Counting calibration

Method a(counts) KxlO a (counts" ) Calibration Curve Slope at Peak of Chromatogram... 

The log Mn vs. count calibration curve is shown on Figure 5. This is a fairly linear calibration curve, but it covers only a relatively narrow molecular weight range of 145,000 to 317,000 g/mole. Although we have sought to prepare higher MW samples for this purpose, we inadvertently obtained polymers with bimodal MWD s and did not use them for this calibration. 

Peacock, S. L., Accomazzo, M. A., Grant, D. C., Quantitative Count Calibration of Light Scattering Particle Counters, J. Environ. ScL, 1986, 29,23-27. 

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. 

All packing materials produced at PSS are tested for all relevant properties. This includes physical tests (e.g., pressure stability, temperature stability, permeability, particle size distribution, porosity) as well as chromatographic tests using packed columns (plate count, resolution, peak symmetry, calibration curves). PSS uses inverse SEC methodology (26,27) to determine chromatographic-active sorbent properties such as surface area, pore volume, average pore size, and pore size distribution. Table 9.10 shows details on inverse SEC tests on PSS SDV sorbent as an example. Pig. 9.10 shows the dependence... 

Most size exclusion chromatography (SEC) practitioners select their columns primarily to cover the molar mass area of interest and to ensure compatibility with the mobile phase(s) applied. A further parameter to judge is the column efficiency expressed, e.g., by the theoretical plate count or related values, which are measured by appropriate low molar mass probes. It follows the apparent linearity of the calibration dependence and the attainable selectivity of separation the latter parameter is in turn connected with the width of the molar mass range covered by the column and depends on both the pore size distribution and the pore volume of the packing material. Other important column parameters are the column production repeatability, availability, and price. Unfortunately, the interactive properties of SEC columns are often overlooked. 

Column manufacturers normally provide basic information about their columns, such as plate count, particle size, exclusion limit, and calibration curve. This information is necessary and fundamental, however, it is not sufficient to allow users to make an intelligent decision about a column for a specific application. For example, separation efficiency, the dependence of separation efficiency on the mobile phase, the ability to separate the system peaks from the polymer peak, the symmetry of the polymer peak, and the possible interaction with polymers are seldom provided. 

Two linear columns from Showa Denko, Shodex SB-806M and Shodex SB-806MHQ, and two linear columns from TosoHaas, TSK GM-PWxl and TSK GM-PW, were evaluated. Prior to the evaluation, the number of theoretical plates for Shodex SB-806MHQ, SB-806M, PWxl, and PW was determined to be 15,100, 15,700, 11,390, and 4710, respectively, as per manufacturer inspection. The lower plate count of the TSK PW column is due to the larger particle size of this column. Two mobile phases, water with 0.1 M LiNOi and 50 50 methanol/water (v/v) with 0.1 M LiNOi, were used for each of the four columns. These four columns were new and only PEO and PVP were analyzed with these columns in this study. Waters Ultrahydrogel columns have also been used in this laboratory. However, Ultrahydrogel columns are exactly the same as the TSK GM-PWxl columns based on the calibrations curves supplied by the manufacturers and by the pyrolysis GC data discussed later. 

The MWD total gamma ray tools cannot be calibrated in the standard pit, since they are too large. Their calibration in API units is difficult because it varies with the spectral content of the radiation. By spectral matching the MWD logs can be made to closely resemble the wireline logs. The logs which were recorded by the MWD companies in counts per second (cps) are now recorded in API units. 

An eyedropper is calibrated by counting the number of drops required to deliver 1.0 mL Twenty drops are required. 

Fig. 7—8. Calibration curve for the determination of tungsten in solution with bromide as an internal standard, for two different counter tubes. Squares = krypton counted total count, 10(16,384) circles = argon counter total count, 5(16,384). (Fagel, Liebhafsky, and Zemany, Anal. Chem., 30, 1918.)...

The last step is facilitated by the use of calibration curves of analytical-line intensity versus counting rate plotted at several levels of background intensity. All steps are rapid and simple. 

Figure 8-9 shows how the calibration for niobium varies with the background counting rate at a single Nb2Os concentration. Similar curves have been proved useful in a large number of uranium determinations on shipping pulp and ores. 

The HPLC method for which data are given had previously been shown to be linear over a wide range of concentrations what was of interest here was whether acceptable linearity and accuracy would be obtained over a relatively narrow concentration range around the nominal concentration in the product the specification limits were 90-110% of nominal. Three concentrations were chosen and three repeat determinations were carried out at each. Two different samples were prepared at each concentration, namely an aqueous calibration solution and a spiked placebo. All samples were worked up according to the method and appropriate aliquots were injected. The area counts are given in the second, respectively the fifth column of Table 4.42. 

Schwartz, L. M., Statistical Uncertainties of Analyses by Calibration of Counting Measurements, Anal. Chem. 50, 1978, 980-985. 

This technique is invasive however, the particle can be designed to be neutrally buoyant so that it well represents the flow of the phase of interest. An array of detectors is positioned around the reactor vessel. Calibration must be performed by positioning the particle in the vessel at a number of known locations and recording each of the detector counts. During actual measurements, the y-ray emissions from the particle are monitored over many hours as it moves freely in the system maintained at steady state. Least-squares regression methods can be applied to evaluate the temporal position of the particle and thus velocity field [13, 14]. This technique offers modest spatial resolutions of 2-5 mm and sampling frequencies up to 25 Hz. 

The extension of the calibration curve beyond a retention vol ome of 58 ml poses less of a risk, in view of the acknowledged capacity of LEG in resolving small diameter particles, than in its extension to retention voliomes of less than U5 ml. The latter has the implication of counting particles as large as 2T8 nm (corresponds to a retention voliome of 38 ml see Fig. 8) which have earlier been shown to be totally trapped in the columns. 

CALIBRATION CURVE 21 LAST DATA POINT COUNT 24.80... 

Detection RI 16X, SP4050 Attenuation 10 Chart speed - Icm/min Analysis time - 24 min Total plate count - 2(10 ) plates Polydichlorophosphazene and cyclic trimer and tetran r standards were used for calibration. Standard methods were applied for integrating peak areas. 

Number and weight average molecular weights for Polysciences Standards and McMaster Standard B, calculated from raw chromatograms using the molecular weight calibration curve M(V) = 0.20 X 10 exp(-0.341 V - 0.006 V ) with V in counts (1 count = 5 ml). 2... 

A = instrument response (integration counts) for flumioxazin in the sample C = concentration of flumioxazin in the calibrating standard (1.0 qgmL ) V = final volume of the sample extract (mL)... 

B = mean integration counts for the calibration standards W = sample weight or volume (g or mL). 

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