Development of Superficially Porous Silica with Polyfunctional C18 Bonding
Technique for Reversed Phase HPLC
Norikazu Nagae1), Tomoyasu Tsukamoto1), Anders Grahn2), Ralf Jutvik2) and Vinay D. Gaitonde2)
1) ChromaNik Technologies Inc., 6-3-1 Namiyoke, Minato-ku, Osaka, Japan2) Biotech AB, Box 133, 439 23, Onsala, Sweden

www.chromanik.co.jp

www.biotech-sweden.com

0.5 mmAbstract

0.5 mmBrand columns packed with superficially porous particles have been available for sometime. The superficially porous media or so called core-shell media offers significantimprovements such as higher efficiency and lower pressure drop for existing HPLC operations
without having to replace existing HPLC systems with UHPLC systems.
In this study, core-shell silica bonded with C18 using polyfunctional bonding technique(SunShell C18) was evaluated. A 2.6 μm core-shell silica with a non-porous core approximately
1.6 μm in diameter and a superficially porous layer of 0.5 μm was used to be bonded withhexamethyloctadecyltetrasiloxane (HMODTS) and end-capped with trimethylsilane.
Proposed core-shell C18 yielded efficiencies close to totally porous sub-2 μm or 2 μm C18
and showed less than half the pressure drop to compare with the sub-2 μm or 2 μm C18.
Stability under both acidic and basic pH conditions as well as peak shape of basic, acidic andmetal-chelating compounds were evaluated and compared with other core-shell typecolumns. Proposed core-shell C18 was more stable than the other core shell C18s under acidic
and basic pH conditions.
Loading capacity of amitriptyline was examined in acid, low-ionic-strength mobile phasessuch as a mixture of 0.1% formic acid and acetonitrile and 20 mM phosphate buffer pH7.0 andacetonitrile.
1814Figure 1. Schematic diagram of a core shell silica particle

Fully porous 3 um

12Fully proous 1.8 um

10SunShell 2.6 um

8630
2520HOSiOSiMeClColumn:C18, 50 x 4.6 mm
Mobile phase: Acetonitrile/water=(60/40)
Temperature: 25 oC Sample : Naphthalene

20510O

SiO

0.5151SiOSiO

SiOOOOOOOSiO OOOSiOSiSiSiSiO

Si O OSiOO O SiSiSiOO OHOOSiOOSiSiSiOO OO OOOSiSi O
O OO
SiOOOSi

Si O Si
SiOO OSiSiOOOOO

Si OSiHO O
O SiOOSiSiO O

Figure 2. Schematic diagram of bonding of SunShell C18 (core Shell)

Table 1. Comparison of retention between fully porous
silica C18 and core shell silica C18s
Fully porous silica C18
Sunniest C18 5 mm

Core shell silica C18
SunShell C18 2.6 mm

340 m2/g

150 m2/g

Specific surface area

Retention
time (ｔR)
1.70
1.90
2.17
13.35
19.19
19.96
24.35

1 = Uracil
2 = Caffeine
3 = Phenol
4 = Butylbenzene
5 = o-Terphenyl
6 = Amylbenzene
7 = Triphenylene

1.52 3 SunShell C18 2.6 mm

51642 3 Sunniest C18 5 mm
1Figure 4. Comparison of Back Pressure for HighThroughput Columns

Figure 3. Comparison of Plate Height PlotsO MeO MeO

Flow rate, mL/min

Mobile Phase Velocity, mm/sec

SiSiO

000Si

Si

Me(HMODTS)

Column dimension: 50 x 2.1 mm
Mobile phase: Acetonitrile/water=(70/30)
Temperature: 25 oC

5M eM eM eM eHexamethyloctadecyltetrasilane

15104Final TMS

Bond

Brand A C18 1.9 um
Brand B C18 1.8 um
Brand C C18 1.7 um
Brand D C18 2.6 um
SunShell C18 2.6 um

35

Pressure, MPa

Plate Height, um

Pore volume: 0.30 mL/g, Specific surface area: 150 m2/g,
Pore diameter: 9 nm

Sunniest C18-HT 2.0 um

40

Fully porous 5 um

Core1.6 mm

Porous silica

4516Core

2.6 mm

2.6 mm05104

Retention
factor (k)
00.12
0.28
6.85
10.29
10.74
13.32

Retention
time (ｔR)
1.35
1.47
1.65
10.01
14.24
15.09
20.33

Core shell silica C18
Kinetex C18 2.6 mmEffective 200 m2/g

Retention
factor (k)
00.09
0.22
6.41
9.55
10.18
14.06

Retention
time (ｔR)
1.36
1.49
1.61
6.19
8.15
8.75
9.44

Retention
factor (k)
00.10
0.18
3.55
4.99
5.43
5.94

75Mobile phase: Methanol/water(75:25)
Temperature: 40oC
Column dimension: 150 x 4.6 mm
Flow rate: 1.0 mL/min

