| It had become a hot research topic that used solid sampling technique for rapid detection of heavy metals in recent years.It was used atomic spectra system of solid sampling technique from Beijing Titan instrument limited company which supported by the national major scientific instruments and equipment development projects. This research built rapid detection of cadmium method of direct sampling atomic fluorescence spectrometry through analyzing cadmium instrument performance and simplifying sample pretreatment process, it would offer evidence for screening or developing a detection method with higher sensitivity and accuracy, as well as provide effective support for surveillance system to detect heavy metals in aquatic products.This work was based on the principle of Direct Sampling Atomic Fluorescence Determination of cadmium device.It could achieve direct cadmium analysis using a porous graphite tube as the vaporizer and a tungsten-coil as the cadmium trap.The study found that the biggest advantage of this equipment is the capture and secondary release of what separable almost all the matrix interference. Besides, it has good stability with RSD < 10%. At the same time, the experiment validated that it had no significant effect on the determination results wherever the sampling boat loaded, so had the individual difference. In addition, it found out the opreating parameters of the direct sampling device through optimizing spectrum conditions and orthogonal experiment according to these parameters. Then, the experimental application of direct sampling atomic fluorescence instrument for rapid determination of cadmium, fish, shrimp, crab, shellfish, algae and other aquatic product samples were method development and application and verification.First of all, this experiment was carried out by solid sample research of Cd, and identified with alumina refractories as stabilizer and thinner samples. Studies have found that analysis time less than 5 minutes, detection error is about 25%. Due to characteristics of solid sampling, its analysis detection limit and precision were not as good as liquid sampling. However, this method did not need sample digestion process, operate simply, fast analysis speed. It could provide an effective way for on-site rapid screening test of heavy metal Cd.Based on the characteristics of high water content, high liquid viscosity, Suspension sampling is a convenient and quick process. Suspension sampling technology is a kind of simple and effective methods in spectrum analysis technology. The experiment found that the homogenate aquatic product sample could be directly detected the concent of Cd under acidic condition, and nitric acid is better than that of hydrochloric acid, sulfuric acid and perchlorate from influence. Further research shows that 1% nitric acid added is well. In addition, Contrast and analysis towards standard curve method and standard addition method that was used, the results showed that both linearity were good, the correlation coefficient R2 were both above 0.995; Sample standard addition recoveries was 96.4% ~ 118.6%, relative standard deviation(RSD) were 3.3% ~ 11.6%, the method detection limit were 0.115 ng and 0.006 ng, respectively. Compared with the standard curve method, standard addition method had better accuracy, precision and stability.Application of these methods to some parts of China representative, including fish, shrimp, crabs and shellfish four categories of aquatic organisms cadmium content analysis of a sample survey done. The study found fish health monitoring area in good condition, eating a high value. However, some crabs and shellfish in some areas have been polluted to some extent, there is a certain risk of eating.Through this project implementation, it can realize the rapid detection of heavy metal cadmium in aquatic products field, obtain the monitoring data, so as to provide effective technical support for quality and safety monitoring system of aquatic products. |
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