GB/T 14506.30-2010Methods for chemical analysis of silicate rocks - Part 30: Determination of 44 elements (English PDF)

4.2 Nitric acid (rho

1.42 g/mL). guaranteed reagent or high-purity grade; purified by sub- boiling distillation before use.

4.3 Nitric acid (1+1).

4.4 Hydrofluoric acid (rho

1.16 g/mL). guaranteed reagent or high-purity grade, purified by sub-boiling distillation before use. WARNING -- Hydrofluoric acid is toxic and corrosive. Wear gloves during handling to prevent skin contact.

4.5 Single-element standard stock solution. for specific preparation details, refer to Annex B.

4.6 Multi-element mixed standard stock solution Prepare the following multi-element mixed standard stock solution by directly aliquoting single-element standard stock solutions (4.5). Alternatively, it may be obtained by diluting a commercially available multi-element mixed standard stock solution (see Table 1). NOTE. When preparing multi-element stock standard solutions, consider the compatibility and stability of the elements. Inspect the primary elemental stock standard solutions to ensure that impurities do not compromise the accuracy of the standards. Transfer newly prepared standard solutions into unused, acid-washed polypropylene bottles for storage, and periodically monitor their stability. Table 1 -- Multi-element mixed standard stock solution

4.7 Calibration standard solution Prepare calibration standard solutions by diluting the multi-element mixed standard stock solution (4.6). Transfer 100 µL of the multi-element mixed standard stock solution (4.6) into a 100 mL volumetric flask. Add 5 mL of nitric acid (4.2) and dilute to the mark with water (4.1). Mix well. Calibration standard solution 3 shall be prepared immediately before use, with the addition of

0.1 mL of hydrofluoric acid (4.4).

4.8 Mixed solution of internal standard elements Directly aliquot rhodium and rhenium single-element standard stock solutions (4.5) to prepare a mixed solution of internal standard elements, with rhodium and rhenium concentrations of 10 ng/mL each.

4.9 Blank solution

a) Calibration blank solution. Nitric acid solution (5+95);

b) Rinse blank solution. Nitric acid solution (2+98).

4.10 Single-element interference solution Single-element solutions of Ba, Ce, Pr, Nd, Zr, and Sn (each at a concentration of 1 µg/mL), Ti (10 µg/mL), and Fe and Ca (each at 250 µg/mL) are prepared to determine the interference coefficient k.

5.1 Inductively coupled plasma mass spectrometer

a) The instrument is capable of scanning within the mass range of 5 u~250 u. The minimum resolution is a peak width of 1 u at 5% of the peak height. Operating parameters for a quadrupole inductively coupled plasma mass spectrometer (ICP- MS), for example, are provided in Annex C.

b) Argon. High-purity grade (argon mass fraction >= 99.99%).

5.2 Sealed sample digestion vessel. stainless steel outer shell, PTFE inner liner, 10 mL capacity.

5.3 Drying oven. Maximum temperature at 250°C.

5.4 Thermostatically controlled electric hot plate. maximum temperature at 250°C.

5.5 Analytical balance. Class II, readability of

0.01 mg.

5.6 Air-displacement pipettes. specifications of 10 µL~100 µL, 100 µL~1000 µL, and 1 mL~5 mL.

5.7 Disposable plastic bottles. capacity of 25 mL or 50 mL.

7.3.1 Accurately weigh 25 mg or 50 mg (to the nearest

0.01 mg) of the test material into the inner vessel of a sealed digestion device.

7.3.2 Add 1 mL of hydrofluoric acid (4.4) and

0.5 mL of nitric acid (4.2), and seal the vessel. Place the dissolution vessel in an oven and heat for 24 h, maintaining the temperature at approximately 185°C ± 5°C.

7.3.3 After cooling, remove the inner vessel and place it on a hot plate to evaporate the contents until nearly dry. Then, add

0.5 mL of nitric acid (4.2) and evaporate until nearly dry. Repeat this step once.

7.3.4 Add 5 mL of nitric acid (4.3), reseal, place in an oven, and heat at 130°C for 3 h.

7.3.5 After cooling, remove the inner vessel. Quantitatively transfer the solution to a plastic bottle (5.7). Dilute with water (4.1) and make up to the mark at 25 mL (or 50 mL). Mix well. This solution is used directly for ICP-MS determination.

7.4 Determination

7.4.1 Start the instrument according to the conditions specified in the operating manual. Select the isotopes and internal standard elements for analysis (see Annex A) and prepare the sample analysis schedule.

7.4.2 Tuning. Allow the instrument to stabilize for at least 30 min after ignition. During this period, optimize the instrument parameters using a tuning solution containing 1 ng/mL of beryllium, cobalt, indium, cerium, and uranium. Introduce the mixed internal standard element solution (4.8) online via a three-way connector during the measurement process.

7.4.3 Calibration. Establish a calibration curve using the calibration blank solution [

4.9 a)] as the zero point and calibration standard solutions (4.7) at one or more concentration levels. Collect calibration data at least three times and calculate the average value.

7.4.4 For each batch of samples analyzed, a laboratory reagent blank solution (7.1) shall be analyzed concurrently.

7.4.5 For each batch of samples, analyze the single-element interference solution (4.10) concurrently to determine the interference coefficient k. Perform interference correction.

7.4.6 Rinse the system with the blank solution [

4.9 b)] between sample determinations.