| abstract |
A composition of a compound of formula I: ** Formula ** a) where the compound of formula I is in an amount of at least 97%, 97.5%, 98%, 98.5%, 99%, 99, 5% or 99.8% by weight of the composition; or b) where the composition does not contain more than 2% per HPLC area of total organic impurities, and preferably not more than 1.5% per HPLC area of total organic impurities in relation to the total area of the HPLC chromatogram; and where R1 and R2 are each independently aliphatic C1-6; and X- is a suitable anion. |