Analytical Chemistry Chemical Cytometry Quantitates Superoxide

More documents

Recommendations

Info

(Graseby-Andersen) was operated at a flow rate of 1.13 m3 / min, and Whatman quartz fiber filters (20.3 cm × 25.4 cm) were used; 24 h samplers were collected. All filters were baked at 550 °Cfor4htoremove organic contaminants. After collection, the filters were stored at -20 °C until they were analyzed. Part of the filters was extracted with methanol. The solvent was then concentrated, filtered, and finally dried completely. All samples were derivatized using the same procedure as described above and measured by GC/C/IRMS. Analytical Systems. The gas chromatography/mass spectrometry (GC/MS) instrument consisted of a Hewlett-Packard (Fullerton, CA) model 6890 gas chromatograph equipped with a DP-5MS device (30 m × 0.25 mm inside diameter, 0.25 µm film thickness), coupled to a Hewlett-Packard model 5975MSD quadrupole analyzer. Data were acquired and processed with Chem- Station (Hewlett-Packard). The temperature program was as follows: initial temperature at 100 °C held for 5 min, a gradient of 3 °C/min up to 200 °C, a gradient of 30 °C/min up to 290 °C, held for 2 min. The mass spectrometer was operated in the electron ionization mode at 70 eV and an ion source temperature of 150 °C. Full scan mode was used in the mass range of m/z 50-420. Two kinds of gas chromatography/combustion/isotopic ratio mass spectrometry (GC/C/IRMS) systems were used in this study. The analysis of MBA derivatives was performed on an HP 6890 GC system (Agilent, Santa Clara, CA) equipped with a DP- 5MS device (30 m × 0.25 mm × 0.25 µm), connected to an isotope ratio mass spectrometer (Isoprime, GV instrument, Manchester, U.K.). The oven temperature program was as follows: initially at 60 °C, a gradient of 4 °C/min up to 110 °C, held for 2 min, a gradient of 50 °C/min up to 290 °C, held for 2 min. The injector was set at 250 °C in splitless mode. Helium was used as the carrier gas at 1.5 mL/min. CO2 with a known δ13C value (-26.65‰) was used as the external reference gas. The combustion furnace containing the CuO catalyst and the reduction oven containing the Cu catalyst were kept at 940 and 650 °C, respectively. The temperature of the interface between the GC and combustion furnace was set at 290 °C. The reproducibility and accuracy of carbon isotopic analyses were evaluated routinely every day using 10 laboratory isotopic standards (C12, C14, C16, C18, C20, C22, C25, C28, C30, and C32 n-alkanes supplied by Indiana University, Bloomington, IN) with known isotopic values (-31.89, -30.67, -30.53, -31.02, -32.24, -32.77, -28.49, -32.11, -33.05, and -29.41‰, respectively). 2-Methyltetrol methylboronates prepared in the laboratory were analyzed 10 times and used as laboratory standards. For δ13C analysis of isoprene, the same GC/C/IRMS system described above and a CP-PoraPLOT Q column (25 m × 0.32 mm × 10 µm, Varian) were used. The GC was run in a split ratio of ∼40:1, and the injector was set at 150 °C. The initial oven temperature was held at 120 °C for 1 min, followed by a gradient of 20 °C/min up to 195 °C, at which point the temperature was held for 10 min. Standard CO2 (δ13C ) -26.65‰) was used as the external reference gas. CH4 with a known δ13C value (-36.30‰) was used as the laboratory isotopic standard to check the reproducibility and accuracy of 6766 Analytical Chemistry, Vol. 82, No. 16, August 15, 2010 the carbon isotopic analysis routinely. 