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A METHOD FOR AUTOMATED ANALYSIS OF 10 ML WATER SAMPLES CONTAINING ACIDIC, BASIC, AND NEUTRAL SEMIVOLATILE COMPOUNDS LISTED IN USEPA METHOD 8270 BY SOLID PHASE EXTRACTION COUPLED IN-LINE TO LARGE VOLUME INJECTION GAS CHROMATOGRAPHY/MASS SPECTROMETRY
Citation:
Kovacs, D. A. A METHOD FOR AUTOMATED ANALYSIS OF 10 ML WATER SAMPLES CONTAINING ACIDIC, BASIC, AND NEUTRAL SEMIVOLATILE COMPOUNDS LISTED IN USEPA METHOD 8270 BY SOLID PHASE EXTRACTION COUPLED IN-LINE TO LARGE VOLUME INJECTION GAS CHROMATOGRAPHY/MASS SPECTROMETRY. Presented at EPA Region VI QA Conference, Dallas, TX, 10/24/2003.
Description:
Data is presented showing the progress made towards the development of a new automated system combining solid phase extraction (SPE) with gas chromatography/mass spectrometry for the single run analysis of water samples containing a broad range of acid, base and neutral compounds listed in USEPA Method 8270. 10 mL samples are transferred automatically to 10mm od X 2mm id SPE cartridges from a Spark Holland Triathalon autosampler using Prospekt 2 syringe pump delivery (HPD) and automated cartridge exchange (ACE). After passing the water sample through the SPE cartridge the sorbent is dried with helium and extracted with 105 uL of 80% methyl tert-butyl ether (MTBE) - 20% n-pentane mixture. This extract is pumped directly, via a 100 uM id fused silica capillary tube, to a large volume GC injection port (LVI) (ATAS GL International B.V., Optic 3) coupled to a 6890 gas chromatograph and 5973 MSD mass spectrometer (Agilent Technologies).
Most compounds in the Method 8270 list were successfully analyzed using a recently developed "universal" SPE sorbent, the Varian "Focus". A second new sorbent, the Phenomenex "Strata X" also shows promise, in early trials. At the present time, however, the largest polyaromatic hydrocarbons (PAHs, such as chrysene and larger) present a problem for analysis, showing low recovery and unacceptable variance. Additional studies with these sorbents are underway to correct this limitation in the method. Experimental results indicate that for the full compliment of Method 8270 PAHs, only, the Spark Holland sorbent "Hyspere C18HD 7 uM" works well with this equipment.
Advantages to this method include small sample volume (10 mL), low volumes of organic solvents used (6 mL methanol, 3 mL MTBE, 1 mL n-nonane), high sensitivity (calibration range used sample concentrations of 0.5 - 15 ug/L, 0.5 ug/L phenol S/N = 650), 32 sample autosampler tray for overnight operation (sample turnaround = 43 min.). Additional work is necessary to optimize the use of "universal" SPE sorbents for the novel application of in-line GC analysis.