ADV06-15_1-412

83 / 413

| 800-356-1688 | Feedback? E-mail 17
The typical procedure for preparing samples according to EPA
Method 527 involves extracting a 1 L water sample, drying the
extract, and concentrating it down to a final volume of 1 mL. To
determine if using CSR-LVSI could eliminate the need for extract
concentration, linearity and recovery were assessed. Water samples
were fortified at 0.1 µg/L and 1 µg/L levels and then extracted using
Resprep® resin SPE disks, dried with anhydrous sodium sulfate, and
diluted to 25 mL with methylene chloride:ethyl acetate (1:1). This
differs from the method, which calls for the samples to be concen-
trated to 1 mL after drying. In order to achieve the detection limits
described in the method, a 12.5 µL injection volume was used.
Linear Responses for Challenging Compounds
Using CSR-LVSI
Calibration curves were built using duplicate 12.5 µL injections of
2, 4, 10, 20, 40, and 80 pg/µL standards. All compounds exhibited
good linearity down to 2 pg/µL, which is equivalent to 25 pg on-
column and 0.05 µg/L in the original water sample (Table I). Results
for Kepone (r = 0.995) are especially notable, as it can be problematic
due to the formation of a hemiacetal that chromatographs poorly.
Good chromatographic separations were obtained using a 15 m x
0.25 mm x 0.25 µm Rxi®-5Sil MS column, and the fast oven program
resulted in an analysis time of less than 10 minutes (Figure 1).
Determine Sub-ppb Levels Without Extract
Concentration
The average recovery for all compounds for the 1 µg/L (500 pg on-
column) and 0.1 µg/L (50 pg on-column) spikes were quite good at
94% and 80%, respectively (Table II). Individual recoveries met EPA
Method 527 criteria, except for the 0.1 µg/L value for hexabromobi-
phenyl 153 (BB-153) and the 1.0 µg/L value for prometryne. Recovery
Figure 1: Extracted ion chromatogram of 80 pg/µL standard from 12.5 µL CSR-LVSI injections.
350 400 450 500 550 Time (s)
1
2
3
4
5
6
7
8
9
10
11
12
13 14
15 16 17
GC_EV1215
Column : Rxi®-5Sil MS, 15 m, 0.25 mm ID, 0.25 µm (cat.# 13620) using IP
Deactivated Guard Column 5 m, 0.53 mm ID (cat.# 10045) with Universal
Press-Tight® Connectors (cat.# 20429); Sample: PBDE Mix (cat.# 33098);
Pesticides Mix #1, Method 527 (cat.# 33007); Pesticides Mix #2, Method
527 (cat.# 33008); Internal Standard, Method 527 (cat.# 33010); Surro-
gate Standard, Method 527 (cat.# 33009); Diluent: ethyl acetate:methylene
chloride (1:1); Conc.: 80 pg/µL (1 ng on-column); Injection: Inj. Vol.: 12.5
µL splitless (hold 0.583 min.); Liner: Gooseneck Splitless (4 mm) w/
Semivolatiles Wool (cat.# 20799-231.5); Inj. Temp.: 250 °C; Purge Flow:
40 mL/min.; Oven: Oven Temp: 40 °C (hold 0.60 min.) to 320 °C at 30 °C/
min. (hold 1.07 min.); Carrier Gas : He, constant flow; Flow Rate: 2 mL/
min.; Detector: MS; Instrument: LECO Pegasus 4D GCxGC-TOFMS;Notes:
Carrier Gas Flow: 2 mL/min. corrected constant flow via pressure ramps
Peaks
1. Atrazine
2. Vinclozoline
3. Malathion
4. Chlorpyrifos
5. Terbufos sulfone
6. Nitrofen
7. Kepone
8. Norflurazon
9. Triphenyl phosphate
10. Bifenthrin
11. BDE-47
12. Mirex
13. BDE-100
14. BDE-99
15. Fenvalerate
16. Esfenvalerate
17. BDE-153
Rxi®-5Sil MS Columns (fused silica)
(low polarity Crossbond® silarylene phase; similar to 5% phenyl/95%
dimethyl polysiloxane)
Description temp. limits cat.#
15m, 0.25mm ID, 0.25µm -60 to 330/350°C 13620
Resprep® Resin SPE Disks
Description qty. cat.#
Resprep Resin SPE Disks 20-pk. 26023
results demonstrated that employing CSR-LVSI and eliminating the
concentration step can be an effective way to meet detection limits
while reducing sample preparation time by more than an hour.
Summary
When the extract concentration step was eliminated, good linearity
and recovery results were obtained while sample preparation time
was significantly reduced. CSR-LVSI with an unmodified Agilent split/
splitless GC inlet has been shown to be a technically viable approach
that has the advantage of speeding up sample preparation without
compromising sensitivity for pesticides and BFRs in drinking water.
For the complete version of this technical article, visit
References
[1] P. Magni, T. Porzano, J. Sep. Sci. 26 (2003) 1491.
[2] Patent No: US 6,995,709 B2.
[3] U.S. Environmental Protection Agency, Method 527, Determination of Selected
Pesticides and Flame Retardants in DrinkingWater by Solid Phase Extraction and
Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS), April 2005.
Website : E-Mail : TelNo : 03 9762 2034 . . . in AUSTRALIA