1
Coupling between chip based isotachophoresis and multi-collector
2
inductively coupled plasma mass spectrometry
3
for separation and measurement of lanthanides
4
5
Laurent Vio1,3, Gérard Crétier3, Frédéric Chartier2, Valérie Geertsen4, Alkiviadis
6
Gourgiotis1, Hélène Isnard1, Pierre Morin5, Jean-Louis Rocca3
7
8
9
10
11
12
13
14
15
16
17
18
1
Commissariat à l’Energie Atomique, Saclay, DEN/DPC/SEARS/LANIE, 91191 Gif sur Yvette Cedex,
France
2
Commissariat à l’Energie Atomique, Saclay, DEN/DPC, 91191 Gif sur Yvette Cedex, France
3 Université
4
de Lyon, Institut des Sciences Analytiques (UMR CNRS 5280), Villeurbanne, France
Commissariat à l’Energie Atomique, Saclay, DSM/IRAMIS/SIS2M/LIONS, 91191 Gif sur Yvette
Cedex, France
5
AREMAC-Polymer, Caluire et Cuire, France
19
-1-
20
Abstract
21
22
23
This paper presents the conception and fabrication of a microsystem for lanthanides
24
separation and its coupling with a multicollector inductively coupled plasma mass
25
spectrometer for isotope ratio measurements. The lanthanides separation is based on the
26
isotachophoresis technique and the microsystem conception has been adapted in order to fit
27
with glove box limitations in view of future spent nuclear fuels analysis. The micro-device
28
was tested by using a mixture of standards solutions of natural elements and the separation of
29
13 lanthanides was successfully performed. The micro-device was then coupled to
30
multicollector inductively coupled plasma mass spectrometer for the on-line meausrements of
31
Nd and Sm isotope ratios. The isotopes of Nd and Sm were acquired online in multicollection
32
mode after separation of the two elements with an injection amount of 5 ng. Results obtained
33
on the Nd and Sm isotope ratio measurements on transient signals are presented and
34
discussed.
35
36
37
38
39
40
41
42
43
44
45
46
Keywords
Isotachophoresis
Multicollector Inductively coupled plasma mass spectrometry
Lab-on-chip
Lanthanides
Fission products
Transient signals
Isotope ratio
47
-2-
a
48
Introduction
49
50
Over the past decade, major progress in the development of analytical chemistry has been
51
accomplished via the miniaturization of separation techniques towards lab-on-chip
52
technology1-4. Research in miniaturization is driven by the need to reduce the costs and the
53
consumption of expensive reagents and to increase throughput and automation. The chip
54
could be directly coupled to high sensitive detection system such as inductively coupled
55
plasma mass spectrometry5, 6. This technique offers the advantages of providing simultaneous
56
multielement capability and facilitating ultra sensitive analysis of samples 7. To obtain
57
uncertainty at several per mil level on isotope ratio, multicollector inductively coupled plasma
58
mass spectrometry (MC-ICPMS) has demonstrated its potential for numerous elements8-10.
59
The coupling between a separative technique and MC-ICPMS is a great challenge related to
60
the limited signal duration. When discrete amounts of analyte are carried into a stream of a
61
flowing liquid, analyte signals do not reach a steady state and transient time-dependent signals
62
are obtained11-13.
63
The major applications in the Laboratory of Nuclear Isotopic and Elementary Analysis in the
64
French Nuclear Agency are the characterisation of isotopic and elemental composition of
65
nuclear fuel samples using multicollector mass spectrometry techniques14-20. In nuclear
66
industry the reduction of reagent and decrease of sample size is a major requirement in
67
relation to the reduction of radiation dose for the analysts. In a previous study21, we have
68
demonstrated the feasibility of the separation for all lanthanides present in a fuel sample using
69
isotachophoresis (ITP). The band shape obtained for lanthanides are quasi-rectangular and the
70
concentration plateau obtained at the top of the eluted band leads to a constant detection
71
signal of a certain duration which can be modulated. ITP allows a quasi steady state
72
acquisition of ion beams which could be very useful for direct coupling with MC-ICPMS.