22 For both analysis systems, the sextuple analysis of laboratory isotopic standards indicated excellent accuracy and reproducibility of carbon isotopic analysis [the corresponding standard deviation ranged from 0.13 to 0.30‰, and the deviation between the measured data and the predetermined data ranged from -0.02 to 0.13‰ (Table 1S of the Supporting Information)]. Elemental analyzer/isotope ratio mass spectrometry (EA/ IRMS) was performed as follows. Standard 2-methyltetrols and recrystallized methylboronic acid were put into cleaned tin capsules and weighed, repectively. Capsules containing weighed samples were placed in the CE (Wigan, U.K.) EA1112 C/N/S analyzer and burned at 960 °C in an O2 atmosphere in a combustion tube. Combustion gases were swept through a reduction oven and entered a GC column where CO2 was separated from other gases. Then the CO2 passed through a Conflo III interface (Finnigan, Waltham, MA) and entered a DELTA plus XL mass spectrometer (Thermo Finnigan MAT, Bremen, Germany) where it was compared to the reference CO2 with a known δ 13 C value (-29.10‰, calibrated against the NBS-22 reference material with a δ 13 C value of -29.70‰). During every batch of analyses, an empty tin capsule was analyzed as a blank to check the background, and the carbon black sample with a known δ 13 C value (-36.91‰) was used to evaluate the reproducibility and accuracy. The standard deviation of analysis and the deviation between the measured data and the predetermined data were less than 0.3‰ (Table 2S of the Supporting Information). All 13 C: 12 C ratios are expressed in conventional delta (δ) notation, which is the per mil (‰) deviation from the standard Vienna Pee Dee Belemnite (VPDB) reference point. RESULTS AND DISCUSSION δ 13 C Analysis of Standard 2-Methyltetrols. Figure 1 shows a typical total ion current (TIC) GC/MS chromatogram from isoprene oxidation products derivatized by BSTFA. Identification of these two major compounds was made by comparison of the retention time and mass spectra with those published in the literature. 1,6,20 Figure 2 presents the TIC GC/MS chromatogram of 2-methyltetrol-MBA derivatives. The mass spectra of these three compounds are very similar, as could be expected for diastereoisomers. The mass spectrum of compound 2 reveals a tiny molecular ion (m/z 184). Characteristic ions at m/z 99 and 85 correspond to the cleavage of the C-C bond at the C2 position. Other ions at m/z 69, 57, and 43 can be explained by the further fragment of the ion at m/z 85 or 99. The δ 13 C values of methylboronic acid and standard 2-methyltetrols were determined by EA/IRMS to be -24.96 ± 0.06‰ (eight measurements) and -32.40 ± 0.14‰ (n ) 6, from M1), -29.84 ± 0.12‰ (n ) 6, from M2), and -32.36 ± 0.18‰ (n ) 6, from M3) (Table 1). δ 13 C Analysis of MBA Derivatives. In derivatization, the preparation of 2-methyltetrol-MBA derivatives alters the original stable isotope compositions of the 2-methyltetrols. To correct for the introduction of carbon during derivatization, it is necessary to assess the isotopic reproducibility of the derivatization method. (22) Wen, S.; Feng, Y.; Yu, Y.; Bi, X.; Wang, X.; Sheng, G.; Fu, J. Environ. Sci. Technol. 2005, 39, 6202–6027.
