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GB/T 18115.2-2020 PDF English


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GB/T 18115.2-2020English405 Add to Cart 0-9 seconds. Auto-delivery. Chemical analysis methods of rare earth impurities in rare earth metals and their oxides -- Part 2: Determination of lanthanum,praseodymium,neodymium,samarium,europium,gadolinium,terbium,dysprosium,holmium,erbium,thulium,ytterbium,lutetium and yttrium content in cerium metal and oxide Valid
GB/T 18115.2-2006English639 Add to Cart 3 days Chemical analysis methods of rare earth impurities in rare earth metals and their oxide Cerium -- Determination of lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium Obsolete
GB/T 18115.2-2000English199 Add to Cart 2 days Cerium oxide-Determination of lanthanum oxide, praseodymium oxide, neodymium oxide, samarium, oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide Obsolete
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GB/T 18115.2-2020: PDF in English (GBT 18115.2-2020)

GB/T 18115.2-2020 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 77.120.99 H 14 Replacing GB/T 18115.2-2006 Chemical Analysis Methods of Rare Earth Impurities in Rare Earth Metals and Their Oxides - Part 2: Determination of Lanthanum, Praseodymium, Neodymium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium and Yttrium Content in Cerium Metal and Oxide ISSUED ON: NOVEMBER 19, 2020 IMPLEMENTED ON: OCTOBER 1, 2021 Issued by: State Administration for Market Regulation; Standardization Administration of the People’s Republic of China. Table of Contents Foreword ... 3 1 Scope ... 7 2 Method 1: Inductively Coupled Plasma Optical Emission Spectrometry ... 9 3 Method 2: Inductively Coupled Plasma Mass Spectrometry ... 17 4 Method 3: Inductively Coupled Plasma Tandem Mass Spectrometry ... 29 5 Quality Assurance and Control ... 37 Appendix A (normative) Conditional Test Operation of C272 Micro-column Separation Eluent Collection Time ... 38 Chemical Analysis Methods of Rare Earth Impurities in Rare Earth Metals and Their Oxides - Part 2: Determination of Lanthanum, Praseodymium, Neodymium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium and Yttrium Content in Cerium Metal and Oxide 1 Scope This Part of GB/T 18115 stipulates the determination method for the contents of lanthanum oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide and yttrium oxide in cerium oxide. This Part is applicable to the determination of the contents of lanthanum oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide and yttrium oxide in cerium oxide. This Part also applies to the determination of the contents of lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and yttrium in cerium metal. This Part includes a total of three methods: Method 1 - inductively coupled plasma atomic emission spectrometry, Method 2 - inductively coupled plasma mass spectrometry, and Method 3 - inductively coupled plasma tandem mass spectrometry. The determination range of Method 1 is shown in Table 1, the determination range of Method 2 is shown in Table 2, and the determination range of Method 3 is shown in Table 3. temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of lanthanum oxide. 2.2.6 Standard stock solution of praseodymium oxide: weigh-take 0.1000 g of praseodymium oxide [w (Pr6O11/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of hydrochloric acid (2.2.2); heat to dissolve it at a low temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of praseodymium oxide. 2.2.7 Standard stock solution of neodymium oxide: weigh-take 0.1000 g of neodymium oxide [w (Nd2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of hydrochloric acid (2.2.2); heat to dissolve it at a low temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of neodymium oxide. 2.2.8 Standard stock solution of samarium oxide: weigh-take 0.1000 g of samarium oxide [w (Sm2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of hydrochloric acid (2.2.2); heat to dissolve it at a low temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of samarium oxide. 2.2.9 Standard stock solution of europium oxide: weigh-take 0.1000 g of europium oxide [w (Eu2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of hydrochloric acid (2.2.2); heat to dissolve it at a low temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of europium oxide. 2.2.10 Standard stock solution of gadolinium oxide: weigh-take 0.1000 g of gadolinium oxide [w (Gd2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of hydrochloric acid (2.2.2); heat to dissolve it at a low temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of gadolinium oxide. 2.2.11 Standard stock solution of terbium oxide: weigh-take 0.1000 g of terbium oxide [w (Tb4O7/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (2.2.3), add 10 mL of hydrogen peroxide (2.2.1); heat to dissolve it at a low temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of terbium oxide. 