73
In this article, the separation was miniaturized to be implanted in glove box environnement
74
for coupling with MC-ICPMS. Chip-based ITP as separation technique was the topic of
75
numerous articles in the years 2000-2006. The major developments published during this
76
period are summarized in the review of Chen et al22. The technique continues to be developed
77
in terms of new application23, device fabrication24 and detection method25. But, to date, there
78
is no report dealing with the use of chip-based ITP for the complete separation of all
79
lanthanides. However, some authors carried out the analysis of model samples containing a
80
few lanthanides mixed with alkaline earth or transition metal cations, in order to demonstrate
81
the separation capability of their miniaturized device26-28. In these three studies, HIBA was
-3-
82
added to the leading electrolyte to improve the separations of metal ions and microchips were
83
fabricated using polymeric substrates such as poly(dimethylsiloxane) (PDMS)28, polystyrene
84
(PS)27 and poly(methylmethacrylate) (PMMA)26. Our microsystem was specially designed to
85
perform an efficient separation of lanthanides and during its conception some requirements
86
must be performed in order to implant the chip in glove box environment.
87
In a first part of this paper we presented the conception of a microchip based on previous
88
studies29,
89
improvements have been brought to the system in order to fulfill glove box regulation in
90
terms of safety and costs. In a second part the coupling between a chip based ITP and a MC-
91
ICPMS was performed and the potentiality for Nd and Sm isotope ratio measurements has
92
been explored.
30
. On this microsystem, the separation of lanthanides was tested and slight
93
94
2. Materials and methods
95
96
2. 1. Isotachophoretic separation with the micro-device
97
98
2. 1. 1. Fabrication of the micro-system
99
100
A layout of the miniaturized isotachophoresis device is shown in Figure 1a. The 65 mm
101
diameter COC (cyclo-olefin copolymers) disk integrates the injection channel IC (130 µm
102
wide, 130 µm deep and 4.5 cm long, corresponding to a volume of 0.8 µL) and the different
103
channels and connectors L(Leader), T(Terminal) and S(Sample), which are used to introduce
104
electrolytes and sample in the micro-system. Separation is carried out in a silica capillary SC
105
(30 µm i.d. x 360 µm o.d. x 70 cm length) connected to the (COC) micro-system via a zero
106
dead volume connector C using an Upchurch (Cluzeau Info Labo) modified nut. The current
107
used to drive the separation is provided by a SL50 10W high voltage power supply
108
(Hauppauge, New York, USA) and applied between the port M (which includes a porous
109
Teflon membrane) and the capillary outlet O which is immersed in a leader electrolyte vial or
110
connected to the inductively coupled plasma mass spectrometer. With this configuration, the
111
Pt electrode is not directly in contact with the working electrolyte solution, which prevents
112
from gas bubble formation by electrochemical reactions inside the separation compartment. A
113
contactless conductivity detector CD is placed at 14 cm from the separation capillary outlet.
114
Full details of the fabrication procedure were previously published31.
115
-4-
116
2. 1. 2. Electrolyte filling and analysis protocol
117
118
As shown in Figure 1a, sample injection and filling of the micro-system with leading
119
electrolyte and terminal electrolyte are achieved using three ISM832C peristaltic pumps PPS,
120
PPL and PPT (Ismatec, Glattbrugg, Switzerland) respectively. When the pumps are stopped
121
during separation, their rollers automatically close the inlet of channels, which minimizes
122
hydrodynamic flow and the consequent dispersion32.
123
The control program used to achieve the separation is given in Table 1. In the first step, PPS
124
and PPT pumps are stopped while the injection channel and the separation capillary are filled
125
with leading electrolyte by PPL pump. Then, PPL pump is disconnected in order to make a
126
waste outlet in the microchip. In step 2, the injection channel is filled with sample by PPS
127
pump. In step 3, lateral channels are filled with terminal electrolyte until the microchip outlet
128
(port L) by PPT pump. Thus, the sample contained in the injection channel, is sandwiched
129
between the leading and terminal electrolytes. The actual isotachophoretic separation takes
130
place in step 4 by the application of a constant current intensity of X µA (with X ≠ 0).
