What Are the Metal Contents of the Silica Used in Cogent TYPE‑C™ HPLC Columns?
Short answer: The base silica for Cogent TYPE‑C™ columns is qualified by ICP (Inductively Coupled Plasma) analysis against strict acceptance specs for common trace metals.
The specification limits are: Al ≤ 5.0 ppm, Fe ≤ 20.0 ppm, Ti ≤ 0.5 ppm, Mg ≤ 5.0 ppm, Ca ≤ 15.0 ppm, Na ≤ 20.0 ppm. Actual measured levels are often significantly lower than these limits.
Why do trace metals matter in HPLC silica?
Even at the parts‑per‑million level, residual metals in silica can influence surface chemistry, potentially affecting:
- Secondary interactions with acidic, basic, or chelating analytes (e.g., tailing or shifting retention).
- Baseline stability or adsorptive artifacts in LC/MS workflows, especially for low‑abundance polar species.
By setting low acceptance thresholds and verifying by ICP, Cogent TYPE‑C™ aims to minimize these effects while preserving the unique silicon‑hydride (Si–H) surface properties that differentiate the platform from ordinary silica.
The specification limits (verified by ICP)
- Aluminum (Al): not more than 5.0 ppm
- Iron (Fe): not more than 20.0 ppm
- Titanium (Ti): not more than 0.5 ppm
- Magnesium (Mg): not more than 5.0 ppm
- Calcium (Ca): not more than 15.0 ppm
- Sodium (Na): not more than 20.0 ppm
Note: The actual levels measured are often well below these maxima.
Context: TYPE‑C™ silica vs. ordinary silica
Cogent TYPE‑C™ employs a silica‑hydride surface with minimal silanol activity, supporting fast equilibration, mixed‑mode (ANP / RP / NP) selectivity, and reduced water sorption compared with conventional silica. Maintaining tight control of trace metals supports this behavior and the column’s consistency across lots.
Summary
Cogent TYPE‑C™ silica is controlled for trace metals by ICP, with tight ppm‑level limits on Al, Fe, Ti, Mg, Ca, Na, and typical results below those limits. This quality control helps preserve the distinctive Si–H surface performance and minimizes unwanted secondary interactions during analysis.
