Counts per minute

Tajima and co-workers [108] determined the surface excess of sodium dode-cyl sulfate by means of the radioactivity method, using tritiated surfactant of specific activity 9.16 Ci/mol. The area of solution exposed to the detector was 37.50 cm. In a particular experiment, it was found that with 1.0 x 10" Af surfactant the surface count rate was 17.0 x 10 counts per minute. Separate calibration showed that of this count was 14.5 X 10 came from underlying solution, the rest being surface excess. It was also determined that the counting efficiency for surface material was 1.1%. Calculate F for this solution. 

The concentration of Mn in steel can be determined by a neutron activation analysis using the method of external standards. A 1.000-g sample of an unknown steel sample and a 0.950-g sample of a standard steel known to contain 0.463% w/w Mn, are irradiated with neutrons in a nuclear reactor for 10 h. After a 40-min cooling period, the activities for gamma-ray emission were found to be 2542 cpm (counts per minute) for the unknown and 1984 cpm for the standard. What is the %w/w Mn in the unknown steel sample ... 

After reaction, the activity of a 25.0-mL water sample is 745 counts per minute (cpm), caused by the presence of Tl+-204 ions. The activity of Tl-204 is 5.53 X 105 cpm per gram of thallium metal. Assuming that 02 is the limiting reactant in the above equation, calculate its concentration in moles per liter. 

The filtrate is found to have an activity of2.50 X 103 counts per minute per milliliter. The 0.050 M Nal solution had an activity of 1.25 X 1010 counts per minute per milliliter. Calculate fCsp for Agl. 

To measure the volume of the blood in an animal s circulatory system, the following experiment was performed. A 5.0-mL sample of an aqueous solution containing 1.7 X 105 counts per minute (cpm) of tritium was injected into the bloodstream. After an adequate period of time to allow for the complete circulation of the tritium, a 5.0-mL sample of blood was withdrawn and found to have 1.3 X 103 cpm on the scintillation counter. Assuming that only a negligible amount of tritium has decayed during the experiment, what is the volume of the animals circulatory system ... 

To determine the ftq, value of Hg a solid sample is used, in which some of the iodine is present as radioactive 1-131. The count rate of the sample is 5.0 X 1011 counts per minute per mole of L An excess amount of Hg2I2(s) is placed in some water, and the solid is allowed to come to equilibrium with its respective ions. A 150.0-mL sample of the saturated solution is withdrawn and the radioactivity measured at 33 counts per minute. From this information, calculate the ft, value for Hg2l2. 

C22-0051. A radioactive nuclide of mass number 94 has been prepared by neutron bombardment. If 4.7 pg of this nuclide registers 20 counts per minute on a radioactivity counter, what is the half-life of this nuclide ... 

The background for each particular system should be determined periodically. This can be accomplished by counting an empty tube overnight in the counter and then by determining the counts per minute. This background is then substracted from all tubes before any calculations are performed. 

Con A Concanavalin A COPD Chronic obstructive pulmonary disease COS Fibroblast-like kidney cell line established from simian cells CoVF Cobra venom CP Creatine phosphate Cp Caeruloplasmin c.p.m. Counts per minute CPJ Cartilage/pannus junction Cr The chemical symbol fir chromium CR Complement receptor CRl, CR2 CR4 Complement receptor types 1, 2 and 4 CR3-a Complement receptor type 3-[Pg.281]

Fig. 6. Conversion of an inhibitory Zn2+ switch to a stimulatory Zn2+ switch by mutation of Ty3356 68. (A) The effect of Zn2+ on [3H]dopamine uptake in COS-7 cells transiently expressing hDAT-Y335A (hlled circles) or WT hDAT (open circles). Each data point is expressed as mean S.E. in count per minutes (CPM) of triplicate determinations from a representative experiment. (B) Zn2+ effect on [3H]dopamine uptake in COS-7 cells transiently expressing hDAT-Y335A (hlled circles) or WT hDAT (open circles). Values are percent of control ([3H]dopamine uptake in the absence of Zn2+) expressed as means + S.E. of 5 (hDAT-Y335A) and 3 (hDAT) experiments performed in triplicate. Reproduced with permission from ref. (66).

Results Average the counts per minute in vials 3 and 4. This is the blank value. Now, subtract the blank from all other counts per minute to obtain the actual counts per minute and average the counts per minute for vials 1 to 2 to find the total count per minute. The percent bound may be calculated using the following expression ... 

When you are finished collecting data, choose 2 STOP AND GRAPH under TRIGGER/PROMPT. The data points (PROMPTED) are stored in LI, the counts per minute (CTS/MIN) are stored in L2. Press ENTER... 

