Determination of Micro and Macro Elements in Waters

Author
FIELD
APPLICATION
REPORT
ICP-Mass Spectrometry and
ICP-Optical Emission Spectroscopy
Determination of Micro and Macro
Elements in Waters with the ELAN DRC-e
Riccardo Magarini
PerkinElmer Italia S.P.A.
via Tiepolo 24
20052 Monza, Italy
Table 1. ELAN DRC-e Instrumental Parameters.
Table 2. Reaction Cell Parameters.
Nebulizer
Meinhard, Type C (glass)
Sample Uptake Rate
1 mL/min
Isotope
Spray Chamber
Peltier-cooled cyclonic at 2 °C
Injector
Alumina, 2 mm
Plasma Power
Cones
Dwell Time
Sweeps/Reading
1-1.5 sec
Replicates
4
0.25
Standard
Na
---
---
0.015
0.25
EDR*
Mg
---
---
0.012
0.25
EDR*
K
---
---
0.0135
0.25
EDR*
Ca
---
---
0.010
0.25
EDR*
O 2
0.80
0.000
0.70
DRC
55
59
60
43
20-50
Cr, Se,
52
Mode
0.000
54
39
25-50 ms
RPq
---
27
26
Ni
RPa
B, Al, Fe, Mn, Co,
Ni, 65Cu, 111Cd, 137Ba, 208Pb ---
11
23
1400 W
Integration Time
Reaction Gas Flow
Gas
(mL/min)
77
AsO
91
* = Extended Dynamic Range
Table 3. Optima 5300 DV Instrumental Parameters.
Introduction
The ability of reaction cell technology to reduce
the effects of spectral interferences is well-known,
but another, lesser-known capability also exists:
extending the dynamic range. This is accomplished
by adjusting the bandpass parameters with no gas
in the cell. Because the bandpass parameters can
be adjusted on a per-mass basis, sensitivity can be
reduced on selected isotopes without affecting
other elements in the method. This advantage is
seen when analyzing samples for both trace and
high-level elements, as shown previously.1
This work demonstrates the ability of the ELAN®
DRC™-e to analyze drinking and saline waters for
both major and minor elements in a single run.
Experimental
Reagents and Sample Preparation
Samples were analyzed without any pre-treatment.
Drinking waters were analyzed directly, while saline
waters were diluted 12.5 times with 1% (v/v) HNO3
(Suprapur®, Merck®).
Internal standards were used to compensate for
possible matrix effects during sample introduction.
An internal standard mix (Y, Rh and Re) was
added on-line by using orange/green peristaltic
pump tubing and an internal standard addition kit.
2
Nebulizer
MiraMist, 0.55 Lpm
Sample Uptake Rate
1.3 mL/min
Spray Chamber
Glass Cyclonic
Injector
Alumina, 2 mm
Plasma Power
1400 W
Integration Time
5-20 sec
Replicates
3
External calibration curves were applied using standards ranging from
5 µg/L to 400 mg/L, depending on the element and expected levels.
For example, elements likely to be present at low concentrations (i.e. As,
Se, Pb) used calibration curves established with 5, 10, 50, and 100 µg/L
standards, while high-level elements (i.e. Na, Mg, K, Ca) used standards
at mg/L concentrations.
Instrumentation
All analyses were performed on an ELAN DRC-e ICP-MS equipped with
Peltier cooled spray chamber and a Meinhard® C-type glass concentric
nebulizer. In the method, the elements were grouped into 3 modes: standard
mode, extended dynamic range mode (i.e. standard mode with the application
of bandpass parameters), and DRC mode using oxygen as a reaction gas.
Instrumental parameters are reported in Table 1, while DRC cell conditions
appear in Table 2.
The samples were also analyzed for comparison by ICP-OES, using an
Optima™ 5300 DV. Taking advantage of the Optima 5300 DV flexibility,
macro elements were determined radially and micro elements axially.
Several wavelengths were used for each element to check for possible
spectral interferences; the preferred wavelengths, along with analysis
mode and instrumental conditions, are reported in Tables 3 and 4.
Table 4. Wavelengths and Analysis Mode.
Table 5. DRC-ICP-MS and ICP-OES Results for Drinking Waters.
Element
Wavelength (nm)
Mode
B
249.677
Radial
Sample 1
Element ICP-MS ICP-OES
Customer*
ICP-MS
Na
589.592
Radial
Mg
285.213
Radial
Al
394.401
Radial
K
766.490
Radial
Ca
315.887
Radial
Cr
205.560
Axial
Fe
238.204
Radial
Mn
257.610
Radial
Co
228.616
Axial
Ni
231.604
Axial
Cu
327.393
Axial
Cu-65
1.47
1.1
0.0
1.97
2.6
2.0
µg/L
As
188.979
Axial
AsO-91
0.09
1.3
0.0
0.51
1.0
0.5
µg/L
Se
196.026
Axial
Se-77
0.74
1.4
0.0
0.09
<1
0.2
µg/L
Cd
228.802
Axial
Cd-111
0.012
<0.1
0.0
0.05
<0.1
0.05
µg/L
Ba
233.527
Axial
Ba-137
26.2
22.1
21.0
2.24
2.04
2.0
µg/L
Pb
220.353
Axial
Pb-208
3.65
8.4
5.6
0.51
2.0
0.5
µg/L
Sample 2
ICP-OES Customer* Units
B-11
0.48
0.56
n.a.
