IonSense, Inc
  January 2012   
What's New with DART? 
The latest developments and news on DART Mass Spectrometry


Greetings!,

We have recently analyzed some explosives with DART and accurate mass, using automated analysis to optimize the method.  Additionally we have the next installment of Danika DART's adventures in chemical analysis.

We have noticed a real increase in the number of publications describing the utility of DART.  If you have a recent publication on DART, please let me know and we'd be happy to feature it in our next newsletter.  We will also be publishing an updated DART Bibliography next month, so be sure to have your publications included.

Please have a look and contact me if you have any questions or comments. Thanks.


Regards,

BM signature

Brian Musselman
President and CEO
IonSense, Inc.
  Explosive DART Data and Method Optimization   

Explosives were among the first chemicals sampled using DART back in 2005.  We revisited the topic recently using our iPod automation method with the DART-SVP and X-Z Scanner to determine the optimum gas temperature for desorption.  Since we do not typically know the ideal temperature for generating high quality mass spectra of these compounds, we spotted small aliquots of some dangerous materials on the X-Z sampling screen.  We then analyzed them while varying the DART gas temperature, without operator intervention.  Accurate mass data were collected providing very high specificity and improving confidence in the results.  

   

For these experiments a DART-SVP was interfaced to the Thermo Exactive Orbitrap for High Mass Resolution screening of PETN and RDX.  The analytes were prepared at a final concentration of 1 g/mL (1 ppm) from reference standards.  The samples were spotted (5 L per sample spot) directly onto a stainless steel mesh support for direct transmission mode analysis with DART.
XZ Spotting 
XZ in Exactive




The X-Z scanner Experiment Module
is controlled by the DART Automated Software Method operated via the iPod Touch.  The X-Z scanner was used to run an automated temperature ramping method that analyzed the samples at 175, 200 and 225C DART heater temperatures.  This provides a thermal profile and enables the optimum temperatures to be selected. 

  

The Thermo Exactive was operated with external mass calibration performed before analyses, and all analytes had ~1 ppm mass accuracy.  The instrument was run in negative mode with resolution of 50,000.  Dichloromethane (CH2Cl2) was used as a dopant during the DART analysis to promote ionization and the formation of the [M+Cl]- ion.  The vapor from small vial of CH2Cl2 was enough to promote Cl-adduct formation.    

In the Figure below you can see how the higher temperature provided superior signal intensity for the PETN.  These samples were analyzed for 5 seconds at a time, and the exact positioning and timing provides good reproducibility as well.
 

PETN Data 
 
 
  

   

 

  

 

  








Of course, with the accurate mass analysis of the Orbitrap, high specificity is obtained.  Below you can see the RDX mass accuracy obtained in this screening method with the  experimental data in the bottom and the calculated in the top. 




Bad Drugs?  - Danika to the Rescue 
.Bad RX


The Latest adventure of Danika DART has her attack the growing problem of counterfeit pharmaceuticals. 
Sometimes you get what you pay for - caveat emptor

Click on the picture or here to view.
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About IonSense  
IonSense, Inc. provides open-air mass spectrometry solutions to the fields of food safety, forensics, drug development, and chemical analysis. They manufacture and develop direct analysis in real time (DART) technology licensed from JEOL USA, Inc. and atmospheric solids analysis probe (ASAP™) licensed from M&M Consulting.

DART and ASAP Sources are available for most commercial LC/MS systems.  Look here to see if your system is DART-ready.  And  check here to see if your system is ASAP-ready.