|Automated combination of Purge & Trap with common GC-MS Injection techniques according to EPA Methods 524.2 and 8260 on the PAL automation platform.
|Automating Complex Sample Workflows
|Dr Stefan Cretnik
|Mr Xiaohui Zhang
Mr Stephen Swesson
Abstract Information :
In recent years, the need for analytical flexibility in sample preparation and analyses has risen. The PAL System is a state-of-art direct sample preparation and injection system capable of providing a wide array of sample introduction techniques for GC and GC-MS. These techniques include: liquid injection, SPME, and Headspace. However, when a customer needed more sensitivity, they had to turn to another technique, Purge & Trap, on another system. The instrumentation was now developed to combine all these techniques on one platform, using the CDS 7000C Purge and Trap concentrator and the PAL RTC Autosampler. The analytical performance was evaluated on aqueous Volatile Organic Compounds (VOC) according to EPA Method 524.2 and 8260.
For the first time, the combination of Purge and Trap could be evaluated together with Headspace, ITEX Dynamic Headspace, and SPME with fully automated switch between the methods. A 64 component mix was used demonstrating linearities better than 0.999 for most analytes. For the new PAL Purge and Trap solution, the RSD of the response factors of the gaseous compounds ranged from 6.8% - 12.4%, and those of BTEX ranged from 2.8% - 8.5%. The reproducibility of the internal standards response for a 5 day period was < 4.0 %. Carryover from a 200 ppb standard to a blank was <1.0% for VOCs; and <2.5% for analytes with high boiling points above 200°C.
With the first-time combination of CDS 7000C P&T concentrator with PAL RTC Autosampler, analytical performances of different injection techniques were evaluated. These measurements took benefit from the complete automation, including calibration dilution, internal standard addition and switch between the different injection techniques. Excellent performance for VOCs determination in water were able to reach according to EPA Method protocols 524.2 and 8260.