Comparison of GC-(NCI)MS, GC-(ICP)MS and GC-(EI)MS/MS for the determination of
PBDEs in water samples according to the requirements of the Water Framework Directive
Adriana Gonzalez-Gago, Daniel Proefrock and Andreas Prange. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung, Department of Marine Bioanalytical Chemistry,
Max Planck Str. 1, Geesthacht, Germany, D-21502; adriana.gonzalez@hzg.de
Introduction
Polybrominated diphenyl ethers (PBDEs) are a family of chemicals that have been widely used as flame retardants in a variety of polymeric materials and textiles. Owing to their persistance and their ability to bioaccumulate and biomagnify, PBDEs have been spread all around the world, being found in almost all environmental compartments. The
extensive contamination by PBDEs, together with their toxicity to living organisms, has led to their classification as Persistent Organic Pollutants (POPs), substances from which human health and the environment should be protected, according to the Stockholm Convention.
On a European level, PBDEs are regulated under the Water Framework Directive (WFD), which deals with the protection of water resources and aquatic environments. The WFD includes some PBDEs (congeners 28, 47, 99, 100 153 and 154) in the list of priority substances that need to be measured in surface waters and sets an Environmental
Quality Standard (EQS), or maximum allowable concentration, of 0.5 ng/L for the sum of the six priority congeners. Moreover, analytical methods must meet certain minimum performance criteria in terms of uncertainty (≤ 50% at EQS, 95% confidence) and limits of quantification (LOQ ≤ 30% of EQS) for a reliable determination of priority substances.
Most of the analytical methods developed and applied to the determination of PBDEs in different environmental samples are based in their detection by Mass Spectrometry (MS), since MS based methods usually provide adequate sensitivity and selectivity. However, existing methods still need to be improved in order to be able to detect the overall very
low concentrations of PBDEs in water meeting the challenging requirements defined by the WFD.
According to this, different MS techniques will be evaluated in terms of instrumental capabilities for the sensitive and reliable determination of PBDEs. Special attention will be paid to the GC-(ICP)MS coupling for being a promising technique to meet the challenging requirements of the WFD, as it shows good selectivity towards brominated compounds
and high sensitivity in the detection of bromine. The selected measurement technique will be applied to quantification of PBDEs by species specific isotope dilution analysis (SS-IDMS). Finally a traceable analytical method for the determination of PBDEs in a river water sample will be developed and validated.
Experimental
Sample preparation
Precision in the measurements
GC-(ICP)MS
Signal RSD (%)
50
WORKING CONDITIONS
Injector
Cold On-Column (oven track)
Retention gap
Siltek ® (3 m x 0.5 mm i.d.)
GC column
DB 5MS (15m x 0.25 mm i.d. x 0.1 µm film
thickness)
He, 2.6 mL min-1
Injection volume
1 µL
Temperature program
Sampling depth
6.0 mm
Rf power
750 W
Carrier gas flow rate
0.95 mL min-1
He, 2 mL min-1
Ions lens type
s-Lens
Additional plasma gas
N2, 50 psi
Measured isotopes/dwell
time
79Br
10
BDE153
Retention time
(min)
(0.1 s), 81Br (0.1 s)
Slope/103
L/µg
Correlation
coefficient
81
BDE 28
6.664
6.664
61.63
0-10
10.2
0.999990
BDE 47
7.331
7.331
51.63
0-10
11.5
0.999996
BDE 99
7.970
7.967
69.90
0-5
11.9
0.99997
BDE 100
7.814
7.814
57.21
0-5
11.5
0.99997
BDE 153
8.551
8.548
66.85
0-5
11.6
0.99995
8.344
8.341
