Chromolith^® RP-18e Standard HPLC Columns

• Easy Method Transfer
• Features and Benefits
• Different Lengths to Suit Your Applications
• Specifications
• Application Examples

Chromolith® RP-18 endcapped HPLC columns are the ideal choice for fast and robust separation of hydrophobic to medium polar compounds, for example carbidopa or steroids, at low column back pressure.

In contrast to conventional particle-packed columns, our Chromolith® RP-18 columns consist of monolithic high-purity silica with a bimodal structure of macropores and mesopores. The large macropores reduce column back pressure and thus allow significantly faster flow rates. The fine mesopore structure of the material, on the other hand, creates a very large active surface area for high-efficiency separations. Thanks to the low back pressure, several columns can be coupled to achieve even higher resolution.

Moreover, column lifetime is substantially enhanced thanks to the rigid monolithic material, and their high-purity silica base minimizes the adverse effects of trace metals. Chromolith® RP-18e HPLC columns are chemically modified with n-alkyl chains with high ligand density and then fully endcapped in order to reduce the effects of unmodified silanol groups.

Easy Method Transfer

The chemical basis of Chromolith® RP-18 endcapped columns is identical to that of high-end particulate silica columns (e.g. Purospher®). They are manufactured from thesame metal-free silanes and undergo the same surface modification procedures. As a result, their selectivity is comparable to high-quality C18 endcapped reversed-phase particle-packed columns. Thus, chromatographers can easily use standard methods when developing new protocols, and method transfer from particulate columns to monolithic Chromolith® RP-18 columns is simple and seamless.

Chromolith® RP-18e columns are included in the US Pharmacopoeia in category L1.

Features and Benefits

• High throughput at high flow rates with the best overall column quality
• Possibility of flow gradients
• Added column performance by column coupling
• Rigid monolithic structure for longer column lifetime
• Lower matrix sensitivity
• Simple method transfer from particulate columns

Different Lengths to Suit Your Applications

Column length is directly proportional to efficiency, back pressure, and retention times. Moreover, increasing column length increases resolution due to the higher number of theoretical plates per column. Chromolith® RP-18e standard columns are available with various lengths and internal diameters (i.d.) in order to perfectly match your application’s requirements. Moreover, two or even more Chromolith® HighResolution columns can be easily coupled thanks to the low back pressure.

Application Examples

Chromolith® SpeedROD RP-18e

Column	Chromolith® SpeedROD RP-18 endcapped, 50-4.6 mm
Mobile phase	A: Acetonitrile B: 0.01M Phosphate buffer pH 5.0
Gradient	Time/min	%A	%B
	0.0	3	97
	2.5	3	97
	2.6	8	92
	5.0	8	92
Flow rate	4 mL/min
Detection	227 nm
Temperature	Ambient
Injection volume	10 μl
Sample	1. Acesulfame-K 2. Saccharin 3. Benzoic acid 4. Sorbic acid 5. Caffeine 6. Aspartame	23 μg/mL 29 μg/mL 13 μg/mL 14 μg/mL 47 μg/mL 100 μg/mL

Separation of carbidopa

Column	Chromolith® Performance RP-18 endcapped, 100-4.6 mm
Mobile phase	A: Methanol B: 0.1% TFA in water
Gradient	Time/min	%B
	0.0	100
	1.0	100
	10	80
Flow rate	2 mL/min
Detection	UV 282 nm
Temperature	Ambient
Injection volume	5 μl
Sample	1. 2,4,5 Trihydroxyphenalalanine 2. Levodopa 3. Methyldopa 4. Dopamine 5. Carbidopa 6. 3,4-Dihydroxyphenylacetic acid 7. 3-o-Methylcarbidopa	125 μg/mL 235 μg/mL 160 μg/mL 190 μg/mL 175 μg/mL 185 μg/mL 105 μg/m

Separation of steroids

Column	2 columns of Chromolith® Performance RP-18 endcapped
Mobile phase	A: Acetonitrile B: Water
Gradient	Time/min	%B
	0.0	80
	7.0	10
Flow rate	3.0 mL/min
Detection	220 nm
Temperature	Ambient
Injection volume	10 μl
Sample	1. Prednisolone 2. Cortisone 3. Nortestosterone 4. Estradiol 5. Testosterone 6. Corticosterone 7. Estrone 8. Progesterone

Specifications