This article describes a simple, robust and reliable method for the measurement of 21 trace elements in high-purity ammonium paratungstate (APT) using an Agilent 7500cx ICP-MS fitted with a High Matrix Introduction (HMI) system. HMI is a new sample-introduction accessory specially designed for concentrated samples with high total dissolved solids (TDS). Comparing results obtained using different APT sample digestion methods shows that dissolving the material in heated 4% H2O2 minimizes the formation of interferences on difficult elements such as phosphorus and silicon. APT samples containing 1% TDS were analyzed directly using the HMI's ultra robust mode. Results were calculated using the method of standard addition (MSA). Interferences on challenging elements such as Ca, K, Fe, and Si were removed by the Octopole Reaction System (ORS), a standard component of the Agilent 7500cx. The short turnaround time, including sample preparation and analy- sis time, indicates that the method is suitable for onsite testing.
The document presents a robust method for determining 21 trace impurities in high-purity ammonium paratungstate (APT) using an Agilent 7500cx ICP-MS fitted with the High Matrix Introduction (HMI) system. The study compares sample digestion methods, finding that dissolving APT in heated 4% H2O2 minimizes interferences for elements like phosphorus and silicon compared to ammonium hydroxide. Samples containing up to 1% total dissolved solids (TDS) were analyzed directly using the HMI's ultra robust mode.
The analysis utilized the Octopole Reaction System (ORS) to remove polyatomic interferences on challenging elements such as calcium, potassium, iron, and silicon. The method of standard addition was used for calibration, and results were corrected using mass-interpolated virtual internal standards. The short turnaround time indicates the method is suitable for onsite testing and quality control.
| Sampling depth | 10mm |
|---|---|
| RF power | 1600 W |
| Plasma gas flow | 16.0 L/min |
| Carrier gas flow | 0.38 L/min |
| HMI dilution gas flow | 0.64 L/min |
| Sample uptake rate | 0.4 mL/min |
| Number of replicates | 3 |
Samples containing 1% TDS were analyzed directly using the HMI's ultra robust mode.
Interferences were removed by the Octopole Reaction System (ORS), a standard component of the Agilent 7500cx, operated in hydrogen reaction mode.