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Ionizing Radiation
Published in Martin B., S.Z., of Industrial Hygiene, 2018
Liquid scintillation counters assay radioactivity in a sample vial where the sample and liquid scintillator are intimately mixed. The liquid scintillation solution consists of an organic scintillant dissolved in an organic solvent along with emulsiflers and other additives. The sample is added to the scintillation solution and mixed until it is dissolved or suspended. Liquid scintillation analysis is typically used for beta radiation but can also detect alpha particles. It is especially good for low-energy beta emitters such as H-3 and C-14, which cannot be easily assayed any other way. The vial containing the liquid is lowered into a dark shielded chamber. Radiation absorbed in the liquid produces a light flash which is detected by opposing photomultiplier tubes. The voltage pulse from the photomultipliers is amplified and sorted into three channels. Beta emitters are not monoenergetic but produce a broad range of beta energies with a maximum energy which is characteristic of the emitter. Therefore, beta spectra from different emitters overlap and cannot easily be resolved. However, computer-based analysis of liquid scintillation beta spectra can usually give quantitative results for several beta emitters whose maximum beta energies differ from each other sufficiently. For example, analysis of a single sample containing H-3, C-14, and P-32 will produce the activities of each radionuclide even though their spectra partially overlap. A practical disadvantage of liquid scintillation counting is the disposal of the spent vials containing waste organic chemicals mixed with radioactivity.
Sampling and Analysis of Dissolved Radon-222 in Surface and Ground Water
Published in Barbara Graves, Radon, Radium, and Other Radioactivity in Ground Water, 2020
In the direct liquid-scintillation counting method, a 10-mL water sample is mixed with 5 mL of toluene-based liquid-scintillation fluid, followed by measurement of radioactivity in a liquid-scintillation counter. The method lacks specificity. Any alpha or hard-beta emitters, other than 222Rn and its daughters, in a form soluble in toluene, also will contribute to the count rate. The detection limit, if no other alpha or beta contaminants are present, is about 10 pCi/L for a 10-mL water sample [4].
Microbial Bioavailability of Residual Organic Contaminants in Soils
Published in Donald L. Wise, Debra J. Trantolo, Remediation of Hazardous Waste Contaminated Soils, 2018
Concentrations of substrate used in this research were selected to represent environmental conditions. Radiolabeled methods were employed because of the high sensitivity and accuracy of the detection method, liquid scintillation counting. In addition, radioisotopes provide clear evidence of metabolism in the form of radiolabeled CO2.
Efficacy of water-based skin decontamination of occupational chemicals using in vitro human skin models: a systematic review
Published in Journal of Toxicology and Environmental Health, Part B, 2021
Chavy Chiang, Nadia Kashetsky, Aileen Feschuk, Anuk Burli, Rebecca Law, Howard Maibach
Nielsen (2010) examined the effect of skin washing with soap following 6 h exposure to 14C-radiolabeled benzoic acid (industrial chemical; decontaminated sample size: n = 12, control sample size: n = 14), glyphosate (pesticide; decontaminated sample size: n = 13, control sample size: n = 14), and caffeine (drug; decontaminated sample size: n = 12, control sample size: n = 14). Human breast and abdominal skin samples from plastic surgery patients were mounted onto in vitro static diffusion cells. The model compounds in aqueous solutions, containing 0.9% NaCl and 2% ethanol, were applied to the donor chamber in concentrations of 4 mg/ml for a total volume of . Decontamination was conducted 6 h post-exposure by washing skin surfaces with soap and a cotton swab, followed by two washing steps in isotonic water without swabs. After 48 h, the epidermis of both groups was wiped four times with swabs wetted with 50% acetonitrile in water and two times with dry swabs to remove remaining contaminant. Radioactivity in samples was quantified with liquid scintillation counting.
Applicability of a 100-mL Polyethylene Vial for Low-Level Tritium Measurement Using a Low-Background Liquid Scintillation Counter
Published in Fusion Science and Technology, 2020
Yoshinari Oshimi, Mayu Ohki, Misato Nagano, Takuyo Yasumatsu, Masanori Hara, Satoshi Akamaru, Masato Nakayama, Miki Shoji
Liquid scintillation counting has been widely used for measuring tritium in liquid samples.1 It has a high counting efficiency and high sensitivity for tritium measurements. Tritium concentrations surrounding a nuclear power plant are routinely measured using a liquid scintillation counter (LSC). On March 11, 2011, the Fukushima Daiichi nuclear power plant was damaged by a tsunami caused by a large earthquake. Various radionuclides containing tritium were released from the reactors to the environment,2 and released tritium spread into the water.3,4 After the incident at the Fukushima Daiichi nuclear power plant, tritium was distributed, and elevated concentrations were observed in Japan. Nuclear fusion reactors, which burn a mixture of tritium and deuterium gases for fuel, are attractive as a new energy resource. In the future, a nuclear fusion reactor will be used as an energy source, and huge amounts of tritium will be handled. Effective tritium measurements in environmental samples will be indispensable for ensuring social acceptance of this nuclear technology.
Quenching Correction with Two-Dimensional Scintillation Spectrum in Tritium Measurement
Published in Fusion Science and Technology, 2020
Masanori Hara, Miki Shoji, Tsukasa Aso
Liquid scintillation counting has been widely used for tritium measurements in liquids.1 In this method, the sample containing tritium is mixed with a liquid scintillator to prepare a scintillation cocktail. The cocktail flashes when a beta decay of tritium has occurred. To determine a counting rate, the number of flashes is counted by a liquid scintillation counter (LSC). A conventional LSC is usually equipped with two photomultiplier tubes (PMTs) and a coincidence circuit to reduce background counts. Output pulses from the PMTs for a decay event are summed, and the summed pulse heights are sent to a multichannel analyzer (MCA) to construct a one-parameter, one-dimensional pulse-height scintillation spectrum.