Study Of On-site Rapid Detection Of Poor-quality SSP

Single Superphosphate is chemical fertilizer products which have extensive useful at present, it obtained by apatite which decomposed from the sulfuric acid and then ripened,and its main ingredients is calcium phosphate primary and calcium phosphate. The results of quality checks over the years showed that quality of SSP product is not optimistic. So, how to fastly and easily detect this chemical fertilizer products has become the focus of attention. The testing standards of SSP primarily was HG 2740-1995,and the current is GB 20413-2006, not only the method of extracting and testing the available phosphorus is complex, time-consuming, moreover its testing way is Weight law of phosphomolybdic acid and quinoline, require large-scale equipment drier of thermostat, and the available phosphorus can not be achieved at the scene, rapid detection. Pointing on the status quo, this subject put forward a new testing technology which the use of microwave extraction and analysis combined with the light. SSP's original standard of testing selected alkaline ammonium citrate as extraction agent, extract available phosphorus include two-step that water-soluble phosphorous and citric acid phosphate with ammonium phosphate, spend about 2h;and the effective testing choose Disodium EDTA (EDTA) as extraction agent, spend about 1h; two available methods of detection are in the process of using the weight of law. The new testing technology which the subject put forward is use microwave extraction and analysis combined with the light, Through introduct the microwave extraction as a sample of actual SSP rapid pretreatment, improve the current standard method of analysis, and the improved method will shorten the time for the extraction of 4.5 min; at the same time, use Spectrophotometric method instead of the weight of analysis, and again introduce the microwave heating in color reaction, detecting method of available phosphorus cut down 2h to 80 s. In the whole time of the former testing standards is 7 h and the new standard be reduced to 3h within 25 min (the shortest time was only 17 min). Thereby it carry out that achieve the quality of SSP on-site, fast and simple monitoring. At the same time, the standards on a trial basis which is a "poor-quality super phosphate on-site rapid detection method" is established.In this studied subject, it emphatically research and explore the following three aspects:1. SSP poor-quality on-site rapid detection method: The establishment of the analysis of the poor-quality SSP , which combined microwave extraction with analysis of photometric determination, System of a process of analysis of the impact of the above-mentioned factors, It was found that: In the conditions of EDTA in the concentration of 0.1 mol / L, extraction of microwave heating 4.5 min, pH value between 4.4 to 11, color reaction of microwave heating time for the selection of 80 s, microwave heating device for the exchange of 220 V, power 800 W, China-made home Microwave ovens use weighing 1 g, a margin of error of±0.01 g of measuring instruments, obtaining satisfactory results. Experiment also found that: Portland interferes with the test results of 0.04 to 0.27 percent. In view of the national standard GB 20413-2006 "SSP": qualified products available phosphorus content of≥12%, in addition to the available phosphorus content below 10% of low-grade SSP detected relative error (recovery) can be relaxed, so This issue to set the scene for rapid detection method of uncertainty that the method used for the error, its value is 12%×(-4 ~ +6%), that is, available phosphorus measured the absolute error is +0.72% -0.48 ~; To Reduce risk and misjudgment, available phosphorus content of this law in more than 10% of the SSP with EDTA after extracting heat to testing results to national standard than the general law on the high side.2. Through verification experiments of precision and check test, it verify inferior quality of SSP on-site rapid detection of uncertainty. We selected 10 representative samples, and repeatedly determin 10 times in the provided method under the same conditions, its standard deviation is 0.04～0.20.And it selected 51 representative sample which from Sichuan and Chongqing quality legal and administrative law enforcement agency. Using this law detection, and compared its testing results with the national standard method, the discrepancy between -0.30～+0.70%,it fit the setting task which error request between -0.48～+0.72%.3.The promote of new test methods and techniques: In this paper, the approach is now in nearly 300 cities and counties to promote the application, From 2006 to 2008, only Jiaxing in Zhejiang Province, Shijiazhuang, Hebei, Shaanxi Baoji, Suining in Sichuan Province, Chongqing and other places quality supervision department, seized more than 100 batches, the number more than 3000 tons, the value of the standard 200 million poor-quality superphosphate.To sum up, this issue is the establishment of a low-grade superphosphate on-site rapid detection method. Selection of 0.1 mol / L solution of EDTA as the agent extracted using spectrophotometry to replace the weight of law, to use two microwave heating technology in extracting and testing the available phosphorus not only greatly reduce the testing time and high accuracy of test results; In addition, spectrophotometry HACH DR/890 selected portable spectrophotometer (or desktop spectrophotometer), replaced the weight of the law of large temperature drying oven and sophisticated balance desktop, portable, achieving the identified issues of poor quality superphosphate at the scene, rapid and accurate detection. Now, This method is becoming the fastest, high-accuracy detection of low-grade superphosphate in China, the new method is also present on-site rapid detection method of fertilizer, the application of the widest range, found the largest number of poor-quality fertilizer, the largest amounts of money involved. In addition, the method is also applicable to the potassium dihydrogen phosphate and compound fertilizer, ammonium phosphate fertilizer products, such as on-site rapid detection.