Analytical Chemistry Chemical Cytometry Quantitates Superoxide

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Figure 4. Mass flow chromatogram obtained for the mixture of BTEX and 1,2,4-trimethylnenzene in water using HS-SPME-GC-Combustion-MS and postcolumn addition of 13 CO2. nately, the CAR/PDMS/DVB fiber generated broader peaks and tailing, resulting in lower signal-to-noise ratio and poorer precision in comparison with the PDMS/DVB fiber, which was finally selected for further experiments. In addition, the fiber/sample distribution constants (Kfs) were calculated for a more reliable comparison between the extraction efficiency of the fibers as it is a parameter related to the phase volume 23 (see Table SI-2 in the Supporting Information). The Kfs values obtained for the PDMS fiber were of the same order of those cited in the literature. 19 Interestingly, Kfs values obtained for the PDMS/ DVB fiber were significantly higher than those obtained for the CAR/PDMS/DVB fiber, in spite that both fibers provided very similar absolute recoveries (see Table 2). These results seem to indicate that the PDMS/DVB stationary phase showed higher affinity for the BTEX compounds. Notably, only nine analysis (three replicates per fiber tested) were necessary to obtain this valuable information in fundamental studies, critical to optimize new procedures of SPME. As an example, Figure 4 shows the mass-flow chromatogram obtained using the PDMS/DVB fiber. In this case, together with the impressive preconcentration factor typically observed by SPME, the carbon background was significantly decreased (two or three times lower). The detection limits obtained using HS- SPME were in the low ng/L level (
ment. Therefore, the long-time dreamed of chromatographic detection allowing generic quantification and complete characterization of organic compounds in a single instrument is realized. In addition, the proposed method turned out to be very cost-effective because expenses associated with the use of isotopically labeled 13 CO2 are negligible and there is no need for external calibration, resulting in considerable savings in time and money (e.g., cost of analytical standards). Beyond its potential use for quantitative quality control in a wide range of standard laboratories (e.g., environmental ones), a powerful application of our approach can be foreseen in oil-spill fingerprinting and in pharmaceutical analysis, for which the number of target organic analytes is increasing exponentially (so it is virtually impossible to have standards for each compound, even if they exist). In addition, the unique compound-independent calibration capabilities of the approach proposed could be advantageously exploited for the assessment of sample introduction procedures in GC. In the present work, we have selected HS-SPME to illustrate this promising ability of our approach. Quantitative data obtained for BTEX compounds in different water samples have demonstrated that quantitative assessment of HS-SPME procedures in terms of absolute absorption yields is successful (the analytical features of different fiber coatings could be evaluated and critically compared in this way), opening its use to assess the performance of many other reported sample preparation and preconcentration methods. ACKNOWLEDGMENT Financial support was provided by the Spanish Ministry of Education (CTQ2006-05722) and FICYT (PC06-016) and technical support by KONIK-TECH. J.R.E. acknowledges the MEC (European Social Fund) for a Ramon y Cajal contract, and S.C.D. acknowledges the FICYT for a PhD grant. SUPPORTING INFORMATION AVAILABLE The mass spectrum obtained for the mass range 43-47 when 1 mL/min of the spike flow was introduced directly to the ion source (Figure SI-1). The optimization of the integration time for the 44/45 isotope ratio measurement (Figure SI-2). The short term (30 min) and long term (9 h) stability of the 12 CO2/ 13 CO2 isotope ratio (Figures SI-3 and SI-4, respectively). The quantification results of a mixture of different families of compounds containing saturated, insaturated and functionalized compounds (Table SI- 1). The Kfs values obtained for reliable comparison between the different fibers used (Table SI-2). The multiple headspace experiment carried out for internal validation of the approach, comparing the sum of the amount obtained in each single extraction to the total amount initially present in the spiked solution (Table SI-3). This material is available free of charge via the Internet at http://pubs.acs.org. Received for review April 12, 2010. Accepted July 2, 2010. AC101103N <strong>Analytical</strong> <strong>Chemistry</strong>, Vol. 82, No. 16, August 15, 2010 6869
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Anal. Chem. 2010, 82, 6745-6750 Let
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purchased from Invitrogen-Molecular
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Figure 3. Electropherograms of TPP-
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Anal. Chem. 2010, 82, 6751-6755 Res
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(pH 8.0) with cysteine and cystamin
