Since every synthesis is unique and quality is our highest priority, ALL our oligos are quality control (QC) checked by mass spectrometry. Enormous investments lead to the development of two innovative MS platforms to allow the most accurate measurements for oligonucleotides. Mass spectrometry is the only cost-effective method to QC for correct length of a sequence and although MALDI-TOF only is considered as ‘the standard’, it is only useful for compounds up to ~15 kDa, or about a 40-mer oligonucleotide. Samples >15 kDa do not ionize/fly effectively and, additionally, are outside the optimal resolution range of these instruments making the data less accurate. Electrospray Ionization (ESI-) MS is 12 to 15 times more sensitive than Maldi-TOF and can therefore resolve longer oligos. However this technique required a high-throughput setting which we obtained in collaboration with MS device developer Novatia.