Amount injected

The protein recovery was found to be 95% of the amount injected, whereas, on the untreated carrier they were almost totally irreversibly adsorbed. Meanwhile, some reduction in the pore volume of the carrier could be deduced from the results of the chromatographic test. The calculated pore volume available for phtalic acid was 0.67 cm2/g (V) whereas for cytochrome C — 0.5 cm2/g. A detailed description of the experiment allows the evaluation of the effective thickness (teff) of the polymeric stationary phase. The tcff calculated as V/Ssp is 2.3 nm. The value... 

S(A RFn) is the sum of the areas times the individual response factors for all the peaks in the chromatogram. The amount injected should be the same for both the standard and the unknown. 

In the author s experience, such confirmation is not appropriate when the calibration range is greater than one order of magniffide or calibration points are not chosen carefully. The reason is that lower concentration levels of a calibration graph influence the correlation coefficient to a much smaller extent than higher concentrations. The hypothetical example of calibration results presented in Table 3 demonstrates this very simply. If the amount injected is correlated with the observed peak area in the second column in Table 3, the calibration graph in Figure 2 is obtained. 

Data on the absorption of simple salts of the lanthanide elements injected intramuscularly into rats are summarized in Figure 10.4 The dependence of the fraction remaining at the injection site on the administered mass is apparent. When the amount injected was less than 0.01 jug, about 0.5 was absorbed in the first few days another 0.4 was absorbed with a half-time of about 25 days and the remaining 0.1 left the injection site with a half-time of 100 to 200 days. As the total mass injected was increased, the fraction absorbed in the first few days declined, and the amounts associated with the lower absorption rates increased. If 100 jug or more were injected, only 0.05 to 0.1 was absorbed during the first few days, and absorption was very slow thereafter. 

Absorption of intramuscularly injected lanthanides (Durbin et al., 1956a) is greatly accelerated if they are administered as citrate complexes. However, the fractional absorption rate is still a function of the amount injected. One day after injection of < 1 jug of the lanthanide citrates, 0.95 had been absorbed 0.75 was absorbed in the first day if the amount of stable lanthanide administered was 1 to 5 jug. After 256 days, only 0.05 of the injected 152,154Eu plus 5 jug Eu remained unab-... 

Single abdominal injection of 1 mg famphur/kg BW whole-body residues of famphur, famoxon, and /V-desmethylfamphur measured 1 h after injection AMERICAN COCKROACH, Periptaneta americana Of total amount injected, 84.6% remained after 1 h 79.4% famphur, 2.2% famoxon, and 3.1% /V-desmethylfamphur 2... 

The rate of this charge transfer (coulomb/second) determines the detector response (ampere). In other words, maximum detector response is obtained at maximum charge transfer rate. A measure for the charge transfer rate is the electrolytic efficiency the fraction of analyte that is electrolyzed during passage through the cell expressed in percentage of total amount injected. 

From Eqs. 17.31a and 17.31b it can be derived that when the amount injected is very small, the detection path length very narrow and the capillary diameter is also very small, only a influences the broadening of a migrating zone. In such a case, afot is approximated by of and Eq. 17.31b can be simplified to... 

The accuracy of the injection volume measurement can be very important for quantitation, since the amount of analyte measured by the detector depends on the concentration of the analyte in the sample as well as the amount injected. In Section 12.8, a technique known as the internal standard technique will be discussed. Use of this technique negates the need for superior accuracy with the injection volume, as we will see. However, the internal standard is not always used. Very careful measurement of the volume with the syringe in that case is paramount for accurate quantitation. Of course, if a procedure calls only for identification (Section 12.7), then accuracy of injection volume is less important. See Workplace Scene 12.1 for an example of a purge-and-trap procedure for injecting a GC sample. 

Since the peak size is directly proportional to concentration, one may think that one could prepare a series of standard solutions and obtain peak sizes to be used for a standard curve of peak size vs. concentration, a method similar to Beer s law in spectrophotometry, for example. But since peak size also varies with amount injected, there can be considerable error due to the difficulty in injecting consistent volumes, as discussed above and in Section 12.3. A method that does away with this problem is the internal standard method. In this method, all standards and samples are spiked with a constant known amount of a substance to act as what is called an internal standard. The purpose of the internal standard is to serve as a reference for the peak size measurements, so that slight variations in injection... 

The packed column can be from 2 to 20 ft in length, typically has a diameter of V8 or V4 in., and has small particles, often coated with a thin layer of liquid stationary phase, packed in the tube. The open-tubular capillary column can be up to 300 ft in length, has an extraordinarily small diameter (capillary), and has the liquid stationary adsorbed on the inside surface of the tube. In terms of separation ability, the open-tubular capillary column is better because the mixture components contact more stationary phase (column is longer) while passing through the column. The amount injected for the open-tubular capillary column must be much less (0.1 mL maximum, as opposed to 20 mL for the V8-in. packed column) because the column diameter is much less and a greater volume would overload it. 