131
132
2.1.3 Radioactivity controlled area analysis protocol
133
134
To prevent contamination and reduce dose exposure, the source of the MC-ICPMS used in
135
this study is confined in a glove box (GB)33. So the initial configuration of the microchip and
136
the analysis protocol must be adapted. To fit the operating system with GB limitations, the
137
peristaltic pump for sample and terminal electrolyte to S and T entries have been substituted
138
by modified back flow valve suppressor Upchurch CV-3301 (Cluzeau Info Labo, St Foy la
139
Grande, France), SBV and TBV. The injection steps are manually completed using a
140
disposable plastic syringes, SS and TS, connected to the valves (Figure 1b). Furthermore
141
inside the syringe, a filter Millex-GV 0.2 µm (Interchim SA, Montluçon, France) was added
142
to prevent channel clogging. A syringe pump (PSL) was introduced inside the glove box. This
143
pump has a double function. During the optimization phase for MC-ICPMS measurements,
144
the role of this pump is to inject the leading electrolyte in all microchip and the separation
145
capillary with a HMBA solution containing Nd. During the analysis of the sample, the syringe
146
pump is connected to the Burgener nebulizer to provide the sheat flow of leading electrolyte
147
(10 µL/min). The L channel of the microchip becomes so the waste channel. According to this
148
new configuration the microchip is compatible with GB environment without changing its
149
operating process previously described (Part 2.1.2).
-5-
150
151
2.1.4. Chemicals and samples
152
153
Natural element standards (Nd, Sm, Eu, Gd) were obtained from SPEX as 1000 mg.L-1 stock
154
standard solutions. Aliquots of the stock solutions of each lanthanide were evaporated to
155
dryness and dry extracts were dissolved in adequate volume of pure water. The isotopic ratios
156
of these Sm and Nd natural SPEX solutions were evaluated in the laboratory by Thermal
157
Ionisation Mass Spectrometry and using the technique of Total Flash Evaporation34, 35. The
158
values of these ratios expressed respectively on the
159
Table 3 as reference ratios.
146
Nd and
149
Sm isotopes36 are listed in
160
161
2.2. Chip – MC- ICPMS Interface
162
163
The Mira Mist CE (Burgener Research, Mississauga, Ontario, Canada) interface was used
164
between ITP micro-device and MC-ICPMS. The parallel flux nebulizer used in this interface
165
is able to operate with low sample flow rates (3 - 10 µL / min). The nebulizer is connected to
166
a linear PTFE micro spray chamber (Burgener Research).
167
168
2. 3. ICP - MS detection
169
170
2. 3. 1. Multi-Collection ICPMS
171
172
The isotopic ratio measurements were performed with a single focusing sector field MC-
173
ICPMS from GV Instruments (Manchester, UK) which was previously modified in order to
174
work with radioactive materials in safe experimental conditions33. It is equipped with a
175
standard ICP source, a Radio-Frequency-only hexapole collision-reaction cell (using Ar as
176
collision gas), a magnetic sector and a multicollector system with nine Faraday cups and one
177
Daly electrode implanted in the axial position. The measurements are performed in static
178
multicollection mode with Faraday cups. The Faraday amplifier gains were calibrated daily
179
before the analytical session yielding to a reproducibility of the electric gains better than 20
180
ppm/day. The integration time for the acquisition of the transient signals was fixed at 300ms.
181
A Nd test solution was pushed via the syringe pump towards the nebulizer by applying
182
constant pressure on the buffer (3 bar) and the parameter were optimized in order to obtain the
183
maximum counting rates on
142
Nd. Torch position, gas flow rate, ion focusing beam and
-6-
184
magnet field settings were daily optimized. The operating conditions and data acquisition
185
procedure are summarized in Table 2. Sm and Nd sensibility was about 15 V/ppm during the
186
analytical session. The baselines were measured at half-masses at the method start and
187
corrected on-line during each measurement.
188
189
2. 3. 2. Mass bias correction for MC-ICPMS measurements
190
191
The analytical developments were performed on natural SPEX solutions well characterized in
192
the laboratory for their isotopic ratios by Thermal Ionization Mass Spectrometry (cf 2.1.4).
193
Internal mass bias correction using the ratios
194
1.93009(51) and the mass bias was corrected by using the exponential law37.
144
Nd/146Nd = 0.72333(8) and
152
Sm/149Sm=
195
196
3. Results and discussion
197
198
3. 1. Separations on hybrid micro-device
199
200
The final objective is to couple a disposable isotachophoretic platform to ICPMS detection.