65.94
0-5
Carrier gas
He, 2.1 mL min-1
Injection volume
1 µL
BDE28
BDE47
BDE99
BDE100
BDE153
BDE154
30
20
10
0.05 0.1 0.2 0.5
250 ºC
235 V
50 µA
CH4 (system pressure 3·10-4 torr)
SIM
Solvent delay
5 min
Measured isotopes/dwell
time
79Br
(0.1 s),
81Br
(0.1 s)
Retention time
(min)
GC column
DB 5MS (15m x 0.25 mm i.d. x 0.1 µm film
thickness)
0.2453 ± 0.003
103.98
1.83
3.81
BDE 47
(81Br4, 99.5%) BDE 47
0.0695
0.2185 ± 0.0111
92.54
0.43
4.45
BDE 99
(81Br2, 99.1%) BDE 99
0.0397
0.2162 ±0.0074
91.56
2.49
3.01
BDE 100
(81Br5, 68.6%) BDE 100
0.0353
0.2565 ± 0.0154
108.53
7.25
13.76
100000
BDE 153
(81Br6, 99.2%) BDE 153
0.0078
0.2040 ± 0.0114
86.37
2.91
4.82
0
BDE 154
(81Br3, 73.7%) BDE 154
0.0268
0.2241 ± 0.0127
94.73
4.51
6.71
153
154
300000
200000
5
6
7
8
9
10
Temperature program
100 ºC (2min), 30ºC
Transfer line
300 ºC
Source temperature
280 ºC
Time (min)
River Elbe water sample
500000
450000
Correlation
coefficient
MRM
Solvent delay
4 min
81Br
47
28
400000
350000
99
300000
Congener
153
Spike
Concentration (ng/L)
BDE 28
(81Br3, 99.3%) BDE 28
0.0118 ± 0.0024 <LOQ
BDE 47
(81Br4, 99.5%) BDE 47
0.0130 ± 0.0064 <LOQ
BDE 99
(81Br2, 99.1%) BDE 99
0.0015 ± 0.0015 <LOQ
BDE 100
(81Br5, 68.6%) BDE 100
0.0053 ± 0.0010 <LOQ
BDE 47
6.931
6.931
71.37
0-10
4.9
0.9998
150000
BDE 99
7.583
7.583
64.67
0-10
5.9
0.9998
100000
BDE 153
(81Br6, 99.2%) BDE 153
0.0044 ± 0.0030 <LOQ
BDE 100
7.421
7.425
65.29
0-5
4.9
0.99990
50000
BDE 154
(81Br3, 73.7%) BDE 154
0.0054 ± 0.0018 <LOQ
BDE 153
8.179
8.176
69.51
0-5
5.8
0.9997
0
BDE 154
7.962
7.966
133.84
0-10
6.2
0.9995
GC-(EI)MS/MS
BDE 28
ILDa (fg)
147.64
BDE 47
217.70
BDE 99
320.20
BDE 100
268.16
BDE 153
463.86
BDE 154
290.16
aILD:
100
250000
5
6
30
20
10
0
1
5
10
BDE28
BDE47
BDE99
BDE100
BDE153
BDE154
Linear
rangeb (µg/L)
0-5
0-10
0-10
0-10
0-10
0-10
Slope/103
L/µg
6.5
2.5
1.9
3.0
0.9
1.4
Correlation
coefficient
0.99994
0.9995
0.998
0.9991
0.998
0.9992
lowest concentration level injected for the calibration curve plus three times its standard deviation
bConcentration levels included in the calibration curve: 0, 0.05, 0.1, 0.2, 0.5, 1, 5, and 10 µg/L
PBDE
7
8
9
10
Time (min)
Conclusions
50
40
154
200000
lowest concentration level injected for the calibration curve plus three times its standard deviation
bConcentration levels included in the calibration curve: 0, 0.05, 0.1, 0.2, 0.5, 1, 5, and 10 µg/L
to 300 ºC (10 min)
Acquisition mode
79Br
0.9993
Concentration (µg/L)
He, 2.25 mL min-1 / N2 1.5 mL min-1
three times the standard deviation of six blanks (m=6, n=5 injections each)
bm=3 replicates
cn=5 injections
5.2
0.05 0.1 0.2 0.5
QQQ collision cell
Quench gas / Collision
gas
aLOQ:
0-10
2 µL
35 µA
0.0151
77.69
min-1
min-1
Reproducibilityb
6.243
Signal RSD (%)
Siltek ® (3 m x 0.5 mm i.d.)
Repeatabilityc
(81Br3, 99.3%) BDE 28
Precision in the measurements
Retention gap
Precision (%RSD)
6.239
Cold On-Column (oven track)
Emission current
(fg)
Recovery (%)
BDE 28
10
Slope/103
L/µg
Concentrationb (ng/L)
BDE 28
WORKING CONDITIONS
70 V
ILDa
Linear rangeb
(µg/L)
LOQa (ng/L)
81
GC-(EI)MS/MS
Source voltage
5
99
100
Spike
79
aILD:
He, 2.6 mL
1
Congener
81Br
Concentration (µg/L)
GC-(NCI)MS
Acquisition mode
0.99998
0
300 ºC
Reagent gas
47
400000
40
100 ºC (2min), 30ºC min-1 to 300 ºC (10 min)
Emission current
79Br
28
Signal (counts)
GC column
DB 5MS (15m x 0.25 mm i.d. x 0.1 µm film
thickness)
Source voltage
11.4
lowest concentration level injected for the calibration curve plus three times its standard deviation
bConcentration levels included in the calibration curve: 0, 0.05, 0.1, 0.2, 0.5, 1, 5, and 10 µg/L
Signal RSD (%)
Siltek ® (3 m x 0.5 mm i.d.)
