Why Mass-Check and when MALDI- or ESI-ToF?

metabion is dedicated to reliably deliver high quality products. While every production step is performed in light of achieving best quality, the product is released only if it passes our final inspection. Mass Spectrometry (MS) has become the state-of-the-art technology for verifying the integrity of oligonucleotides, and metabion has been the first custom oligo house who introduced routine mass checks into its operations. Each and every oligo is characterized by either MALDI- or ESI-ToF and stringent release criteria are applied.

Mass Spectrometry allows for the most sensitive detection of low-level by-products/impurities such as:

• n-1/n-x oligos;
• depurination;
• incomplete deprotection;
• acrylonitrile adducts;
• high salt content identification.

Moreover, it is the fastest and most efficient way to identify potential product mix-ups.

We run two different types of Mass Spectrometry instruments in order to cope best with quality and quantity/throughput issues determined by the specifications of the respective oligo/analyte. While each instrument type precisely characterizes oligonucleotides in terms of composition through direct molecular weight measurement, their field of application is diligently adjusted to suitability considerations.

MALDI-ToF instruments typically have a higher throughput, while the limits of using this technique become manifest, if it comes to analyzing long oligonucleotides, or oligos carrying certain photo-labile modifications (e.g.common quenchers like BHQ®s, Dabcyl used in DLPs).

ESI-ToF is less efficient in terms of throughput but perfectly compensates for resolution issues with long oligos as well as for a potential detrimental laser impact on labile/photosensitive modifications – thus being a "natural" complement to MALDI-ToF analysis.

Synthetic oligonucleotide purification is particularly challenging because of the small differences in size, charge and hydrophobicity between the full-length product and impurities, which often co-elute.

For improved analysis of complex samples like long and/or multiple labeled oligos, metabion offers liquid chromatography (LC) coupled with electrospray ionization mass spectrometry (ESI-MS). The mass spectrometer is connected to a high pressure liquid chromatography (HPLC) system, which allows premium analyte characterization via chromatographical separation, followed by respective molecular weight determination. With this system, the mass of oligonucleotides between 2 and 220 bases can be analysed with high accuracy, resolution and sensitivity. Our expert production team will take care of the method (MALDI- or ESI-ToF) that best applies to your sample.