High Throughput Extraction of Basic and Polar Drug Compounds from Biological Matrices with a Novel Polymeric Solic-Phase Sorbent in a 96-Well Format

Library Number:
Judy L Carmody;Yung-Fong Cheng;Pamela Iraneta;Mark Capparella;Dorothy Phillips;Edouard Bouvier;Uwe Neue
Drug Analysis ''98, Brussels, Belgium, May 11-15th, 1998
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Other Symposium
Procainamide; Acetaminophen; Ranitidine; Propranolol; Doxepin; Betamethasone; Dipropyl Phthalate; Betamethasone Valerate; Theophylline; Nordoxepin; Imipramine; Trimipramine; Nortriptyline; Amitriptyline
Porcine plasma; serum
SymmetryShield RP8 3.5 µm Steel 4.6 mm 75 mm SymmetryShield RP8 5 µm Sentry Guard Column N/A N/A SymmetryShield RP8 3.5 µm Steel 4.6 mm 100 mm Oasis HLB Extraction N/A 96-well plate (30 mg; 10 mg) N/A N/A
Historically, sample preparation has been the bottleneck in laboratory productivity, especially with the onslaught of LC/MS/MS. Rapid and reproducible quantation of classically difficult, basic and polar drug comopounds from biological matrices has, in the past, been a challenging, time-consuming endeavor. Necessary sample preparation techniques used to concentrate or clean up were irreproducible. Presently, the most commonly used technique for high-throughput sample preparation is reversed-phase solid phase extraction in a 96-well plate format. The sorbent generally utilized is porous silica surface-bonded with C18. The major disadvantage of employing this type of system with basic compounds is that the silanols on the silica surface can deleteriously affect the recovery of basic compounds. The surface silanols interact through ion exchange with basic compounds, such as doxepin. This interaction prevents complete elution of basic compounds and results in low, variable recovery. With polar compounds, such as procainamide and ranitidine, the analyte/sorbent interaction is weak, resulting in breakthrough of the polar analyte. This, subsequently, yields poor, irreproducible recoveries. Another notable disadvantage to using traditional silica-based reversed-phase sorbents is that the wetted condition must be maintained by the tedious manipulation of stopcocks. The capacity of C18 is severely compromised if the sorbent runs dry. In this paper we show that the sample preparation bottleneck has been eliminated. Highly reproducible and uncomplicated SPE methods were developed for these types of basic and polar drug compounds using a novel polymeric solid-phase sorbent, Oasis® HLB, in a 96-well format. Recoveries greater than 90% and reproducibilities less than 5% RSD (n=96) for basic antidepressant and polar drugs were realized. Most importantly, because Oasis® HLB is a water-wettable polymer, these results were achieved without concern as to whether or not the sorbent ran dry.

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