title: Development and validation of a highly sensitive LC-MS/MS method for organic cation transporter (OCT) substrate tetraethylammonium (TEA) in rabbits.
abstract: Tetraethylammonium is widely used as a probe in organic cation transporters studies. A simple, highly sensitive, and specific method using direct protein precipitation was developed using Hydrophilic Interaction Liquid Chromatography coupled with positive electrospray ionization tandem mass spectrometry for the determination of tetraethylammonium (TEA) in rabbit plasma. Isocratic separation was achieved using a ZIC-HILIC column with acetonitrile and 5mM ammonium acetate in the ratio of 8:2 containing 0.1% formic acid. Acquisition was performed in multiple reaction monitoring mode with the transitions: m/z 130→100 and 130→86 for TEA and m/z 276.1→142.2 for internal standard (homatropine). This method was validated to determine selectivity, linearity, sensitivity, precision, accuracy, recovery and stability. A good linearity was found within a range of 1.53-784.6 ng/mL. The above method has been demonstrated for its capability to estimate the plasma levels of TEA after its topical instillation in rabbit eyes. This method provides an accurate, precise and sensitive tool for determining TEA levels for transporter studies.
authors.affiliation: High Precision Bio-analytical Facility, Department of Ocular Pharmacology and Pharmacy, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India.
authors.forename: Jayabalan
authors.initials: J
authors.lastname: Nirmal
authors.forename: Thirumurthy
authors.initials: T
authors.lastname: Velpandian
authors.forename: Sundararajan Baskar
authors.initials: SB
authors.lastname: Singh
authors.forename: Nihar Ranjan
authors.initials: NR
authors.lastname: Biswas
authors.forename: Vasantha
authors.initials: V
authors.lastname: Thavaraj
authors.forename: Rajvardhan
authors.initials: R
authors.lastname: Azad
authors.forename: Supriyo
authors.initials: S
authors.lastname: Ghose
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods*; D004355:Drug Stability; D016014:Linear Models; D008954:Models, Biological; D008956:Models, Chemical; D009883:Ophthalmic Solutions; D027701:Organic Cation Transport Proteins; D011817:Rabbits; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods*; D019789:Tetraethylammonium / Q000097:blood* / Q000378:metabolism / Q000493:pharmacokinetics
chemical_list: D009883:Ophthalmic Solutions; D027701:Organic Cation Transport Proteins; D019789:Tetraethylammonium