Gerstel: Intelligent Automation for GC/MS and LC.MS

Automated Online Desorption and Analysis of DNPH Derivatives of Airborne Aldehydes and Ketones

The analysis of airborne aldehydes and ketones first involves collection of the analytes by passing air through a cartridge containing 2,4-dinitrophenylhydrazine (DNPH). As the air passes through the cartridge, the analytes react with the DNPH to form hydrazones which are immobilized on the cartridge. The cartridges are then eluted with solvent and the DNPH derivatives determined using HPLC with UV detection.

The GERSTEL MultiPurpose Sampler (MPS) can be configured with a special tray to hold DNPH cartridges, enabling efficient automation of the entire process of desorbing the analytes and injecting the eluate into the LCUV system. Automating the desorption of these cartridges can significantly improve both accuracy and reproducibility. In addition, the risk of operator error is reduced. The MAESTRO software PrepAhead function enables desorption of a cartridge during the chromatographic separation of the previously injected sample. This means that the next sample is always prepared and ready to be injected as soon as the HPLC system has completed the previous analysis, ensuring maximum sample throughput.

In this report, the automation of the online desorption and analysis of DNPH derivatives by the robotic autosampler is discussed. Examination and calibration for a variety of aldehyde- and ketone-DNPH derivatives is described. Finally, DNPH cartridges used to collect samples from representative matrices are desorbed and analyzed online and the resulting data provided.

As a result of this study, it is shown that:

  •  Fully automated desorption from DNPH cartridges and HPLC determination of derivatized carbonyl compounds was successfully performed using the dual head GERSTEL MultiPurpose Sampler (MPS DH) combined with an HPLC-UV system. 
  •  The air samples were reliably and reproducibly collected using a hand-held air sampler.
  •  Previously published studies were expanded to include additional aldehyde and ketone DNPH derivatives from plywood and car interior air samples.
  •  Linear calibration curves resulting in R2 values of 0.99 or greater were obtained based on injection of the calibration standards.

Please review the full study for further details