AN INNOVATIVE DERIVATIZATION-FREE IC-MS/MS METHOD FOR THE DETECTION OF BISPHOSPHONATES IN HORSE PLASMA.

Bisphosphonates are prohibited drugs according to Article 6 of the International Agreement on Breeding, Racing and Wagering of the International Federation of Horseracing Authorities (IFHA) and the International Equestrian Federation (FEI). These compounds are used for the treatment of lameness, navicular and bone diseases in horses and are divided into two groups: non-nitrogen-containing bisphosphonate drug (e.g. clodronic acid) and nitrogen-containing bisphosphonate drug (e.g. zoledronic acid). Their hydrophilic properties and high affinity for the bone matrix make the control of their use quite difficult. Current analytical strategies to detect such compounds often rely on a solid phase extraction (SPE) followed by detection by means of UHPLC-MS/MS after methylation with chemical reagents. To improve the analysis throughput and eliminate the need of chemical derivatization, an innovative 96-well SPE followed by ion-chromatography hyphenated to mass spectrometry was developed. Analyses are conducted on an ICS-6000 HPIC system coupled to a TSQ Altis™ (Thermo Scientific™). The use of 96-well SPE allowed 5-fold sample amount and 6-fold throughput improvements. While preliminary results conducted on horse plasma exhibited similar performances of the method for the detection of non-nitrogen-containing bisphosphonates, analytical performances of nitrogen-containing bisphosphonates were greatly improved.