Absorbance values, table

With a fixed amino acid concentration of 0.02 M, the rate constant proved independent of the concentration of BrO" over the range (0.38-3.09) x 10"3M for N-Br-aminoisobutyric acid and N-Br-Proline. The plot of the obtained initial absorbance values against the initial N-Br-amino acid cone tration shows that Beer s law is obeyed, and the values for the molar absorptivity of the studied N-bromoamino acids are listed in Table 2. 

UV spectra of these solutions were recorded and the concentration of zinc was measured from the absorbance value and the results obtained have been shown in Table 9.11. In another experiment, the nephelometric and conductometric analysis were carried out but only after diluting the solutions from 5 to 1 M of NaOH, since the conductivity of solutions above this concentration was beyond the scale of the conductivity meter. 

Performing an analysis requires the preparation of a standard curve, which is also called a calibration curve. A series of standard solutions (four to six typically) containing known amounts of the component of interest are prepared. There are two primary restrictions on these solutions (1) they should cover the range of the expected concentrations of the component of interest, and (2) all absorbance values obtained for the extracted component must fall in between the lowest and highest absorbance values obtained for the standards. If a result is beyond these limits, its concentration cannot be determined with a high degree of confidence. In the table of data for Figure 14.10, Unkl... 

Clean the cuvette with a cotton swab and fill it about three-fourths full with the unknown dye solution. Place the cuvette in the colorimeter and close the lid. From the MAIN MENU, select COLLECT DATA (do not select SET UP PROBES as this will erase your data lists). Select MONITOR INPUT from the DATA COLLECTION MENU. Press ENTER to monitor the absorbance value of the colorimeter. After about 10-15 seconds, record the absorbance value and record it in your data table. 

As shown in Figs. 49.1-49.6, when the electronic spectra of the compound was investigated, the same peculiarities were observed as mentioned above. Increasing the polarity of the solvent as DMSO > DMF > MeOH > THF > CHCI was shown to generally result in electronic spectra. Absorbance of the solutions were observed at 230-310 nm. The maximum absorbance value changed and a new absorption appeared at 510-550 nm as 1 fresh, 2 one day, 3 two months. The assay resirlts obtained for each solvent are sitmmarised in Table 49.1. 

A drug such as morphine is almost completely absorbed (f = 1), so that loss in the gut is negligible. Flowever, the hepatic extraction ratio for morphine is 0.67, so (1 - ER) is 0.33. The bioavailability of morphine is therefore expected to be about 33%, which is close to the observed value (Table 3-1). 

Acceptance. Typical accuracy 0.01 AU, or the specific absorbance value falls with the limit outlined in Table 10.9. Six replicate measurements of the 0.006% w/v potassium dichromate solution at 235, 257, 313, and 350 nm should be less than 0.5% RSD. 

The FTIR spectrum of PS-MIPK is shown in Figure 4. Band A is the ketone carbonyl absorption at 1700 cm-1 and is used to monitor changes in photochemistry. Bands (1600 cm-1), C (1495 cm-1) and D (1455 cm-1) are well resolved bands from the styrene portion of the copolymer. Provided that they are not involved in the photochemistry, which seems unlikely, they can be used as a practical measure of film thickness. Measurements were made on the actual thickness of a number of PS and PS copolymer films using a Talley-step apparatus, followed by FTIR measurements. Based on these results, the relative absorbance values were found to be B, 2.56 C, 7.40 and D, 6.83 absorbance units per micron. The UV absorbance was also measured for films of various thickness at 254 nm, and the data are summarized in Table III. The constancy of these data suggests that this also could be used as a simple method of determination of film thickness. 

Table 3.7.1 Colorimetric assay of plasma biotinidase activity pipetting schedule and typical absorbance values obtained with normal plasma. B-PABA biotinyl-p-aminobenzoic acid, BSA bovine serum albumin, DTT dithiothreitol, PABA p-aminobenzoic acid, S substrate stock solution...

Table 3.7.1 shows typical absorbance values obtained with a normal plasma sample after setting the absorbance zero with demineralised water. 

