Analytical Chemistry Chemical Cytometry Quantitates Superoxide

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Figure 3. Normalized product ion abundances of [CxHyO2 + Met] + vs Cn (n denotes carbon position from the carboxylate end of a fatty acid) in EID of Ni(II)- and Mg(II)-adducted arachidonic acid. The structure of arachidonic acid is shown with double bond locations. repeated three times on three different days to verify the reliability of EID as a method for double bond localization in fatty acids. As shown in Figure 2, EID spectra of Mn(II)-adducted fatty acids provided highly reproducible structural information regarding double bond positions for each fatty acid. Lower product ion abundances at the C4 position, observed in EID of Mn(II)adducted linolenic acid, oleic acid, and stearic acid, indicated that those fatty acids do not have double bonds between C5 and C6. In contrast, the lower product ion abundance at C5 compared to C4 was indicative of the existence of a double bond between C5 and C6 in arachidonic acid. Other double bond locations in each fatty acid could be obtained from valley positions in the graph of normalized charge-remote product ion abundances vs carbon position (Cn), as shown in Figure 2. Gas-phase ion fragmentation reactions are charge remote when there is no important interaction between the charge and the cleavage sites. However, hydrocarbon chains are flexible, and such interactions can, therefore, occur even in the presence of a terminal fixed charge, particularly at less remote sites. 15 Gross and co-workers have reported that some product ions formed by cleavage near the charge are stabilized by a cyclic conformation. 15 6944 Analytical Chemistry, Vol. 82, No. 16, August 15, 2010 For example, C4-C5 bond cleavage in deprotonated palmitic acid was enhanced due to formation of a cyclic structure. 18 Similarly, enhanced cleavage at the C3 position occurred in EID of Mn(II)adducted linolenic, oleic, and stearic acid (Figure 2b-d), possibly due to ring formation. Mn(II) is expected to bind tightly with the carboxylate anion end of fatty acids because both Mn(II) and the carboxylate anion have hard Lewis acid and base properties, respectively. Binding energies of divalent metal ions and H2O/OH - increase sharply at the transition between d 0 (Ca(II)) and d n (Sc(II)) due to electron occupation in d orbitals. 38 These chemical properties may explain why Mn(II) appears to be more efficient than other divalent metals examined (see below) for “fixing” a charge at the carboxylate end of fatty acids. Charge-Remote Fragmentation in EID of Arachidonic Acid Adducted with Metals Other than Mn(II). In addition to Mn(II), which yielded successful charge remote fragmentation in EID (see above), Li(I) and other divalent metals (Zn(II), Co(II), Ni(II), Mg(II), Ca(II), and Fe(II)) were examined as adducts in EID of (38) Magnusson, E.; Moriarty, N. W. Inorg. Chem. 1996, 35, 5711–5719.
Figure 4. EID (a) and IRMPD (b) of Mn(II)-adducted arachidonic acid. ν2 and ν3 denote the second and third harmonic peaks. [CxHyO2 + Mn] + product ion peaks are labeled with “b”, and [CxHy] + -type peaks are labeled with “4”. Figure 4a shows the same spectrum as in Figure 1a, but here, all peaks are labeled for comparison with the IRMPD spectrum. Y-axis is zoomed 200 or 5 times, indicated by “×200” or “×5”. arachidonic acid. Lithium was our first metal of choice because doubly Li(I)-adducted fatty acids, [M + 2Li - H] + , have been shown to yield charge-remote fragmentation in high energy CAD. 9,10,16,18 Electron irradiation (∼26 eV electrons) of the [M + 2Li - H] + form of arachidonic acid did not yield any product ions (Supplementary Figure 1a, Supporting Information). One explanation for this discrepancy may be the different means of electronic excitation in EID vs high energy CAD: the latter involves interactions between ions and neutrals whereas the former involves ion-electron interactions. Thus, physical parameters such as polarizibility (which is low for lithium) should be more important in EID compared to high energy CAD. EID (∼20 eV electrons) of Zn(II)- and Co(II)-adducted arachidonic acid yielded very limited charge-remote fragmentation (Supplementary Figure 1b,c, Supporting Information). In contrast, EID of Ni(II)-, Mg(II)-, Ca(II)-, and Fe(II)-adducted arachidonic acid provided extensive charge-remote product ions of the type [C xHyO2 + Met] + . (As an example, EID of Ni(II)-adducted arachidonic acid is shown in Supplementary Figure 1d, Supporting Information.) Figure 3 shows charge-remote product ion abundances as a function of alkyl chain carbon position from EID spectra of Ni(II)and Mg(II)-adducted arachidonic acid. Similar to the Mn(II) data in Figure 2, [CxHyO2 + Met] + -type product ions were used to generate this plot. EID of Ca(II)- and Fe(II)-adducted arachidonic acid provided very similar results; thus, the corresponding data are not shown. EID of these metal-adducted arachidonic acid did not provide characteristic ion abundance patterns at all double bond positions. The double bond (C14-C15) far from the carboxylate end could not be identified from EID of Ni(II)-adducted arachidonic acid (Figure 3a). Further, the double bond (C5-C6) close to the carboxylate end could not be determined from EID Analytical Chemistry, Vol. 82, No. 16, August 15, 2010 6945
