Interactions reagents

Gennaro, M. C., Bertolo, P. L., and Marengo, E., Determination of aromatic amines at trace levels by ion interaction reagent reversed-phase high-performance liquid chromatography. Analysis of hair dyes and other water-soluble... 

In particular, the priority pollutant phenols (PPP), identified by EPA since the 1970s are widespread water pollutants that must receive the greatest attention due to their recognized toxicity. For the separation of eleven PPP, an ion-interaction reagent (HR) RP HPLC/UV method has been developed that allows limits of detection lower than 30 J,g in river waters, after LLE in dichlo-romethane and a 500-fold pre-concentration [82]. Through on-line SPE followed by both UV and electrochemical detection [83], 16 priority phenols have been determined in water samples with the LOD value for chlorophenols lower than 1 ng L [84]. LODs at ng L levels were obtained for all the PPPs in samples of river water, employing a relatively small volume of sample through an on-line SPE HPLC/MS method with an APCI source. 

An overview and discussion is given of literature methods published after 1989 devoted to the ion-interaction chromatographic determination of inorganic anions. Seventy references are quoted. Ion-interaction chromatography makes use of commercial reversed-phase stationary phase and conventional high-performance liquid chromatography instrumentation. The basis of the technique, the modification of the stationary phase surface, the choice of the ion-interaction reagent as well as the dependence of retention on the different variables involved are discussed. Examples of application in the fields of environmental, clinical and food chemistry are presented. The experimental conditions of stationary phase, of mobile phase composition as well as detection mode, detection limit and application are also summarized in tables. 1997 Elsevier Science B.V. 

Modification of the reversed-phase stationary phase choice of the ion-interaction reagent detection. 190... 

The mobile phase is an aqueous or hydro-organic solution of a suitable ion-interaction reagent. 

M. C. Gennaro, Separation of water-soluble vitamins by reversed-phase ion-interaction-reagent high-performance liquid chromatography Application to multivitamin pharmaceuticals, J. Chromatogr. Sci., 29 410(1991). 

Figure 5.20 Response surface ( two-dimensional window diagram ) for the separation of a mixture of nine acidic solutes by RPLC. Variables are pH and the concentration of an ion interaction reagent (NOA = n-octylamine). The vertical axis represents the lowest value of a observed for any combination of two solutes in the sample (ffmin). Figure taken from ref. [559J. Reprinted with permission.

A certain bias in correct K determination can be introduced by stacking of the sample zone, occurring when the injected sample has an ionic strength less than BGE. Stacking leads to an uncontrolled increase in concentration of the interacting reagents which may disturb equilibrium [6]. 

Cecchi, T., Pucciarelli, F., and Passamonti, P. Ion interaction chromatography of zwitterions fractional charge approach to model the inflnence of the mobile phase concentration of the ion-interaction reagent. Analyst 2004, 129, 1037-1042. 

Cecchi, T. et al. The fractional charge approach in ion-interaction chromatography of zwitterions influence of the stationary phase concentration of the ion interaction reagent and pH. J. Liq. Chromatogr. Rel. Technol. 2005, 28, 2655-2667. 

Cecchi, T. Pucciarelli, F. Passamonti, P. Ion-Interaction Chromatography of Zwitterions. The Fractional Charge Approach to Model the Influence of the Mobile Phase Concentration of the Ion-Interaction Reagent The Analyst. 2004, 129, 1037-1046. (article B404721D available DOI 10.1039/b404721d http //www.rsc.org/is/joumals/current/ analyst/ anlpub.htm). 

Highlights of research results from the chemical derivatization of n-type semiconductors with (1,1 -ferrocenediyl)dimethylsilane, , and its dichloro analogue, II, and from the derivatization of p-type semiconductors with N,N -bis[3-trimethoxysilyl)-propyl]-4,4 -bipyridinium dibromide, III are presented. Research shows that molecular derivatization with II can be used to suppress photo-anodic corrosion of n-type Si derivatization of p-type Si with III can be used to improve photoreduction kinetics for horseheart ferricyto-chrome c derivatization of p-type Si with III followed by incorporation of Pt(0) improves photoelectrochemical H2 production efficiency. Strongly interacting reagents can alter semicon-ductor/electrolyte interface energetics and surface state distributions as illustrated by n-type WS2/I-interactions and by differing etch procedures for n-type CdTe. 

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