Peak reproducibility

FIGURE 2-8 Ideal cyclic voltammetric behavior for a surface layer on an electrode. The surface coverage, FT can be obtained from the area under the peak. (Reproduced with permission from reference 11.)... 

Figure 2. Hel photoelectron spectra of Mo2(TFA)k (left) and W2(TFA)k (right). The spectra have been computer fitted to combination Lorentzian-Gaussian peaks. (Reproduced with permission from Ref. 4. Copyright 1982, The Royal Society of Chemistry.)...

Bad peak reproducibility even when conditions 1-4 are satisfied A. Increased peak retention times... 

Fig. 11.19. Partial ESI mass spectrum of BSA and molecular weights after charge deconvolution (inset). Charge states are assigned to both series of peaks. Reproduced from Ref. [24] by permission. John Wiley Sons, 2000.

Fig. 12.6. Shorter retention times are observed for [Dyiglncose than for glucose eluting from a SE30 GC column as demonstrated for three pairs of peaks. Reproduced from Ref. [35] by permission. American Chemical Society, 1966.

Fig. 2. Integrated ion current curve for iron 8-hydroxyquinolinate on the FeOXa" " peak. [Reproduced by permission from Major and Reade (129)).

Fig. 6. Selected spectral regions of a NOESY spectrum of BPTI recorded with the pulse sequence of fig, 5(A), except that the first spin-lock pulse was omitted and a Bo gradient was applied during the NOESY mixing time. Protein concentration 20 mM in 90% H2O / 10% D2O, pH 6.9, 36°C. The relaxation reagent GdDTPA-BMA was added at a concentration of 750 pM to enhance the relaxation of the water protons. Spin-lock pulse 2 ms, rm(NOE) = 50 ms, r = 190 ps. Positive and negative levels were plotted without distinction. The arrow identifies the cross section containing the intermolecular water-protein cross peaks. (Reproduced by permission of the American Chemical...

FIGURE 10.17 Relationship between the isotherm, its slope and the retention time of perturbation peak. (Reproduced from Tondeur, D. et ah, Chem. Eng. Sci., 51, 3781, 1996. With permission from Elsevier.)... 

This book is rooted in an informal discussion with three researchers. Dr Alatzne Carlosena, Dr Monica Felipe and Dr Maria Jesus Cal, after they had some problems measuring antimony in soils and sediments by electrothermal atomic absorption spectrometry. While we reviewed the results and debated possible problems, much like in a brainstorming session, I realized that some of their difficulties were highly similar to those found in molecular spectrometry (mid-IR spectroscopy, where I had some experience), namely a lack of peak reproducibility, noise, uncontrollable amounts of concomitants, possible matrix interferences, etc. 

Fig. 11. (a) Far ultraviolet rotatory dispersion of ribonuclease. Corrected mean residue specific rotation vs. wavelength [to R = [aLAf/100 [3/(n2 + 2)l where a — specific rotation, M mean residue weight, and n = solvent refractive index. Bars give maximal deviation at peaks. Reproduced from Jirgensons (311). (b) Near ultraviolet rotatory dispersion of 0.48% pancreatic ribonuclease in a 1-mm cell, in (a) 0.15 M phosphate buffer at pH 62 (b) 0.15 M glycine-NaOH buffer at pH 11.5 (c) 0.1 N HC1 (d) 15% sodium dodecyl sulfate. Reproduced from Glazer and Simmons (313). (c) Far ultraviolet circular dichroic spectra of RNase-A, RNase-S, and S-protein at 25° and 3°. Reproduced from Pflumm and Beychok (313). (d) Near ultraviolet circular dichroic spectra of RNase-A as a function of pH. Reproduced from Pflumm and Beychok (313). 

Figure 19. Distribution of the thiophenes in the pyrolysis oil of Athabasca asphaltene as determined by SIR-GC/MS. The number above each peak corresponds to the number of carbon atoms in the n-alkyl side chain. Each fragmentogram is normalized to the most abundant peak. (Reproduced with permission from Ref. 26. Copyright 1988, Alberta Oil Sands Technology and Research Authority.)...

Hz along FI and F2 axis, respectively 16 increments 32 transients each, total measuring time 1 h). Proton chemical shifts along F2, only heteronuclear couphngs along FI axis. Only two levels are plotted for negative peaks. Reproduced by permission of Academic Press from Reference 323... 

Figure 4-29 Pressure dependence of (a) the low-frequency region and (b) high-frequency region Raman peaks of CsVC The vertical dashed lines mark the pressure-induced phase transitions. The symbols (w = weak, m = medium, s = strong) signify the relative intensity of the Raman peaks. (Reproduced with permission from Ref. 50. Copyright 1991 John Wiley Sons, Ltd.)...