201
Once the ITP separation was optimized on a commercial instrument, a cost-effective hybrid
202
micro-device composed of two parts was developed (Figure 1a). The first one is a microchip
203
made of COC including injection channel, driving electrode, pump inlets and channels system
204
needed to filling process. The second one is a 30 µm i.d. x 70 cm length PVA-coated silica
205
capillary used as separation capillary and connected to the COC microchip by means of a zero
206
dead volume connexion. Prior to investigate hyphenation with MC-ICPMS detection, the
207
ability of the hybrid micro-device to separate lanthanides was checked using contactless
208
conductivity detection. Figure 2b shows the isotachophoregram obtained for the sample of 13
209
lanthanides separated under the same conditions as those previously used with a coupled
210
capillary configuration (Figure 2a)21. As can be seen in figure 2a and 2b, there is a good
211
agreement between results obtained in both experiments. However, the resolutions observed
212
with the hybrid micro-device are slightly lower than those obtained with the coupled capillary
213
configuration: the average resolution is equal to 0.72 in the former case and 0.78 in the latter
214
one21. A possible cause of these lower RS values with hybrid micro device is that, during
215
separation, sample is in contact with two different materials (COC in injection compartment
216
and PVA-coated silica in separation capillary). The difference of electro kinetic properties of
217
these inner surfaces probably involves a difference of EOF which is responsible for an
-7-
218
additional dispersion phenomenon. Indeed, the presence of a non-negligible cathodic EOF on
219
COC surface under acidic conditions was also demonstrated38, 39.
220
221
3. 2. Coupling chip based ITP with MC-MC-ICPMS and nuclearization
222
223
The hybrid micro-device was then coupled with a multicollector inductively coupled plasma
224
mass spectrometer (ITP/ MC-ICPMS). The separation was focused on the four lanthanides
225
Nd, Sm, Eu, and Gd. Four non-interfered isotopes (146Nd, 147Sm, 151Eu, 155Gd) were acquired
226
in multicollection mode with a dwell time of 300 ms. As previously observed by ICP-QMS
227
using a capillary separation system21, the separation profile obtained by MC-ICPMS (Figure
228
3) shows for the Eu element two different plateaus probably due to europium subspecies like
229
EuOH+ and/or Eu(II)21.
230
The implantation of the micro-device in the glove box requires refinements that were
231
previously presented in Part 2.1.3.
232
233
3. 3. Isotopic ratio measurements by MC-ICPMS
234
235
The transient signals provided by ITP coupled with an MC-ICPMS have the particularity to
236
present a plateau within a specific time window. In contrast to ITP, Gas Chromatography
237
(GC) or High Performance Liquid Chromatography (HPLC) methods provide transient
238
signals with characteristic Gaussian peaks’ shape. For isotope ratio measurements in the
239
single data points of GC/HPLC transient signals, a significant drift has been observed that
240
deteriorate the isotope ratio accuracy11, 13, 40-43. In many cases the authors attribute this drift to
241
the data acquisition system behind the Faraday cups, which is not suitable for fast changing
242
signals44. For this reason, in this section we would like to investigate the potential use of the
243
plateau portion of the transient signals provided by ITP for isotope ratio measurements. Thus,
244
the hybrid micro device was coupled with the MC-ICPMS and only Nd and Sm in a first
245
approach were selected for isotope ratio measurements.
246
A solution of 5 ng of Nd and Sm in a volume of 0.8 l was injected on the hybrid micro
247
device and the nine selected isotopes were measured simultaneously on the nine Faraday cups
248
with an integration time of 300 ms (Table 3). As can be seen in the Figure 4, two quasi-
249
rectangular bands corresponding to Nd and Sm solutes are observed. The duration of the two
250
peaks on the plateau was evaluated at about 9 s. The signal stability of the intensities on the
251
major isotopes of 142Nd and 147Sm evaluated by the standard deviation (RSD), was equal to ~3
-8-
252
%. In Figure 5 only two isotopes (146Nd and 147Sm) are illustrated in logarithmic scale in order
253
to better visualise the mixing zone between the two solutes. As illustrated in this figure no
254
important contribution of Sm fraction within Nd is observed while a contribution of Nd tailing
255
(~1%) during Sm elution is observed.
