Chromatography patterns

IV as a cinerin-type compound, peak V as cinerin II, and peak VI as pyrethrin II. It is evident that peak IV also contains another component. The peaks beyond peak VI are known to be of the pyrethrin type as they respond to the color test. This gas chromatography pattern was obtained with a 6-foot lA -inch column packed with 20% SE-30 on 40-60-mesh Chromosorb P. Later work provided good resolution of the peaks with a 2-foot 4-inch column packed with 20% Dow-11 silicone oil on 45-60-mesh Chromosorb P. 

Fig. (7). Affinity chromatography pattern for isolation of anti-lactose antibodies, n-p, non-proteins Ah, antibody.

In paper chromatography using 50% acetonitrile in water, the activity corresponding to the Lu-DOTATATE complex moved towards the solvent front with = 0.8-0.9, while uncomplexed Lu remained at the point of spotting (Rf = 0). The paper chromatography patterns of LuCU, and the Lu-DOTATATE conjugate are shown in Fig. 8.4. 

G. R. Magelssen and J. W. Elling, /. Otromatogr. A, 775, 231 (1997). Chromatography Pattern Recognition of Aroclors Using Iterative Probabilistic Neural Networks. 

Figure 18 Size exclusion chromatography pattern of a wheat protein hydrolysate (left) and percent composition of the fractions having molecular mass within the known values of standard substances (right). Molecular weights of peptides are only approximately determinable, since their hydrodynamic properties are not necessarily identical with those of the marker substances. Chromatographic conditions stationary phase TSKgel Toyopearl HW-40F (Tosoh Co., Japan) 10 X 500 mm eluant 0.1 M NaCl in 0.1 M phosphate buffer pH 7.1 flow 0.4 ml/min detection UV 220 nm. (Unpublished data.)...

Figure 24 Size exclusion chromatography patterns of high-temperature (solid Une) and high-salt (dotted line) fractions desorbed form damaged (a) and virgin hair (b) after application of a collagen hydrolysate. A higher amount of large peptides was adsorbed on bleached/waved hair than on virgin hair. Large peptides were found to be less effectively bound than smaller peptides, as they were selectively removed by hot water (32).

J. A. Pino, J. E. McMurry, P. C. Jurs, B. K. Lavine, and A. M. Harper, Anal. Chem., 57, 295 (1985). Application of Pyrolysis-Gas Chromatography-Pattern Recognition to the Detection of Cystic fibrosis Heterozygotes. 

Siek, T. J., Stradling, C. W., McCain, M. W., and Mehary, T. (1997). Computer-aided identification of thin layer chromatography patterns in broad-spectrum drug screening. Clin. Chem. (Washington, D.C.) 43 619-626. 

The infrared spectra of a set of 2-thiazolylthioureas are reported in Ref. 486. The ultraviolet spectra of l-aryl-3-(2-thiazolyl)thioureas are characterized by two bands of approximate equal intensity around 282 and 332 nm (492). For l-alkyl-3-(2-thiazolyl)thioureas these bands are shifted to 255 and 291 nm, respectively (492). The shape of the spectrum is modified further when l.l -dialkyl-3-(2-thiazolyl)thioureas are considered (491). Fragmentation patterns of various 2-thiazolylthioureas have been investigated (100, 493), some of which are shown in Scheme 158. Paper and thin-layer chromatography provide an effective tool for the analysis of these heterocyclic thioureas (494. 495). 

The combined techniques of gas chromatography/mass spectrometry (gc/ms) are highly effective in identifying the composition of various gc peaks. The individual peaks enter a mass spectrometer in which they are analyzed for parent ion and fragmentation patterns, and the individual components of certain resoles are completely resolved. 

Figure 12.12 Coupled SEC-RPLC separation of Plioflex rubber stock (a) SEC (b) RPLC ti ace of fraction 1, Wingstay 100 (Eive-peak pattern is representative of diarylphenylenedi-amine isomers) (c) RPLC ti ace of fraction 2, mixed disulfide and MBTS (2,2 -thiobis (ben-zothiazole)). Obtained under the same conditions as given for Eigure 12.11. Reprinted from Journal of Chromatography, 149, E. L. Johnson et al, Coupled column chromatography employing exclusion and a reversed phase. A potential general approach to sequential analysis , pp. 571-585, copyright 1978, with permission from Elsevier Science.

Ion chromatography (see Section 7.4). Conductivity cells can be coupled to ion chromatographic systems to provide a sensitive method for measuring ionic concentrations in the eluate. To achieve this end, special micro-conductivity cells have been developed of a flow-through pattern and placed in a thermostatted enclosure a typical cell may contain a volume of about 1.5 /iL and have a cell constant of approximately 15 cm-1. It is claimed15 that sensitivity is improved by use of a bipolar square-wave pulsed current which reduces polarisation and capacitance effects, and the changes in conductivity caused by the heating effect of the current (see Refs 16, 17). 

