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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
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
This work compares modifications of EPA Method 525.2
intended to improve analyte recoveries.
Can methylene chloride be used as the extraction
solvent?
Do pre-filters improve extraction efficiency and
reproducibility?
Does nitrogen gas drying enhance analyte recoveries?
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.
Zymark Acenaphthene-d10 Phenanthrene-d10 Chrysene-d12
Spike # % Recovery % Recovery % Recovery
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
Mean 95 Mean 101 Mean 105
Std Dev Std Dev Std Dev
Whatman GMF Filter & Empore Disk vs. Plain Empore Disk
Drinking Water Matrix Samples-8 Minutes Ambient Air Drying
Data Acenaphthene-d10 Phenanthrene-d10 Chrysene-d12
Name % Recovery % Recovery % Recovery
Whatman Empore Whatman Empore Whatman Empore
GMF Filter Disk GMF Filter Disk GMF Filter Disk
2757 97 66 98 76 104 83
2759 68 72 70 77 79 84
2760 96 84 92 88 96 86
2761 94 83 95 88 102 89
2762 92 78 100 84 107 85
2763 93 79 96 83 105 85
2764 94 87 101 89 110 91
2765 87 79 93 85 101 86
2766 94 92 102 92 105 90
2767 90 74 97 80 94 76
Mean 91 79 94 84 100 86
Std Dev 8.0 7.2 8.7 5.0 8.4 4.0
PAE and PAH % Recovery- - - - - Laboratory Fortified Blanks
Whatman GMF Filter and Empore Disk - - - Ambient Air Drying
Avg STD
ANALYTE #1 #2 #3 #4 #5 #6 #7 #8 #9 #10
% rec. Dev
Naphthalene 100 91 101 99 85 88 101 99 89 90 94 5.9
Dimethyl phthalate 109 105 96 110 103 100 104 111 111 115 106 5.5
Acenaphthylene 99 90 101 98 103 99 96 101 75 88 95 8.1
Acenaphthene 99 98 103 95 85 97 99 100 95 95 97 4.6
Diethyl phthalate 126 126 110 109 113 114 121 118 124 133 119 7.5
Fluorene 106 105 102 105 105 95 103 102 97 110 103 4.1
Phenanthrene 104 102 102 98 101 96 100 104 95 93 100 3.6
Anthracene 103 107 105 108 108 105 111 106 97 91 104 5.6
Di-n-butyl phthalate 109 116 109 113 113 114 109 112 108 108 111 2.7
Fluoranthene 103 105 97 98 107 105 94 97 98 95 100 4.4
Pyrene 105 112 101 102 104 102 96 98 100 98 102 4.3
Butylbenzyl phthalate 108 116 97 108 108 105 105 113 100 114 107 5.7
Bis(2-ethylhexyl) adipate 78 106 93 93 100 109 95 92 102 105 97 8.6
Benzo[a]anthracene 98 101 100 110 96 99 93 97 93 94 98 4.8
Chrysene 98 98 97 93 102 97 102 99 95 101 98 2.8
Bis(2-ethylhexyl)phthalate 87 92 96 103 98 102 117 97 109 115 102 9.2
Di-n-octyl phthalate 87 101 82 99 107 114 102 79 90 102 96 10.7
Benzo[b]&[k]fluoranthene 93 98 95 95 97 96 97 94 90 101 96 2.8
Benzo[a]pyrene 95 97 99 103 98 101 96 89 90 88 96 4.9
Indeno[1,2,3-cd]pyrene 87 94 88 89 89 101 96 78 81 99 90 7.0
Dibenzo[a,h]anthracene 75 84 81 80 81 74 88 67 73 78 78 5.7
Benzo[g,h,i]perylene 84 80 85 80 94 95 90 63 83 78 83 8.7
Sample Concentration Using a A “helical flow” of
air is created by the