Each of the Datasets A-F were also of fenvalerate and were obtained from an extensive study of fenvalerate residues in chickens and eggs. They show how much variability in data quality can be obtained in practice. Table VII describes the number of calibration levels, replicates at each level, and ranges in ng of amounts injected into the gas chromatograph. Dataset A is an "ideal" set, a set that looked ideal at the time it was recorded. Dataset B is a set of data taken over two days under constant... 

For the CE analyzer, a sample method is run to demonstrate that the entire system is functioning properly. A cystosine molecule, 100 ppm, is injected and separated at 30 kV. Reproducibility of migration time and area is tested. The reproducibility for nine consecutive runs is expected to have an RSD of less than 1 % for migration time, peak area, and corrected area. The linearity is tested by injecting sample at three different pressures and adjusting the time to arrive at equal amounts injected [Equation (2)]. The three settings and three consecutive runs should have an RSD of less than 5% for migration time, peak area, and corrected area. 

Viscosity differences-. Different sample vial temperatures create different viscosities, and thus different amounts injected. To reduce the effect, use the instrument temperature control (see Section IV). However, often the sample and buffer vials reside outside the temperature-controlled area. The effect of this might vary depending on the climate system in your lab and how the lab temperature varies over the year. Besides temperature control, it is important to match samples and standards in terms of viscosity and conductivity. 

Figure 1. HPLC separation of four sulfonamide drugs on a CN-NH2 bonded polar phase (1) Sulfadiazine (2) sulfapyridine (3) sulfanilamide (4) sulfathiazole. Mobile phase 95% methylene chloride-5% methanol flow rate 1 ml/min. Detection 254 nm. Amount injected 0.2 ]ig each (as the free acids obtained from Sigma Chemical Co.).

As long as the boundary and initial conditions remain unchanged, the band profiles on the reduced time and length scale depend only on the column efficiency. The conventional boundary and initial conditions for all modes of chromatography state that (1) the column is equilibrated with the mobile phase prior to the beginning of the separation (2) the sample is then injected as a rectangular pulse and (3) the separation proceeds as required by the specific mode selected. The amount of sample injected is determined by the volume and the concentration of the feed injected. As long as we avoid serious volume overload, the actual values of these two parameters are immaterial. Only their product, i.e., the amount injected, will influence the band profile. 

The amount of solvent needed for the purification of a unit amount of target compound is conveniently described by the term specific production. Thus, the minimum solvent consumption can be determined for a given purification. The amount of solvent pumped through the column during one cycle is proportional to the mobile phase flow rate and the cycle time. The amount of purified product made in one cycle is the product of the amount injected and the recovery yield. Thus, the specific production can be written as [43]... 

To calibrate the needle in order to estimate the amount injected, place a small drop of halocarbon oil onto a micrometer and release a drop of the injectable onto the oil. The drop should hang in the oil to form a perfect sphere. If the drop falls and spreads out on the slide, use a larger volume of oil to create a thicker layer. Measure the size of the sphere and calculate the volume (Volume of a sphere = 4/37tr ). 

Because column performance decreases with age, it is important to keep good records of its performance. Entries useful to keep track of are chromatogram number, sample identification number, amount injected, volume injected, solvents used (A and B components), column characteristics (ID number, packing, size), back pressure, flow rate, detector setting (UV, absorbance units full scale at given wavelength), gradient conditions, results (retention time of desired product), remarks (baseline shifts, unusual wash profile, etc.), and date. 

Linearity of response versus absolute amount injected must be confirmed for each different sample type and for each different set of chromatographic operating conditions. This linearity cannot be assumed. Nonlinearity may result from column overload, detector overload, or adsorption problems. 

Five microliters of derivatized sample is injected into the gas chromatograph. The injection port temperature should also be controlled. However, the amount injected will have to be mediated according to the concentration of any individual aromatic acid present in the urine. Some aromatic acids may be present in amounts that may overload the column. 

Overall extraction efficiencies were calculated by determining the total peak area count for all components, with the exception of the solvent peak. The latter peak area was also noted as this value gives a number proportional to the actual amount of sample reaching the column, (as opposed to the amount injected). By proportionality and normalization, the relative percent of SFE extractables were compared to die Soxhlet method. The results of these calculations are included as Table Vffl. 

FIGURE 17 The effects of amount injected on the chiral resolution of (a) cyclohexyl-phenylglyconic acid and (b) ephedrine (A), methamphetamine ( ), and selegiline (O) on -CD-based CSPs. (From Refs. 26,112.)... 

Specify a precision limit for the amount at the limit of quantitation. Prepare six standard solutions with the amounts in the range from the expected limit of quantitation to 20 times this amount. Inject all samples six times and calculate the standard deviations of the amounts. Plot the standard deviations versus the amounts. Take the specified standard deviation at the corresponding LOQ amount from the plot. 

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