Fig. 1. Water charge density in the molecular plane, (a) the contour map. The outermost contour has the value 0.0067 eA-3. The density increases almost exponentially for inner contours. The bond paths, the interatomic surfaces and the bond critical points are also indicated. (b) The relief map where the atom-cores are seen as peaks (reproduced with permission from Bader [2]).

FIGURE 7-22. Effect of gradient steepness upon resolution. The retention depends upon the steepness. The steeper the gradient, the lower the retention and the sharper the peaks. (Reproduced with permission from LC Resources, Inc.)... 

Chromatographic trace obtained by capillary electrophoresis and spectrum of the mixture of doubly or triply charged glycopeptides eluted together in the peak. Reproduced (modified) from Kelly J.F., Ramaley L. and Thibault P., Anal. Chem., 69, 51-60, 1997, with permission. 

Figure 1.6. Electron impact spectra of isomeric (synlanti) oxime-t-butyldimethylsilyi derivatives of 13,14-dihydro-15-ketoPGFz . Both spectra are dominated by loss of the t-butyl radical giving m/e 669 (M-57) as the base peak (reproduced from reference [31])... 

Figure 6-30. Peak intensities calculated for a hypothetical NOESY experiment involving four nuclei, D—A-B-C, with D 4 A from A and B 2 A from A and C. The curve labeled AA is for the diagonal peak, and the remaining curves are for the various cross peaks. (Reproduced from F. J. M. van de Ven, Multidimensional NMR in Liquids, VCH, New York, 1995, p. 188.)...

Figure 12. The density of states (DS) on the potential energy (e) space for an M7 cluster, (a) DS in configuration space f2g(s) calculated for the Lennard-Jones potential, increasing with 8. (b) DS in momentum space (1p(E — s), decreasing with 8. (c) A product 3(e) = Qq(e)Qp(E — e) giving the total density of state at the total energy E after the convoluting integral over 8. 3(8) has a single sharp peak. (Reproduced from Ref. 11 with permission.)...

Figure 11 2D HNN-COSY spectrum of the 38-nt RNA construct from the consensus stem D of the cloverleaf domain of enteroviruses sequence is shown in the inset. Labeled peaks in the upper part of the spectrum arise from the one-bond correlations of the NH imino groups. Cross-peaks in the lower part of the spectrum (not labeled) arise due to the scalar coupling (2Jnn of 5-7 Hz) between 15N nuclei across the NH-N hydrogen bonds in Watson-Crick AU and GC pairs. They have the opposite phase compared with the diagonal NH peaks. Reproduced with permission from Z. Du J. Yu N. B. Ulyanov R. Andino T. L. James, Biochemistry 2004, 43, 11959-11972, with permission from the American Chemical Society. Copyright (2004) American Chemical Society.

Figure 13.6 Indirect detection of anions and cations. Stationary phase //-Bondapak-Phenyl. Mobile phase naphthalene-2-sulfonate 4 x 10 M in 0.05 M phosphoric acid. Sample (1) butyl sulfate, (2) pentyl amine, (3) hexane sulfonate, (4) hep-tylamine (5) octane sulfonate (6) octyl sulfate (S) system peak. Reproduced with permission from J. Crommen, G. Schill, D. West-erlund and L. Hackzell, Chromatographia, 24 (1987) 252 (Fig. 1).

Figure 2.26 Three types of peak shapes in X-ray diffraction pattern (a) peak height proportional to peak area (b) peak height not proportional to peak area and (c) peak area overlapped by other peaks. (Reproduced with permission from R. Jenkins and R.L. Snyder, Introduction to X-ray Powder Diffrac-tometry, John Wiley Sons Inc., New York. 1996 John Wiley Sons Inc.)...

Figure 19.10 Peak areas and system peaks. (Reproduced by permission of Elsevier Science Publishers BV from G. Sehili and J. Crommen, Trends Anal. Chem., 6, 111 (1987).) The two peaks indicated by Sare system peaks. Sample, racemate of bupivacaine (equal amounts of both isomers) stationary phase, EnantioPac (aq-acid glycoprotein on silica) mobile phase, phosphate buffer (pH 7.2)-isopropanol (92 8), UV detector, 215 nm (the mobile phase shows some absorbance at this wavelength).

MAS spectra (14.1 T) of recombinant Cur. inaequalis VClPO (bottom trace, with the best model for the vanadium environment indicated). For comparison, the solid-state NMR spectra of a model compound (centre), sodinm orthovanadate (top) and hovine serum alhumin [BSA, trace (h)] are also shown. An asterisk indicates the isotropic peak. Reproduced from N. Pooransingh-Margohs et at, J. Am. Chem. Soc. 128, 5190-5208. Copyright (2006), with permission from the American Chemical Society. 

