A General Screening Method for Acidic, Neutral, and Basic Drugs in Whole Blood using the Oasis MCX(R) Column

Abstract

Solid-phase extraction (SPE) is becoming a commonly used extraction technique. Most existing SPE methods extract a single drug from a relatively clean biological matrix (e.g., plasma, serum, or urine) using a silica-based column. These methods, however, are generally not satisfactory for forensic applications because the majority of biological samples are not as clean (e.g., whole blood, bile, tissues). Silica-based columns also may have reproducibility and stability problems. Polymer-based columns have been developed to overcome some of these limitations. In this study, sequential extraction of acidic, neutral, and basic drugs from whole blood using a polymer-based column, Oasis MCX, was undertaken. The extraction procedure developed involved a conditioning step using methanol followed by water; a three-step wash sequence using water, 0.1 M hydrochloric acid, then water/methanol (95:5); and two elution steps. One elution step was for acidic and neutral drugs utilizing acetone/chloroform (1:1), and a second used ethyl acetate/ammonium hydroxide (98:2) for basic drugs. Of the drugs tested, 75% were extractable from whole blood and detectable at therapeutic concentrations. Good recoveries and clean extracts were achieved for the basic drugs; however, the extracts were not as clean for acidic drugs. Unfortunately, the Oasis MCX procedure was not suitable for extracting all drugs (e.g., benzodiazepines).

Determination of several psychiatric drugs in whole blood using capillary gas–liquid chromatography with nitrogen phosphorus detection: comparison of two solid phase extraction procedures

“…Until now, only a few publications have described SPE methods for whole blood [13][14][15][16][17][18][19][20][21][22][23]. However, hemolyzed whole blood is in practice the matrix most frequently encountered in forensic toxicology.…”

Ionic liquid-molecularly imprinted polymers for pipette tip solid-phase extraction of (Z)-3-(chloromethylene)-6-flourothiochroman-4-one in urine

“…The condition of Al 2 O 3 , silica, HLB, MCX, C 18 , NH 2 , and IL-NIPs referred to previous reports [34][35][36][37][38][39]. The loading sample was 1 mL of spiked urine (5 g mL −1 ).…”

Rapid screening for 61 central nervous system drugs in plasma using weak cation exchange solid-phase extraction and high performance liquid chromatography with diode array detection

“…Emulsion formation and poor reproducibility are additional problems of LLE. Furthermore, LLE is labor intensive, time consuming, and difficult to automate (Yawney et al, 2002). Protein precipitation (PP), a conventional method of sample pretreatment, is a fast, easy-to-handle procedure.…”

“…The use of solid-phase extraction (SPE) in biological sample preparation has recently become more accepted in STA (Lai et al, 1997;Franke and de, 1998;Soriano et al, 2001;Yawney et al, 2002;Alabdalla, 2005). SPE has a number of advantages over LLE, such as cleaner extracts, no emulation formation, increased selectivity for the compounds of interest, and easy to be automated (Yawney et al, 2002).…”

“…SPE has a number of advantages over LLE, such as cleaner extracts, no emulation formation, increased selectivity for the compounds of interest, and easy to be automated (Yawney et al, 2002). Various SPE columns such as HLB (Hydrophilic-Lipophilic Balance) (Sturm, 2005), MCX (Mix Cation Exchange) (Yawney et al, 2002), and Bond Elut Certify column (Lai et al, 1997;Soriano et al, 2001) have been widely used in STA. A new SPE column, named Weak Cation Exchange (WCX) column, contains a mixed-mode cation-exchange sorbent.…”