Partition column chromatography for separating several of the primary constituents of the pyrethrum extract has been reported. The elution pattern for some of the constituents of the pyrethrum mixture recovered from the partition column is shown in Table I. 

Adsorption column chromatography has been employed to separate the constituents of pyrethrum. Florisil and aluminum oxide have been used as adsorption columns to retain much of the pigmented materials. The pyrethroids may be caused to elute with several solvents. In our experience mixtures of hexane with ethyl acetate, methanol, ethyl ether, dichloromethane, or acetone have provided different elution patterns. 

The carbon number distribution of technical secondary alkanesulfonates determined by pyrolysis gas chromatography and mass spectrometry (GC-MS) is shown in Fig. 13 together with the corresponding carbon number pattern of the raw material paraffins obtained by GC [16]. Pyrolysis was performed in a crucible-modified SGE pyrojector after covering the mixture with quartz wool. The presence of up to 10 wt % of disulfonates in technical alkanesulfonates is demonstrated by fast atom bombardment and mass spectrometry (FAB-MS) (Fig. 14) [24],... 

An alternative technique to NMR spectroscopy is chromatography. The partially functionalized sample is completely fimctionahzed with a group different from the one present, the product carefully de-polymerized, its structure examined with a chromatographic technique. For example, partially substituted CA was further derivatized with methyl vinyl ether, the product hydrolyzed, the monomers produced examined with gas chromatography [241]. HPLC has been advantageously applied for the determination of substitution pattern for CAs with DS 0.8 to 3.0, by employing the same approach, i.e., further derivatization of the partially derivatized polymer with methyl trifluoroacetate, followed by de-polymerization. The results obtained by this technique compared favorably with those obtained by NMR [242]. 

By far the most parsimonious, but nonstatistical, explanation for the observed pattern is that the titrations differ in selectivity, especially as regards basic and acidic impurities. Because of this, the only conclusion that can be drawn is that the true values probably lie near the lowest value for each batch, and everything in excess of this is due to interference from impurities. A more selective method should be applied, e.g., polarimetry or ion chromatography. Parsimony" is a scientific principle make as few assumptions as possible to explain an observation it is in the realm of wishful thinking and fringe science that combinations of improbable and implausible factors are routinely taken for granted. 

Lipid Screening. The problems of lipid analysis in the newborn is difficult because of the fact that most methods for analysis for lipids require substantial amounts of serum, yet a total lipid determination is very important in various types of disease. This problem can be solved by thin-layer chromatography (59). Figure 38 shows a typical pattern obtained when an extract 7rom 10 microliters of serum is subjected to thin-layer chromatography. If these specimens are scanned, and an internal standard is run, one can obtain a rough approximation of the distribution of the various lipids in the serum. This is shown in Figure 39, in which a normal specimen is run in an adult. 

Figure 38, Patterns obtained from the extract of 10 fd of serum for lipid fraction by thin-layer chromatography. In sequence, starting from the bottom, phospholipids, pee cholesterol, cholesterol aniline as an internal standard, triglycerides, and cholesterol esters. The free fatty acids occur between cholesterol and the internal standard and are only barely visible in the print, on the extreme right. They are readily visible, normally, to the eye.

FIGURE 5.4 Typical application pattern for a preparative sample applied as band, if desired with application of a control standard (spot at right side), documentation of the lower part of the plate after chromatography at UV 254 nm. 

FIGURE 10.5 Elution profile on OH-B12 treated by microwave heating for 6 min during silica gel 60 column chromatography. Fifty milliliters of the treated OH-B12 solution (5 mmol/1) was evaporated to dryness and dissolved in a small amount of w-butanol/2-pro-panol/water (10 7 10, v/v) as a solvent. The concentrated solution was put on a column (1.4 X 15.0 cm) of silica gel 60 equilibrated with the same solvent and eluted with the same solvent in the dark. The eluate was collected at 4.0 ml with a fraction collector. Fractions I to V were pooled, evaporated to dryness, dissolved with a small amount of distilled water, and analyzed with silica gel TLC. Inset represents the mobile pattern of the OH-B12 degradation products of fractions I to V on the TLC plate. Data are typical, taken from one of five experiments. (Reprinted with permission from Watanabe, F. et al., J. Agric. Food Chem., 46, 5177-5180, 1998. Copyright (1998) American Chemical Society.)... 

FIGURE 10.13 The TLC profiles of labeled peaks isolated from [U- C]ascorbic-acid-modified calf lens protein obtained from Bio-Gel P-2 chromatography. Peaks 2 to 7 were spotted on a preparative silica gel TLC plate and developed with ethanol/ammonia (7 3, v/v). The fluorescence in each lane was detected by irradiation with a Wood s lamp at 360 nm, and the pattern of radioactivity was determined by scanning the plate with AMBIS imaging system. (Reprinted with permission from Cheng, R. et al., Biochim. Biophys. Acta, 1537, 14-26, 2001. Copyright (2001) Elsevier.)... 

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