Search

Multiple linear regression analysis determines the increments in reversed- phase liquid chromatographic (RPLC) retention of 75 4,4'-disubstituted benzanilides and benzamides as a function of variations in the stationary and mobile phases. The study, which illustrates the sensitivity of RPLC to slight changes in molecular environments, shows that functional group retention depends on both the stationary and mobile phases. A statistical intracolumn bilogarithmic analysis, however, yields standardized functional group substituent constants that are phase-independent.

The Neuse River, North Carolina, U.S., exemplifies a typical de facto potable reuse scenario, where drinking water sources are located downstream of treated wastewater effluent discharges. The study results imply that planned potable water reuse, whether in an indirect or direct potable reuse scenario, might provide better control over water quality than the status quo conditions. Using fluorescence excitation-emission matrix (EEM) measurements, anthropogenic influence of a wastewater treatment plant (WWTP) discharge was observed in samples near the location of drinking water treatment plant (WTP) intakes, eight or more miles downstream of the WWTP, implying that anthropogenic compounds were not fully removed or degraded by natural processes in this reach of the river. PARAllel FACtor (PARAFAC) analysis supported a two-component model of humic-like and nonhumic-like dissolved organic matter (DOM). A nonmodeled anthropogenic feature was also indicated. Significantly, the quenched fluorescence of humic-like DOM (static and/or dynamic quenching) by nonhumic-like DOM-previously demonstrated for probe molecules but first reported here in a natural/anthropogenic-influenced system-offers exciting insight into studies of humic/nonhumic interactions with important implications for pollutant fate and transport, sensing applications, and water treatment. A molecular spectroscopic explanation for dual fluorescing peaks in amino acids and humic substances is postulated. [ABSTRACT FROM AUTHOR]

The potential to distinguish juvenile wild from cultured fishes and to discriminate among juvenile fishes by species based on fatty acid composition was demonstrated. Statistical approaches to data evaluation included analysis of variance, correlation analysis, principal component analysis (PCA), and quadratic discriminant analysis (QDA). Differences were determined between wild and cultured fishes both within and between species and between hatcheries. Fatty acid compositions were compared among individual (not composited) specimens of wild and cultured, age-0, freshwater species: largemouth bass Micropterus salmoides, black crappies Pomoxis nigromaculatus, white crappies P. annularis, and black-nose crappies. Four fatty acids were investigated: linoleic acid (18:2n-6), linolenic acid (18:3n-3), arachidonic acid (20:4n-6), and docosahexaenoic acid (22:6n-3). Linoleic acid was the primary fatty acid used to differentiate juvenile wild from cultured fishes. Concentrations of linoleic acid were significantly different (p < 0.05) in cultured largemouth bass and black crappies from the wild counterparts. Linolenic acid concentrations were not significantly different (p < 0.05) between wild and cultured largemouth bass but were significantly different between wild and cultured black crappies. Wild largemouth bass contained higher concentrations of arachidonic acid than the cultured bass, and concentrations of docosahexaenoic acid were twice as high in wild black crappies than cultured black crappies. On the basis of four signature fatty acids, 90 of 91 juvenile fishes were correctly classified as wild or cultured; 32 of 37 wild juvenile fishes originating from the same reservoir were differentiated by species. Data from the training set were used to classify a test set of fishes as to species, source, or origin with 100% accuracy.

The transport and fate of pesticides applied to ornamental plant nursery crops are not well documented. Methodology for analysis of soil and water runoff samples concomitantly containing the herbicides simazine (1-chloro-4,6-bis(ethylamino)-s-triazine) and 2,4-D ((2,4-dichlorophenoxy)acetic acid) was developed in this research to investigate the potential for runoff and leaching from ornamental nursery plots. Solid-phase extraction was used prior to analysis by gas chromatography and liquid chromatography. Chromatographic results were compared with determination by enzyme-linked immunoassay analysis. The significant analytical contributions of this research include (1) the development of a scheme using chromatographic mode sequencing for the fractionation of simazine and 2,4-D, (2) optimization of the homogeneous derivatization of 2,4-D using the methylating agent boron trifluoride in methanol as an alternative to in situ generation of diazomethane, and (3) the practical application of these techniques to field samples.