IL). Initial experiments showed that uptake was complete within 2 hours. At the end of 2 hours (uptake) the mussels were rinsed, antipyrine solution was replaced with fresh Instant 0ceanR, and sampling at intervals continued. Portions of the water were also analyzed for antipyrine and metabolites. Data expressed in counts per minute per 1.0 ml were used to represent uptake and elimination of antipyrine. Experiments were routinely done in triplicate. 

Thus the counting rate should be sufficiently high to ensure a precision sufficient for isotope effect measurements a target precision of 0.1% is obtained for total counts of 106. Radiolabeled material used for isotope effect measurements usually has counting rates of 15,000 counts per minute (cpm). To achieve 0.1% precision such samples must be counted for 8 h or more. More often counting time is limited to several cycles of about 10 min each with a commensurate increase in the statistical error. 

Figure 1. Elution pattern of toxins from Bio-Rex 70 column in C-labeled arginine feeding. (Fr. fraction number cpm counts per minute and MU mouse units)...

Figure 1-4 (a) Logarithm of the activity of Be (counts per minute) in Be(OH)2 versus time to demonstrate that the decay is a first-order reaction and that the decay constant is 0.012977 day (or half-life is 53.41 days). Error is about the size of the points, (b) ln(j4Mo)- -0.012977t versus t to compare the decay constant of Be in different compounds. The error bars are at the 2a level. The data indicate that the decay constant of Be depends on the chemical environment. Data from Huh (1999). 

Counts per minute (CPM)totli = CPM in blank sample (or CPhdtotal x 10 in ml proteoliposomes)... 

A scintillation counter is used to measure tritium /3 particles adjacent to the surfaces of tritiated sodium dodecyl sulfate in 0.115 M aqueous NaCl solution and tritiated dodeca-nol in dodecanol. The former system is surface active and the latter is not, so the difference between the measured radioactivity above the two indicates the surface excess of sodium dodecyl sulfate. The number of counts per minute arising from the surface excess As is related to the surface excess in moles per square centimeter r by the relationship As = 4.7 x 1012 T1. Use the following data (25°C) to construct the adsorption isotherm for sodium dodecyl sulfate on 0.115 M NaCl ... 

Oxidation of Initiated Habilitate Pakrritate uniformly labeled with tritium (3H) to a specific activity of 2.48 X 10 counts per minute (cpm) per micromole of palmitate is added to a mitochondrial preparation that oxidizes it to acetyl-CoA. The acetyl-CoA is isolated and hydrolyzed to acetate. The specific activity of the isolated acetate is 1.00 X 107 cpm//xmol. Is this result consistent with the /1-oxidation pathway Explain. What is the final fate of the removed tritium ... 

A sample of a particular radioisotope is placed near a Geiger counter, which is observed to register 160 counts per minute. Eight hours later, the detector counts at a rate of 10 counts per minute. What is the half-life of the material ... 

Field data. In the measurements performed In the field, the tracer response was monitored as counts-per-minute as a function of time. This count rate fR) is proportional to the concentration of the radioactive isotope passing through the exit pipe. R.(t) is then taken as the area under the count-rate curve1 and E(t) = R(t)/fc,(t). 

When radioactive isotopes disintegrate, they obey a rate law that may be expressed as log N = -kt + K, where / is time, and N is the number of radioactive atoms (or something proportional to it) present at time t A common way to describe the number of radioactive atoms present in a given sample is in terms of the number of disintegrations observed per minute on a Geiger counter (this is referred to as "the number of counts per minute," or simply as cpm)... 

The radioactivity of an isotope is studied, and the following counts per minute (cpm) are obtained at five-minute intervals, starting with t = 0 4500, 3703,... 

N may be expressed in any convenient units because whatever is used cancels out in the ratio NJN2. A common unit is "counts per minute" (cpm) because, through Equation 26-1, the observed cpm are a direct measure of the number of radioactive atoms present. 

What is the half-life of an isotope if a sample of it gives 10,000 cpm (counts per minute), and 3.50 hrs later it gives 8335 cpm ... 

Radioactive decay with emission of particles is a random process. It is impossible to predict with certainty when a radioactive event will occur. Therefore, a series of measurements made on a radioactive sample will result in a series of different count rates, but they will be centered around an average or mean value of counts per minute. Table 1.1 contains such a series of count rates obtained with a scintillation counter on a single radioactive sample. A similar table could be prepared for other biochemical measurements, including the rate of an enzyme-catalyzed reaction or the protein concentration of a solution as determined by the Bradford method. The arithmetic average or mean of the numbers is calculated by totaling all the experimental values observed for a sample (the counting rates, the velocity of the reaction, or protein concentration) and dividing the total by the number of times the measurement was made. The mean is defined by Equation 1.1. 

---