Figure 1. GC/MS total ion chromatograms obtained for the reaction mixtures of isoprene with H2O2 and sulfuric acid derivatized by BSTFA and spectra for products (insets) 1 (2-methylthreitol) and 2 (2-methylerythritol). Figure 2. GC/MS total ion chromatogram obtained for 2-methyltetrols derivatized by MBA and mass spectra for the products (insets). Compounds 1 and 2 correspond to 2-methylerythritol-MBA derivatives, and compound 3 corresponds to a 2-methylthreitol-MBA derivative. Table 1. Stable Carbon Isotopic Compositions of Isoprene, 2-Methyltetrols (2-MT), and MBA Derivatives Measured and Predicted in the Derivatization Reaction supplier measured isoprene b,c measured 2-MT b,d The reproducibility of the carbon isotope composition for three 2-methyltetrols (with different δ 13 C values) was evaluated. Their δ 13 C values and those of the corresponding MBA derivatives are listed in Table 1. The analytical errors (standard deviation) obtained for six EA/IRMS analyses of 2-methyltetrols produced from isoprene from the same supplier ranged from 0.12 to 0.18‰, with an average of 0.15 ± 0.03‰, while for GC/C/IRMS analyses of MBA derivatives, the analytical errors were from 0.15 to 0.22‰, with an average of 0.17 ± 0.04‰. The reproducibility compares well with those obtained in the derivatization of fatty acids. 23 Isotopic Effects of the Method. According to eq 1, the theoretical δ 13 C values of methylboronates can be calculated (23) Abrajano, T. A.; Murphy, D. E., Jr.; Fang, J.; Comet, P. A.; Brooks, J. M. Org. Geochem. 1994, 21, 611–617. δ 13 C a measured methylboronates b,c,e calculated methylboronates b,f M1 -24.54 ± 0.18 (n ) 7) -32.40 ± 0.14 (n ) 6) -29.98 ± 0.22 (n ) 6) -30.27 0.29 M2 -23.72 ± 0.23 (n ) 7) -29.84 ± 0.12 (n ) 6) -28.08 ± 0.15 (n ) 6) -28.24 0.16 M3 -25.19 ± 0.19 (n ) 7) -32.36 ± 0.18 (n ) 6) -30.35 ± 0.16 (n ) 6) -30.25 -0.10 a Stable carbon isotopic compositions reported in per mil relative to PDB. b Arithmetic means and standard deviations. c δ 13 C values determined by GC/C/IRMS. d δ 13 C values determined by EA/IRMS. e Derivatized by methylboronic acid with a δ 13 C value of -24.96 ± 0.06‰ (eight measurements) determined by EA/IRMS. f On the basis of mass balance relationship eq 1. g Calculated δ 13 C - measured δ 13 C. according to stoichiometric mass balance and reflect the relative contributions of carbon from 2-methyltetrols, methylboronic acid, and their respective δ 13 C values: δ 13 C methylboronate ) f MBA δ 13 C MBA + f 2-methyltetrol δ 13 C 2-methyltetrols (1) where fMBA and f2-methyltetrol are the molar fractions of carbon in methylboronate arising from underivatized 2-methyltetrol and MBA reagent, respectively. Here, fMBA ) 2 /7, and f2-methyltetrols ) 5 /7. The stable carbon isotopic compositions obtained for 2-methyltetrols and derivatives are listed in Table 1. The measured data for methylboronates were compared with Analytical Chemistry, Vol. 82, No. 16, August 15, 2010 ∆ g 6767
Page 1 and 2: Anal. Chem. 2010, 82, 6745-6750 Let
Page 3 and 4: purchased from Invitrogen-Molecular
Page 5 and 6: Figure 3. Electropherograms of TPP-
Page 7 and 8: Anal. Chem. 2010, 82, 6751-6755 Res
Page 9 and 10: (pH 8.0) with cysteine and cystamin
Page 11 and 12: Figure 4. Ion mobility mass spectra
Page 13 and 14: GOx glucose + O298 gluconic acid +
Page 15 and 16: coater at 2000 rpm for 20 s, and th
Page 17 and 18: Figure 5. Comparison of cyclic volt
Page 19 and 20: in channels with either no grooves
Page 21: indicators of atmospheric processin
Page 25 and 26: Table 2. Concentrations and Stable
Page 27 and 28: on a substrate are preferred. 20-24
Page 29 and 30: Figure 4. SERS analysis of NAADP co
Page 31 and 32: Anal. Chem. 2010, 82, 6775-6781 Hig
Page 33 and 34: tion, 2 µL of proprionaldehyde wer
Page 35 and 36: Figure 4. Analysis of 2a by HPLC-MS
Page 37 and 38: eaction of 1a with PBH can be condu
Page 39 and 40: Numerous references had demonstrate
Page 41 and 42: Figure 1. TEM images of the prepare
