ScavCart™ Application note
Metal contamination is a major problem for the pharmaceutical and fine chemical industries. A large amount of time and resources are spent purifying compounds after catalytic steps so that the metal concentration is within the acceptable limit. Generally, the acceptable limit is 0.05-10ppm, for those metals that are utilized in hydrogenation. Scavenger resins are often used for metal contamination purification. In this application note, we will demonstrate how the H-Cube® and a scavenger cartridge(ScavCart™) may be combined to perform a reaction and purification in 1 step.
EXAMPLES FOR HYDROGENATION REACTIONS
The H-Cube® is a continuous flow hydrogenation reactor. During the reaction process, the substrate is mixed with hydrogen and passed through a catalyst cartridge(CatCart®). The reaction takes place on the catalyst before flowing out of the cartridge and into a collection vial. All solid catalyst remains behind in the cartridge, but any dissolved metal must be removed through purification before proceeding to the next step. This is typically done using prep-HPLC and is a time-consuming and costly process. Not to mention the environmental impact in the amount of solvent used during the purification process.
At ThalesNano, we have integrated the purification step into the reaction process. A scavenger resin cartridge(ScavCart™) is inserted into the reaction line just before the reaction mixture flows into the collection vial. Any dissolved metal from the CatCart® is adsorbed by the scavenger resin, purifying the reaction mixture before it is collected. Further purification is not necessary, saving time, value, and money. The experiments below detail the ScavCarts™ capacity to remove dissolved metals from the reaction mixture.
STANDARD EXPERIMENTAL PROTOCOL
A metal-containing solution is passed through the scavenger-filled cartridge using H-Cube at atmospheric pressure, room temperature, and a flow rate of 1 mL/min in no hydrogen mode. The metal content was measured both before the reaction and afterward by ICP-MS analysis.
PALLADIUM SCAVENGING
A standard solution of 1000 ppm Pd(NO3)2 in 1M HNO3 was diluted with water and the pH was adjusted to 7 using solid Na2CO3. Two different concentrations of Pd metal were used to determine the absorption capacity at different concentrations. The exact concentration of the starting material was measured by ICP-MS and the solution was passed through the H-Cube® containing a particular ScavCart™. Four different scavengers were tested: QuadraSil™ AP, QuadraSil™ MP, Metalscavenger Phosphotungstic acid modified carbon („C”), and Metal scavenger Phosphotungstic acid-modified alumina („Al”) scavengers. A 10 mL analytical sample was taken in all cases to measure the Pd content by ICP-MS before and after the scavenging.
Graph. 1:
Results of Pd scavenging with QuadraSil™ AP,QuadraSil™ MP scavengers (in the boxes: Pd content ofstarting material in ppm)
| cPd/ppm | ||
|---|---|---|
| Starting solution metal concentration | 178 | 529 |
| After QuadraSil™ AP/ppm | 0.13 (100%) | 0.41 (100%) |
| After QuadraSil™ MP/ppm | 0.83(100%) | 25 °C/1 bar |
Table 1.:
Results of Pd scavenging with % of scavenged meta
Graph. 2:
Results of Pd scavenging with QuadraSil™ AP, QuadraSil™ MP scavengers (in the boxes: Pd content of starting material in ppm)
| cPd/ppm | ||
|---|---|---|
| Starting solution concentration | 17.10 | 83.90 |
| After Metal scavenger Phosphotungstic acid modified carbon („C”)/ppm | 0.05 (100%) | 0.07 (100%) |
| After Metal scavenger Phosphotungstic acid modified alumina („Al”)/ppm | 0.09 (100%) | 16.60 (80%) |
Table 2.:
Results of Pd scavenging with % of scavenged metal
RESULTS OF PALLADIUM SCAVENGING
All scavengers eliminated 80 - 99.9% of Pd. As seen in Graph. 1, testing the solutions with 178 and 529 ppm Pd content using QuadraSil™ MP and QuadraSil™ APscavengers, the concentration of the metal was dramatically reduced. The same results can be seen in Graph. 2 when solutions with smaller amounts of Pd were passed through the ScavCart™ using the “C” and“Al” scavengers.
