摘要: The NIOSH validated method for the determination of tantalum (7440257) is described. One hundred liters of air (flow rate at 1.5 liters per minute) is drawn through a mixed cellulose ester membrane filter to trap the tantalum. The... 展开 The NIOSH validated method for the determination of tantalum (7440257) is described. One hundred liters of air (flow rate at 1.5 liters per minute) is drawn through a mixed cellulose ester membrane filter to trap the tantalum. The sample and filter are digested successively with 3 milliliters (ml) concentrated nitric-acid twice, 3ml nitric-acid plus 5 drops concentrated perchloric-acid, 1ml nitric-acid plus 5ml of 5 percent hydrofluoric-acid, evaporating to dryness between each step, except the last which is evaporated until only a droplet of solution remains. Three to 5ml of 5 percent hydrofluoric-acid are added. After cooling, the solution is added to a 10ml volumetric flask and filled to the mark with 5 percent hydrofluoric-acid. The solution is analyzed by a plasma emission spectrometer at the wavelength of 3320 angstroms. Tantalum concentration is determined by comparing with a calibration curve obtained by analyzing standards having concentrations equal to 0.5, 1, and 2 times the OSHA standard of 5 milligrams per cubic meter (mg/cu m). The method is useful for determining tantalum concentrations of 2.5 to 10.0mg/cu m with a standard deviation of 0.356mg/cu m. The detection limit is estimated to be 0.01mg/cu m. 收起