256
This tailing is probably due to the short washout time for eliminating Nd memory effects from
257
the introduction system. Direct injection systems should be an alternative way in order to
258
minimize the tailing effect.
259
260
3.3.1 Nd isotopic ratio
261
262
For Nd isotopic ratio measurements the plateau area between 993 s and 1002 s was used
263
(Figure 5). The average isotope intensities before the elements elution were used for the
264
evaluation of the background noise.
265
All isotope intensities in the plateau were corrected after data acquisition for the background
266
noise. As illustrated in Figure 5 a drift (~2%) of the point by point 142Nd/146Nd isotope ratio is
267
observed indicating an isotopic fractionation between 142Nd and 146Nd during the plateau area.
268
In order to better investigate this drift, the relative difference between the raw Nd isotope
269
ratios, and the Nd reference values was calculated according to the next equation:
270
271
 X 
 X  
   146
 
 146
 Nd  ref  Nd  m 
X
 (%) 
 100
 X 
 146

 Nd  ref
(2)
272
where X and (X/146Nd)m are the Nd isotopes and the measured Nd ratios (no corrected for
273
instrumental mass bias), respectively and where (X/146Nd)ref is the Nd reference ratio values as
274
reported by Dubois et al36. A drift during the peak elution for all Nd(%) ratios was observed
275
indicating a continuous fractionation of the Nd isotope ratios within the plateau area (Figure
276
6a). Plotting the linear regression slopes of the Nd(%) as a function of mass as illustrated in
277
Figure 7, shows that isotope fractionation is mass dependent. Two independent injections of 5
278
ng of Nd and Sm were carried out in the same experimental conditions and the same drift for
279
Nd isotope ratios was observed.
280
For transient signals in order to continuously monitor the machine drift an external tracer
281
directly connected in the nebulizer is generally used. Here, we should point out that an isotope
282
ratio drift of about 2% generated from within the machine in a time window of 9 s and for a
-9-
283
no time-changing signal seems unrealistic. Although, data acquisition conditions and system
284
configuration could generate an isotope ratio drift during transient signals acquisition46, in this
285
case the mass-depended drift (Figure 7) suggests that this drift could come from the ITP
286
separation system. During element separation lighter ions should migrate faster (kinetic
287
isotope fractionation) and thus their concentrations increase in the beginning of the element
288
bands. Isotope ratio fractionation has already been observed for capillary zone electrophoresis
289
(CZE) and also the potential use of CZE for performing elemental and isotopic separations in
290
natural abundance chloride has already been investigated45.
291
292
293
Despite the fact that Nd isotope ratios drift in plateau area, the precision of the mass bias
294
corrected Nd isotope ratios was investigated. The linear regression slopes of the
295
simultaneously collected intensities for all Nd isotopes were calculated using the method
296
developed by Fietzke et al. and recently applied by Epov et al.46, 47 for transient signals. They
297
show that “the slope of the linear regression of the simultaneously measured intensities of two
298
isotopes represents their isotopic ratio”. The internal error varies between 4 and 6% (Table 3)
299
and is inferior to the drift observed along the plateau (~2%). The slope values and their
300
associated errors (expressed at a 95% confidence level) of all the linear regressions used in
301
this work were calculated by employing the robust regression option of the ISOPLOT
302
program version 3.27. ISOPLOT developed by K.R. Ludwig (Berkeley Geochronology
303
Center) and is a flexible tool for isotope data interpretation.
304
To have an evaluation of the bias between the corrected Nd ratio and the reference value36, we
305
have chosen to perform an internal mass bias correction. The measured
306
ratio and the exponential law37, 48 were used for this correction. The Nd isotope ratio accuracy
307
varies between 0.1 and 1.2 % (Table 3).
