Instrument Blank

  • If you see chloroform, the water filter probably needs to be changed. Inform the supervisor so they can arrange a filter replacement.
  • If you see styrene and the vials are from a brand new shipment, the vials need to be baked before using. Inform the supervisor so they can tell the sample custodian to bake the vials.
  • If you see anything else and the samples from the previous day had extremely high responses for that analyte, the instrument itself is contaminated and you need to run rinses to flush out the contamination. In extreme cases, you may even need to change the trap and transfer line. Do not analyze samples until the contamination is gone.

Adding 100uL of methanol to the rinse helps with cleaning up the instrument faster. Do not add more than 100uL; it will cause the instrument to stop running.

Trip Blank

  • If the trip blank from the sample custodian has contamination, inform the supervisor.
  • If the trip blank received from a client has contamination and it's an EMAX trip blank, reanalyze to confirm and write down the trip blank ID in the analysis log.

If there was only one trip blank vial, report the data and make a note in the case narrative explaining why it wasn't reanalyzed.

  • If the trip blank received from a client has contamination and it's NOT an EMAX trip blank, don't rerun the sample. The contamination could be from anywhere and it's not our responsibility to verify the source of contamination (unless it was carryover from a previous sample).

This also applies to equipment blanks and other blanks provided by the clients.

Strange compound peaks

  • The trap probably needs to be changed if the peaks are splitting (especially common with trichlorofluoromethane).
  • If the alcohol peaks are dragging and you ran a foaming sample, change the water management.
  • If the peaks look fine but the retention time is shifted significantly (>0.16min), run the sample at a dilution factor (start at 5x). The sample probably has matrix interference that’s causing the retention time to shift.

Missing Data

First, check that you input the correct data path when you started the sequence. It's possible you forgot to change the data folder before running the sequence (this happens a lot when you're setting up your sequence for the day and you overlooked that).

The folder is correct, but there's still nothing

Check the run log in Instrument Control. If it says any error along the lines of No emission current at [x] minutes, that means the filament in the ion source burnt out. When the filament burns out, it's completely unusable and you have to either switch to the other filament or open the MS to replace it.

Checking filaments

Opening the MS

The filament is fine, but the data looks weird

Sometimes, the computer will collect data but the data is blank or the responses look significantly lower than usual. This usually indicates an issue when purging the sample (didn't purge, needle plugged, foaming sample, etc).

No peaks?

Sometimes the autosampler will move the vial to the soil cup but there was a problem in the process (it dropped the vial, the elevator jammed when raising the vial up, etc). Check the septa for the sample that had issues to see if there's a puncture. If there isn't one, then the autosampler didn't purge the sample at all. If possible, try to watch the autosampler while it moves the vial to see if you can spot a specific issue with the movements. If it's a consistent issue, let Diem know so she can schedule a repair.

Low responses?

If the responses are significantly lower than usual, it's most likely one of three possibilities:

  1. Bad IS/SS spike
  2. Low purge flow
  3. Foaming sample or matrix interference

These are less common, but may also happen:

  1. Concentrator isn't heating up (likely a fuse or electrical issue)
  2. Column is broken (big big problem if it happens, but exceptionally rare)

BFB Failing

Fixing this depends on what is is failing specifically. Most of the time, retuning the instrument will solve the problem. On instruments running Agilent software, you can fine-tune the dynamically ramped parameters to adjust specific ions.

Dynamically ramped parameters

This works when the highlighted ion is failing high/low.

BFB

  1. Go to View > Tune and Vacuum Control > Parameters > Edit Dynamically Ramped Parameters.
  2. Adjust the value of Mass 219 up/down by 0.2 (Up if failing low, down if failing high).

DYNAMIC

  1. Click Send Values Now before closing the screen and returning to Instrument Control. You do not need to save the BFB.

DYNAMIC1

  1. Rerun tune check to see if it passes. Adjust as needed.

Repeller

This works when the highlighted ion is failing high/low (usually high). This is especially common on J1.

BFB repeller

  1. Go to View > Tune and Vacuum Control > Parameters > Edit MS Parameters.
  2. Adjust the Repeller value up/down by about 2.0-3.0 (up if low, down if high).

repeller1

  1. Save BFB.U and return to Instrument Control.
  2. Rerun tune check to see if it passes. Adjust as needed.

Incorrect Update Time

ChemStation

In my experience, usually the issue is that the update time when you generate the List Compounds and Response Factors are different from the time shown when you calculate/generate a quantitation report. To fix this:

  1. Go to File > Edit Method.
  2. Run through the prompts. Calculate/Generate Report should be checked and Summary to Screen should be unchecked (unless you want to close a bunch of windows every day I guess).
  3. Click Save Method. This will not change the update time permanently, but it will correct the update time on the Response Factors sheet, the List Compounds, and the ConCal sheet showing percent recoveries and RRF.

Agilent

Sometimes, the update time gets "stuck" and the update time shown when the data is collected is different from the update time shown when you recalculate the data.

When this happens, you just have to remember to recalculate all the data before you proceed with data reduction. There's no permanent fix for this unfortunately, but on the bright(?) side this problem usually resolves itself the next time you process an ICAL for that method.

If it helps you to remember, you can write down the correct update time/date for that ICAL on a sticky note and leave it on the monitor as a reminder to check.