In view of interference of the existence of selenium in determination of gold and silver in crude selenium sample, the sample with an addition of concentrated sulfuric acid was firstly heated to remove selenium. Then, sodium chloride solution was added to precipitate silver therein, and the obtained residue after filtration was taken for gold and silver determination using fire assay by gravimetry. Thus, a process of heating with sulfuric acid to remove selenium followed by fire assay gravimetry was established for continuous determination of gold and silver in crude selenium, and the effects of residual selenium, sulfuric acid dosage and heating time on the determination results were also discussed. Furthermore, such continuous determination process was also compared to the industrial standard method in terms of the analysis of gold and silver in crude selenium. By using the proposed continuous method, the relative standard deviations (RSD7) of gold was within a range of 0.54%-1.30%, and the RSD7 of silver was within a range of 0.28%-0.39%. The spike recovery of gold was 94.6%-101.3%, and the spike recovery of silver was 96.3%-100.1%. It is shown that the analysis results are consistent with those by industrial standard method. It is concluded that the proposed determination method, being fast and accurate, is suitable for determination of gold and silver in crude selenium.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |