AE or AEO

Following previous studies on lauryl sulfate and AES, Cuzzola et al. [44] also studied the Fenton oxidation products of AEO and NPEO. The aerobic biodegradation of AEO and NPEO and anaerobic biodegradation of NPEO were studied by Schroder [27] by means of FIA-MS and LC-MS and MS-MS in positive-ion and/or negative-ion APCI. Methyl ethers of AEO ate persistent in aerobic conditions. NPEO degradation results in NPEC. Anaerobic biodegradation of NPEO results in nonylphenols. 

Only the apphcation of LC-MS analysis can be conceived of as reliable surfactant analysis. To elaborate determination methods for the analysis of the anionic surfactant mixture of alkyl ethoxysuUates (AES) APCI and ESI-MS(-t/-) studies combined with in-source MS/MS examinations were performed and results were compared (cf. Pig. 15.4 and 15.5 and 15.3.3.2 ESI, surfactants). APCI fragment ion spectra revealed the aUcyl chain length and the number of ethoxylate moieties therefore APCI was found to be the method of choice [326]. To confirm determination methods apphed in surfactant analyses an inter-laboratory comparison study of LC-MS techniques and enzyme-hnked immunosorbent assay for the determination of surfactants in wastewaters was performed in seven laboratories. The quantitative determination of the non-ionic NPEOs, AEOs, coconut diethanol amides (CDEAs) and the anionic LAS, NPEO-sulfates and the secondary alkane sulfonates (SAS) was performed under APCI or ESI-interfacing conditions in positive or negative... 

As demonstrated (cf. Fig. 15.1 and 15.2) with the results of ionisation observed in the spectra of the non-ionic surfactant mixtures of AEOs or APOs or for ionisation of the anionic surfactant mixture of AES (cf Fig. 15.3), if APCl or ESI interfaces were applied, both API interface types presented considerable differences in the ionisation processes. These differences were in both the type of ions and the efficiency of ionisation, i.e., either high molecular or low molecular compounds were favoured in ionisation and no ionisation takes places with the one interface whereas the other interface type ionises the compounds with high sensitivity. Obviously ESI is the interface which handles the very polar, partly charged compounds with low as well as high molecular weights in the best way, while the APCl interface can be used successfully for the more lipophilic compounds contained in water samples, e.g. phenol compounds. With the improved flexibility of ESI handhng low and high flow rates of eluents ESI-CEz-MS became a powerful tool to separate complex mixtures with an improved separation efficiency never previously observable with any kind of LC (see Eig. 15.6) [395]. 

A prediction of AE /AEo to within 0.1 kcal/mol may produce a AG /AGo accurate to maybe 0.2 kcal/mol. This corresponds to a factor of 1.4 error (at T = 300 K) in the rate/equilibrium constant, which is poor compared to what is routinely obtained by experimental techniques. Calculating AG /AGo to within 1 kcal/mol is still only possible for fairly small systems. This corresponds to predicting the absolute rate constant, or the equilibrium distribution, to within a factor of... 

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