The Sunshell Coreshell Advantage

Schematic Diagram of Core Shell SIlica (SunShell)
This slide shows a structure of our core shell particle, SunShell. Particle diameter is 2.6 um. Core diameter is 1.6 um. Thickness of the porous silica layer is 0.5 um. Pore volume is 0.3 mL/g. Specific surface area is 150 m2/g. Average pore diameter is 9 nm. Finally the ratio of porous silica volume is 77%.
Comparison of Standard Samples
6 types of core shell C18 columns were compared using neutral standard samples.
Mobile phase is methanol and water 75 to 25.
Sample include: uracil, caffeine, phenol, butylbenzene, o-terphenyl, amylbenzene and triphenylene.
Retention Time: Sunshell showed the longest retention time. Company P showed the shortest retention time. Retention factor of amylbenzene is k6 = 5.6 for Company P and k6 = 10.4 for Sunshell. Company P had half the retention factor of amylbenzene compared to Sunshell C18.

Back Pressure: Sunshell C18, Company S C18, and Company T C18 showed similar back pressure

Sunshell C18 21.8 MPa 218 bar 3162 psi
Company S C18 22.2 MPa 222 bar 3220 psi
Company T C18 22.7 MPa 227 bar 3292 psi
Company P had a 20% higher back pressure.
Company P 26.1MPa 226 bar 3785 psi
Company A had 40% higher back pressure.
Company A 30.6 MPa 306 bar 4,438
Company W showed lower back pressure.
Company W 18.5 MPa 185 bar 2,683 psi

Each core shell column manufacturer indicates their particle size of their C18 columns are 2.6 um or 2.7um
Company W has a larger particle size than the other players. Company W shows lower back pressure but theoretical plate number was 23,300 while the others showed more than 30,000 plates.
3 parameters were obtained: hydrogen bonding , hydrophobicity and steric selectivity were obtained as shown in this table.
Comparison of Pyridine
Pyridine peak shape was compared and the effect of residual silanol groups was evaluated. Mobile phase is methanol and water 30 to70. Number 2 peak is pyridine. SunShell C18 showed a good peak shape. However Company P Kinetex C18 and company T Accucore C18 showed a bad peak shape.
Comparison of oxine, metal chelating compound
8-quinolinol, a Oxine peak shape (peak number 1) was compared with other columns. The amount of metal impurities in the core shell silica was evaluated because oxine is a metal chelating compound and the metal impurity causes oxine to peak tail. SunShell C18 had the best peak shape with the least amount of tailing compared to the other columns in the analysis.
Comparison of Formic Acid
Formic acid, an acidic compound was used for comparison of core shell C18 columns. Formic acid is a compound that easily turns to a bad peak shape. SunShell C18, along with company P and Company A showed a good peak shape.
Particle Size Distribution
The sintered core shell silica particle size distribution was measured via the Beckman Coulter Multisizer 3 which uses the coulter counter method.
SunShell C18, Company S and Company A showed a similar particle size distribution. Company P and Company A showed around a 10% smaller particle size than SunShell C18. This means that a back pressure increases 20% because a back pressure is inversely proportional to the square of the particle size. Company W showed 10% larger particle size than SunShell C18, so that Company W showed 20% lower back pressure than SunShell C18.
The result of particle size distribution and Median particle size can explain the difference of back pressure of each column shown in the previous slide.
Loading Capacity of Amitriptyline I
This slide shows loading capacity and a peak shape of basic compounds like amitriptyline.

6 kinds of Core shell C18s and Sunniest C18 (as a fully porous C18) were compared.

Loading capacity of SunShell C18 is the same as that of the Sunniest C18. Surprisingly Company P showed only 1/100 of loading capacity to compare with SunShell C18 or Company A. Regarding a peak shape of amitriptyline, SunShell C18 and Sunniest C18 showed a symmetrical peak shape. However the other core shell C18 showed a tailing peak.
Loading Capacity of Amitriptyline I
Company T and Company W showed a strange behavior. When sample weight increased from 0.3 ug, the theoretical plate number increased too. The higher the sample loading, the higher the observed theoretical plate. It is speculated that both C18s have some strongly active residual silanol groups that amitriptyline can adsorb to. Thus the influence of the silanol group was lost after these active sites become saturated.

A peak shape improves as amitriptyline sample loading increases.
Loading Capacity of Amitriptyline II
In the previous slide, the phosphate buffer was used as a mobile phase. In this slide, ammonium acetate was used.

This is a mobile phase for LC/MS measurement.

A similar result was obtained.
Loading Capacity of Amitriptyline III
This slide shows loading capacity of amitriptyline with less than 0.1% formic acid mobile phase condition. In this acidic condition, loading capacity is very low. Overloading causes peak tailing. SunShell C18 has 7 times more loading capacity than Company P.
Comparison of Basic Compounds I
Separation of basic compounds was compared using 3 kinds of mobile phases.

Condition A: Methanol and phosphate buffer; pH7.5; 40°C
Condition B: Methanol and phosphate buffer; pH 6.0; 22°C
Condition C: Acetonitrile and phosphate buffer; pH 7.0; 40°C

Evaluation of peak shape of amitriptyline, when methanol is used as an organic solvent in a mobile phase.

Condition (A): Many conventional C18's show a good peak shape.
Condition (B): When temperature decreases conventional C18's show a tailing peak.
Condition (C): When acetonitrile is used instead of methanol, conventional C18's show a significant tailing peak.

Chromanik Sunniest C18 showed a good peak shape in all three conditions.
Stability Under Acidic pH Condition
This slide shows stability under acidic pH condition. The upper is a durable test condition. Mobile phase is acetonitrile and 1.0% TFA pH1 (10 to 90). Temperature is 80 degree Celsius. This condition is accelerated. As a comparison at 90% of relative retention, SunShell C18 endured 120 hours, significantly better than the other players.
Stability Under Basic pH Condition
This shows stability under basic pH condition. Mobile phase is methanol and 20 mM sodium borate and 10 mM sodium hydroxide (30% to 21% to 49%) pH 10. Temperature is 50 degree Celsius. Under basic pH condition, C18 is deteriorated by dissolving silica gel and a void yields in the column so that the theoretical plate decreases. The Vertical axis is relative theoretical plate.

SunShell C18 can be used 5000 mL of elution volume. SunShell C18 is much more stable than the other players under basic pH condition as is the case under acidic pH condition.