Rtx-35

Rtx-35 column

Restek Rtx-35 GC Columns

Restek Rtx-35 GC columns are medium-polarity columns designed for analysts who require increased selectivity over standard 5% phenyl phases, while maintaining excellent thermal stability and broad applicability for volatile and semi-volatile organic compounds. Featuring a 35% phenyl, 65% dimethylpolysiloxane stationary phase, Rtx-35 offers stronger aromatic, dipole, and polar interactions than Rtx-5 or Rtx-5MS—allowing for improved resolution of compounds with similar boiling points, including aromatic hydrocarbons, esters, amines, and structurally complex semi-volatiles.

The higher phenyl substitution provides enhanced retention and separation of analytes that exhibit π-π, dipole, or polarizable interactions, making Rtx-35 an excellent choice for environmental, forensic, petrochemical, industrial, and flavor/fragrance workflows. These columns are frequently used for EPA 604, 625, and 8270-type applications, as well as general-purpose separations where additional polarity is required without moving to fully cyano- or fluorinated phases.

With robust deactivation chemistry, low bleed at high temperatures, and consistent column-to-column reproducibility, Rtx-35 supports both GC and GC-MS, delivering sharp peaks for active, aromatic, and semi-volatile analytes. Its balanced selectivity makes it a dependable workhorse column for analysts who need more separation power than a 5% phenyl column can deliver, but do not require the extreme polarity of phases such as 1701, 225, or 2330.

As an authorized Restek distributor, Chrom Tech offers a full range of Rtx-35 column dimensions suitable for complex mixture analysis, regulatory testing, impurity profiling, and routine high-performance GC work.
Key Definitions ▸
35% Phenyl Polysiloxane Phase
A medium-polarity GC stationary phase with enhanced aromatic and dipole interactions, offering greater selectivity than standard 5% phenyl columns.
Aromatic (π–π) Selectivity
The enhanced retention and separation of aromatic compounds due to phenyl ring interactions, allowing better resolution of polyaromatic and substituted aromatic analytes.
SVOC Retention
The increased polarity of Rtx-35 improves retention and peak shape for semi-volatiles commonly analyzed in environmental and forensic workflows.
Dipole Interaction Selectivity
Enhanced dipolar interactions improve separation of esters, amines, alcohols, and polarizable semi-volatile compounds that may coelute on lower-polarity phases.
Rtx® Deactivation
Restek’s specialized deactivation minimizes active sites, ensuring sharp peaks and accurate quantitation for aromatic, polar, and semi-volatile compounds.
Frequently Asked Questions ▸
When should I choose Rtx-35 instead of Rtx-5 or Rtx-5MS?
Choose Rtx-35 when you need more polarity and aromatic selectivity than a 5% phenyl column can provide—especially for aromatic hydrocarbons, esters, amines, and semi-volatiles requiring additional separation power.
Is Rtx-35 compatible with GC-MS analysis?
Yes. Rtx-35 columns exhibit low bleed at elevated temperatures, making them suitable for GC-MS workflows involving aromatic, polar, and semi-volatile analytes.
What methods commonly specify Rtx-35 columns?
Rtx-35 is widely used for environmental methods such as EPA 604, 625, and 8270-type applications, as well as general-purpose separations needing stronger polarity than standard phenyl phases provide.
What types of compounds benefit most from Rtx-35 selectivity?
Aromatics, substituted benzenes, esters, alcohols, amines, and semi-volatiles with dipole or π–π interaction characteristics exhibit improved resolution on Rtx-35 compared to lower-polarity phases.