RP-cartridge-Gold™ was launched in 1987 at Eurogentec. It is a “reverse-phase” (RP) -chromatography based on the difference in hydrophobicity between the full-length product (which still contains 4, 4’-dimethyltrityl (DMT) group at the 5’ OH of the synthetic oligonucleotide last base) and truncated sequences (without DMT group).
During elution, mobile phase polarity is progressively decreased to ensure that all the non-DMT truncated sequences are first eluted. The pressure and the porosity of the matrix are adapted to get the optimum separation. After failure sequences elimination, the DMT group is removed from the support-bound oligonucleotide. The fully deprotected product can then be eluted and isolated by lyophilisation. The RP-cartridge system is stable over a wide pH range 1-13, thus the ammonium hydroxide solution, diluted with water, is loaded directly onto the packing.
The RP-cartridge method typically yield a product up to 80 % purity. This is a fast and efficient purification method which represents the best compromise for most applications where full-length or high reproducibility is essential, including: cloning, PCR, mutagenesis, probes. The absence of salts, ammonium contamination and acid residues - which may occur after HPLC purification – allows to obtain of oligonucleotides particularly suitable for use in cell culture.