An enzyme-linked immunosorbent assay (ELISA) was compared to a gas chromatography/mass spectrometry (GC/MS) procedure for the analysis of triazine herbicides and their metabolites in surface water and groundwater. Apparent recoveries from natural water and spiked water by both methods were comparable at 0.2-2 micrograms/L. Solid-phase extraction (SPE) was examined also, and recoveries were determined for a suite of triazine herbicides. A significant correlation was obtained between the ELISA and GC/MS method for natural water samples that were extracted by SPE. Because ELISA was developed with an atrazine-like compound as the hapten with conjugation at the 2-position, it was selective for triazines that contained both ethyl and isopropyl side chains. Concentrations for 50% inhibition (IC50) were as follows: atrazine, 0.4 microgram/L; ametryne, 0.45 microgram/L; prometryn and propazine, 0.5 microgram/L; prometon, 0.7 microgram/L; simazine and terbutryn, 2.5 micrograms/L; hydroxyatrazine, 28 micrograms/L; deethylatrazine and deisopropylatrazine, 30 micrograms/L; cyanazine, 40 micrograms/L; didealkylatrazine had no response. The combination of screening analysis by ELISA, which requires no sample preparation and works on 160 microL of sample, and confirmation by GC/MS was designed for rapid, inexpensive analysis of triazine herbicides in water.
T he debate on the cause and the amount of global warming and its effect on global climates and economics continues. As world population continues its exponential growth, the potential for catastrophic effects from climate change increases. One previously neglected key to understanding global climate change may be found in examining events of world history and their connection to climate fluctuations.Climate fluctuations have long been noted as being cyclical in nature, and many papers have been published on this topic (1). These fluctuations also can be quite abrupt (2) when climate displays a surprisingly fast transition from one state to another. Possible causes of the cyclic variations and abrupt transitions at different time intervals have been theorized. These theories include internal drivers such as CO 2 concentrations (3), ocean temperature and salinity properties (4), as well as volcanism and atmospheric-transmissivity variations (5). External drivers include astronomical factors such as the Milankovitch orbital parameters (6), which recently have been challenged (7), and variations in the Sun's energy output (8-10).The most direct mechanism for climate change would be a decrease or increase in the total amount of radiant energy reaching the Earth. Because only the orbital eccentricity aspect of the Milankovitch theory can account for a change in the total global energy and this change is of the order of only a maximum of 0.1% (11), one must look to the Sun as a possible source of larger energy fluctuations. Earth-satellite measurements in the last two decades have revealed that the total energy reaching the Earth varies by at least 0.1% over the 10-to 11-year solar cycle (12). Evidence of larger and longer term variations in solar output can be deduced from geophysical data (13-17).In an extensive search of the literature pertaining to geophysical and astronomical cycles ranging from seconds to millions of years, Perry (18) demonstrated that the reported cycles fell into a recognizable pattern when standardized according to fundamental harmonics. An analysis of the distribution of 256 reported cycles, when standardized by dividing the length of each cycle, in years, by 2 N (where N is a positive or negative integer) until the cycle length fell into a range of 7.5 to 15 years, showed a central tendency of 11.1 years. The average sunspot-cycle length for the period 1700 to 1969 is also 11.1 years (19). In fact, the distribution of the sunspot cycles is very nearly the same as the distribution of the fundamental cycles of other geophysical and astronomical cycles. Aperiodicity of the cycles was evident in two side modes of 9.9 and 12.2 years for the geophysical and astronomical cycles and 10.0 and 12.1 years for the sunspot cycle. The coincidence of these two patterns suggests that solar-activity cycles and their fundamental harmonics may be the underlying cause of many climatic cycles that are preserved in the geophysical record. Gauthier (20) noted a similar unified structure in Quaternary climate data...
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