Inert (U)HPLC columns for oligonucleotides

Several substances such as oligonucleotides or nucleotides are able to interact with the usual inert column hardware materials such as stainless steel or titanium. Even if the stationary phase used is not showing any coordinating abilities due to the absence of metal impurities, interaction with the metallic surfaces is possible. The absorption on metallic surfaces typically leads to peak tailing, loss of recovery and sample carry over. This behaviour can especially be seen when a new column is used without any conditioning before the actual analysis.

Dedicated bioinert and metal-free hardware

YMC offers a special hardware as an option for their YMC-Triart (U)HPLC column family for challenging compounds such as oligonucleotides. The so-called metal-free YMC-Triart columns are fully bioinert columns due to their PEEK lined stainless steel column bodies and the use of PEEK frits. The stationary phase and hence the samples are only in contact with PEEK once inside the column. Due to the use of stainless steel as outer body, the same pressure limits as for standard columns can be maintained, namely 100 MPa/1,000 bar for UHPLC purposes and 45 MPa/450 bar for HPLC use.

Ideal combination of stationary phase and hardware

Due to its organic/inorganic hybrid silica base material, YMC-Triart stationary phases contain virtually no metal impurities. In combination with the bioinert metal-free column hardware and metal-free chromatographic systems, YMC-Triart columns show excellent peak shapes for sensitive compounds, prevent carry over, secure recovery and are ideal for the use of highly sensitive LC/MS analyses. The LC-HRMS analysis of the antisense oligonucleotide Mipomersen (Kynamro®) fully demonstrates the advantages of metal-free YMC-Triart columns.

Phase options

All YMC-Triart phases with 1.9 µm for UHPLC or 3 or 5 µm for HPLC are available in this metal-free hardware. The preferred choices for oligonucleotide separations are YMC-Triart C18 or YMC-Triart C8 with a pore size of 120 Å. YMC-Triart Bio C18 with a larger pore of 300 Å is particularly suitable for more hydrophobic oligonucleotides. Other column options are the polar YMC-Triart Diol-HILIC, YMC-Triart Bio C4 with 300 Å as well, the aromatic YMC-Triart Phenyl and PFP and the extremely hydrophobic YMC-Triart C18 ExRS:

How to get optimum results

Even though most interactions with metal can take place in the column itself, YMC-Triart metal-free columns are best combined with bioinert or optimised “non-metal” UHPLC/HPLC chromatographic systems to obtain optimum results. Furthermore, due to the column design the columns have to be attached using either connectors without a ferrule or with a flexible ferrule, such as MarvelXACT™ UHPLC/HPLC connectors. They are available either as PEEK-lined stainless steel or as PEEKsil fittings.