Peaks identifying

The ehromatogram from the first eolumn was divided into five areas of five heart-euts eaeh. Some peaks identified in the ehromatogram from the first eolumn were used as heart-eut markers. This method has some limitations whieh mainly eoneem eontamination of the system, and also with the determination of less volatile pollutants. However, sueh a system is able to deteet and aeeurately identify about 40 pollutants. 

FIGURE 3 The infrared spectrum of an amino acid, with the groups contributing to some ol the peaks identified. Notice that the spectrum displays the intensity of absorption. 

In some data acquisition and processing systems, software is included that mathematically analyze convoluted (unresolved) peaks, identify the individual peaks that make up the composite envelope and then determine the area of the individual peaks. 

Figure 5.29 (a) The H-NMR spectrum of ethyl acrylate showing signals for olefinic protons, (b) A phase-sensitive COSYsjiectrum recorded at higher digital resolution, (c) Expansion of the downfield cross-peak identified by a dashed circle in (b). 

Usually, HPLC analysis resolves four peaks identified by co-chromatography with authentic standards as copper pheophorbide a, Cn(II) chlorin e6, Cn(II) chlorin e4, Cu rhodin g7, and their degradation products, but a sum of other colored components can also be found, for example, native chlorophylls, pheophytins, pheophor-bides, and rodochlorins (free carboxyl forms of pheophorbides) besides epimers, allomers, and degradation products that have been only tentatively identified. 

The operative mechanisms have been deduced by considering various peaks identified in the daughter spectrum employing the reflectron technique. One corresponds to a mass loss of 32 amu from a parent ion cluster that enters the drift region as H+(CH3OH) via ... 

Figure 13.3 Electropherogram (total ion current) of the madder lake extract and ESI mass spectra taken at the apex of the peaks. Identified colourants alizarin, m/z 239 purpurin, m/z 255. Reproduced from M. Puchalska, M. Orlihska, M.A. Ackacha, K. Pofec Pawlak and M. Jarosz. J. Mass Spectrom., 38, 1252 1258 (2003). By permission of John Wiley ...

FIGURE 6.17 Chromatogram overlay for 24 consecutive runs performed on a single column. (A) results of overlay for the chromatograms obtained with UV absorbance detection. Peaks are identified as (with increasing retention time) uracil (dead volume marker), methyl paraben, and propyl paraben. (B) results of overlay for chromatograms obtained from fluorescence detection (peak identified as rhodamine 110 chloride). 

An X-ray fluorescence spectrometer needs to resolve the different peaks, identify them and measure their area to quantify the data. There are two forms of X-ray spectrometers (Fig. 5.5), which differ in the way in which they characterize the secondary radiation - wavelength dispersive (WD), which measures the wavelength, and energy dispersive (ED), which measures the energy of the fluorescent X-ray (an illustration of the particle-wave duality nature of electromagnetic radiation, described in Section 12.2). 

Figure 1.2 XRD patterns for three Ti02 samples obtained by hydrothermal treatments at 80°C (a) and 180°C (b) and after calcination at 450°C (c) [21 ]. From the six XRD peaks identified with the anatase phase, the broadening of the (101) peak at 25.4° was chosen to estimate the average grain size of these samples. Generally, the sharper the peaks, the larger the particle size. The differences in grain size identified in these experiments were correlated with photocatalytic activity. (Reproduced with permission from The American Chemical Society.)...

Fig. 3.—Mass Fragmentography of Methylated Neuraminic Acids. [Detection at m/e 274 A, disialosyl-lactosylceramide B, the disialosyl ganglioside isolated C, B after treatment with neuraminidase D, the fraction containing the trisialosyl ganglioside. Detection at m/e 330 E, the disialosyl ganglioside F, the trisialosyl fraction. The peaks identified are (1) the permethylated (terminal) N-acetylneuraminic acid, and (2) the 8-O-acetyl (8-O-substituted) derivative of the methylated N-acetylneuraminic acid. Conditions 1% of SE-30, at 240°. Reproduced, by permission, from Ref. 80.]...

