Liquid scintillation cocktail

To illustrate the composition of liquid scintillation cocktails (LSC), some formulations follow. 

Pseudocumene is used as a component in liquid scintillation cocktails for clinical analyses. Pseudocumene and durene are oxidized to trimel-litic anhydride and pyromellitic dianhydride, respectively. Mesitylene is a key building block for important antioxidants and agricultural chemicals. Prehnitene, isodurene, pentamethylbenzene, and hexamethylbenzene... 

Stop-Flow Mode The LC-ARC StopFlow controller performs two major functions. First, the controller maintains the back pressure during stop-flow data acquisition. This function is crucial for maintaining the shape and resolution of a peak. The second function is to deliver a liquid scintillation cocktail necessary for peak detection by the radiochemical detector. 

On-line detection can be classified as either homogeneous or heterogeneous. In the homogeneous system, the effluent is mixed with a liquid scintillation cocktail before passing through a flow cell that is positioned in a scintillation counter. In the heterogeneous system, the effluent passes through a flow cell packed with a solid scintillator. 

To measure the transport of drugs across the BBB in vitro 2.5 iCi of 3H-labelled drug and 14C-sucrose are applied to each Transwell (in case of 14C-labeled substances, permeability studies are performed with 3H-sucrose). This concentration is high enough to ensure sufficient excess to neglect the decrease of tracer in the donor (apical) compartment during the experiments. Volumes of 1.5 ml in the donor (apical) and 2.5 ml in the acceptor (basolateral) compartment avoid hydrostatic pressure. After addition of the radiolabeled compound, samples of 50 til are taken in duplicate from the basolateral acceptor compartment every 20 min and replaced by 100 xl of fresh assay medium. Cells are kept under culture conditions during the whole transport experiment. Radioactivity is measured after addition of liquid scintillation cocktail in a counter. 

Ultima gold liquid scintillation cocktail (Perkin Elmer BioScience B.V., The Netherlands). 

Soils were extracted on the same day as application and after 28 days of incubation at 25°C. Every 2-3 days during the interim, flasks were opened and the center wells were removed and placed directly in liquid scintillation cocktail (Biosafe II) for determination of radioactivity. Soils were extracted twice by stirring with ethyl acetate followed by a third extraction with a 1 1 1 mixture of hexane/acetone/methanol. After the last extraction, the soil was filtered through glass microfiber filter paper. The solvents were combined and evaporated to dryness under vacuum at 35°C. 

Transfer to a scintillation counter vial and add 4.5 mL of liquid scintillation cocktail. 

The HPLC equipment is a Perkin-Elmer Nelson Model 1022 Plus Chromatograph, connected to a Perkin-Ehner series 200 LC Pump, a LC295 UV/VIS detector, a 7125 BIO injector with a 20-pL loop, and a Canberra Packard Elow Scintillation Analyzer 500 TR Series, with a 0.5-mL flow cell. The system is interfaced with a Compaq Prolinea 5100 computer, using a Canberra Packard ELO-ONE software for system control and data processing. The RP-HPLC columns are Pecosphere Ci8, 5 jam, 30 X 3 mm i.d. (SGE Inc.), with a 5- im C18 guard column (SGE Inc.). Mobile phase is a mixture of methanol water acetic acid (85 15 0.1), and the elution of metabolites is done at a constant flow rate of 0.8 mL/min. Absorbance values are measured at 204 nm. Liquid scintillation cocktail (Ultima Ho M, Canberra Packard) is mixed with the eluent at a 1 2 (eluent(LSC) ratio. Retention times of AEA and arachodonic acid (AA) are 3.2 and 4.5 min, respectively. The concentration of AA is calculated from radioactivity of peak area, and FAAH specific activity is expressed as pmol AA released/min/mg protein. 

Used flammable (e.g., toluene) liquid scintillation cocktails. 

Filter paper assays. Phosphorylated membranes were pelleted by centrifugation at 12000 g for 3 min and aliquots of the peptide containing supernatant spotted onto 2 cm x 1 cm Whatman P81 paper strips. After drying at room temperature the strips were washed for 4x5 min in IM phosphoric acid/10% (w/v) trichloroacetic acid and 1x5 min in absolute ethanol. The strips were dried again at room temperature and counted for radioactivity in 2 ml Optiphase Safe (LKB) liquid scintillation cocktail. 

The system presented here, allows continuous measurement of the radioactivity of C02 the gas is bubbled through a liquid scintillation cocktail enclosed in a special vial, which is placed directly in the detection chamber of a liquid scintillation counter. 

Finally, 002 exhaled by the animal has been measured both directly, by bubbling through the liquid scintillation cocktail and after transformation of C02 into Ba C03 in which case the activity is measured with Geiger-Muller and liquid scintillation counters. Results of these measurements expressed as counts/0.2 min or specific activity versus time (Fig. 3) show that the slope of the curves is the same with the three techniques. 

Benzene associated with the adsorbent pellet was determined by oxidizing the organic materials at 900 C in a stream of oxygen. For this work a Harvey Biological Oxidizer, model OX-100, was used. Gasses from the oxidizer were bubbled into a CO2 -gathering liquid scintillation cocktail. The efficiency of C02-trapping was determined before each day s samples were oxidized. The amount of hen determined by liquid... 

Efforts have been made to develop liquid scintillation cocktails that can be utilized to count low energy gamma emitters in a liquid scintillation counter, but these require careful preparation, have been generally inefficient with volumes greater than 3 cc, require quench correction, and are expensive (3) (4) (5) (6)(7). Since both beta and gamma emitters are commonly employed to label antigens in radioimmunoassay procedures, the ability to utilize both isotopes has obvious economic advantages. 

On a specimen support that is compatible with the chemical nature of the species analyzed, with the specific radiation to be measured, and with the detector system, e.g., liquid scintillation cocktails for weak S-emitters. 

---