Zymark TurboVap II 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
Varian Saturn II Mass Spectrometer
Varian Star 3400 GC with SPI Injector
Varian 8200 Autosampler
Solid Phase Extraction
Materials Evaluated
3M Empore™ Octadecyl (C-18) Extraction Disks
3M Empore™ Filter Aid 400 High Density Glass
Beads
Whatman ® Glass Microfiber (GMF) Filters, 2 um
Nitrogen Gas Drying - - Empore Disk and Whatman GMF Filter
Manifold
Tuna Can
Regulator
Glass Funnel
Gas Tank
Aluminum Clamp
Whatman GMF Filter
Empore Disk
Support Screen
PTFE Gasket
Glass
Support Base
Empore Disk and Empore Disk Empore Disk
Whatman GMF Filter and Filter Aid
Glass
Glass Glass Funnel
Funnel Funnel
Aluminum Aluminum
Clamp Aluminum Clamp
Clamp
Whatman Filter Aid
GMF Filter Empore
Empore Disk Empore
Disk Disk
Support
Support Screen Support
Screen Screen
PTFE PTFE PTFE
Gasket Gasket Gasket
Glass Glass Glass
Support Support Support
Base Base Base
Acenaphthene-d10 Recovery
Whatman GMF Filter & Empore Disk vs. Empore Disk
Ambient Air Drying
120
100
% Recovery
80
60
Whatman GMF + Empore Disk
40
Empore Disk
20
0
1 2 3 4 5 6 7 8 9 10
Chrysene-d12 Recovery
Whatman GMF Filter & Empore Disk vs. Empore Disk
Ambient Air Drying
120
100
80
% Recovery
60
40 Whatman GMF + Empore Disk
Empore Disk
20
0
1 2 3 4 5 6 7 8 9 10
Phenanthrene-d10 Recovery
Whatman GMF Filter & Empore Disk vs. Empore Disk
Ambient Air Drying
120
100
% Recovery
80
60
40 Whatman GMF + Empore Disk
Empore Disk
20
0
1 2 3 4 5 6 7 8 9 10
Acenaphthene-d10 Recovery
105
90
% Recovery
75
Empore Disk
Empore Disk & Filter Aid
60 N2 Drying 5 min, 20 psi Whatman GMF & Empore Disk
N2 Drying 5 min, 30 psi Whatman GMF & Empore Disk
N2 Drying 8 min, 25 psi Whatman GMF & Empore Disk
N2 Drying 8 min, 30 psi Whatman GMF & Empore Disk
45
0 2 4 6 8 10 12
Phenanthrene-d10 Recovery
105
90
% Recovery
75
Empore Disk
Empore Disk & Filter Aid
N2 Drying 5 min, 20 psi Whatman GMF & Empore Disk
60
N2 Drying 5 min, 30 psi Whatman GMF & Empore Disk
N2 Drying 8 min, 25 psi Whatman GMF & Empore Disk
N2 Drying 8 min, 30 psi Whatman GMF & Empore Disk
45
0 2 4 6 8 10 12
Chrysene-d12 Recovery
105
90
% Recovery
75
Empore Disk
Empore Disk & Filter Aid
60 N2 Drying 5 min, 20 psi Whatman GMF & Empore Disk
N2 Drying 5 min, 30 psi Whatman GMF & Empore Disk
N2 Drying 8 min, 25 psi Whatman GMF & Empore Disk
N2 Drying 8 min, 30 psi Whatman GMF & Empore Disk
45
0 2 4 6 8 10 12
Average Internal Standard
% Recovery Comparison
Acenaphethene-
d10
Phenanthrene-
d10
Chrysene-d12
0 20 40 60 80 100
Whatman GMF & Empore Disk
N2 Drying, 8 min/25 psi Whatman GMF & Empore Disk
N2 Drying, 8 min/30 psi Whatman GMF & Empore Disk
Filter Aid and Empore
Empore Disk
N2 Drying, 5 min/20 psi Whatman GMF & Empore Disk
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.
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