UHPLC users have access to a number of high performance choices, including a selection of Ultisil UHPLC (1.8 micron) phases with overlapping selectivity; Xtimate Hybrid UHPLC phases (C18 and C8); and Welch inline filters and guard columns designed for UHPLC applications.  All Welch UHPLC columns feature:


  • Column bed lengths: 30 mm to 150 mm
  • Column inner diameters: 2.1, 3.0, 4.6 mm
  • All phases available in all sizes
  • Optimized low dead volume
  • UHPLC frit design
  • Optimized packing technique to enable use up to 15,000 psi

Xtimate UHPLC

Xtimate UHPLC C18 (USP L1) is a 1.8 micron hybrid stationary phase synthesized with octadecyl silane. Xtimate UHPLC C18 is 14% carbon loaded, giving it selectivity distinct from Ultisil UHPLC C18. In addition, Xtimate UHPLC C18 provides the widest useful pH range of the UHPLC phases: 1.0 – 12.5 pH.

Ultisil UHPLC Phases

Seven Ultisil Phases for UHPLC include six reversed phase options plus HILIC. Ultisil UHPLC stationary phases are based on 1.8 micron, B ultrapure silica. Higher peak heights and narrower peak widths contribute to improved sensitivity of 70% and 40% compared to 5 micron and 3.5 micron particles.

C18 (USP L1) with standard carbon loading.

C18 (USP L1) with improved tolerance of aqueous mobile phases.

C18 (USP L1) with improved tolerance of low pH.

C8 (USP L7) is less retentive, as an option for C18.

Alternate selectivity (USP L11) for phenyl groups.

For very polar and strong basic analytes (USP L60, L1).

For hydrophilic interaction liquid chromatography.