GB/T 15076.5-2017 in English

Interpretation of the standard for determination of molybdenum and tungsten content

This standard specifies the determination method for molybdenum (Mo) and tungsten (W) in tantalum (Ta) and niobium (Nb) and their compounds, using inductively coupled plasma atomic emission spectrometry (ICP-OES), and is suitable for the analysis of samples with a mass fraction range of $0.0005\% \sim 3.00\%$.

Background of Standard Formulation

GB/T 15076.5—2017 replaced GB/T 15076.5—1994. The main technical improvements include:

• The determination method was changed from spectrophotometry to inductively coupled plasma atomic emission spectrometry (ICP-OES)
• The determination range was extended to $0.0005\% \sim 3.00\%
• New requirements for precision and test reports

Technology Evolution Analysis

ICP-OES has the advantages of high sensitivity, low detection limit and simultaneous determination of multiple elements, and is particularly suitable for trace analysis of complex samples. Compared with traditional spectrophotometry, it has stronger resistance to matrix interference and a wider range of applications.

Comparison of standard frameworks

Reagents and instruments

Main reagents:

• Nitric acid (density $1.42~\mathrm{g/mL}$)
• Hydrofluoric acid (density $1.14~\mathrm{g/mL}$)
• Molybdenum standard solution and tungsten standard solution

Instruments and equipment:

• Inductively coupled plasma atomic emission spectrometer (with hydrofluoric acid injection system)
• Argon purity not less than $99.99\%$
• Hot plate or electric heating furnace

Analysis steps

1. Sample preparation:

• Sample particle size requirements: molybdenum powder $\leq 150~\mu\mathrm{m}$, button powder $\leq 180~\mu\mathrm{m}$
• Sample treatment: Dissolve in nitric acid and hydrofluoric acid, and measure in dilute acid medium

2. Working curve drawing:

• Select the concentration of standard solution according to the content range
• 0.0005\% \sim 0.10\%: use molybdenum and tungsten standard solutions
• 0.10\% \sim 3.00\%: use molybdenum and tungsten standard storage solutions

3. Blank test:

• Take an equal amount of matrix material to the sample as a blank sample
• Measure together with the sample

Result calculation and precision

1. Result calculation formula:

2. Precision requirements:

Implementation suggestions

To ensure the accuracy of the measurement results, it is recommended that:

• Strictly follow the standard operating procedures for sample preparation and instrument calibration
• Regularly check the performance of the equipment to ensure that the purity of argon and the spectral resolution meet the requirements
• Establish a quality control procedure, including blank test and standard curve verification
• For high content samples ($>3.00\%$), consider diluting before measurement