2.2.12 Standard stock solution of dysprosium oxide: weigh-take 0.1000 g of dysprosium oxide [w (Dy2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of hydrochloric acid (2.2.2); heat to dissolve it at a low temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of dysprosium oxide. 2.2.13 Standard stock solution of holmium oxide: weigh-take 0.1000 g of holmium oxide [w (Ho2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of hydrochloric acid (2.2.2); heat to dissolve it at a low temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of holmium oxide. 2.2.14 Standard stock solution of erbium oxide: weigh-take 0.1000 g of erbium oxide [w (Er2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of hydrochloric acid (2.2.2); heat to dissolve it at a low temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of erbium oxide. 2.2.15 Standard stock solution of thulium oxide: weigh-take 0.1000 g of thulium oxide [w (Tm2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of hydrochloric acid (2.2.2); heat to dissolve it at a low temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of thulium oxide. 2.2.16 Standard stock solution of ytterbium oxide: weigh-take 0.1000 g of ytterbium oxide [w (Yb2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of hydrochloric acid (2.2.2); heat to dissolve it at a low temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of ytterbium oxide. 2.2.17 Standard stock solution of lutetium oxide: weigh-take 0.1000 g of lutetium oxide [w (Lu2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of hydrochloric acid (2.2.2); heat to dissolve it at a low temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of lutetium oxide. 2.2.18 Standard stock solution of yttrium oxide: weigh-take 0.1000 g of yttrium oxide [w (Y2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of hydrochloric acid (2.2.2); heat to dissolve it at a low temperature, then, cool to room temperature; transfer the solution into a 100 mL volumetric it in a 100 mL beaker, add 10 mL of nitric acid (3.2.6); heat at a low temperature, until it completely dissolves, remove it, then, cool to room temperature; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of europium oxide. 3.2.19 Standard stock solution of gadolinium oxide: weigh-take 0.1000 g of gadolinium oxide [w (Gd2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (3.2.6); heat at a low temperature, until it completely dissolves, remove it, then, cool to room temperature; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of gadolinium oxide. 3.2.20 Standard stock solution of terbium oxide: weigh-take 0.1000 g of terbium oxide [w (Tb4O7/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (3.2.6), add 2 mL of hydrogen peroxide (3.2.3); heat at a low temperature, until it completely dissolves, remove it, then, cool to room temperature; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of terbium oxide. 3.2.21 Standard stock solution of dysprosium oxide: weigh-take 0.1000 g of dysprosium oxide [w (Dy2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (3.2.6); heat at a low temperature, until it completely dissolves, remove it, then, cool to room temperature; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of dysprosium oxide. 3.2.22 Standard stock solution of holmium oxide: weigh-take 0.1000 g of holmium oxide [w (Ho2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (3.2.6); heat at a low temperature, until it completely dissolves, remove it, then, cool to room temperature; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of holmium oxide. 3.2.23 Standard stock solution of erbium oxide: weigh-take 0.1000 g of erbium oxide [w (Er2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (3.2.6); heat at a low temperature, until it completely dissolves, remove it, then, cool to room temperature; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of erbium oxide. 3.2.24 Standard stock solution of thulium oxide: weigh-take 0.1000 g of thulium oxide [w (Tm2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (3.2.6); heat at a low temperature, until it completely dissolves, remove it, then, cool to room temperature; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of thulium oxide. 3.2.25 Standard stock solution of ytterbium oxide: weigh-take 0.1000 g of ytterbium oxide [w (Yb2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (3.2.6); heat at a low temperature, until it completely dissolves, remove it, then, cool to room temperature; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of ytterbium oxide. 3.2.26 Standard stock solution of lutetium oxide: weigh-take 0.1000 g of lutetium oxide [w (Lu2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (3.2.6); heat at a low temperature, until it completely dissolves, remove it, then, cool to room temperature; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of lutetium oxide. 