Activity with 1 x S subtract the corresponding blank value (or the individual background value if this is higher than the blank value) from the absorbance values of both reaction tubes with 1 x S (Table 3.7.1 tubes 3 and 4). Divide by the standard factor to obtain nmols/assay. Further divide by 60 min (assay time) to obtain nmol/min/assay. Multiply by 20 (1 ml/0.050 ml) to obtain nmol/min/ml plasma. Calculate the mean value of activity with 1 x S. 

The first problem is deciding on which of these two common models to use. It has been argued that for spectrophotometric methods where the Beer-Lambert Law is known to hold, Y = bX + e, the force through zero model is the correct model to choose if the absorbance values are corrected for the blank." The correct way to carry out the calibration regression is to include the blank response at assumed zero concentration and use the model Y = bX + a + instead. This may be a nicety from a practical standpoint for many assays but there are instances where a force through zero model could produce erroneous results. Note that the e denotes the random error term. Table 15 contains a set of absorbance concentration data from a UV assay. 

When we scan across the three absorbance values in each row of Table 4-7, the number 0.392 seems out of line It is inconsistent with the other values for 15.0 p-g, and the range of values for the 15.0-p.g samples is much bigger than the range for the other samples. The linear relation between the average values of absorbance up to the 20.0-p.g sample also indicates that the value 0.392 is in error (Figure 4-10). We choose to omit 0.392 from subsequent calculations. 

Figure 4-10 Average absorbance values in Table 4-7 versus micrograms of protein analyzed. Averages for 0 to 20 ng of protein lie on a straight line if the questionable datum 0.392 at 15 (j.m is omitted.

B 9. A student group completed the biuret assay on their mitochondrial preparation. Assume that the following absorbance values were obtained as described in Table E10.2. 

The safe levels established for parathion + paraoxon, azinphosmethyl + azinphosmethyl oxon and methidathion + methi-dation oxon on foliage have absorbance values determined by the rapid field method (4 ) equal to those given in Table III. Absorbance values greater than those listed in Table III signal an unsafe working condition. Field testing can also be conducted by standard gas chromatographic analysis of the leaf disk samples by state-approved laboratories. 

Table III. Absorbance Values for Safe Levels of Total OP Residues on Foliage...

Approximate detection limits were calculated from the mean absorbance and relative standard deviation values obtained for each spinach slurry concentration, and the results are presented in Table 7.1. Although the values cannot be directly compared as they have been calculated at different absorbance values, and they do not represent true detection limits as the concentrations used are too high owing to the level of lead in the spinach sample used, they clearly indicate that an increase in spinach concentration allows lower detection limits to be achieved. 

Equation (11) estimates sunlight photoreaction rate constants using computed or tabulated values for Zk or tabulated values of L> at the appropriate latitude and time of year (Zepp and Cline, 1977 Mill and Mabey, 1985 Leifer, 1988), together with measured values of > and <1>. Equation (2) can be used to estimate values of > from a uv spectrum measured in water or, if aqueous solubility is low, a polar organic solvent such as acetonitrile or methanol. Absorbance values are converted into ex values at wavelength centers corresponding to those Table 15.1 lists. 

Table 4, the relative fluorescence intensity also can decrease substantially as the polarity of the solvent increases. Next the absorbance for o-phenylphenol, maretin, and pyrazophos was compared in both hexane and methanol. A Beckman DG-GT Spectrophotometer was used to obtain the absorbance values. 

No appreciable difference in absorbance values was observed between solutions in hexane or methanol (Table 5). We therefore attribute the change in fluorescence to solute-solvent interactions between the solvent and the pesticide in its excited state. 

Table 1 Absorbance values for three trials of the experiment at 360, 420, and 540 nm.

Included in this latter set is a double mutant protein, a T1D/T2D protein that lacks both the type 1 and the type 2 copper atoms. Only the type 3 binuclear cluster contributes to the nonprotein absorbance in this protein, demonstrating that the shoulder at 330 nm is due to this cluster. This cluster also contributes a broad absorbance centered at 720 nm as the spectrum of this double mutant demonstrates. The absorbance of the wild-type protein at 608 nm is clearly due to the type 1 Cu(II) since it is seen only in protein forms that possess this site. The spin Hamiltonian and absorbance values for the copper sites in FetSp are summarized in Table I. Additional properties of these copper site-depleted Fet3p mutant proteins are discussed below. 

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