Page 43 and 44: Figure 4. Schematic representation
Page 45 and 46: esult in a big SPR signal change wi
Page 47 and 48: also reduces chemical noise, which
Page 49 and 50: Table 1. Extraction Yields, Liquid
Page 51 and 52: scanning of AMPP amides of the anal
Page 53 and 54: Anal. Chem. 2010, 82, 6797-6806 δ
Page 55 and 56: Figure 1. Schematic view of the pre
Page 57 and 58: from the specimen and enclosed in a
Page 59 and 60: Figure 4. (A) IRMS mass-44 chromato
Page 61 and 62: Table 3. Ambient Measurement Result
Page 63 and 64: Anal. Chem. 2010, 82, 6807-6813 Dir
Page 65 and 66: Polymerase (1 U per sample). Reacti
Page 67 and 68: of which was constant for all ampli
Page 69 and 70: analytically useful signals at less
Page 71 and 72: carbon black and RP-C18 for the ext
Page 73 and 74:
solution in an equal volume, and 1
Page 75 and 76:
Table 2. Concentrations and Ratios
Page 77 and 78:
Anal. Chem. 2010, 82, 6821-6829 Mac
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
Page 93 and 94:
Figure 5. Extinction spectra and co
Page 95 and 96:
wished to explore the dehydration o
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
Page 111 and 112:
mercial microarray scanner and fabr
Page 113 and 114:
Figure 2. Optical transmission meas
Page 115 and 116:
Figure 5. Volcano plots detailing t
Page 117 and 118:
data as well. The 41 genes in Table
Page 119 and 120:
corresponding compound if its chemi
Page 121 and 122:
Figure 1. Schematic illustration of
Page 123 and 124:
Table 1. Absolute Quantification Re
Page 125 and 126:
ment. Therefore, the long-time drea
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
Page 151 and 152:
Anal. Chem. 2010, 82, 6895-6903 Ele
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 and 200:
Figure 2. Normalized product ion ab
Page 201 and 202:
Figure 4. EID (a) and IRMPD (b) of
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
Page 251 and 252:
Table 2. Capillary Electrophoresis
Page 253 and 254:
Figure 4. (A) Typical raw electroph
Page 255 and 256:
field. DNA profiles were delivered
Page 257 and 258:
Another approach to handle this lim
Page 259 and 260:
(principal components, PCs) in whic
Page 261 and 262:
Figure 5. Relevant score plots and
Page 263 and 264:
CONCLUSIONS In this paper we have i
Page 265 and 266:
electroactive-species loaded liposo
Page 267 and 268:
Figure 2. Qdot-based FLFTS response
Page 269 and 270:
Figure 6. Fluorescence imaging of Q
Page 271 and 272:
Anal. Chem. 2010, 82, 7015-7020 Sel
Page 273 and 274:
Table 1. Effect of 1 D-LC Condition
Page 275 and 276:
Figure 3. Peak-production rate vers
Page 277 and 278:
Anal. Chem. 2010, 82, 7021-7026 Cel
Page 279 and 280:
luciferase (T7 control vector) was
Page 281 and 282:
Figure 3. Inhibitory effects of luc
Page 283 and 284:
Anal. Chem. 2010, 82, 7027-7034 Pat
Page 285 and 286:
Electrochemistry. Electrochemical m
Page 287 and 288:
Figure 2. SEM images of Au substrat
Page 289 and 290:
Table 3. Film Thickness Measurement
Page 291 and 292:
Anal. Chem. 2010, 82, 7035-7043 Qua
Page 293 and 294:
Figure 1. (A) FL spectra of BSPOTPE
Page 295 and 296:
Figure 4. (A) Variation in the FL i
Page 297 and 298:
Figure 6. (A) FL spectra of BSPOTPE
Page 299 and 300:
Scheme 1. Proposed Mechanism for Fl
Page 301 and 302:
one or more drawbacks including poo
Page 303 and 304:
Figure 2. Free fluorophores do not
Page 305 and 306:
Anal. Chem. 2010, 82, 7049-7052 Dev
Page 307 and 308:
Figure 2. Comparative analysis of d
show all

Analytical Chemistry Chemical Cytometry Quantitates Superoxide

Create successful ePaper yourself

Delete template?

Save as template?