HK-8100 single-channel scanning spectrometer to measure rare earth elements - Database & Sql Blog Articles

Inductively coupled plasma optical emission spectroscopy (ICP-AES) has the advantages of low detection limit, wide linear range and simultaneous determination of multiple elements. It has become the main means of rare earth element analysis. Computer controlled single-pass scanning ICP-AES is widely used in the determination of rare earth elements due to its flexible selection.
Experimental part:

Equipment and working conditions:

HK-8100

Single pass scanning emission spectrometer. Wavelength range 190 ~ 500nm, plasma generator: Cherni Turner maximum power 1 20 0W, continuously adjustable, fixed operating frequency 27.12 MHz. Working conditions: High frequency power is 0. 65 kW, and the reflected power is zero. Argon gas flow rate: plasma gas flow rate 15 L/min, atomizing gas flow rate 1 1 0 L/min, auxiliary gas flow rate 0 1 3 L/min. Observation height: 15 mm on the load coil. Lifting capacity: 1 1 4 mL / min. Integration time: 1 s. Peak search steps: Standard 24 steps, sample 10 steps.

Standard solution and main reagent: each rare earth element single element standard stock solution is prepared by using spectral pure reagent, and the oxides of each rare earth element are: La 2 O 3 , CeO 2 , Pr 4 O 11 , Nd 2 O 3 , Sm 2 O 3 , Eu 2 O 3 , Gd 2 O 3 , Tb 4 O 7 , Dy 2 O 3 , Ho 2 O 3 , Er 2 O 3 , Tm 2 O 3 , Yb 2 O 3 , Lu 2 O 3 , Y 2 O 3 and Sc 2 O 3 . The rare earth standard medium for the rare earth mixed standard working solution prepared by diluting the stock solution step by step is 1.2 mol/L HCl. HNO 3 (analytical grade), 1. 20 mol/L, tartaric acid with ρ = 10 g/L. EGTA (analytical grade), 0.1 mol/L. The effect of different power on the detection limit of rare earth elements: high frequency power is one of the important parameters of ICP. It has different effects on the detection limits of various elements in plasma. The rare earths under different powers are determined under given conditions. The detection limit of the element. According to the definition and regulation of IUPAC detection limit, the detection limit of each rare earth element is determined by 10 times of blank solution. The calculation formula is: LD = Ks where s is the standard deviation of 10 times of blank solution, and K is the confidence coefficient. 2 . Table 2 gives a comparison of the detection limits for each rare earth element at powers of 0 1 65 kW and 0 1 80 kW, indicating that the rare earth elements have lower detection limits at low power. Stability experiments at low power: Due to reduced power, stability may be affected. To this end, a stability test was performed under the given conditions. The mixed rare earth standard was determined 10 times within 2 h. The results showed that the relative standard deviations of all rare earth elements were less than 10%, and most of them were less than 5%, which proved that the stability under low power was reliable. Line wavelength and background subtraction position: Call the computer work program, carefully study the spectral line of each element, and determine the optimal buckle background position with the actual separated sample solution to make it more suitable for the determination of polymetallic nodules and deep sea sediments. In the rare earth element. The spectral line interference between rare earth elements is most obvious with Ce 442. 431 nm to Sm 442. 434 nm. After multiple measurements, the interference correction coefficient of Ce to Sm is 0.01, and the correction coefficient can be used to deduct the interference to obtain Sm. The correct result. Sample analysis process: Weigh 1 000 g air-dried sample into high aluminum crucible, add 3 ~ 4 g Na ₂ O ₂ , mix well, cover the surface with a layer of flux, melt in a muffle furnace that has been heated to 700 °C 10min. After taking out the cooling, the crucible was placed in a beaker to which 10 mL of 0.1 mol/L EGTA, 5 mL of triethanolamine and 80 mL of distilled water were added, and heated to boiling. Remove and rinse off after cooling. After filtration, the precipitate was washed 5 to 8 times with 20 g/L NaOH solution, and the precipitate was washed twice with distilled water. Remove the precipitate together with the filter paper into the original beaker, add 10 mL 6 mol / L HCl, heat and stir until the precipitate is completely dissolved, cool and filter, wash the filter paper with 40 mL 20 g / L tartaric acid, dilute the filtrate to 100 mL, add a small amount Ascorbic acid is reduced to a solution colorless. The solution was transferred to a cation exchange column equilibrated with 0.6 mol/L HCl, and washed with 1.2 mol/L HNO 3 (containing tartaric acid, 20 g/L) 80 mL and 1.2 mol/L HCl 40 mL, respectively. Impurities, then elute the rare earth with 6 mol/L HCl 80 mL. The solution is evaporated to 1 mL on a hot plate. After cooling, transfer to a 10 mL colorimetric tube, dilute to the mark, and shake it at HK-8100. Determined on a scanning spectrometer. Due to the relative enrichment of such samples, particularly polymetallic nodules, such as incomplete separation, spectral interference can be produced for the determination of rare earth elements. Through research, the overlap interference of Mn 353. 185 nm to Dy 353. 170 nm is very serious. In addition, Mn 398. 867 nm has a certain line to La 398. 852 nm and Mn369. 285 nm to Er 369. 265 nm. Interference. However, after alkali fusion, ion exchange can separate and remove most of the Mn. Finally, the residual Mn in the solution is less than 10 mg/L, which does not affect the determination of rare earth elements. Results and discussion: The results were in good agreement with the standard values. The relative standard deviation of each element was 1.3% to 5.3 %, and the reproducibility of some lower content elements such as Tb and Tm was significantly improved. Prove that the accuracy and precision of this law meet the requirements.