Liquid scintillation spectrometry

These two methods produce different release profiles in vitro. Figure 5 demonstrates the release kinetics of BCNU from wafers loaded with 2.5% BCNU pressed from materials produced using these two methods. The wafers containing tritiated BCNU were placed into beakers containing 200-ml aliquots of 0.1 M phosphate buffer, pH 7.4, which were placed in a shaking water bath maintained at 37 C. The shaking rate was 20 cycles/min to avoid mechanical disruption of the wafers. The supernatant fluid was sampled periodically, and the BCNU released was determined by liquid scintillation spectrometry. The BCNU was completely released from the wafers prepared by the trituration method within the first 72 hr, whereas it took just about twice as long for the BCNU to be released from wafers... 

Nozaki Y, Zhang J, Takeda A (1997) °Pb and °Po in the equatorial Pacific and Bering Sea the effects of biological productivity and boundary scavenging. Deep-Sea Res II 44 2203-2220 Nozaki Y, Dobashi F, Kato Y, Yamamoto Y (1998) Distribution of Ra isotopes and the °Pb and °Po balance in surface waters of the mid Northern Hemisphere. Deep-Sea Res. 145 1263-1284 Pates JM, Cook GT, MacKenzie AB, Anderson R, Bury SJ (1996) Determination of Th-234 in marine samples by liquid scintillation spectrometry. Anal Chem 68 3783-3788... 

DOE. 1995b. Separation and analysis of actinides by extraction chromatography coupled with alpha liquid scintillation spectrometry. Washington, DC U.S. Department of Energy. NTIS/DE96060013. 

Biggin et al. [115] have described a time efficient method for the determination of 210lead, 210bismuth, and 210polonium activities in seawater using liquid scintillation spectrometry. 

Pates et al. [41] have described a liquid scintillation spectrometry method for the determination of 234thorium in seawater with 230thorium as the yield... 

Groundwater age at each NGMP site has been assessed using multiple tracers. Tritium was analyzed in a 1 L unfiltered unpreserved sample using 70-fold electrolytic enrichment prior to ultra-low level liquid scintillation spectrometry (Morgenstern Taylor 2005). Samples for analysis of CFCs and SF6 (125 ml and 1 L, respectively) were collected in strict... 

The apparent retinal influx clearance,. Kin,retina expressed as mL/(min g retina), of the test substrate labeled with either [3 H] or [14C] from the circulating blood to the retina is determined by integration plot analysis. In brief, rats are anesthetized, followed by injection of the test substrate (e.g., an [3H]-labeled compound, about 10 /u.Ci/head) into the femoral vein. After collection of plasma samples, rats are decapitated and the retinas removed. The retinas are dissolved in 2 N NaOH and subsequently neutralized with 2 N HC1. The radioactivity of retinal cell lysates is measured by liquid scintillation spectrometry. As an index of the retinal distribution characteristics of the radiolabeled test substrate, the apparent retina-to-plasma concentration ratio (Vd) as a function of time is used. This ratio [Vd(Q] (mL/g retina) is defined as the amount of [3H] per gram retina divided by that per milliliter plasma, calculated over the time-period of the experiment. The Kjn,retina can be described by the following relationship ... 

In brief, the rats are anesthetized, followed by an injection of 0.2 mL of the test solution into the common carotid artery. The injection solution consists of a HEPES buffered Ringer s solution (containing 141 mM NaCl, 4 mM KC1, 2.8 mM CaCl2, and 10 mM HEPES, pH 7.4) which contains both the test substrate (e.g., a [3H]-labeled compound, about 10 /xCi) and a reference compound, which is highly extracted by the tissue (e.g., 0.1 /xCi [14C]n-butanol) in the presence or absence of transport inhibitors. If a [14C]-labeled compound is used as a test substrate, [3H]H20 can be selected as a reference compound. Rats are decapitated at 15 s after injection and the retina is removed. The retina is dissolved in 2 N NaOH and subsequently neutralized with 2 N HC1. The radioactivity is measured by liquid scintillation spectrometry. The RUI value, an index of the retinal distribution characteristics of the [3H] test substrate, is estimated using the following relationship ... 

Salonen, L. 1993. Measurement of low levels of 222Rn in water with different commercial liquid scintillation counters and pulse shape analysis. In J.E. Noakes, F. Schoenhofer, and H. A. Polach (eds), Advances in Liquid Scintillation Spectrometry 1992, pp. 361-371.Tucson Radiocarbon Publishers, University of Arizona. 

Sediment Slow microbial degradation due to tight bonding of adsorbed Diquat to the clay minerals on the sediment (shake flask-liquid scintillation spectrometry, Simsiman Chesters 1976) t,/2 > 158 d for 1.5 pg/mL of infested sediment-water microcosm to biodegrade (derived from results of Simsiman Chesters 1976 Muir 1991). 

Triton X-100 solution are added to culture dishes to lyse cells by shaking the dish on a shaker for 20 min at room temperature. An aliquot (1 ml) of lysate is analysed by liquid scintillation spectrometry. All values for taurocholate uptake into cell monolayers are corrected for non-specific binding to the collagen... 

The colour quenching effect of carotenoids in liquid scintillation spectrometry has been studied in detail. The most efficient quenchers were lycopene [i/>, -carotene (225)] and echinenone [j8,/3-caroten-4-one (226)]. Use of the external standards ratio method to correct for colour quenching in the radioassay of carotenoids is justified.84... 

Oikari, T., Kajola, H., Nurmi, I., Kaihola, L. Simultaneous counting of low alpha-and beta-particle activities with liquid scintillation spectrometry and pulse-shape analysis. Appl. Radial Isot 38A, 875-878 (1987)... 

Several methods that do not require chemical separation are available for measuring uranium in urine (in units of total mass or total activity). These methods include spectrophotometric (total mass), fluorometric (total mass), kinetic phosphorescence analysis (KPA) (total mass), and gross alpha (total activity) analyses (Wessman 1984). The most widely used methods for routine uranium analysis are a-spectrometry and liquid scintillation spectrometry. These methods utilize the natural radioactivity of uranium and are sensitive and require little sample preparation. Photometric techniques such as fluorometry and phosphorometry are less widely used, but kinetic phosphorescence analysis is becoming more widely used. Measurements of total uranium do not provide the relative isotopic abundance of the uranium isotopes, but this may only be important when converting between activity and mass when the isotopic ratios are uncertain. 

E. Rapkin and J. A. Gibbs, Int. J. Appl. Radiat. Isot., 14 71 (1963). Polyethylene Containers for Liquid Scintillation Spectrometry. 

McDowell, W.J. Case, G.N. A Procedure for the Determination of Uranium on Cellulose Air-Sampling Filters by Photon-Electron-Rejecting Alpha Liquid Scintillation Spectrometry ORNL/TM 10175 Aug 1986. 

Uptake of a-Aminoisobutyric Acid (AIB) and Sucrose. Leaves of Egeria or Vida were incubated with radioacti-vely labelled solutes as described (2). The uptake rate was calculated from the initial specific activity in the external medium. The radioactivity in the methanolic extracts was recorded by liquid scintillation spectrometry. 

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