Large Volume Injection Liquid Chromatography Tandem Mass Spectrometry for Organic Contaminants in Aqueous Samples and Organic Extracts

Oral Presentation

Prepared by A. Robel, J. Field
Oregon State University, 1500 SW Jefferson St., Corvallis, Oregon, 97331, United States


Contact Information: robela@oregonstate.edu; 541-737-2267


ABSTRACT

Solid phase extraction (SPE) was developed as an alternative to liquid-liquid extraction for sample preparation to concentrate organic analytes from water for analysis by gas chromatography in the 1970's. SPE came into use for the concentration of polar analytes when liquid chromatography tandem spectrometry (LC-MS/MS) became commercially available in the late 1990s and early 2000's. The early LC-MS/MS systems required low flow rates (mL/min), which was incompatible with large volume injections (LVI) that can accommodate higher (mL/min) flow rates, effectively halting the development and application of LVI in LC-MS applications. Oregon State University ‘rediscovered’ LVI in 2001 by purchasing commercially available LVI hardware for an Agilent 1100. The kit includes a 900 ?L analytical head and seat capillaries, and 6 mL capacity autosampler vials. Additional hardware modifications include use and operation of the mainpass/bypass valve on the LC, and the divert valve on the MS/MS which are critical for control over LVI systems. From both a theoretical and practical perspective, concentrating polar analytes from aqueous matrices by SPE and then separating the analytes on analytical columns is ‘chemically redundant.’ For example, reverse-phase SPE sorbents, which are characterized by large particles sizes (e.g., 40 mm), cannot separate analytes from matrix components that co-elute on a reverse-phase analytical column comprised of smaller particles (e.g., 5 mm). Highlighted examples of LVI for aqueous samples will include the determination of illicit drugs in wastewater effluent (1,800 ?L), and surfactants in Corexit oil dispersant in seawater (1,800 ?L). Examples of LVI for large volumes (900 ?L) organic extracts include the analysis of per- and polyfluoroalkyl substances in extracts of landfill leachates and groundwater obtained by micro liquid-liquid extraction. The cost savings and the ‘green’ aspects of LVI will also be compared to SPE.