Chromatographic patterns

The columns labeled PI reflect the total of pyrethrin I and cinerin I just as in the AO AC procedure. The gas chromatographic results are in terms of the total amount of the mixture but were analyzed as the methyl ester of chrysanthemic acid. The present state of the determination of PII (pyrethrin II plus cinerin II) is not complete because of the erratic extractability of the dicarboxylic acids from the hydrolysis mixture. The gas chromatographic pattern is distinct and straightforward. As the extraction procedure for PII is improved, the gas chromatographic method will be more applicable. The present recovery of PII is in the range of 80 to 90%. The average of the values shown in Table II for PI is 98.0%. 

Samples of PB-DPE were subjected to RP-HPLC producing the chromatographic patterns shown in Figure 1. The two major peaks of Penta (Fig. lA, peaks 1 and 2), were isolated by preparative HPLC and analyzed by NMR. The spectra (Table 1) were in excellent agreement with previously published data (refs. 3-6). The two HPLC peaks were identified as 2,2, 4,4 tetrabromo DPF and 2,2, 4,4, 5 pentabromo DPF, respectively. 

Comparative chromatographic patterns of leaf exudate components from shrubby... 

After alkaline hydrolysis and extraction of acidic and neutral compounds, the samples were submitted to GC/MS analyses. They gave similar chromatographic patterns, as shown in Figure 7.3. 

The chromatographic pattern and/or aqueous/nonaqueous partitioning of the biotransformation products of the administered compound. 

Figure 6. Chromatographic pattern for carp liver microsomal 14C-labeled organo-soluble metabolites of [ring-14C]-molinate. Incubation was conducted under standard conditions for one hr m number represents metabolite code.

Figure 10. Chromatographic pattern for organosoluble uC-labeled metabolites from [ring-14C]-molinate-treated water which contained carp for 4 days. F number represents metabolite code.

Patel, P. C. and Adhikari, H. R. 1973. Effect of gamma-irradiation on gel chromatographic patterns of cottage cheese whey. J. Dairy Sci. 56, 406-408. 

Adding 2 drops of one of the paraffins in the middle (e.g., tridecane) will yield a chromatographic pattern that makes it easy to identify all the peaks quickly. Knowledge of the exact concentration of the paraffins is not essential for indexing, but such information could be used to monitor GC performance. 

To identify the type of a petroleum product, laboratories rely on characteristic fingerprints obtained as chromatographic patterns and use petroleum product standards for the pattern recognition and fuel quantitation. That is why TPH results are usually reported in relation to a fuel standard TPH as gasoline, TPH as diesel, TPH as motor oil. 

Figure 2.5 shows chromatographic patterns of fresh gasoline, diesel fuel, and motor oil standards. Pattern recognition is a delicate matter that requires experience in hydrocarbon analysis and knowledge of petroleum product transformations in the environment. The effects of natural attenuation (bacterial activity, dissolution, adsorption, and evaporation) will produce uncharacteristic fuel patterns in environmental samples, which may be different from the patterns of fresh standards (Weiner, 2000). 

Figure 2.5. Chromatographic patterns of fresh gasoline, diesel fuel, and motor oil.

Much more difficult to detect are data interpretation and judgment errors, such as the unrecognized false positive and false negative results and the incorrect interpretation of mass spectra and chromatographic patterns. The detection and correction of these errors is made possible through internal review by experienced analysts. 

On the other hand, PCBs, which are also the mixtures of individual chemical constituents (congeners) and which also have characteristic and recognizable chromatographic patterns, require second column confirmation. This is because they are quantified using individual peaks, the presence of which must be confirmed on the second column. 

Another successful approach to determination of choline is through the use of pyrolysis-gas chromatography-mass spectrometry using electron impact (Stavinhoa and Weintraub, 1974). Low nanomolar concentrations of choline can be detected by this sophisticated procedure. A particular advantage of this methodology is twofold it allows a positive identification of choline by the gas chromatographic pattern of the pyrolysis products, and the mass spectroscopic peaks provide an absolute proof of structure in this case. 

Figure 9.35 Typical chromatographic patterns of the hydrolysis of Gly-Pro-Ala with different concentrations (A, 0 /xg B, 100 /xg C, 200 /xg) of rabbit kidney microvillous fractions. Peak 1 (A), Gly-Pro-Ala (3.3 nmol, retention time 6.4 min) decreased peak 2 (B,C), Gly-Pro (retention time 5.0 min) increased at each protein concentration. Mobile phase, 10.0 mM potassium dihydrogen phosphate containing 1.0 mM, 1-octanesulfonate (pH 2.5). (From Harada et al., 1988.)...

B12. Brummer, F., and Kulonen, M., Chromatographic pattern of ninhydrin staining compounds in gastric juice and its relation to acid gastric secretion. Acta Med. Scand, 167, 61-64 (1960). 

W12a. Welsh, J. D., Russell, L., and Wolf, S., Chromatographic patterns of individual gastric juice specimens from normal human subjects. J. Clin. Invest. 41, 660-665 (1962). 

The F/S labeled p-lactams were prepared as described. On the basis of their mode of action against bacteria I is termed "lytic" and 11, "non-lytic." That is, diastereomers of II produce the microbiological Liesegang effect (MLEs)(14). 1 and II each produced characteristic chromatographic patterns in the F/S labeled penicillin interactive proteins, the penicillin binding proteins (PBPs), by RPLC (7). The hydrophobic PBPs elute much later than the cytosolic proteins. 

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