# Quality > Every oligonucleotide we supply undergoes UPLC-MS analysis and must meet defined quality requirements prior to dispatch. Canonical URL: Published: 2026-09-25 Last updated: 2026-09-25 ## Our quality standards Every Assemblon oligonucleotide undergoes UPLC-MS analysis and must meet defined quality requirements prior to dispatch. ISO 9001 Quality Management certified by BSI under certificate number FS 843542. [Verify on the BSI directory of certified clients](https://www.bsigroup.com/en-GB/products-and-services/assessment-and-certification/validation-and-verification/client-directory-results/?q=FS%20843542) UPLC-MS (electrospray ionisation) is used to confirm that the observed mass matches the mass calculated from the sequence. Mass confirmation is performed on every order before release UltraPerformance Liquid Chromatography (UPLC) analysis is performed on all oligonucleotides, with methods chosen for the sequence and its modifications. Products are assessed against defined purity specifications, and only material meeting these criteria is approved for dispatch to customers. We also offer [bespoke analytical and characterisation services](/analysis) for customer-supplied oligonucleotides. HPLC-purified oligonucleotides are released at ≥90% full-length product by UV peak area, with a deconvoluted mass within 0.02% of the calculated mass. Desalted oligonucleotides are not held to a purity specification; the datasheet reports what was measured. Heavily modified or unusual sequences may occasionally be released against criteria agreed at quotation, and the datasheet records the criteria each order was held to. Cross-contamination control and full batch traceability on every order. Every Assemblon order is dispatched with a datasheet including: - Nucleotide sequence and modifications - Synthesis scale, purification method, and physical form - Observed and expected molecular mass (UPLC-MS) - Confirmation that each oligonucleotide meets defined UPLC purity requirements - Concentration and volume of sample where applicable - [Tell us your requirements](#contact-form) --- Website and LIMS by Alex Soldatkin alex.soldatkin@gmail.com