Microplate scintillation counting

Kiffe, M., Jehle, A., and Ruembeli, R. (2003). Combination of high-performance liquid chromatography and microplate scintillation counting for crop and animal metabolism studies A comparison with classical on-line and thin-layer chromatography radioactivity detection. Anal. Chem. 75 723-730. 

Zhu, M., Zhang, D., and Skiles, G. L. (2005). Quantification and structural elucidation of low quantities of radiolabeled metabolites using microplate scintillation counting techniques in conjunction with LC-MS. In Identification and Quantification of Drugs, Metabolites and Metabolizing Enzymes by LC-MS (Chowdhury, S. K., Ed.). Elsevier, Amsterdam, pp. 195-223. 

Zhu M, Zhao W, Vazquez N, Mitroka JG. Analysis of low level radioactive metabolites in biological fluids using high-performance liquid chromatography with microplate scintillation counting method validation and application. J Pharm Biomed Anal 2005 39 233-245. 

Liquid chromatography is routinely used for the quantitative analysis of a drug and its metabolites in radiolabeled in vitro metabolism experiments and in humans and animal ADME studies. Online radio-flow detection (RFD) and offline microplate scintillation counting (MSC) are the most commonly used radiochromatographic techniques in radiolabeled metabolite profiling and quantification (Boernsen et al., 2000 Nassar et ah, 2003 Bruin et al., 2006). LC/RFD is compatible with ESI mass spectrometry and provides high analytical speed and excellent separation resolution (Athersuch et al., 2008). 

Nassar, A. E., Martine, M., Parmentier, Y., and Lee, D. Y. (2003). Comparison between liquid chromatography-accurate radioisotope counting and microplate scintillation counter technologies in drug metabolism studies. Drug Metab. Rev. 35(Suppl. 2) 79. 

To quantify luciferase reporter gene expression in cell lysates, transfer 50 pi cell lysate from each well into a 96-well black flat-bottom microplate. Add 100 pi luciferase buffer per well, and optionally mix with a pipette. Measure the chemiluminescence intensity (count time 0.20 min with background correction) using a luminometer, e.g., a Microplate Scintillation Luminescence Counter (Canberra Packard) or a Wallac Victor 2 Multi-label Counter (PerkinElmer). 

Scintillation analyzer (Top count NXT microplate scintillation and luminescence counter Perkin Elmer). 

Count radioactivity bound to SPA beads in a Topcount microplate scintillation and luminescence counter (Packard). 

Conventional scintillation counters such as the Microbeta (Wallac/Perkin Elmer, Turku, Finland) or the TopCount (Packard, Meriden, USA) use photomultiplier detection systems that count 8 or 12 wells at a time, resulting in a readout time of 40 minutes per 384-well microplate. Bialkali photocathodes (Sb-Rb-Cs or Sb-K-Cs) used in standard photomultipliers have a maximum spectral response at about 420 nm, with a quantum efficiency for detection of up to 30%. Thus, the aforementioned instruments are ideally suited for filtration assays and SPA assays with the blue-emitting YSi and PVT beads. 

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