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Quality Control

The objective of the department of Quality Control is to provide default free products to insure that SiliCycle’s clients have full satisfaction. In light of this, we have determined the critical points that need to be addressed for each product line. These points are based on clients and salespersons recommendations as well as from the scientific knowledge of our employees.

Each product family has its own quality control procedures and every procedure is strictly followed. Finally, the results of the QC tests are checked and confirmed by the responsible person before signing off for shipping. When required, a certificate of analysis is sent with the product. The complete procedures for each product line are available upon request.

Silica Gel
The backbone of all our products is SiliCycle’s UltraPure silica gel. Which provides superior performance for chromatographic applications due to the narrow particle distribution and high purity.

Before we utilize the silica for any product it is rigorously characterized and tested. We perform a proprietary “acid wash” procedure to remove 99% of the impurities present on many other commercially available silica gels. Only after completing two washes do we analyze the silica to make sure it meets our required standards for our products. We perform the following tests:

Elemental Analysis
ICP-MS: Trace metal analysis for analysis of trace metals.
BET Analysis: to determine the surface area, pore diameter, pore size distribution and volume.
Particle size analysis
Water content
pH

Elemental analysis of organic and inorganic compounds
Our UltraPure Gel has a very low organic content. All lots are subjected to elemental analysis to determine the carbon, nitrogen and sulfur levels.

To improve your separation we manufacture our gel with a very low level of trace metals (section 2.2.2). Up to 0.5% of silica gel may be comprised of different metal oxides. Fortunately, most are inert. Iron is usually the most abundant oxide, but others may be present and act as Lewis acids. Such acids can affect or destroy some products. The “tailing” of most polar compounds (frequently ionizable) is another major problem in silica with a high metal content. After the acid wash, SiliCycle’s silica gel is analyzed for more than 45 metals by ICP-MS (ppm level), in order to reduce or eliminate the problems mentioned above.

B.E.T. analysis
The efficiency and reliability of silica gel depends on its surface condition. The B.E.T. test determines the surface area, pore diameter and pore volume of the silica gel, which are all closely linked to separation performance. A larger surface area results in more contact or interaction with the analyte, thereby increasing the segregation of different products.Pore diameter and pore volume permit semi-exclusion chromatography where smaller molecules fit into pores more easily than larger ones. This justifies the use of several types of silica to achieve better discrimination in chromatographic separations.

Silica gel activity
The amount of water on the silica’s surface affects chromatographic performance. An anhydrous silica gel will be extremely polar, while a wetted one will be considerably less so. Every batch is carefully adjusted to a specific percentage of water content. Most normal chromatography applications require a water content between 6.0 and 7.0%, which is obtained by drying the silica gel at 160°C.

Silica gel pH
Silica pH can increase the retention of some ionizable compounds. However, some products can become hydrolyzed or rearranged in contact with acidic silica. A neutral pH, with a range between 6.5 and 7.0, is the most important factor in determining the reliability and inert behavior of the silica. This pH test involves suspending the silica gel in pure water (10% w/v).

Particle size distribution
Particule size distribution is determined by screening the silica through different mesh sizes. Usually, more than 90% of the silica gel is kept within the granularity range.

Functionalized Products

The process for functionalizing the silica is highly dependant on the group being attached. However, we are still able to functionalize 90% of the surface, verified by silicon(Si) NMR. The remaining 10% of the surface is end capped to provide a completely inert support.After functionalizing the product undergoes further analysis and quality control outlined below.

Loading: depending on the product we use a variety of tests to verify the functional reactivity of our products
Elemental Analysis: used to verify the loading
FTIR: verify the chemical nature of the functional group and the loading