effect of acetonitrile as dissolving solvent for samples on gc column or on quad?

HI everyone

my friends tooled me that  acetonitrile as dissolving solvent for samples on GC/MS has bad effect on stationary phase of column or on quad of ms

I tried to search it but did not find any thing 

some regional engineers who worked at regional agilent services in Egypt tolled me that is true on the practical way and there is no any theoretical principle or guidelines for that

so i am very confused because on theoretical bases there is no bad effect on using acetonitril 

so any help in that topic I appreciate  it

  • From the GC side:

    Acetonitrile as the GC Injection Solvent

    • Large expansion volume
    • Not compatible with relatively non-polar GC stationary phases
    • Forms droplets rather than a continuous film upon recondensation in the GC column, causing peak distortions for early eluting analytes
    • Splitless injection: the initial oven temperature has to be at or above its boiling point (e.g. at 90°C) to prevent acetonitrile condensation in the GC column
    • PTV (programmable temperature vaporizer) with solvent vent – ideal to eliminate acetonitrile from the inlet prior reaching the GC column
    • Alternative approach: solvent exchange into toluene (or adding toluene to the acetonitrile extract)

    (NACRW, Agilent Users Meeting, July 25, 2013)

    "Acetonitrile is not a suitable solvent for a nonpolar GC column such as the HP-5ms Ultra Inert. Due to the polarity difference, acetonitrile could not wet the stationary phase very well. This caused peak splitting when using the oven program for solvent focusing, especially with the early eluters.  As a result, the LVI optimization process was centered to achieve better recovery and peak shape of early eluting pesticides."   5991-1196EN_5989_5672.qxd (agilent.com)

    From the MS side:

    Acetonitrile was tested in 1999 as a very alternative Chemical Ionization reagent gas on Agilent GCMSs.  5968-5707.indd (fortlewis.edu)  

    " Into a 2 mL vial, mix 25 fold diluted extract with 100% high purity, pesticide grade acetonitrile in a 1-to-5 proportion resulting in a 125 fold dilution factor. Vortex for 10 seconds. The sample is now ready for injection on the GC/MS/MS system. "  application-california-cannabis-pesticides-gc-ms-ms-5994-1019en-agilent.pdf

    There are solvents, matrices, and samples that require quite specific methodology, columns, sample preparation, etc.  It is easiest to equate "Acetonitrile is a pain on a GCMS" with "Don't use acetonitrile on a GCMS."  That does not mean it won't work, but it does mean that you may have trouble getting it to do exactly what you want and making a robust method that handles its unique characteristics.

  • From personal experience, running a single injection that was reconstituted in acetonitrile and MTBSTFA made the column bleed ions (m/z 207) on a DB-1ms column go from ~500 abundance (on hexane injections or no injection blanks after removing needle) to over 9 million... likely indicating loss of stationary phase of the column. The column was no longer useful for other assays that actually utilized the stationary phase of the column, but continued to "work" for the acetonitrile samples. That being said, acetonitrile blanks still looked like crap in full scan with lots of peaks. Not to mention how quickly the repeller voltage maxes with this assay (need to clean the source). 

    My suggestion is to avoid acetonitrile in the assay development stage to avoid the headaches later. Just because you can find literature using acetonitrile injections with GCMS for assays that "work" doesn't mean it is the best way to go about things. 

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