3.2.27 Standard stock solution of yttrium oxide: weigh-take 0.1000 g of yttrium oxide [w (Y2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (3.2.6); heat at a low temperature, until it completely dissolves, remove it, then, cool to room temperature; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of yttrium oxide. 3.2.28 Mixed rare earth standard solution I: respectively transfer-take 2.00 mL of the standard stock solutions of rare earth oxides (3.2.14 ~ 3.2.27) into the same 100 mL volumetric flask, add 10 mL of nitric acid (3.2.6), use water to dilute to the scale and mix it well. 1 mL of this solution contains 20 g of each single rare earth oxide. Then, use nitric acid (3.2.6) to dilute this solution into 1 mL of standard solution containing 1 g of each single rare earth oxide. 3.2.29 Mixed rare earth standard solution II: transfer-take 10.00 mL of mixed rare earth standard solution I (3.2.28) into a 100 mL volumetric flask, add 10 mL of nitric acid (3.2.6), use water to dilute to the scale and mix it well. 1 mL of this solution contains 100 ng of each single rare earth oxide. 3.2.30 Cesium internal standard solution: weigh-take 0.1270 g of cesium chloride (3.2.2), add 10 mL of water to completely dissolve it, add 10 mL of nitric acid (3.2.6); transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of cesium. Then, use nitric acid (3.2.7) to gradually dilute this solution into 1 mL of internal standard solution containing 1 g of cesium. 3.2.31 Argon [ (Ar)  99.99%]. 3.3 Instruments 3.3.1 Inductively coupled plasma mass spectrometer The mass resolution is better than (0.8  0.1) amu. 3.3.2 C272 micro-column separation device in the column, and it shall be degassed before use. 3.5.4.3.2 Matrix separation Respectively insert the leacheate pipeline and eluent pipeline into the leacheate (3.2.12) and eluent (3.2.13), and use the leacheate (3.2.12) to equilibrate the separation column for 6 minutes. Insert the test solution pipeline into the test solution (3.5.4.1), and after the test solution (3.5.4.1) fills the pipeline, switch the rotary valve 1 and accurately collect 1.00 mL of the test solution (3.5.4.1). Switch Valve 1 to the original position, use the leacheate (3.2.12) to drip wash the separation column for 20 minutes, wash out the matrix cerium, and discharge it to the waste liquid. Switch the rotary valve 2, after using the eluent (3.2.13) to elute for 1 minute, switch the rotary valve 3, and continue to use the eluent (3.2.13) to elute for a certain period of time, so as to elute the gadolinium and terbium enriched on the separation column. Collect the separating liquid in a 10 mL or 25 mL colorimetric tube, and switch Valve 3 to the original position. After 10 minutes, switch Valve 2 to its original position. Due to differences in the performance of the separation column, the conditional test operation for the collection time of the C272 micro- column separation eluent shall comply with Appendix A. 3.5.4.3.3 Preparation of test solutions for determination of gadolinium and terbium In the 10 mL or 25 mL colorimetric tube that collects the separating liquid, add 0.50 mL or 1.25 mL of cesium internal standard solution (3.2.30), use water to dilute to the scale and mix it well. 3.5.4.4 Preparation of analytical test solution for determination after TODGA matrix separation (gadolinium and terbium) 3.5.4.4.1 Preparation of separation column Use 20 mL of nitric acid (3.2.8) to equilibrate the separation column and reserve it for later use. 3.5.4.4.2 Matrix separation Place the test portion (3.5.1) in a 50 mL beaker, add 5 mL of water, 5 mL of nitric acid (3.2.6) and 1 mL of hydrogen peroxide (3.2.3); heat it at a low temperature, until it completely dissolves; transfer it to 50 mL volumetric flask, use water to dilute to the scale and mix it well. Accurately transfer-take 5.00 mL of the analytical test solution and add it to the seapration column. Open the valve and use 150 mL ~ 200 mL of nitric acid (3.2.8) to drip wash the separation column (the flow rate is not greater than 0.5 mL/min), so as to separate the matrix cerium. Discharge the leacheate into the waste liquid cup, until the cerium content in the leacheate is less than 1 g/mL. Then, use 20 mL of hydrochloric acid (3.2.5) to elute it, discharge the eluent into the waste liquid cup, continue to use hydrochloric acid (3.2.5) to elute the element to be determined. Collect 40 mL of separating liquid in a 50 mL colorimetric tube, add 2.50 mL of cesium internal standard solution (3.2.30), use water to dilute to the scale, mix it well, and reserve it for determination. 3.5.5 Preparation of standard series solutions 4.2.4 Nitric acid (1 + 1), guaranteed reagent. 