Ppm from TMS. B, V, LB, and LV indicate the HB unit, the HV unit, the P(3HB) lattice, and the P(3HV) lattice, respectively. S-CH2 indicates side-chain methylene of HV units. X indicates HV mol% content of P(3HB-3HV) copolymers. Broad peak. (Reproduced from Ref. [53] with permission). 

Two typical spectra obtained with wet and dry samples are shown in fig. 13. For the wet sample, the NQES spectra are composed of a sharp peak reproducing the resolution function of the instrument superimposed on a broad component having about 100y eV FWHM. The dry sample on the contrary, exhibits only the sharp peak. This observation immediately tells us that the broad... 

Figure 16 (a) Triplet-triplet absorption spectrum of compound shown in the inset (absorbance against wavenumber), (b) Triplet circular dichroism o/R and S enantiomers corrected to 100% optical purity. The value g = />L R/ averag calculated at the peak (Reproduced by permission from Nouv. J. Chem., 1980, 4, 423). 

Figure 3.21 Two-dimensional correlation spectroscopy of a highly siliceous ZSM-12 zeolite enables all seven different sites to be resolved, and for the Si-O-Si site connectivity to be determined by looking for Si-Si cross peaks. [Reproduced from reference 112 with permission. Copyright 1990...

FIGURE 2.9 H/D-exchange mass spectra for deprotonated (a) 5 P-dGG, (b) S P-dAA, (c) 5 P-Dag, and (d) 5 P-dGA after 10 s exchange with DjO. Peaks are annotated as D(n) where n is the number of exchanged hydrogen atoms. Peaks labeled as C can be attributed solely to the isotopic contribution of the other exchanged peaks. (Reproduced from Chipuk, J.E. Brodbelt, J.S. Int. J. Mass Spectrom, 2009 (In Press). With permission from Elsevier.)... 

Samples, chosen for ready availability and to illustrate a large range of properties, are listed in Table 1. Dimensions were chosen to keep instrument compliance corrections less than 10%. Removal of moisture and residual cure potential of the composites required repetitive DMA scans under nitrogen to achieve +1 C damping peak reproducibility in successive scans. 982 DMA temperature scans (shown in Figure 4) were also made after the stress relaxation experiments, to check property stability. Stress relaxations were all done below the maximum temperature attained in the DMA pre-scans. 

Figure IQA SE-HPLC of total protein (upper), SDS-buffer extractable protein (middle), and SDS-buffer unextractable protein (lower). T in (a) is an omega-glia-din subpeak that coelutes with extractable polymeric proteins in the later part of the polymeric protein peak. (Reproduced with permission from Gupta, R. B. et al. 1993. Journal of Cereal Science 18 23-41.)...

Figure 1.16 Electroionisation and chemical ionisation spectra of polystyrene (a) Partial El spectrum of polystyrene. The solid lines are the trimer spectrnm and the nnmbers in parenthesis give the first number of monomer units present and second the assigned monoisotropic mass. The numbers in parenthesis give the evaporation temperature in kelvin. The dashed lines are fragment sequence peaks. Reproduced with permission from H.R. Udseth, Analytical Chemistry, 1981, 53, 29. 1981,...

Figure 28 Top left PPI structure, top right H-NMR in CDCI3 acquired at 750 MHz and bottom multidimensional NMR for total assignment of the PPI NMR spectra. Eleven 2D flfZ slices from the 3D HMQC-TOCSY spectrum are displayed in a-k along with the shift of that slice. In each slice, the peak marked D is the diagonal peak and the peak marked C is the cross-peak. Reproduced with permission from Chai, M. H. Niu, Y. H. Youngs, W. J. Rinaldi, P. L. Macromoto/es 2000, 33, 5395." Copyright 2000 American Chemical Society.

I-phenethyl-2-picolinium in acetate buffer (pH 4.6). Detection 254 nm. Peaks I, acetic acid 2, propionic acid 3, butyric acid 4, valeric acid 5, caproic acid (12 nmole of each) S = system peak. Reproduced from M. Denkert et al . Chromaiogr., 218, 34 (1981) by permission of Elsevier Science Publishers. 

Figure 9. Separation of amines and sulfonates [56]. Stationary phase /iBondapak Phenyl (lOum). Mobile phase 4 x 10 M naphthalene-2-sulfonate in 0.05 M phosphoric acid. Detection 254 nm. Peaks 1, pentanesulfonate 2, diisopropylamine 3, hexanesulfonate 4, heptylamine 5, octanesulfonate. S, and Sj = system peaks. Reproduced from L. Hackzell and G. Schill, Chromatogmphia, 15, 439 (1982) by permission of Vieweg-Publishing.

Figure 3 Schematic detector response in the heat desorption method (A) adsorption peak (B) desorption peak. (Reproduced with permission from Paryjczak T (1986) Gas Chromatography in Adsorption and Catalysis, p. 130. Warsaw PWN-Poiish Scientific Pubiishers. Chichester Eiiis Norwood.)...

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