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Figure 4. Ion mobility mass spectra
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GOx glucose + O298 gluconic acid +
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coater at 2000 rpm for 20 s, and th
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Figure 5. Comparison of cyclic volt
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in channels with either no grooves
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indicators of atmospheric processin
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Figure 1. GC/MS total ion chromatog
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Table 2. Concentrations and Stable
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on a substrate are preferred. 20-24
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Figure 4. SERS analysis of NAADP co
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Anal. Chem. 2010, 82, 6775-6781 Hig
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tion, 2 µL of proprionaldehyde wer
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Figure 4. Analysis of 2a by HPLC-MS
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eaction of 1a with PBH can be condu
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Numerous references had demonstrate
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Figure 1. TEM images of the prepare
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Figure 4. Schematic representation
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esult in a big SPR signal change wi
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also reduces chemical noise, which
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Table 1. Extraction Yields, Liquid
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scanning of AMPP amides of the anal
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Anal. Chem. 2010, 82, 6797-6806 δ
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Figure 1. Schematic view of the pre
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from the specimen and enclosed in a
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Figure 4. (A) IRMS mass-44 chromato
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Table 3. Ambient Measurement Result
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Anal. Chem. 2010, 82, 6807-6813 Dir
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Polymerase (1 U per sample). Reacti
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of which was constant for all ampli
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analytically useful signals at less
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carbon black and RP-C18 for the ext
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Page 75 and 76: Table 2. Concentrations and Ratios
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Page 79 and 80: mg/mL protein, followed by separati
Page 81 and 82: Figure 2. Productivity of SEQUST an
Page 83 and 84: Figure 4. High-resolution MS/MS spe
Page 85 and 86: Figure 6. Characterization of PSMs
Page 87 and 88: containing T-T mismatches. 23 Based
Page 89 and 90: Figure 1. Extinction spectra of sol
Page 91 and 92: Figure 3. (A) The value of Ex650 nm
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Page 97 and 98: constant medium for separation; we
Page 99 and 100: Figure 2. Standards of (Pi)n, n ) 1
Page 101 and 102: Figure 5. Quantitative calibration
Page 103 and 104: Anal. Chem. 2010, 82, 6847-6853 Met
Page 105 and 106: Figure 1. 226 Ra spectrum by liquid
Page 107 and 108: Table 1. Counting Properties and De
Page 109 and 110: Table 3. Analysis of 226 Ra in Sedi
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Page 113 and 114: Figure 2. Optical transmission meas
Page 115 and 116: Figure 5. Volcano plots detailing t
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Page 119 and 120: corresponding compound if its chemi
Page 121 and 122: Figure 1. Schematic illustration of
Page 123: Table 1. Absolute Quantification Re
Page 127 and 128: Figure 1. Chemically actuated micro
Page 129 and 130: Figure 2. Influence of a surfactant
Page 131 and 132: Figure 5. Device to eject and mix s
Page 133 and 134: Anal. Chem. 2010, 82, 6877-6886 Imm
Page 135 and 136: NaCl, phosphate buffer saline (PBS)
Page 137 and 138: Figure 2. Product ion mass spectra
Page 139 and 140: -70 °C resolved the problem, givin
Page 141 and 142: Table 1. Intraday Precision and Acc
Page 143 and 144: Anal. Chem. 2010, 82, 6887-6894 Fer
Page 145 and 146: Figure 1. Infrared spectra of (A) u
Page 147 and 148: Figure 3. Cyclic voltammograms obta
Page 149 and 150: Figure 6. Calculated charge from ch
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Page 153 and 154: Table 1. Chemical Structure, pKa Va
Page 155 and 156: pH with a tilted baseline (Figure 1
Page 157 and 158: Table 2. Linearity and Detection Li
Page 159 and 160: ascorbic acid (AA), uric acid (UA),
Page 161 and 162: the multielement capabilities, the
Page 163 and 164: RESULTS AND DISCUSSION Sulfur Detec
Page 165 and 166: Table 2. Molecular Properties and C
Page 167 and 168: Anal. Chem. 2010, 82, 6911-6918 Dir
Page 169 and 170: dilution and hybridization buffer.