142
Nd/146Nd isotope
308
309
310
3.3.2 Sm isotopic ratio
311
312
For Sm isotopic ratio the plateau area between 1004 s and 1013 s was used (Figure 5). Like
313
Nd, the Sm plateau area starts 2 seconds after the beginning of the Sm plateau and its end is
314
~1 s before the decreasing phase of the signal. All isotope intensities in the plateau were
315
corrected after data acquisition for the background noise. Before examining the point by point
316
Sm isotope ratios, the
144
Sm/147Sm,
148
Sm/147Sm and
- 10 -
150
Sm/147Sm ratios were corrected for
144
Nd,
148
Nd and
150
317
isobaric interferences from
Nd, respectively. This correction has been
318
realized using the interference-free isotope, 146Nd, according to the next equation:
319
320
i

 i Nd  
 
Smtrue  i Smmeas   146 Nd   146
Nd


 meas 
(3)
321
322
where iSmtrue and iSmmeas are the corrected and the measured intensities of the interfered Sm
323
isotopes (144, 148, 150). (iNd/146Nd)meas are the measured ratios for the Nd isotopes of
324
interest. As can be seen in Figure 5 the non-interfered point by point 147Sm/149Sm isotope ratio
325
shows a drift of about 1% within the plateau area. By following the same procedure as for the
326
Nd ratios, it is clear that the point by point Sm isotope ratios drift in the plateau (Figure 6b)
327
and this drift is mass dependent (Figure 7).
328
For Sm, isotope ratios are evaluated by the linear regression method previously described and
329
the measured
330
correction. Table 3 shows that the internal error is ~2% for 148Sm/149Sm and 150Sm/149Sm and
331
~9.5% for the 144Sm/149Sm ratio (144 is the minor isotope of Sm with a natural abundance of
332
about 3.07%). The Sm isotope ratio accuracy varies between 0.14 and 1.69%.
147
Sm/149Sm isotope ratio and the exponential law were used for mass bias
333
334
4. Conclusion
335
336
In this article the conception and fabrication, based on lab on chip technology, of a micro-
337
device dedicated to the separation of lanthanides in nuclear fuel samples is shown. The micro-
338
device fabrication is standardized and high reproductibility between chips replicas is obtained.
339
The isotachophoretic separation of lanthanides is effective along a capillary, connecting the
340
microsystem directly with the detection system. The separation is based on the presence of a
341
complexing agent (HMBA) added to the leading electrolyte. The lenght of the capillary could
342
be adapted to the different amounts of lanthanides present in a fuel sample. The micro-device
343
was adapted to be implanted in glove box and the solutions are never in contact with the
344
hardware fixed on the micro-device in order to prevent their contamination and allow
345
successive uses.
346
The micro-device was directly coupled to an MC-ICPMS for the on-line measurements of Nd
347
and Sm isotopic ratio. This is the first time that such a coupling is performed and the
348
feasibility is demonstrated in this study. Accuracy and reproducibility obtained for isotope
- 11 -
349
ratio measurements are very promising. However, further work in order to investigate and
350
control the drift on isotope ratio during the plateau elution is major for future applications.
351
352
- 12 -
353
354
355
Table 1 : Control program of the different steps for isotachophoretic separation on the micro-
356
device.
357
Step
Current
Pump status
(µA)
PPL
PPS
PPT
1
0
on
off
off
2
0
disconnected
on
off
3
0
disconnected
off
on
4
X≠0
disconnected
off
off
358
359
- 13 -
360
361
Table 2: Instrument settings of the MC-ICPMS.
362
Parameter
Value / description
Make-up flow
10 µL / min
RF power
1350 W
Nebulizer gas flow
0.7 - 0.8 L / min
Auxiliary gas flow
1.2 L / min
Cool gas flow
14 L / min
Hex. RF Amplitude
80%
Acquisition mode
Static multicollection
Resolution (10%)
400 RP
Integration time
300 ms
363
364
- 14 -
365
366
Table 3: Reproducibility and
accuracy for Nd and Sm isotopic ratios derived from linear slope
367
regression of natural Nd, Sm solution obtained by ITP-MC-ICPMS.
Nd isotopic ratios
142Nd/146Nd
143Nd/146Nd
144Nd/146Nd
145Nd/146Nd
148Nd/146Nd
150Nd/146Nd
Corrected ratio Rtrue
0.706(33)
1.378(55)
0.4800(93)
0.340(13)
0.330(20)
% Error (2σ)
4.6
0.70641(11)
4.0
1.3825(2)
1.9
0.48213(6)
0.095
0.35
0.44
36
Reference ratio Rref
1.5756(3)
Accuracy (%)
Sm isotopic ratios
144Sm/149Sm 147Sm/149Sm 148Sm/149Sm 150Sm/149Sm
Corrected ratio Rtrue
0.225(22)
0.815(16)
0.525(09)
% Error (2σ)
Reference ratio36 Rref
9.5
0.22382(14)
2.0
0.81419(6)
1.8
0.53366(15)
Accuracy (%)
0.75
0.14
1.69
1.0868(2)
368
- 15 -
3.7
6.1
0.33597(14) 0.32932(12)
1.24
0.26
369
Références
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
1.
