We startwith thebestwidepore silica…
• Largest available surface area in250-350Åpores—ideal for largermolecules.
• Excellent base deactivation.
• Viva
™
silicamanufacturedbyRestek for consistency.
Conventional reversedphaseHPLCpackingmaterialswith60-150Åpores gen-
erally are poorly suited for separating peptides, proteins, or other larger bio-
molecules. The analyte molecules cannot access the surface area within these
pores, and the pores can be fouledwith largemolecular weight debris. Silicas
withwiderpores address thisneed formore resolvingpower: theoretically, larg-
er analytes enter the pores, accessmore of the surface, and are retained longer,
promotingbetter selectivity.
For analytes withmolecular weights larger than 3000, pore diameters of 250-
350Å offer the best combination of retention and stability - pores larger than
500Å canmake a silica impractically fragile formany applications. A narrow
distribution about themeanpore diameter can aid in separating analytes that
differ only slightly in hydrodynamic size. A large pore volume allows more
analytemolecules into the pores, and provides better separations of complex
mixtures. Pore volumes exceeding 1.2mL/g, however,make the silica particles
more fragile.
IndevelopingViva™widepore silica,we evaluatedmaterials fromotherman-
ufacturers, and found some donot possess sufficient pore volume in the pore
diameter rangeneeded for effectively separating largemolecules.Of themate-
rialswe tested,Viva™300Å silicahas thegreatest available surface area in250-
350Åpores (Table I),and thegreatestpercentageof poresnarrowlydistributed
around themeandiameter (Figure 1).
…whichmakes exceptional HPLC columns…
• Excellent efficiency andpeak symmetry.
• Best selectivity and retention among five testedmanufacturers’ columns.
We compared column efficiency, peak asymmetry, and retention for Viva™
C18 and four other popular C18 wide pore columns. Table II and Figure 2
show theViva™ column ranked highest in retention and selectivity and pro-
duced the best peak symmetrymeasurements.
…forpeptides, proteins, orother largemolecules.
• Exceptional selectivity, for resolving larger biomolecules.
• Excellent base deactivation, formore symmetrical peaks and greater sensi-
tivitywithoutmobile phasemodifiers.
Evenwithwideporepackings, limitationsoftenareencounteredwhen samples
contain closely related compounds, such as complex tryptic digests or genetic
variants of a protein. These applications call for columns with maximum
resolvingpower.
Viva™HPLC columns are ideal for challenging analyses.Todetermineoverall
separatingpower, retention,andpeak shape,weevaluatedeachmanufacturer’s
columnwithpeptide andprotein testmixes. TheViva™C18 columnprovid-
ed excellent resolution andpeak shapes, as Figures 3 and4 show.
Sizeexclusion studies showViva™wideporecolumnsarewell suited foranaly-
ses ofmolecules over aweight range of approximately 800 to 212,000Dalton.
For additional technical informationaboutViva™wideporecolumns, request
RestekAdvantage 2005v1 (lit.#59077) and2005v2 (lit.#59923).
Exceptionally large available surface area, a highly desirable pore volume, and
a narrow pore diameter distribution help ensure effective retention of pep-
tides, proteins, or other largemolecules, andmakeViva™wide pore columns
the best choice for your analysis.
Figure1
OnlyViva™ silicahas amajorityof
pores in the250-350Å range, inanarrow
distribution. (BJHdesorption)
PoreDiameter, (Å)
PoreVolume, (cm³/g-Å)
100 200 300 400 500 600 700 800 900 1000
0.0000
0.0005
0.0010
0.0015
0.0020
0.0025
0.0030
0.0035
0.0040
0.0045
0.0050
0.0055
Viva
™
300Å
3
1
2
1. mfr. A 200Å
2. mfr. F 200Å
*
3. mfr. G 200Å
*
Table II
Viva™widepore columnsprovide
thebest overall performance.
Efficiency
Retention
(plates/m) Asymmetry
Time
Pressure
Column
(10
3
)
(biphenyl)
(biphenyl)
(bar)
Viva
™
C18
>50
1.16
6.30
60
mfr. F C18
>50
1.30
5.89
66
mfr. C C18
~50
1.46
5.77
72
mfr. D C18
>50
1.46
4.96
102
mfr. H C18
<50
1.49
3.79
80
150 x 2.1mm C18 phase columns, 5µm particles; reversed phase
test mix
Table I
Viva™ silicahas the largest available
surfacearea in250-350Åpores, allowing the
greatest interactionwith largemolecules.
Surface Area (m
2
/g)
Total Pore
0-
250-
Total
Volume
Silica
100Å 350Å Desorp BET (mL/g)
Nominal PoreDiameter (300Å)
Viva
™
lot X
1.6
46.5 144.5 116.9
0.880
Viva
™
lot Y
2.3
40.6 138.6 112.4
0.823
mfr. A
2.9
34.4 118.2 101.6
0.885
mfr. A
4.2
33.1 130.3 111.3
0.941
mfr. B
3.7
22.2
83.6
73.9
0.627
Nominal PoreDiameter (200Å)
mfr. A
41.0
2.7 231.6 189.2
0.852
mfr. A
34.1
0.9 243.4 200.0
0.911
mfr. D*
9.2
23.0 158.4 129.8
0.795
mfr. E
21.7
19.2
90.7
93.0
0.509
mfr. F*
24.7
15.6 105.8
58.5
0.530
mfr. G*
2.6
6.7 115.3
91.6
0.595
*Materials D, F, andG are 200Åmaterials being sold as 300Å.
*Materials F andG are 200
Å
materials being sold as 300
Å
.
