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Experience with a modern microprocessor-controlled liquid scintillation counter
International Conferenceon Liquid Scintillation Counting standards was counted repeatedly in both machines to determine the accuracy of each technique. Both quench correction methods had a standard deviation in counting efficiency of less than 35 over the range of the quenched standards. The correlation between the variation in counting efficiency and the degree of sample quenching is also discussed.
E X P E R I E N C E WITH A M O D E R N M I C R O P R O C E S S O R CONTROLLED LIQUID SCINTILLATION COUNTER*
B. E. Gordon, Laboratory of Chemical Biodynamics o[ Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 This report describes two years of experience with the Beckman LS-9000 counter. Because this instrument is used by a large number of research workers involved in a wide variety of projects, sample type size, cocktail and vial size have all been variable. Our experience with this very useful instrument has revealed some interesting limitations of which the user should be aware. First, the random coincidence monitor to measure chemiluminescence overloads at high C. L. count rates ( ,~107 cpm) and prints out erroneously low RCM values. Second, the normal variation in the H # from several cycles of the same set of samples can produce significant errors. A graph of the error as a function of H # magnitude and variation is shown. Third, the use of the H# function from a set of sealed, quenched standards in a toluene scintillator is more prone to serious error when the samples are in other cocktails than is the external standard channels ratio method. A possible explanation for this effect will be given. "Work supported by the Biomedicaland EnvironmentalResearchDivisionof the U.S. Departmentof Energy under Contract W-7405-ENG-48.
SESSION E: SAMPLE P R E P A R A T I O N I N T R O D U C T O R Y REMARKS ON SAMPLE PREPARATION METHODS A. Kalbhen, Institute o[ Pharmacology and Toxicology, University o[ .Bonn, 5300 Bonn, West Germany D.
Besides reliable instrumentation for liquid scintillation counting, suitable and reproducible sample preparation techniques are essential for precise measurement of radioactivity. The large variety of specimens to be assayed, especially of biological origin, requires appropriate sample preparation methods for homogeneous or heterogeneous incorporation into the scintillation solution. Methodological progress within the past 15 years has led to the development and evaluation of a number of valuable procedures for manual or automatic preparation of samples for LSC.
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E X P E R I E N C E WITH A M O D E R N M I C R O P R O C E S S O R CONTROLLED LIQUID SCINTILLATION COUNTER*
B. E. Gordon, Laboratory of Chemical Biodynamics o[ Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 This report describes two years of experience with the Beckman LS-9000 counter. Because this instrument is used by a large number of research workers involved in a wide variety of projects, sample type size, cocktail and vial size have all been variable. Our experience with this very useful instrument has revealed some interesting limitations of which the user should be aware. First, the random coincidence monitor to measure chemiluminescence overloads at high C. L. count rates ( ,~107 cpm) and prints out erroneously low RCM values. Second, the normal variation in the H # from several cycles of the same set of samples can produce significant errors. A graph of the error as a function of H # magnitude and variation is shown. Third, the use of the H# function from a set of sealed, quenched standards in a toluene scintillator is more prone to serious error when the samples are in other cocktails than is the external standard channels ratio method. A possible explanation for this effect will be given. "Work supported by the Biomedicaland EnvironmentalResearchDivisionof the U.S. Departmentof Energy under Contract W-7405-ENG-48.
SESSION E: SAMPLE P R E P A R A T I O N I N T R O D U C T O R Y REMARKS ON SAMPLE PREPARATION METHODS A. Kalbhen, Institute o[ Pharmacology and Toxicology, University o[ .Bonn, 5300 Bonn, West Germany D.
Besides reliable instrumentation for liquid scintillation counting, suitable and reproducible sample preparation techniques are essential for precise measurement of radioactivity. The large variety of specimens to be assayed, especially of biological origin, requires appropriate sample preparation methods for homogeneous or heterogeneous incorporation into the scintillation solution. Methodological progress within the past 15 years has led to the development and evaluation of a number of valuable procedures for manual or automatic preparation of samples for LSC.
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