SiliaMetS® Metal Scavengers Leaching & Stability Studies
Now that our SiliaMetS Metal Scavengers are being used by many pharmaceutical and biotechnological companies, each SiliaMetS manufactured by SiliCycle is submitted to an extensive washing procedure which ensures a product with extremely low levels of extractables and leachables.
SiliCycle has implemented a quality control procedure regarding possible leaching that includes loading and reactivity determination, as well as leachables and extractables analysis (silica gel purity ≥ 99.995%). The solution must be free of contaminants for the product to successfully pass the rigorous quality control tests.
To address the end users concerns for potential leaching of impurities into reaction mixtures using SiliaMetS, we have performed three typical metal containing reactions. We then investigated the detection, identification, and quantification of possible impurities resulting from the scavengers used.
Transition metal catalyzed reactions performed
The following three transition metal catalyzed reactions were performed:
Experimental Procedure
Crude reaction mixtures (8 mL) were placed in a standard polypropylene tube equipped with a 20 µm frit and filled with 1 g of the appropriate SiliaMetS Metal Scavenger and mixed for 4 h at either room temperature or 80°C. Solutions were then filtered through a 0.02 µm filter prior to analysis.
Leaching Analysis
For each SiliaMetS, silanes leaching was analyzed by ICP-OES which has proven to be very sensitive for silicon quantification (detection limit in solution is 0.125 ppm). Traces of non-silicon containing impurities were also analyzed by GC-MS and 1H NMR Analysis. Only results for SiliaMetS Thiol and DMT are shown. However, no evidence of any impurities was found for allSiliaMetS. Contact us to get the complete study.
Gel Purity Calculation Example
Silanes Leaching Analysis by ICP-OES
Results shown in the table below for SiliaMetS Thiol & DMT confirm that minimal leaching occurs with SiliCycle SiliaMetS.
Note: concentration given are in ppm and represent mg of silicon leached per kg of SiliaMetS.
| Stability of SiliaMetS in Suzuki, Stille and Ring-Closing Metathesis reactions | |||||
| Reaction (solvent) | Temperature | SiliaMetS Thiol | SiliaMetS DMT | ||
| [Silicon] | Gel Purity | [Silicon] | Gel Purity | ||
| Suzuki (Toluene) | 22°C | 2 ppm | 99.9998 % | 1 ppm | 99.9999 % |
| 80°C | 2 ppm | 99.9998 % | 2 ppm | 99.9998 % | |
| Stille (1,4-Dioxane) | 22°C | 2 ppm | 99.9998 % | 1 ppm | 99.9999 % |
| 80°C | 1 ppm | 99.9999 % | 3 ppm | 99.9997 % | |
| Ring-Closing Met (DCM) | 22°C | 2 ppm | 99.9998 % | 2 ppm | 99.9998 % |
| Note: Very low levels of silicon were detected in most experiments, giving products purity higher than 99.995 %. | |||||
Non-Silicon Leaching Analysis
| Gas chromatography-mass spectrometry (GC-MS) | 1H NMR Analysis (d6-dmso) |
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Compared to the silica blank spectrum (bare silica in solvent), neither experiment showed evidence of any impurities for either SiliaMetS Thiol or DMT.
Note: each experiment was ran on a 1 g aliquote of SiliaMetS and was shaken for one hour at room temperature. In GC-MS spectrum, peak at 8.5 minutes is the internal standard (1-fluoronaphthalene, 100 ppm). In NMR spectrum, peaks at 2.4 and 3.4 ppm are, respectively, d6-dmso and water contained in deuterated solvent.
Stability Study (Shelf Life)
| SiliCycle certifies that SiliaMetS Metal Scavengers stored under recommended conditions in an undamaged container are guaranteed to perform for over two years from the manufacturing date without loss of performance, prouved by results at right. |
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SiliaMetS® Thiol
SiliaMetS® Thiol (Si-Thiol) is a robust metal scavenger for a variety of metals including Pd, Pt, Cu, Ag and Pb under a wide range of conditions. It has been used in pharmaceutical processes up to the pilot plant scale. It is our most versatile metal scavenger and is the preferred metal scavenger for Pd(II), Cu, Ag, and Hg.
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SiliaMetS® Thiourea
SiliaMetS® Thiourea (Si-THU) is a versatile metal scavenger for all forms of palladium and is widely used in the pharmaceutical industry. It works particularly well in organic solvents. It can also be used to scavenge Ag, Pt, Ru, Rh and Hg. Once complexed with a transition metal, it has been reported as being an effective catalyst.
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SiliaSep™ Flash Cartridges Thiol
SiliaSep flash thiol cartridges offer a superior alternative to the other cartridges available on the market.
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SiliaSep™ Flash Cartridges Thiourea
SiliaSep flash thiourea cartridges offer a superior alternative to the other cartridges available on the market.
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SiliaSep™ Flash Cartridges - Open Top (OT) Thiol
SiliaSep™ OT flash cartridges are compatible with FlashMaster instrument.
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SiliaPrep™ SPE Cartridges Thiol
SiliaPrep Metal Scavengers will lower the residual metal concentration of various metal complexes to single digit ppm.
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SiliaPrep™ SPE Cartridges Thiourea
SiliaPrep Metal Scavengers will lower the residual metal concentration of various metal complexes to single digit ppm.
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