Tailing effect

This ESI(+) TIC, however, is dominated by strong and broad signals that eluted between 17 and 31 min, neither observable under APCI(+/—) nor ESI(-) conditions. Even under gradient RP-C18 conditions a strong tailing effect was observed while isocratic RP-C18 failed. The information obtained by ESI—LC—MS(+) was that the compounds could be ionised in the form of [M]+ ions at m/z 230, 258 and 286. ESI-LC-MS-MS(+) resulted in product ion spectra which, by means of a MS-MS library, were found to be characteristic for the amphoteric amine oxide surfactants. These compounds not yet observed in household formulations will be presented later on with the RIC of LC separation (cf. Fig. 2.5.11(d)). After identification as amine oxides, the separation and detection of this compound mixture now could be achieved by an isocratic elution using a PLRP-column and methane sulfonic acid and ESI(+) ionisation with the result of sharp signals (RT = 4-6 min) as presented in Fig. 2.5.11(d). 

The analysis was limited in part by the scarcity of measurements, and clear discrepancies between measured and calculated values may be observed. As discussed in Chapter 10, tailing effects often are due to non-Fickian transport behavior, which was not accounted for in this model. Interestingly, the field-scale retardation coefficient values of the reactive contaminants were smaller by an order of magnitude than their laboratory values, obtained in an accompanying experiment. 

The extraordinary antinociceptive potency of the unknown compound was determined in a mouse model of acute nociception, the hot plate test. Despite the Straub-tail effect observed earlier, the antinociceptive effect of the compound could not be not antagonized with the p-opioid receptor antagonist naloxone but with the nAChR antagonist mecamylamine, so the unknown compound was deduced to be a potent nicotinic analgesic (Spande et al., 1992 Qian et al., 1993 Badio and Daly, 1994 Sullivan and Bannon, 1996). 

Since tailing effects were often observed with adsorption peaks, they were not used in the calculation of surface area (Figure 11.1). A comparison of the specific surface area of several materials obtained by the classical BET method and the N/E method is given in Table 11.1... 

Stewart, E.M., Stevenson, M.H. and Gray, R. (1992). Detection of irradiation in scampi tails - effects of sample preparation, irradiation dose and storage on ESR response in the cuticle, lnt. J. Food Sci. Technol. 27. 125. 

These columns offer excellent loadability and easy separability of light hydrocarbon isomers. Some nonlinear absorption is experienced with these columns, and as a result, some peaks will exhibit tailing effects. Water absorption by the alumina can reduce the selectivity of the column. Conditioning the column at 200 °C is generally sufficient to remove the surface-absorbed water. 

The introduction of the more sensitive hydrogen flame ionisation detector has made possible the analysis of dilute aqueous solutions of organic acids by gas-liquid chromatography. Problems, such as ghosting at high acid concentrations and an excessive tailing effect of the water in dilute solutions, masking the components, have been reported for aqueous solutions [573],... 

When the reaction temperature is raised to temperatures above 873 K, the 3450 cm 1 Si-NH2 band shows a tailing effect. Figure 12.3 illustrates this phenomenon by a FTIR spectrum of Kieselgel 60, thermally pretreated at 973 K and reacted with NH3 at 923 K for 5 hours. A band centred around 3405 cm 1 can be observed, attributable to silazane (Si-NH-Si) species. 

In the adsorption experiment of binary mixture (Figure 4), breakthrough time of the activated carbon bed was longer than the zeolite SA bed, moreover the zeolite SA bed had more tailing effect than the activated carbon bed. 

A decision was also needed about the stationary phase to be chosen for the generic methods. Because we wanted to keep the run times as short as possible (within reason) the latest generation of base deactivated phases were investigated. These gave an excellent performance and were particularly resistant to peak tailing effects. The... 

It would therefore seem that the tail effect is either not relevant or was fortuitously similar in the tests conducted by all laboratories. 

Ten months into the control period there has been no detectable area increase dependent on temperature or humidity. Thus far, no environmental conditions have been found that could produce the tailing effect described. 

In addition to tartrate, a-hydroxyisobutyrate can be utilized as the complexing anion. It was employed by Cassidy et al. [144] for the separation of lanthanides. In comparison to tartrate, no particular advantages are revealed in the separation of divalent metal ions. Fig. 3-150 shows a separation of the seven heaviest lanthanides with an eluent mixture of ethylenediamine and a-hydroxybutyric acid. The pronounced tailing effects observed under isocratic conditions for late eluting ions are unsatisfactory. 

Since the peak width on the baseline may be affected by adsorption and tailing effects, the peak s half width is used in the area calculation. This procedure for peak area calculation should only be applied to symmetrical signals. The area thus calculated is proportional to the concentration but slightly smaller than the true value. For an accurate determination of the half widths, a high chart speed must be chosen. 

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