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Autosampler randomly freezes during sampling

EKKemble

We have a relatively new (about 1 year old) 5977C/8890 GC/MS that we use with an autosampler for semi-volatile testing. On occasion, it will freeze during sampling. The syringe inserts into the sample vial, then the sampling process stops until we abort the run and restart it. It seems to happen randomly. Sometimes once per sequence, sometimes more often, sometimes less often. What could be causing this?We have a relatively new (about 1 year old) 5977C/8890 GC/MS that we use with an autosampler for semi-volatile testing. On occasion, it will freeze during sampling. The syringe inserts into the sample vial, then the sampling process stops until we abort the run and restart it. It seems to happen randomly. Sometimes once per sequence, sometimes more often, sometimes less often. What could be causing this?

  • 0

    When this occurs, is there a red LED blinking on the autosampler tower?  How many solvent washes, sample washes, and sample pumps are you using?  Is it a PTFE tipped syringe plunger?

    Please upload the sequence log file found at D:\masshunter\gcms\1\ sequence_info.log      (1 is the instrument number if you have more than one configured )

  • 0 in reply to paulsalverda

    I will check for the blinking light the next time it happens. I believe there is, but I can't remember for sure. Before I get the sequence log, does it have to be from a sequence that this occurred on or can it be any sequence? 

    Solvent washes: 2 Solvent A, 2 solvent B

    Sample washes: 2

    Sample pumps: 4

  • 0 in reply to EKKemble

    If there is a blinking led on the tower, there is a fault at the sampler tower. See page 256-258 in the 7693 Installation, Operation, and Maintenance manual.  G4513-90010.pdf (agilent.com) 

    Yes, to troubleshoot a sequence error the sequence log from the sequence that had the error is required.

    The more washes and pumps, the better, up to a point. The injector uses solvent washes, sample washes, and sample pumps to control carryover. Each of these actions reduces the amount of sample left in the syringe.  The optimum number depends on the amount of carryover you can accept, the viscosity and solubility of the analyte(s), the viscosity and volatility of the solvent(s), the degree of wear in the syringe barrel, and the wash volume.  Four to six of each wash, A, B, and Sample, works well.  SIx pumps. 2 seconds viscosity delay has been proven to improve reproducibility.

    There is a solvent saver mode where you can choose to use less than full syringe volume for the washes. This requires a PTFE tipped syringe plunger.

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