0.02
0.02
0.01
mg/L
Na-23
420
445
490
193
180
200
mg/L
Mg-26
88.5
90.0
n.a.
0.08
0.09
n.a.
mg/L
Al-27
0.003
0.007
0.000
0.003
0.007
0.001
mg/L
K-39
13.9
15.1
13.0
9.17
9.61
10.0
mg/L
Ca-43
151
147
168
0.16
0.17
n.a.
mg/L
Cr-52
0.54
1.4
0.0
0.71
0.8
0.5
µg/L
Fe-54
0.07
0.08
0.09
0.006
0.005
0.002
mg/L
Mn-55
0.006
0.010
0.000
0.001
0.002
0.001
mg/L
Co-59
0.15
0.3
n.a.
0.01
<0.2
n.a.
µg/L
Ni-60
1.13
1.0
2.1
2.12
2.1
2.0
µg/L
* = GF-AAS; HG-AAS; ICP-OES
Results
Figure 1 shows calibration curves for
Na, Mg, K, and Ca, which demonstrates
linearity up to 400, 100, 40, and 200 mg/L
levels, respectively. Higher level standards
were not analyzed. The ability to extend
the linearity is the result of the capability
to selectively suppress the analyte signal
using one of the bandpass parameters.
The extent of signal suppression can be
controlled by varying the RPa value.
Tables 5 and 6 show both the ICP-MS and ICP-OES results for drinking waters and
saline waters, respectively, along with results supplied by the customer, which were
generated by using graphite furnace AAS, hydride generation AAS, and ICP-OES.
There is good agreement between all techniques for elements present at both trace and
elevated levels, which confirms the concentrations. The effectiveness of extending the
dynamic range is evidenced by the results for Na and Mg in the saline waters: the
concentrations from both ICP-MS and ICP-OES are nearly identical.
3
Figure 1. Calibration curves for Na, Mg, K, and Ca demonstrating extended dynamic range.
4
Conclusion
Table 6. DRC-ICP-MS and ICP-OES Results for Saline Waters.
Sample 1
Element ICP-MS ICP-OES
Customer*
ICP-MS
Sample 2
ICP-OES Customer* Units
B-11
0.11
4.54
5.06
2.30
0.10
n.a.
mg/L
Na-23
10950
10608
11000
108
103
103
mg/L
Mg-26
1283
1308
1300
146
149
146
mg/L
Al-27
0.08
0.10
0.005
10.9
10.4
10.0
mg/L
K-39
409
398
390
7.36
6.70
5.80
mg/L
Ca-43
440
410
448
158
163
200
mg/L
Cr-52
9.95
7.5
2.5
1.69
1.8
0.0
µg/L
Fe-54
0.11
0.15
0.09
8.02
7.88
8.00
mg/L
Mn-55
0.07
0.08
0.07
8.84
8.43
8.60
mg/L
Co-59
1.04
0.8
n.a.
88.9
109
n.a.
µg/L
Ni-60
17.8
13.1
10.0
169
194
110
µg/L
Cu-65
15.8
13.6
10.0
5.50
4.2
0.0
µg/L
AsO-91
10.4
4.8
10.2
0.15
1.8
n.a
µg/L
Se-77
3.29
12.0
1.0
<0.02
<1
0.0
µg/L
Cd-111
0.32
0.3
0.25
0.55
0.6
0.0
µg/L
Ba-137
53.2
42.5
37.0
56.4
51.5
51.0
µg/L
Pb-208
4.07
12.9
2.5
0.62
9.5
0.0
µg/L
* = GF-AAS; HG-AAS; ICP-OES
This work has demonstrated the ability of
DRC-ICP-MS to analyze elements present at
both trace and elevated levels in drinking and
saline water samples. The capability to selectively suppress signal intensity without the use
of a cell gas allows the dynamic range of DRCICP-MS to be extended, which allows for
matrix elements to be measured. All results
were confirmed using ICP-OES. Although
both ICP-OES and DRC-ICP-MS give similar
results for these samples, it should be remembered
that these are complementary techniques, with
each having their strengths and weaknesses for
various sample types and analyte levels.
References
1. F. Abou-Shakra, “Extending the Dynamic
Range of the ELAN DRC by Selective
Attenuation of High Signals”, PerkinElmer
FAR 007437_01, 2005.
Table 7. Calibration report.
Analyte
Mass
Curve Type
Slope
Intercept
Corr Coeff
B
10.013
Linear Thru Zero
0.036264
0.000
0.998990
B
11.009
Linear Thru Zero
0.161083
0.000
0.999266
Na
22.990
Linear Thru Zero
0.034193
0.000
0.999943
Mg
25.983
Linear Thru Zero
0.062046
0.000
0.999956
Al
26.982
Linear Thru Zero
1.176079
0.000
0.999969
K
38.964
Linear Thru Zero
0.246574
0.000
0.999961
Ca
42.959
Linear Thru Zero
0.003598
0.000
0.999927
Fe
53.940
Linear Thru Zero
0.114004
0.000
0.999870
Mn
54.938
Linear Thru Zero
1.106387
0.000
0.999844
Y
88.905
Linear Thru Zero
0.000000
0.000
0.000000
Rh
102.905
Linear Thru Zero
0.000000
0.000
0.000000
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The data presented in this Field Application Report are not guaranteed. Actual performance and results are dependent upon the exact methodology used and laboratory conditions. This data should only be used to demonstrate the
applicability of an instrument for a particular analysis and is not intended to serve as a guarantee of performance.
008584_01
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