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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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solution in an equal volume, and 1
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Table 2. Concentrations and Ratios
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Anal. Chem. 2010, 82, 6821-6829 Mac
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mg/mL protein, followed by separati
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Figure 2. Productivity of SEQUST an
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Figure 4. High-resolution MS/MS spe
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Figure 6. Characterization of PSMs
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containing T-T mismatches. 23 Based
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Figure 1. Extinction spectra of sol
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Figure 3. (A) The value of Ex650 nm
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Figure 5. Extinction spectra and co
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wished to explore the dehydration o
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constant medium for separation; we
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Figure 2. Standards of (Pi)n, n ) 1
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Figure 5. Quantitative calibration
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Anal. Chem. 2010, 82, 6847-6853 Met
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Figure 1. 226 Ra spectrum by liquid
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Table 1. Counting Properties and De
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Table 3. Analysis of 226 Ra in Sedi
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mercial microarray scanner and fabr
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Figure 2. Optical transmission meas
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Figure 5. Volcano plots detailing t
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data as well. The 41 genes in Table
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corresponding compound if its chemi
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Figure 1. Schematic illustration of
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Table 1. Absolute Quantification Re
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ment. Therefore, the long-time drea
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Figure 1. Chemically actuated micro
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Figure 2. Influence of a surfactant
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Figure 5. Device to eject and mix s
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Anal. Chem. 2010, 82, 6877-6886 Imm
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NaCl, phosphate buffer saline (PBS)
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Figure 2. Product ion mass spectra
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-70 °C resolved the problem, givin
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Table 1. Intraday Precision and Acc
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Anal. Chem. 2010, 82, 6887-6894 Fer
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Figure 1. Infrared spectra of (A) u
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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
Page 175 and 176: Anal. Chem. 2010, 82, 6919-6925 Ele
Page 177 and 178: the ×10 objective, to have a large
Page 179 and 180: Figure 2. With a suitable removal o
Page 181 and 182: the NB signal in a much better foot
Page 183 and 184: Scheme 1. Reactions of Selenium Rea
Page 185 and 186: Figure 2. (a) ESI-MS spectrum showi
Page 187 and 188: Figure 4. (a) ESI-MS spectrum showi
Page 189 and 190: Anal. Chem. 2010, 82, 6933-6939 Dif
Page 191 and 192: trode 28 by a finite element using
Page 193 and 194: Figure 4. Comparison between simula
Page 195 and 196: Figure 6. Comparison between simula
Page 197 and 198: educed in the vicinity of double bo
Page 199: Figure 2. Normalized product ion ab
Page 203 and 204: Anal. Chem. 2010, 82, 6947-6957 Ide
Page 205 and 206: Figure 1. Schematic flowchart showi
Page 207 and 208: difference, ppm compound Table 1. I
Page 209 and 210: isoforms, its successful use, in th
Page 211 and 212: Figure 5. Extracted ion current ESI
Page 213 and 214: m/z 1172.935 was observed for Ser14
Page 215 and 216: linked products via affinity tags.
Page 217 and 218: Scheme 2. Fragmentation Mechanism o
Page 219 and 220: Figure 1. (A) ESI-LTQ-CID-MS 2 prod
Page 221 and 222: Figure 3. (A) ESI-LTQ-CID-MS 2 prod
Page 223 and 224: Figure 5. (A) MALDI-TOF/TOF product
Page 225 and 226: Anal. Chem. 2010, 82, 6969-6975 Ana
Page 227 and 228: Figure 3. Equilibrium response as a
Page 229 and 230: Figure 6. The average measured resp
Page 231 and 232: for the fill time, and we find that
Page 233 and 234: nucleotide tails. 3-5 Thus, the amo
Page 235 and 236: allow the use of higher aptamer con
Page 237 and 238: quent ligation of the aptamers afte
Page 239 and 240: Anal. Chem. 2010, 82, 6983-6990 Imp
Page 241 and 242: Figure 2. Configuration editor wind
Page 243 and 244: Figure 4. Dependencies between volu
Page 245 and 246: Since the time for liquid expulsion
Page 247 and 248: Anal. Chem. 2010, 82, 6991-6999 Int
Page 249 and 250: 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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