Phosphorus time history

GC is coupled with many detectors for the analysis of pesticides in wastewater. At the present time the most popular is GC-MS, which will be discussed in more detail later in this section. The flame ionization detector (FID) is another nonselective detector that identifies compounds containing carbon but does not give specific information on chemical structure (but is often used for quantification because of the linear response and sensitivity). Other detectors are specific and only detect certain species or groups of pesticides. They include electron capture,nitrogen-phosphorus, thermionic specific, and flame photometric detectors. The electron capture detector (ECD) is very sensitive to chlorinated organic pesticides, such as the organochlorine compounds (OCs, DDT, dieldrin, etc.). It has a long history of use in many environmental methods,... 

But then the duke sent Leibniz away on a diplomatic mission. By the time the philosopher returned, he had turned to other endeavors and lost interest in his phosphorus project. At this point Brandt disappears from history, and all that is known about the rest of his life is that he lived a fairly long time. Brandt might have still been alive in 1710, when he would have been in his eighties, according to Leibniz. Leibniz remarked that at least he had not heard of Brandt s death. 

There are several chemical elements the history of whose discovery is not clear. We had every reason to classify the nine elements described in Chapter 1 as the elements of antiquity. For the five elements—phosphorus, arsenic, antimony, bismuth, and zinc—discussed in this chapter, there is evidence that people knew these elements (with the exception of phosphorus), or at least their ores and minerals, in prehistoric times, or at any rate before the Christian era. But the knowledge of them was confused and ambiguous. It became better much later, at the time of alchemistry when various chemical procedures were performed in laboratories and chemist s shops. Although their nature remained unclear, they were a basis of many useful compounds (particularly, acids and salts). 

There have been a number of major episodes in the history of chemistry when half a dozen or so elements were discovered almost at once, or within a period of a few years. Of course, some elements, such as iron, copper, gold, and other metak, have been known since antiquity. In fact, historians and archeologists refer to certain epochs in human history as the Iron Age or the Copper Age. The alchemists added several more elements to the list, including sulfur, mercury, and phosphorus. In relatively modem times, the discovery of electricity enabled chemists to isolate many of the more reactive elements that, imUke copper and iron, could not be obtained by heating their ores with carbon. The English chemist Humphry Davy seized upon the use of electricity or, more specifically, electrolysis to isolate as many as 10 elements, including calcium, barium, magnesium, sodium, and chlorine. 

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