P.-A. Auroux, D. Iossifidis, D. R. Reyes and A. Manz, Anal. Chem., 2002, 74, 2637.
2.
D. Figeys and D. Pinto, Anal. Chem., 2000, 72, 330 A.
3.
D. R. Reyes, D. Iossifidis, P.-A. Auroux and A. Manz, Analytical Chemistry, 2002, 74,
2623.
4.
T. Vilkner, D. Janasek and A. Manz, Anal. Chem., 2004, 76, 3373.
5.
A. O. AlSuhaimi and T. McCreedy, Arab. J. Chem., 2011, 4, 195-203.
6.
T.-T. Shih, W.-Y. Chen and Y.-C. Sun, J. Chromatogr. A, 2011, 1218, 2342.
7.
D. Beauchemin, Anal. Chem., 2010, 82, 4786.
8.
A. N. Halliday, D. C. Lee, J. N. Christensen, M. Rehkamper, W. Yi, X. Z. Luo, C. M.
Hall, C. J. Ballentine, T. Pettke and C. Stirling, Geochim. Cosmochim. Acta, 1998, 62, 919940.
9.
F. Vanhaecke, L. Balcaen and D. Malinovsky, J. Analyt. Atom. Spectrom., 2009, 24,
863.
10.
L. Yang, Mass Spectrom. Rev., 2009, 28, 990.
11.
V. N. Epov, S. Berail, M. Jimenez-Moreno, V. Perrot, C. Pecheyran, D. Amouroux
and O. F. X. Donard, Analyt. Chem., 2010, 82, 5652-5662.
12.
I. Günther-Leopold, B. Wernli, Z. Kopajtic and D. Günther, Analyt. Bioanalyt. Chem.,
2004, 378, 241-249.
13.
E. Krupp, C. Pécheyran, S. Meffan-Main and O. X. Donard, Analyt. Bioanal. Chem.,
2004, 378, 250-255.
14.
F. Chartier, H. Isnard, J. P. Degros, A. L. Faure and C. Frechou, Int. J. Mass
Spectrom., 2008, 270, 127-133.
15.
A. Gourgiotis, M. Granet, H. Isnard, A. Nonell, C. Gautier, G. Stadelmann, M. Aubert,
D. Durand, S. Legand and F. Chartier, Int. J. Mass Spectrom., 2010, 25, 1939-1945.
16.
M. Granet, A. Nonell, G. Favre, F. Chartier, H. Isnard, J. Moureau, C. Caussignac and
B. Tran, Spectrochim. Acta Part B, 2008, 63, 1309-1314.
17.
F. Guéguen, A. Nonell, M. Granet, G. Favre, H. Isnard and F. Chartier, J. Anal. At.
Spectrom., 2010, 25, 201-205.
18.
H. Isnard, M. Aubert, P. Blanchet, R. Brennetot, F. Chartier, V. Geertsen and F.
Manuguerra, Spectrochim. Acta Part B, 2006, 61, 150-156.
19.
H. Isnard, M. Granet, C. Caussignac, E. Ducarme, A. Nonell, B. Tran and F. Chartier,
Spectrochim. Acta Part B, 2009, 64, 1280-1286.
20.
J. Moureau, M. Granet, F. Chartier, G. Favre, H. Isnard and A. Nonell, J. Analyt.
Atom. Spectrom., 2008, 23, 1538-1544.
21.
L. Vio, G. Crétier, F. Chartier, V. Geertsen, A. Gourgiotis, H. Isnard and J. L. Rocca,
Electrophoresis., submitted.
22.
L. Chen, J. E. Prest, P. R. Fielden, N. J. Goddard, A. Manz and P. J. R. Day, Lab on a
Chip, 2006, 6, 474-487.
23.
J. E. Prest, M. S. Beardah, S. J. Baldock, S. P. Doyle, P. R. Fielden, N. J. Goddard and
B. J. T. Brown, Journal of Chromatography A, 2008, 1195, 157-163.
24.