Table 9.1 Oxide peak identifieation in the lignin sample...

Figure 9. Resonance Raman spectrum of the 2Fe-2S-4Cys cluster In oxidized spinach ferredoxln. Protein ( 2 mM) maintained at 15 K In a helium Dlsplex and probed with 488.0 nm excitation. Spectral contribution of Ice In 220-320 cm" 1 region has been subtracted. (Data from Ref. 21). Starred features Indicate peaks Identified as totally symmetric Aig vibrations (23,24).

During a proton NMR examination of a CCI4 solution of MejNsBgFs, an extraneous peak was observed in the spectrum, although the borazine was known to be analytically and mass spectrometrically pure. One microliter of the solution was subjected to GC/MS analysis. Peaks identified as trimethylsilane (TMS) and CCI4 were obtained followed by the expected MesNjBsFs (m/e 177, 176, etc.). An additional component... 

Elemental composition Os 74.82%, 0 25.18%. The compound can be identified by its physical properties, such as, odor, color, density, melting-, and boiling points. Its acrid odor is perceptible at concentrations of 0.02 mg/hter in air. The oxide also produces an orange color when a small amount of the compound or its aqueous solution is mixed with an aqueous solution of ammonia in KOH (see Reactions). Aqueous solution of the tetroxide may be analyzed for osmium by AA or ICP spectrometry (see Osmium). Vapors of the tetroxide may be purged from an aqueous solution by helium, adsorbed over a trap, and desorbed thermally by helium onto a GC. Alternatively, a benzene or carbon tetrachloride solution may be injected onto the GC and the compound peak identified by mass spectrometry. The characteristic mass ions for its identification should be 190 and 254. 

The peak identified as salvinorin A (1) from authentic standard solutions was observed in extracts of leaves and stem from S. divinorum. In order to examine the concentration range of 1 found in various populations of S. divinorum, 20 different samples of leaves were collected from cultivated plants in private collections as well as endemic populations of the plant in Oaxaca. Representative... 

Figure F1.3.2 HPLC chromatogram of cranberry juice. Peaks identified on figure.

The exact gradient will have to be determined by the analyst, as variations in column brands causes significant differences in the retention times of the peaks of interest. A good material to use as a reference sample is commercial cranberry juice cocktail. It has a simple profile of four major peaks and two minor ones that cover the retention times of most peaks of interest, and will give the experimenter some assurance that the analytical system is behaving satisfactorily. See Figure FI.3.2 for a sample chromatogram with the peaks identified. Another alternative is purified anthocyanins. 

Figure 3 shows the negative SSIMS spectra obtained from Si and Cr surfaces at room temperature. Table 2 shows the chemical formulae for the peaks identified in Fig. 3. The negative ion spectra from these surfaces are again found to be very similar. Comparison of Figs 3(a) and (b) shows that the Cr and Si surfaces yield similar 3-APTHS related ions with roughly comparable intensities. Negative ions consistent with a chromium native oxide were also observed for the Cr surface. Parent ions due to 3-APTHS were absent from both the positive and negative SSIMS spectra. No dimer, trimer, or higher molecular weight...

Peaks identified penta-O-methyl-mono-O-acetylmyoinositol derived from mono-linked myoinositol, 2,3,6-tri-O-methyl-1,4,5-tri-O-acetylglucitol derived from a 4-linked glucose, and 3,4,6-tri-O-methyI-l, 5,di-0-aeetyl-2-acetamido-2-N-methylglucitol derived from a terminal H-acetylglucosamine. The PMAA sample was chromatographed on a 1.5 m X 2 mm ID column packed with 3% OV-210 in a Finnigan automated GC/MS model 3300/6110. Temperature program 150° to 215°C at 6°C/min. 

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