The Sunshell Advantage vs. Other Coreshell C18’s and Other Totally Porous C18’s with 2μm and Less Than 2μm

Efficiency and Back Pressure
Efficiency, theoretical plate number and a back pressure were compared between key columns.. Acetonitrile and water 60 to 40 was used as a mobile phase. Flow rate was 0.5 mL/min. This flow rate is typical for UHPLC. The theoretical plate of acenaphthene was measured. All C18 columns except for Company W C18 showed more than 24,000 plates. Company W showed a very low theoretical plate number. It is only 14,500 plates. The back pressure was around 50 MPa. Sunshell C18 48.5 MPa 7,034 psi 485 Bar Company S 53.5 MPa 7,760 psi 535 Bar Company P 53.8 MPa 7,803 psi 538 Bar Company W 54.1 MPa 7,847 psi 541 Bar Company S 43.9 MPa 6367 psi 439 Bar Monodisperse
Generation of Frictional Heat
We measured the temperature of the surface of the column outlet when methanol flowed at 5 ml/min at 70 MPa. Initially temperature is 22.8 degree C, after 6 minutes, temperature then increased to 37 degree C. This means that frictional heat was generated in the column. Frictional heat is not a problem at below 25 MPa pressure. So when a 5um or 3um column is used, nobody notices an issue with frictional heat.
Efficiency Loss by Thermal Friction*
Regarding hybrid silica C18 columns, it shows a large efficiency loss from thermal friction. A 100 mm length column shows more than 50 MPa, so that the effect of frictional heat is larger compared to that with a 50 mm length column. Some scientists wrote papers regarding efficiency loss by thermal friction. Totally porous hybrid silica showed the highest plate number at a low flow rate of 0.2 ml/min because of efficiency loss by thermal friction at a high flow rate. Totally porous silica particle catches influence of thermal friction less than totally porous hybrid silica particle.
Separation of Standard Samples
This slide shows a comparison of separation of standard samples for 2 um or sub 2 um C18 columns as well as 2.6 um or 2.7 um core shell C18 columns. Regarding Separation Factor k6, company P and company W showed only 70% of retention factor of amylbenzene compared with SunShell C18. Company S shows almost the same retention factor as SunShell C18 although in regards to retention time, company S showed longer retention time than SunShell C18.
Pyridine Peak
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 the best peak compared to the other C18's.
Oxine Peak
Oxine is a metal chelating compound. It is considered that Company P and Company S shows a low theoretical plate number and tailing. This means that they have a lot of metal impurities. Company W has a bad peak shape. SunShell C18 shows a good peak shape which shows that SunShell C18 has little metal impurities.
Formic Acid Peak
Sunshell C18 shows a good peak shape.
Amitriptyline Peak
Amitriptyline was used as a basic compound and two kinds of mobile phases were used. SunShell C18 showed the best peak shape and the highest theoretical plate for a basic compound like amitriptyline.