J. E. Prest, P. R. Fielden, N. J. Goddard and B. J. T. Brown, in Measurement Science
and Technology. 2008, vol. 19, p. 065801.
25.
R. D. Chambers and J. G. Santiago, Analyt. Chem., 2009, 81, 3022-3028.
26.
S. J. Baldock, P. R. Fielden, N. J. Goddard, H. R. Kretschmer, J. E. Prest and B. J.
Treves Brown, Journal of Chromatography A, 2004, 1042, 181-188.
27.
S. J. Baldock, P. R. Fielden, N. J. Goddard, J. E. Prest and B. J. Treves Brown,
Journal of Chromatography A, 2003, 990, 11-22.
- 16 -
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
28.
J. E. Prest, S. J. Baldock, P. R. Fielden and B. J. T. Brown, Analyst, 2001, 126, 433437.
29.
M. Masár, D. Kaniansky, R. Bodor, M. Jöhnck and B. Stanislawski, J. Chromatogr. A,
2001, 916, 167-174.
30.
E. Olvecka, M. Masar, D. Kaniansky, M. Johnck and B. Stanislawski, Electrophoresis,
2001, 22, 3347-3353.
31.
K. Faure, M. Albert, V. Dugas, G. Crétier, R. Ferrigno, P. Morin and J.-L. Rocca,
Electrophoresis, 2008, 29, 4948-4955.
32.
D. Kaniansky, M. Masár, R. Bodor, M. Žúborová, E. Ölvecká, M. Jöhnck and B.
Stanislawski, Electrophoresis, 2003, 24, 2208-2227.
33.
H. Isnard, R. Brennetot, C. Caussignac, N. Caussignac and F. Chartier, Int. J. Mass
Spectrom., 2005, 246, 66-73.
34.
E. L. Callis and R. Abernathey, Int. J. Mass Spectrom. Ion Process., 1991, 103, 93105.
35.
R. Fiedler, Int. J. Mass Spectrom. Ion Process., 1995, 146-147, 91-97.
36.
J. C. Dubois, G. Retali and J. Cesario, Int. J. Mass Spectrom. Ion Process., 1992, 120,
163-177.
37.
W. A. Russell, D. A. Papanastassiou and T. A. Tombrello, Geochim. Cosmochim.
Acta, 1978, 42, 1075-1090.
38.
P. Mela, A. van den Berg, Y. Fintschenko, E. B. Cummings, B. A. Simmons and B. J.
Kirby, Electrophoresis, 2005, 26, 1792-1799.
39.
V. Tandon, S. K. Bhagavatula, W. C. Nelson and B. J. Kirby, Electrophoresis, 2008,
29, 1092-1101.
40.
R. Clough, S. T. Belt, E. H. Evans, B. Fairman and T. Catterick, Analyt. Chim. Acta,
2003, 500, 155-170.
41.
I. Günther-Leopold, N. Kivel, J. Kobler Waldis and B. Wernli, Analyt. Bioanal.
Chem., 2008, 390, 503-510.
42.
I. Gunther-Leopold, J. K. Waldis, B. Wernli and Z. Kopajtic, Int. J. Mass Spectrom.,
2005, 242, 197-202.
43.
M. Tanner and D. Günther, Anal. Chim. Acta, 2009, 633, 19-28.
44.
E. M. Krupp and O. F. X. Donard, Int. J. Mass Spectrom., 2005, 242, 233-242.
45.
C. A. Lucy and T. L. McDonald, Anal. Chem., 1995, 67, 1074-1078.
46.
V. N. Epov, S. Berail, M. Jimenez-Moreno, V. Perrot, C. Pecheyran, D. Amouroux
and O. F. X. Donard, Anal. Chem., 2010, 82, 5652-5662.
47.
J. Fietzke, V. Liebetrau, D. Guenther, K. Gurs, K. Hametner, K. Zumholz, T. H.
Hansteen and A. Eisenhauer, J. Anal. At. Spectrom., 2008, 23, 955-961.
48.
C. C. Shen, R. L. Edwards, H. Cheng, J. A. Dorale, R. B. Thomas, S. B. Moran, S. E.
Weinstein and H. N. Edmonds, Chem. Geol., 2002, 185, 165-178.
- 17 -