Automated Online Desorption and Analysis of DNPH Derivatives of Formaldehyde, Acetaldehyde, and Related Carbonyl Compounds using a New Robotic Autosampler


App Note 195/2017

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 can be determined using HPLC with UV detection.

The new GERSTEL MPS roboticPRO sampler with a dedicated tray to hold DNPH cartridges enables the entire process of eluting the analytes and injecting the eluate into the LC-UV system to be easily controlled. Automating the elution of these cartridges can result in significant improvement in accuracy and reproducibility as well as reduced potential for operator error. An integrated Balance Option allows weight data to be automatically collected following cartridge elution to further improve the accuracy of the exported results. The intuitive software includes tools that allow the elution of a cartridge to take place during the chromatographic separation of a previously injected sample to ensure maximum sample throughput.

In this report, the complete automation of the online elution, introduction of the eluate to the analysis system, and determination of the DNPH derivatives of the airborne aldehydes and ketones is presented. Performance evaluation and calibration for a variety of aldehyde- and ketone-DNPH derivatives is described. Finally, analytes from air sampled onto DNPH cartridges from representative matrices are eluted and determined online and the resulting precision data presented.