By pillin on Monday, February 17, 2003 - 11:33 pm:
Hello friends!
1,1-cyclobutanedicarboxylic acid (CBDCA) is a product of decomposition of carboplatin in aqueous solutions. Its retention time is about two time the retention time of carboplatin. LC analysis shows a second peak with about the half retention time of carboplatin, showing exactly the same MS spectra like CBDCA. A few milligrams of this unknown substance were isolated and some experiments were made (esterification with benzyl alcohol). Surprisingly the CBDCA ester with benzyl alcohol can be detected!
So far as i know, there is no stable optical isomer of CBDCA. Can this second substance be a stable complex of CBDCA with a cation? Is there anyone out there with the right answer or experience with the LC analysis of carboplatin?
By Einar Pontén - SeQuant AB on Tuesday, February 18, 2003 - 02:48 pm:
It seems that you already have a plausible explanation. Numerous of metal complexing agents are dicarboxylic acids. The co-ordination number is likely dependant on pH.
Why don't you collect a sample peak and check for metals by ICP (at a nearby lab?) against a blank.