Development of Superficially Porous Silica with Polyfunctional C18 Bonding
Technique for Reversed Phase HPLC
www.chromanik.co.jp

Norikazu Nagae1), Tomoyasu Tsukamoto1), Scott Silver2)

1) ChromaNik Technologies Inc., 6-3-1 Namiyoke, Minato-ku, Osaka, Japan
2) Innovations United, 300 East 57th Street, Suite 11J, New York, NY 10022 USA

www.innovationsunited.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 significant
improvements 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.

Fully porous 5 um

35

Fully porous 3 um

30

12Fully proous 1.8 um

10SunShell 2.6 um

Pressure, MPa

Plate Height, um

14862520

200SiO

MeMeMeClSiO

5100.51SiOMeSiOOMeOMe

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

Table 1. Comparison of retention between fully porous
silica C18 and core shell silica C18s
Fully porous silica C18Sunniest C18 5 mmCore shell silica C18
SunShell C18 2.6 mm

340 m2/g

150 m2/g

Specific surface area

Retention
time (ｔR)
1 = Uracil
1.70
2 = Caffeine
1.90
3 = Phenol
2.17
4 = Butylbenzene
13.35
5 = o-Terphenyl
19.19
6 = Amylbenzene
19.96
7 = Triphenylene
24.35
52 3 SunShell C18 2.6 mm
1

1.5

45105

4

SunShell C18(core shell)

12000

100 times
Kinetex C18

8000

Sunniest
C18 3mm(fully porous)

Ascentis Express C18
SunShell C186000

Sunniest C18 3um

4000

Kinetex C18(core shell)

2000
00.0010.01

0.11, mgSample weight/mg

04.4%

1234567Retention time/min

8960
Brand K core shell C18
40

Brand A core shell C18
SunShell C18

2000204060

Time (h)80100120Measurement 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

SunShell C18

2.91

2.4

01.8

10.001430

Column: SunShell C18, 2.6 mm
100 x 2.1 mm
Mobile phase: CH3CN/H2O=60/40
Flow rate: 0.3 mL/min
Pressure: 12.5 MPa
Temperature: 25 ºC

6Sample: 1 = Uracil
2 = Toluene
3 = Acenaphthene
4 = BUtylbenzene

85 min612Plates(3)=38,000
34Figure 6. Loading capacity of amitriptyline II0In 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.

1008060
Brand K core shell C1840

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

2SunShell C18001,000 2,000 3,000 4,000 5,000 6,000

Elution volume (mL)

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

Figure 9. Stability under basic pH condition

46Retention time/min

Column: SunShell C18, 2.6 mm
150 x 4.6 mm
Mobile phase: CH3CN/H2O=70/30
Flow rate: 1.0 mL/min
Pressure: 11.5 MPa
Temperature: 25 ºC810Figure 7. Chromatogram of standard samples of SunShell C18＋Q1: 5.997 min to 7.999 min of Sample

TIC of ＋Q1

Brand A core shell C18

20

Retention
factor (k)
00.10
0.18
3.55
4.99
5.43
5.94

14

0.01
0.1
Sample weight, mg

25

Retention time/min

1.3

1.5

742

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

Mobile phase: Methanol/water(75:25)
Temperature: 40oC
Column dimension: 150 x 4.6 mm
Flow rate: 1.0 mL/minPlates(3)=21,300

210Durable 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

80

3.6

7 times

Sample: 1=Uracil, 2=Propranolol,
3= Nortriptyline, 4=Amitriptyline

Figure 5. Loading capacity of amitriptyline I

100

Brand A Core Shell C18

2Ascentis ExpressC18(core shell)

10

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

2.5

Relative plate of butylbenzene(%)

10000

3

Effective 200 m2/g

Retention
factor (k)
00.09
0.22
6.41
9.55
10.18
14.06

3USP Tailing factor

Brand k Core Shell C18

3.5Core shell silica C18Kinetex C18 2.6 mm

61520
Retention time/min

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

USP tailing factor

14000

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

62 3 Sunniest C18 5 mm
10Retention
factor (k)
00.12
0.28
6.85
10.29
10.74
13.32
7416000

OOOSiOO

Figure 4. Comparison of Back Pressure for HighThroughput Columns

Figure 3. Comparison of Plate Height Plots

Si(HMODTS)

Flow rate, mL/min15Si
SiOO O Si Si
SiSi
Si OOO OSi O SiO OHOSiSi
Si OOOOOSi
SiO SiOSiSiSiOO
HO OOOSiOO OO OOSiOSiOSiOOSiSiSi
Si O
Si
O O
O Si O O OOOSiOOOOOOOOSiOSi

Si OFigure 2. Schematic diagram of bonding of SunShell C18 （Core Shell particle）

Column dimension: 50 x 2.1 mmMobile phase: Acetonitrile/water=(70/30)
Temperature: 25 oC0MeMeHexamethyloctadecyltetrasilane

0Mobile Phase Velocity, mm/sec

Theoretical Plate

HO155Column:C18, 50 x 4.6 mm
Mobile phase: Acetonitrile/water=(60/40)
Temperature: 25 oC Sample : Naphthalene

Final 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

104Relative retention (%)

Figure 1. Schematic diagram of a core shell silica particle

Sunniest C18-HT 2.0 um

4016Core1.6 mm

Porous silica

4518Core

2.6 mm

2.6 mmBrand L C18

SunSell 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-4000
Ionization:
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.