PLATINUM SCAVENGING
Standard concentration of 1000 mg/L PtCl6 in 2 M HCl was diluted with water and the pH of the starting material was set to 7-8 with NaOH. Metal scavenger Phosphotungstic acid modified carbon („C”) and Metalscavenger Phosphotungstic acid modified alumina („Al”) were used to eliminate the concentration of the Pt metal. The amount of dissolved Pt present was measured by ICP-MS before and after the solutions were passed through the scavenger-filled ScavCarts™ at 25°C, atmospheric pressure, and flow rate of 1 mL/min. 10 mL samples were used for analysis.
Graph. 3:
Results of Pt scavenging using Metal scavenger Phosphotungstic acid modified carbon („C”) and Metalscavenger Phosphotungstic acid modified alumina („Al”)(in the boxes: Pt content of starting material in ppm)
| cPt/ppm | ||
|---|---|---|
| Starting solution concentration | 13.20 | 41.70 |
| After Metal scavenger Phosphotungstic acid modifiedcarbon („C”)/ppm | 0.17 (99%) | 0.69 (98%) |
| After Metal scavenger Phosphotungstic acid modifiedalumina („Al”)/ppm | 2.32 (82%) | 8.43 (80%) |
Table 3.:
Results of Pt scavenging with the % of scavenged metal
RESULTS OF PLATINUM SCAVENGING
The same scavengers that were used in the Pd scavenging were used for the Pt scavenging, namely Metal scavenger Phosphotungstic acid modified carbon („C”) and Metal scavenger Phosphotungstic acid modified alumina („Al”) The results of scavenging can be seen in Table 3. and Graph. 3. which indicates that these scavengers can also, eliminate 80 - 98% of the Ptresidues from a solution with low metal content.
RUTHENIUM SCAVENGING
Standard concentration of 1000 mg/L RuCl3 in 1 M HCl was diluted with water and the pH was adjusted to 8 with solid Na2CO3. The ruthenium was scavenged by QuadraSil™ AP and QuadraSil™ MP. The amount of Ru was measured by ICP-MS collecting 10 mL samples before and after the solutions were passed through the scavenger filled ScavCarts™ at 25°C, atmospheric pressure and flow rate of 1 mL/min.
Graph. 4:
Result of Ruthenium scavenging with QuadraSil™ APand QuadraSil™ MP scavengers.
| cRu/ppm | ||
|---|---|---|
| Starting solution concentration | 229 | 358 |
| After QuadraSil™ AP/ppm | 11.40 (95%) | - |
| After QuadraSil™ MP/ppm | - | 5.19 (98%) |
Table 4.:
Results of Ru scavenging with the % of scavenged metal
RESULTS OF RUTHENIUM SCAVENGING
The ruthenium content of two solutions with different Ruconcentrations were scavenged with QuadraSil™ APand QuadraSil™ MP scavengers. Both of the used scavenger eliminate more than 95% of the metal content from the solution.
COPPER SCAVENGING
Solution with standard concentration of 1000 ppm high purified copper in 2 w/w% cHNO3 was diluted with water and was passed through each scavenger-filled cartridge at a flow rate of 1 mL/min, atmospheric pressure and at room temperature.
| cPt/ppm | ||
|---|---|---|
| Starting solution concentration | 13.20 | 41.70 |
| After Metal scavenger Phosphotungstic acid modifiedcarbon („C”)/ppm | 0.17 (99%) | 0.69 (98%) |
| After Metal scavenger Phosphotungstic acid modifiedalumina („Al”)/ppm | 2.32 (82%) | 8.43 (80%) |
Table 5.:
Results of Cu scavenging with % of scavenged metal
RESULTS OF COPPER SCAVENGING
As displayed in Graph. 5 and Table 5. these scavengers dramatically reduced the amount of copper present in the starting solution.
Graph. 5:
Copper scavenging using silica-supported triamine tetraacetate, Metal scavenger Phosphotungstic acid modified carbon („C”) and Metal scavenger Phosphotungstic acid modified alumina („Al”).
Graph. 6.:
Results of ScavCarts™ with % of scavenged metal
CONCLUSION
The results demonstrate that the scavengers tested are highly effective in reducing the amount of dissolved metals. They were effective in reducing the palladium, platinum, nickel, and copper concentrations by up to 99%.