4.2.5 Nitric acid (1 + 19), guaranteed reagent. 4.2.6 Standard stock solution of lanthanum oxide: weigh-take 0.1000 g of lanthanum oxide [w (La2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.4); heat at a low temperature, until it completely dissolves, remove and cool it; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of lanthanum oxide. 4.2.7 Standard stock solution of praseodymium oxide: weigh-take 0.1000 g of praseodymium oxide [w (Pr6O11/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.4); heat at a low temperature, until it completely dissolves, remove and cool it; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of praseodymium oxide. 4.2.8 Standard stock solution of neodymium oxide: weigh-take 0.1000 g of neodymium oxide [w (Nd2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.4); heat at a low temperature, until it completely dissolves, remove and cool it; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of neodymium oxide. 4.2.9 Standard stock solution of samarium oxide: weigh-take 0.1000 g of samarium oxide [w (Sm2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.4); heat at a low temperature, until it completely dissolves, remove and cool it; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of samarium oxide. 4.2.10 Standard stock solution of europium oxide: weigh-take 0.1000 g of europium oxide [w (Eu2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.4); heat at a low temperature, until it completely dissolves, remove and cool it; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of europium oxide. 4.2.11 Standard stock solution of gadolinium oxide: weigh-take 0.1000 g of gadolinium oxide [w (Gd2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.4); heat at a low temperature, until it completely dissolves, remove and cool it; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of gadolinium oxide. 4.2.12 Standard stock solution of terbium oxide: weigh-take 0.1000 g of terbium oxide [w (Tb4O7/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.4), add 2 mL of hydrogen peroxide (4.2.3); heat at a low temperature, until it completely dissolves, remove and cool to room temperature; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of terbium oxide. 4.2.13 Standard stock solution of dysprosium oxide: weigh-take 0.1000 g of dysprosium oxide [w (Dy2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.5), add 2 mL of hydrogen peroxide (4.2.3); heat at a low temperature, until it completely dissolves, remove and cool it; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of dysprosium oxide. 4.2.14 Standard stock solution of holmium oxide: weigh-take 0.1000 g of holmium oxide [w (Ho2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.4); heat at a low temperature, until it completely dissolves, remove and cool it; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of holmium oxide. 4.2.15 Standard stock solution of erbium oxide: weigh-take 0.1000 g of erbium oxide [w (Er2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.4); heat at a low temperature, until it completely dissolves, remove and cool it; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of erbium oxide. 4.2.16 Standard stock solution of thulium oxide: weigh-take 0.1000 g of thulium oxide [w (Tm2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.4); heat at a low temperature, until it completely dissolves, remove and cool it; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of thulium oxide. 4.2.17 Standard stock solution of ytterbium oxide: weigh-take 0.1000 g of ytterbium oxide [w (Yb2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.4); heat at a low temperature, until it completely dissolves, remove and cool it; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of ytterbium oxide. 4.2.18 Standard stock solution of lutetium oxide: weigh-take 0.1000 g of lutetium oxide [w (Lu2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.4); heat at a low temperature, until it completely dissolves, remove and cool it; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of lutetium oxide. 4.2.19 Standard stock solution of yttrium oxide: weigh-take 0.1000 g of yttrium oxide [w (Y2O3/REO)  99.999%, w (REO)  99.5%] that has been burned at 950 C for 1 hour, place it in a 100 mL beaker, add 10 mL of nitric acid (4.2.4); heat at a low temperature, until it completely dissolves, remove and cool it; transfer it into a 100 mL volumetric flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 1 mg of yttrium oxide. 4.2.20 Mixed rare earth standard solution I: respectively transfer-take 2.00 mL of the standard stock solutions of rare earth oxides (4.2.6 ~ 4.2.19) into a 100 mL volumetric flask, add 10 mL of nitric acid (4.2.4), use water to dilute to the scale and mix it well. 1 mL of this solution ......
 
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