7615
20
Retention time/min

2530

7752 3
164

Brand A
core shell C18752 3
10SunShell
4C182468

Hydrogen bond Hydrophobicity Steric selectivity(Caffeine/Phenol)610 12 14(Amylbenzene/Butylbenzene) (Triphenylene/o-Terphenyl)

Brand K C18

0.48

1.54

1.20

Brand A C18

0.44

1.60

1.31

SunShell C18

0.40

1.59

1.47

16 18 20 22 24

Retention time/min

Mobile phase: Acetonitrile/20mM phosphate buffer pH7.0=(60:40)
Column dimension: 150 x 4.6 mm, Flow rate: 1.0 mL/min, Temp.: 40oC
31600014000

1 212000

6000

Brand A core shell C18

4000

SunShell C18

2000

Relative retention, %80
60
Brand K core shell C1840

Brand A core shell C18
SunShell C18

200020406080Time ,(h)hour100120Measurement condition
Column size: 50 x 2.1 mm
Mobile phase: CH3CN/H2O=60/40
Flow rate: 0.4 mL/min
Temperature: 40 ºC
Sample: 1 = Uracil
2 = Butylbenzene

Figure 8. Stability under acidic pH condition

Conclusion

12312 34

Brand K
Core Shell
C184

Brand ACore Shell
C1800.001

0.010.1

1100, mg
Sample weight/mg

Theoretical plate was calculated by 5σ
method using peak width at 4.4% of peakheight.

1234567Retention time/min

894.4%

1008060
Brand K core shell C1840

SunShell C1800

1,000 2,000 3,000 4,000 5,000 6,000, mL
Elution volume(mL)

2.9

SunShell C18

2.5

2.4

7 times

21.8

1.5

1.3

140.001

0.01

0.1

5 min

1Sample weight, mg

Figure 7. Loading capacity of amitriptyline II
In the case of using acetonitrile /0.1% formic acid as a mobile phase, amitriptyline peak shows
more tailing because a loading capacity decreases in an acidic, low-ionic-strength mobile phase.

＋Q1: 5.997 min to 7.999 min of Sample

Durable test condition
Column Size: 50 x 2.1 mm
Mobile phase: CH3OH/20mM
Sodium borate/10mM
NaOH=30/21/49 (pH10)
Flow rate: 0.4 mL/min
Temperature: 50 ºC

TIC of ＋Q1

Measurement condition
Column Size: 50 x 2.1 mm
Mobile phase: CH3OH/H2O=70/30
Flow rate: 0.4 mL/min
Temperature: 40 ºC
Sample: 1 = Butylbenzene

Brand L C18

Figure 9. Stability under basic pH condition

3.6

Brand A Core Shell C18

3

Brand A core shell C18

20

USP Tailing factor

Brand k Core Shell C18

3.5

10Sample: 1=Uracil, 2=Propranolol,
3= Nortriptyline, 4=AmitriptylineFigure 6. Loading capacity of amitriptyline I

Relative plate of butylbenzene, %Durable test condition
Column size: 50 x 2.1 mm
Mobile phase: CH3CN/1.0% TFA,pH1=10/90
Flow rate: 0.4 mL/min
Temperature: 80 ºC

SunShell
C18

Brand K core shell C18

8000

Mobile phase: Acetonitrile/0.1% formic acid=(30:70)
Column dimension: 150 x 4.6 mm, Flow rate: 1.0 mL/min, Temp.: 40oC

4100 times

10000

Figure 5. Comparison of standard samples

1004USP tailing factor

64

Theoretical plate

2 31Column:
Brand K C18, 150 x 4.6 mm
Brand AC18, 150 x 4.6 mm
SunShell C18, 2.6 mm 150 x 4.6 mm
Mobile phase: CH3OH/H2O=75/25
Flow rate: 1.0 mL/min
Temperature: 40 ºC
Sample: 1 = Uracil, 2 = Caffeine, 3 = Phenol,
4 = Butylbenzene, 5 = o-Terphenyl,
6 = Amylbenzene, 7 = Triphenylene

Brand K
core shell C18

5SunSell C18

Column size: 50 x 2.1 mm
Mobile phase:A) 0.1% acetic acidB) CH3CN
Gradient:
Time: 0min 1min 5min 7min
%B: 5% 5% 100% 100%
Flow rate: 0.4 mL/min
Temperature: 40 ºC
MS： ABI API-4000Ionization:
Turboionspray (cation)
Measurement mode:
Q1 Scan m/z 100-1000

Figure 10. Bleeding test using LC/MS*Core shell particle bonded with polyfunctional C18 (SunShell C18) showed 2 times higher retention factor than Kinetex C18.
*SunShell C18 had 7 to 100 times higher loading capacity than the other core shell C18.
*Furthermore, SunShell C18 was not only stable under acidic and basic pH conditions to compare with the other core shell C18s, but also showed lessbleeding under a typical LC/MS condition.

6