ADV01-05_1-298

196 / 298

• 7 •
EPA Method 528 is a solid phase extraction
(SPE)/gas chromatography/mass spectrometry
screening method developed to measure 12 envi-
ronmentally important phenols in drinking water
and determine whether to regulate these contami-
nants in order to protect public health. Method 528
is an improvement over previous methods because
MS affords positive identification of all 12 phenols
without need for confirmation.*
Method 528 detection limits for phenols range from
0.02-0.58µg/L—concentrations below those need-
ed for drinking water monitoring, based on current
health effect information. Figure 1 illustrates an
analysis of the 12 phenols, at a concentration of
5ng/L. Several critical steps enable us to obtain
excellent peak shape and sensitivity at this low con-
centration:
1.Phenols tend to break down in the injection port
and exhibit excessive tailing and poor sensitivity.
We minimized contact with metal surfaces by
using a Drilled Uniliner® liner.** A press-tight
seal between the column and the liner eliminates
sample contact with the inlet seal. This improves
peak shape and increases sensitivity, relative to
other hot injection techniques.
2.Reducing the injection port temperature from
330°C to 220°C also contributed to transfer of
the phenols to the column with minimal thermal
degradation.
3.A pulsed splitless injection (50psi, 0.5 min.) rap-
idly transfers the analytes to the column inlet.
set the initial temperature to 40°C to prevent
excessive tailing for the early eluting phenols.
5. All 12 phenols elute during the first temperature
ramp of 12°C/min.; the second ramp to 300°C
bakes out high molecular weight contamination.
The Rtx®-5Sil MS column performs at this high tem-
perature with low bleed and excellent inertness.***
We have developed a full set of standards for
Method 528—calibration standard, internal stan-
dard, analyte fortification solution, surrogate stan-
dard, and GC/MS tune check solution. MS sensitivity
to four of the phenols is significantly less than for
the others, so we incorporate these at a higher con-
centration, 500µg/mL, in the fortification solution.
Some of the substituted phenols exist as isomers
that have similar mass spectra, but can be differen-
tiated by retention time. The only coelutions are
deuterated surrogates, which do not share common
ions with the target analytes.
Because of the potential problems associated with
these analytes, Method 528 calls for a low bleed
column that provides adequate analyte separation.
Rtx®-5Sil MS column performance is characterized
by low bleed, excellent inertness, and high maxi-
mum operating temperature. A Drilled Uniliner®
liner significantly reduces the loss of active com-
pounds and ensures more precise results.
by Christopher English, Environmental Innovations Chemist, and Katia May, Ph.D., R&D Chemist
GC/MS Screening for Phenols
Using an Optimized Analysis
✔ Full complement of reference materials for US EPA Method 528.
✔ Fortification solution formulated based on MS sensitivity to each analyte.
✔ Rtx®-5Sil MS column allows phenols identification at 5ng on-column.
4-chloro-3-methylphenol
2-chlorophenol
o-cresol
2,4-dichlorophenol
2,4-dimethylphenol
2,4-dinitrophenol
2-methyl-4,6-dinitrophenol
2-nitrophenol
4-nitrophenol
pentachlorophenol
phenol
2,4,6-trichlorophenol
2,000µg/mL each in methylene chloride, 1mL/ampul
Phenol Calibration Mix 1, EPA 528
Each 5-pk. 10-pk.
31694 31694-510
w/data pack
31694-500 31694-520 31794
3-nitro- o-xylene 1,000µg/mL
2,3,4,5-tetrachlorophenol 2,000µg/mL
In methylene chloride, 1mL/ampul
Internal Standard Mix, EPA 528
Each 5-pk. 10-pk.
31696 31696-510 —
w/data pack
31696-500 31696-520 31796
4-chloro-3-methylphenol 100µg/mL
2-chlorophenol 100
o-cresol 100
2,4-dichlorophenol 100
2,4-dimethylphenol 100
2,4-dinitrophenol 500
2-methyl-4,6-dinitrophenol 500
2-nitrophenol 100
4-nitrophenol 500
pentachlorophenol 500
phenol 100
2,4,6-trichlorophenol 100
In methanol, 1mL/ampul
Phenols Fortification Mix, EPA 528
Each 5-pk. 10-pk.
31695 31695-510
w/data pack
31695-500 31695-520 31795
2-chlorophenol-d4 1,000µg/mL
2,4-dimethylphenol-d3 1,000
2,4,6-tribromophenol 2,000
In methanol, 1mL/ampul
Surrogate Standard Mix, EPA 528
Each 5-pk. 10-pk.
31697 31697-510
w/data pack
31697-500 31697-520 31797
decafluorotriphenylphosphine (DFTPP)
2,500µg/mL in methylene chloride, 1mL/ampul
SV Tuning Compound
Each 5-pk. 10-pk.
31001 31001-510
w/data pack
31001-500 31001-520 31101
Figure 1
Excellent sensitivity and peak shape for phenols at 5ng on-column, using an Rtx®-5Sil MS column
and Restek reference materials.
6 7 8 9 10 11 12 13 14 15
15
16
13
14
17
9 11
10 12
5
1
2,3
4 8
6 7
GC_EV00664
1. phenol
2. 2-chlorophenol-3,4,5,6-d4 (SS)
3. 2-chlorophenol
4. 2-methylphenol
5. 2-nitrophenol
6. 2,4-dimethylphenol-3,5,6-d3 (SS)
7. 2,4-dimethylphenol
8. 2,4-dichlorophenol
9. 4-chloro-3-methylphenol
10. 1,2-dimethyl-3-nitrobenzene (IS#1)
11. 2,4,6-trichlorophenol
12. 2,4-dinitrophenol
13. 4-nitrophenol
14. 2,3,4,5-tetrachlorophenol (IS#2)
15. 2-methyl-4,6-dinitrophenol
16. 2,4,6-tribromophenol (SS)
17. pentachlorophenol
* Requirements for testing and analysis are outlined in Number 40 Code of Federal Regulations (CFR), Chapter 1, Part 141.40.
**For more information about Drilled Uniliner ® inlet liners, see page 13.
***Rtx ®-5Sil MS columns are listed on page 5.
Rtx®-5Sil MS 30m, 0.25mm ID, 0.25µm (cat# 12723)
US EPA Method 528 analytes, 1µL, 5ppm
Phenol Calibration Mix 1, EPA 528 (cat# 31694)
Internal Standard Mix, EPA 528 (cat# 31696)
Surrogate Standard Mix, EPA 528 (cat# 31697)
Inj.: 1.0µL pulsed splitless (hold 0.5
min.), 4mm Drilled Uniliner®
(cat.# 21055), pulsed pressure
50psi for 0.5 min.
GC: Agilent 6890
Inj. temp.: 220°C
Carrier gas: helium, constant flow
Flow rate: 1.3 mL/min.
Oven temp.: 40°C (hold 1 min.) to 220°C @
12°C/min. (hold 0 min.) to 300°C
@ 30°C/min (hold 1 min.)
Det: Agilent 5973 GC/MS
Transfer line temp.: 280°C
Scan range: 35-550 amu
Solvent Delay: 5.5 min.
Tune: DFTPP
Ionization: EI