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Arkansas Department of HealthDivision of Public Health Laboratories: 

Arkansas Department of Health Division of Public Health Laboratories Joe Mobley, Paula Barnes, Joseph Dussex Arkansas Department of Health, Organic Water Laboratory, 4815 West Markham, Little Rock, AR 72205 Himansu Javahar Vyas U.S. Vanadium, Strategic Mineral Technology Center, 4343 Malvern Road, Hot Springs, AR 71901

Introduction: 

Introduction EPA Method 525.2 employs ethyl acetate as the primary elution solvent for the extraction of SOCs (Synthetic Organic Compounds) in drinking water by solid phase extraction (SPE). Ethyl acetate replaced methylene chloride used in earlier versions of the method because it improved analyte recoveries. However, the use of ethyl acetate can greatly increase GC/MS instrument maintenance when performed with temperature programmable injections. The implementation of performance based methodology will allow modification of EPA methods. Phthalate acid esters (PAEs) and polyaromatic hydrocarbons (PAHs) are spiked into distilled water and extracted by SPE. The study uses a C-18 extraction disk with methylene chloride as the elution solvent. Spikes are extracted using C-18 disks only and C-18 disks with pre-filters. Two pre-filters and C-18 disks alone are presented. Additionally, drying the disks with nitrogen gas is evaluated. The study shows that analyte recoveries are improved so that methylene chloride alone can be used as the elution solvent.

Objective: 

Objective Can methylene chloride be used as the extraction solvent? Do pre-filters improve extraction efficiency and reproducibility? Does nitrogen gas drying enhance analyte recoveries? This work compares modifications of EPA Method 525.2 intended to improve analyte recoveries.

Extraction Apparatus: 

Extraction Apparatus Samples are extracted using six station Empore Extraction Manifolds. Nitrogen gas is delivered to the manifold from the gas outlet of a liquid nitrogen tank. The gas line runs through a high purity line regulator to a manifold. From the manifold, the gas line steps down from a 1/4 inch line to 0.5 mM i.d. Teflon tubing which runs through the top of a cleaned empty tuna can. The tuna can closely fits over the top of the extraction funnel. The Teflon line is looped inside the can so that the gas flow is diffused and does not directly blow onto the surface of the extraction disk.

Slide5: 

1 89 97 97 2 95 99 103 3 100 97 104 4 100 104 106 5 94 102 107 6 94 101 107 7 94 101 104 8 94 101 103 9 99 103 105 10 98 101 100 11 98 100 105 12 92 96 101 13 95 100 103 14 94 103 105 15 91 98 104 16 96 104 111 17 98 98 106 18 94 102 111 19 98 103 104 20 92 103 107 Zymark Spike # Phenanthrene-d10 % Recovery Acenaphthene-d10 % Recovery Chrysene-d12 % Recovery Mean 95 Std Dev 2.9 Mean 101 Std Dev 2.5 Mean 105 Std Dev 3.1

Whatman GMF Filter & Empore Disk vs. Plain Empore DiskDrinking Water Matrix Samples-8 Minutes Ambient Air Drying: 

Whatman GMF Filter & Empore Disk vs. Plain Empore Disk Drinking Water Matrix Samples-8 Minutes Ambient Air Drying

PAE and PAH % Recovery- - - - - Laboratory Fortified BlanksWhatman GMF Filter and Empore Disk - - - Ambient Air Drying: 

PAE and PAH % Recovery- - - - - Laboratory Fortified Blanks Whatman GMF Filter and Empore Disk - - - Ambient Air Drying

Sample Concentration Using a Zymark TurboVap II: 

Sample Concentration Using a Zymark TurboVap II A “helical flow” of air is created by the stream of gas directed into each sample tube. To evaluate analyte loss in the concentration step, internal standards are spiked directly into 25 mL methylene chloride in a 50 mL TurboVap tube and concentrated to the 1 mL mark using the sensor endpoint setting.

Instrumentation: 

Instrumentation Varian Saturn II Mass Spectrometer Varian Star 3400 GC with SPI Injector Varian 8200 Autosampler 3M Empore™ Octadecyl (C-18) Extraction Disks 3M Empore™ Filter Aid 400 High Density Glass Beads Whatman ® Glass Microfiber (GMF) Filters, 2 um Solid Phase Extraction Materials Evaluated

Slide10: 

PTFE Gasket Support Screen Aluminum Clamp Glass Funnel Whatman GMF Filter Empore Disk Tuna Can Manifold Regulator Gas Tank Glass Support Base Nitrogen Gas Drying - - Empore Disk and Whatman GMF Filter

Slide11: 

Empore Disk and Filter Aid Empore Disk Empore Disk and Whatman GMF Filter

Acenaphthene-d10 RecoveryWhatman GMF Filter & Empore Disk vs. Empore DiskAmbient Air Drying: 

Acenaphthene-d10 Recovery Whatman GMF Filter & Empore Disk vs. Empore Disk Ambient Air Drying

Chrysene-d12 RecoveryWhatman GMF Filter & Empore Disk vs. Empore Disk Ambient Air Drying: 

Chrysene-d12 Recovery Whatman GMF Filter & Empore Disk vs. Empore Disk Ambient Air Drying

Phenanthrene-d10 RecoveryWhatman GMF Filter & Empore Disk vs. Empore Disk Ambient Air Drying: 

Phenanthrene-d10 Recovery Whatman GMF Filter & Empore Disk vs. Empore Disk Ambient Air Drying

Acenaphthene-d10 Recovery: 

Acenaphthene-d10 Recovery

Phenanthrene-d10 Recovery: 

Phenanthrene-d10 Recovery

Chrysene-d12 Recovery: 

Chrysene-d12 Recovery

Average Internal Standard% Recovery Comparison: 

Average Internal Standard % Recovery Comparison

Conclusions: 

Conclusions Very little analyte loss occurs in the concentration step. Nitrogen gas drying does not significantly improve recoveries Extraction with the Empore disk produces excellent recoveries for the internal standards in laboratory fortified blanks. Extraction with Filter Aid and the Empore disk produces inconsistent and low internal standard recoveries for laboratory fortified blanks. Internal standard recoveries are improved and are most consistent for drinking water matrices extracted with the Whatman GMF filter and the Empore disk. PAE and PAH recoveries are excellent for laboratory fortified blanks extracted with the Whatman GMF filter and the Empore disk.