Phosphate contaminants limits

Confirmation by GC/MS is recommended. Recovery is acceptable (82%). Tributyl phosphate and triphenyl phosphate contamination was reported in procedural blanks and may prevent determination of phosphate esters at levels near the detection limit (1 ng/g) (LeBel and Williams 1983 1986). 

The most widely deployed industrial explosion suppressant is mono-ammonium phosphate powder (MAP). This suppressant has a wide range of effectiveness. However, it can prove to be a contaminant, necessitating stringent clean-down procedures after a suppressed explosion incident. This limitation is overcome by selecting a sodium... 

The view at Cadmium changed with time starting from a valuable resource and ending up as a toxic element with a limited number of applications not substituted by alternative products. The decontamination of the technosphere works to a certain extent. Due to the character of Cd as trace contamination of phosphate fertilizers and of Zn ores and fossil fuels, there is no final solution for the environmental contamination. Due to the restrictions issued in many countries, there is reason to fear that Cd could end up in unknown material streams. From an analysis of the refining of Zn ores in 2002, it has been concluded that about one quarter of Cd generated as by-product ( 7,000-8,000 Mg) could not be found either in the products analyzed or in the emissions from the process [27]. 

Two studies with raw materials used to prepare parenteral formulations were carried out to show their content of aluminum and arsenic [15,16]. It is possible to see in Figures 2 and 3 that aluminum and arsenic were present in all investigated raw materials. There were also different levels of contamination among the substances. While salts such as NaCl and KC1 presented low aluminum contaminations, phosphates, gluconate, and also citric acid were relatively contaminated. The authors attributed this difference to the affinity of aluminum to the latter substances. Arsenic showed a more uniform distribution of contamination. With the exception of the amino acid tyrosine, the arsenic level in all substances was below 1 qg/g, not exceeding the limits prescribed by pharmacopeias. 

The studies by Eighmy and Eusden [10] are limited to stabilization of Pb, Cd, and Zn, which are sole contaminants of the MSW ash. By extension, it is believed that similar minerals are formed during phosphate treatment of other waste streams. For example, Singh et al. [50] have studied the interaction of Pb, Cd, and Zn with phosphatic clay and reported their investigations on the sorption and desorption of these metals. They report precipitation of Pb as fluoropyromorphite. In the case of Cd and Zn, their studies are not as conclusive, but Singh et al. suspect sorption and coprecipitation of phosphates are still the main mechanisms of stabilization. 

Often, the rates of fertilization in intensively managed agriculture are intended to satiate the needs of crop plants for these chemicals, so their productivity will not be limited by nutrient availability. However, excessive rates of fertilization have important environmental costs. These include the contamination of ground water with nitrate eutrophication of surface waters caused by nutrient inputs (especially phosphate) acidification of soil because of the nitrification of ammonium to nitrate large emissions of nitrous oxide and other nitrogen gases to the atmosphere, with implications for acid rain and Earth s greenhouse effect and the need to use herbicides to control the weeds that flourish under artificially nutrient-rich conditions. 

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