GC-(ICP)MS
600000
50
Retention gap
1) Rotary evaporator
2) Heated N2 stream
~ 100 µL
Method validation
Precision in the measurements
Cold On-Column (oven track)
3 x 30 mL Hex/DCM (1:1)
extracts cleaning
river water
79
BDE 154
preconcentration
1L
500000
Injector
Source temperature
1L
10
Linear rangeb
(µg/L)
WORKING CONDITIONS
Transfer line
5
ILDa (fg)
GC-(NCI)MS
Temperature program
2) 81Br-PBDEs
3) equilibration
BDE154
1
LLE
1) native PBDEs
(only for validation)
BDE100
Concentration (µg/L)
aILD:
Injection volume
BDE99
20
0
GC-(ICP)MS
Cell gas
Carrier gas
BDE47
100 ºC (2min), 30ºC min-1 to 300 ºC (10 min)
300 ºC / 300 ºC
Injector
30
0.05 0.1 0.2 0.5
Transfer line/injector
temperature
SPIKING
BDE28
Signal (counts)
Carrier gas
40
Retention
time (min)
Precursor ion
(m/z)
[M-Br2]+
m/z loss
Product ion
(m/z)
Collision
energy (V)
Dwell (ms)
[COBr]
139.1
26
50
BDE 28
6.067
246.0
BDE 28 (13C12, 99%)
6.069
417.8 [M]+
[Br2]
258.0
17
50
BDE 47
6.756
325.9 [M-Br2]+
[COBr2]
325.9
18
35
BDE 47 (13C12, 99%)
6.757
497.7 [M]+
[Br2]
337.9
20
35
BDE 99
7.411
565.6 [M]+
[Br2]
405.8
20
50
BDE 99 (13C12, 99%)
7.410
575.6 [M]+
[Br2]
415.8
20
50
BDE 100
7.250
565.6 [M]+
[Br2]
405.8
20
50
BDE 100 (13C12, 99%)
7.249
575.6 [M]+
[Br2]
415.8
20
50
BDE 153
8.006
643.5 [M]+
[Br2]
483.7
20
40
BDE 153 (13C12, 99%)
8.002
655.5 [M]+
[Br2]
495.7
20
40
BDE 154
7.793
643.5 [M]+
[Br2]
483.7
20
40
BDE 154 (13C12, 99%)
7.793
655.5 [M]+
[Br2]
495.7
20
40
 Three different MS techniques have been compared in terms of sensitivity/instrumental limits of detection and precision
for the detection of PBDEs in water samples. The GC-(ICP)MS system was selected for the traceable measurement of
PBDEs in water samples as it shown the highest sensitivity as well as appropriate limits of detection (required
preconcentration factors around 5000) and precision for the six priority congeners.
 A sample preparation procedure based in the liquid-liquid extraction (LLE) of whole water samples has been
developed based on the capabilities of the selected measurement technique and the requirements of the WFD.
 The proposed methodology has been applied to the determination of PBDEs in a river water sample and validated
by analyzing the same river water sample fortified with a mixture of native PBDEs. The LOQs were in all cases below
0.07 ng/L. Accuracy was expressed in terms of recoveries which showed values between 85-110% at 0.2 ng/L.
 The use of GC-(ICP)MS in combination with 81Br-BDE analogues of the six priority congeners has allowed the
development of a traceable measurement approach (based on SS-IDMS) for the fast and reliable quantification PBDEs
in water samples.
This work has been performed within the scope of an EMRP Researcher Grant for the development of a traceable measurement approach for monitoring PBDEs in coastal water, awarded in accordance with the EURAMET process to complement the JRP “Traceable measurements for monitoring critical pollutants
under the European Water Framework Directive” . The authors would like to acknowledge Agilent Technologies for the GC-(EI)MS/MS measurements carried out in its laboratories placed in Waldbronn (Germany).