Catalog Number - 65518-25P

Zx Similars C18™ is a traditional reversed-phase HPLC stationary phase manufactured on high-purity Type-B spherical silica with a fully endcapped octadecyl (C18) bonded phase. Designed as a cost-effective alternative to Agilent Zorbax® C18 columns, it offers comparable chromatographic behavior for USP L1 methods while providing the strong hydrophobic retention, reproducibility, and broad applicability expected from a conventional C18 stationary phase.

65518-25P is a 250 mm x 4.6 mm ID analytical column packed with 5 µm Zx Similars C18 particles. The extended 250 mm length provides increased theoretical plate counts and enhanced resolving power for impurity profiling, complex sample matrices, and challenging separations where maximum resolution is required. The 5 µm particle size provides excellent robustness, broad method compatibility, and lower operating pressure than smaller particle columns, making it well suited for conventional HPLC systems. Typical operating flow rates are approximately 1.0–2.0 mL/min.

This USP L1 column is ideal for hydrophobic and neutral compounds requiring strong reversed-phase retention. Common applications include pharmaceutical analysis, impurity profiling, long-chain fatty acid separations, method development, and quality control testing. This configuration remains one of the most popular Zx Similars C18 columns in the product line.

Key Benefits

• Type-B spherical silica stationary phase

• Suitable alternative for USP L1 methods

• Comparable selectivity to Agilent Zorbax® C18 columns

• Increased resolution from 250 mm column length

• Broad compatibility with conventional HPLC systems

• Lower operating pressure than smaller particle columns

• Strong hydrophobic retention

• One of the most popular Zx Similars C18 column configurations

Typical Applications

• USP L1 methods

• Reversed-phase HPLC

• Pharmaceutical analysis

• Impurity profiling

• Method development

• Long-chain fatty acid analysis

• Quality control testing

• Method transfer and validation

Specifications

• Product Type: HPLC Column

• Stationary Phase: Zx Similars C18

• USP Classification: L1

• Particle Size: 5 µm

• Particle Type: Type-B Spherical Silica

• Bonded Phase: C18 (Octadecyl)

• Endcapped: Yes

• Column Dimensions: 4.6 mm ID x 250 mm

• Length: 250 mm

• Recommended Flow Rate: 1.0–2.0 mL/min

• Brand: Cogent

Important Notes

• Designed for reversed-phase chromatography

• Longer column length provides increased resolving power

• Compatible with conventional HPLC systems

• Lower operating pressure than smaller particle columns

• Excellent alternative for many USP L1 methods

• Strong retention for hydrophobic compounds

• One of the most popular Zx Similars C18 column configurations

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