Page 171 and 172: solution under appropriate incubati
Page 173 and 174: Figure 4. Standardization curve for
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Anal. Chem. 2010, 82, 6919-6925 Ele
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the ×10 objective, to have a large
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Figure 2. With a suitable removal o
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the NB signal in a much better foot
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Scheme 1. Reactions of Selenium Rea
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Figure 2. (a) ESI-MS spectrum showi
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Figure 4. (a) ESI-MS spectrum showi
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Anal. Chem. 2010, 82, 6933-6939 Dif
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trode 28 by a finite element using
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Figure 4. Comparison between simula
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Figure 6. Comparison between simula
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educed in the vicinity of double bo
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Figure 2. Normalized product ion ab
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Figure 4. EID (a) and IRMPD (b) of
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Anal. Chem. 2010, 82, 6947-6957 Ide
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Figure 1. Schematic flowchart showi
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difference, ppm compound Table 1. I
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isoforms, its successful use, in th
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Figure 5. Extracted ion current ESI
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m/z 1172.935 was observed for Ser14
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linked products via affinity tags.
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Scheme 2. Fragmentation Mechanism o
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Figure 1. (A) ESI-LTQ-CID-MS 2 prod
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Figure 3. (A) ESI-LTQ-CID-MS 2 prod
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Figure 5. (A) MALDI-TOF/TOF product
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Anal. Chem. 2010, 82, 6969-6975 Ana
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Figure 3. Equilibrium response as a
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Figure 6. The average measured resp
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for the fill time, and we find that
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nucleotide tails. 3-5 Thus, the amo
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allow the use of higher aptamer con
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quent ligation of the aptamers afte
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Anal. Chem. 2010, 82, 6983-6990 Imp
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Figure 2. Configuration editor wind
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Figure 4. Dependencies between volu
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Since the time for liquid expulsion
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Anal. Chem. 2010, 82, 6991-6999 Int
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Figure 1. Representation of the Car
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Table 2. Capillary Electrophoresis
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Figure 4. (A) Typical raw electroph
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field. DNA profiles were delivered
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Another approach to handle this lim
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(principal components, PCs) in whic
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Figure 5. Relevant score plots and
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CONCLUSIONS In this paper we have i
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electroactive-species loaded liposo
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Figure 2. Qdot-based FLFTS response
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Figure 6. Fluorescence imaging of Q
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Anal. Chem. 2010, 82, 7015-7020 Sel
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Table 1. Effect of 1 D-LC Condition
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Figure 3. Peak-production rate vers
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Anal. Chem. 2010, 82, 7021-7026 Cel
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luciferase (T7 control vector) was
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Figure 3. Inhibitory effects of luc
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Anal. Chem. 2010, 82, 7027-7034 Pat
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Electrochemistry. Electrochemical m
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Figure 2. SEM images of Au substrat
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Table 3. Film Thickness Measurement
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Anal. Chem. 2010, 82, 7035-7043 Qua
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Figure 1. (A) FL spectra of BSPOTPE
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Figure 4. (A) Variation in the FL i
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Figure 6. (A) FL spectra of BSPOTPE
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Scheme 1. Proposed Mechanism for Fl
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one or more drawbacks including poo
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Figure 2. Free fluorophores do not
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Anal. Chem. 2010, 82, 7049-7052 Dev
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Figure 2. Comparative analysis of d
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Analytical Chemistry Chemical Cytometry Quantitates Superoxide

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