(a)
Interpretation:
A working curve from the data should be constructed.
Concept introduction:
Standard addition method is used to analyze complex samples which matrix effect is significant. One common approach is standard addition technique is spiking of sample. In this method, one or more increments of a standard solution is added to the several aliquots of sample containing same volume. Each solution is then diluted to a fixed volume and experiment is proceeded.
(b)
Interpretation:
A linear least-squares equation for the data should be determined.
Concept introduction:
The slope of the line,
The intercept,
(c)
Interpretation:
The standard deviation of the slope and intercept and the standard deviation about regression for the curve should be determined.
Concept introduction:
Standard deviation about regression,
N − number of points used.
The standard deviation of the slope,
The standard deviation of the intercept,
(d)
Interpretation:
The concentration of Zn2+ in the sample should be calculated.
Concept introduction:
Standard addition method is used to analyze complex samples which matrix effect is significant. One common approach is standard addition technique is spiking of sample. In this method, one or more increments of a standard solution is added to the several aliquots of sample containing same volume. Each solution is then diluted to a fixed volume and experiment is proceeded.
(e)
Interpretation:
The standard deviation for the result in part (d) should be calculated.
Concept introduction:
Standard deviation of the results obtained from standard addition method =
M − number of replicates
N- number of calibration points.
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Chapter 15 Solutions
Principles of Instrumental Analysis, 6th Edition
- Exactly 5.00 mL aliquots of a solution containing analyte X were transferred into 50.00-mL volumetric flasks and the pH of the solution is adjusted to 9.0. The following volumes of a standard solution containing 2.00 µg/mL of X were then added into each flask and the mixture was diluted to volume: 0.000, 0.500, 1.00, 1.50 and 2.00 mL. The fluorescence of each of these solutions was measured with a fluorometer, and the following values were obtained: 3.26, 4.80, 6.42, 8.02 and 9.56, respectively. ii. Using relevant functions in Excel, derive a least-squares equation for the data, and use the parameters of this equation to find the concentration of the phenobarbital in the unknown solution.arrow_forwardQuinine in a 1.553-g antimalarial tablet was dissolved in sufficient 0.10 M HCl to give 250 mL of solution.A 10.00-mL aliquot was then diluted to 50.00 mL with the acid. The fluorescence intensity for the dilutedsample at 347.5 nm provided a reading of 196 on an arbitrary scale. A standard 100-ppm quinine solutionregistered 125 when measured under conditions identical to those for the diluted sample. Calculate the massin milligrams of quinine in the tablet.arrow_forwardIn order to measure riboflavin in a breakfast cereal, a 5.00-gram sample of the cereal was extracted with acetic acid and filtered. The extract was transferred to a 50.0 mL volumetric flask and diluted to the mark. The sample was transferred to a cuvette and the fluorescence was measured. The instrument read 59 units (Fluorescence units –an arbitrary scale). 24.00 mL of the cereal extract was sample was mixed with 1.0 mL of a riboflavin standard that was 0.500 ug/mL. The fluorescence of this mixture was measured and read 94 fluorescence units. Calculate the concentration of riboflavin per gram of cereal (use µg/gram of cereal).arrow_forward
- The determination of iron in wines was carried out by atomic absorption spectrophotometry, using the standard addition method. To do this, 10 mL of wine were placed in five 50 mL volumetric flasks; then 0, 5, 10, 15 and 20 mL of a 10 ppm iron standard solution were added to each of them. Next, they were gauged with distilled water and the absorbance was measured, obtaining the values of 0.040, 0.062, 0.081, 0.102 and 0.125 respectively. Calculate the regression parameters and obtain the iron concentration in the wine, in µg / mL.arrow_forwardA new water-soluble anti-diabetic drug with a molecular weight of 210.2 g/mol has an absorption maximum at 278 nm and a molar absorptivity (ε) of 6.15 x 103 M-1cm-1. One tablet of the drug was crushed and quantitatively transferred to a 100 mL volumetric flask and the flask was filled to the mark with deionized water. This solution had an absorbance of 0.770 at 278 nm in 1.00-cm cell. A blank was prepared by treating a tablet with identical composition but without the anti-diabetic drug in an identical manner. The absorbance of this blank solution was 0.052 at 278 nm in a 1.00-cm cell. (Show your work) a. Calculate the concentration of the final solution from Beer’s Law. b. Calculate the mass in mg of the anti-diabetic drug in the tablet.arrow_forwardTo determine the content of Pb in a canned sausage, 5.00 g were weighed and after adequate treatment they were gauged to a volume of 100 mL, from there an aliquot of 2 mL was taken and brought to a volume of 250 mL. The readings of a series and of the sample were taken in an Atomic Absorption spectrophotometer, recording the following data: mg Pb/mL 0 1 2 3 4 Sample Absorbance 0.00 0.15 0.29 0.44 0.58 0.38 What is the% Pb in canned sausage?arrow_forward
- An absorbance calibration curve for Zn was fitted to equation A = 0.913×`Zn, ppm`. Flask 1: To the first flask, a 1.00 mL aliquot of the unknown Zn solution was diluted to 100.0 mL in a volumetric flask; the absorption intensity from this sample was measured to be A = 0.204. Flask 2: To a second flask, a 1.00 mL aliquot of the unknown Zn sample and a 1.00 mL aliquot of 10.00 ppm Zn solution were added and diluted to 100.0 mL in a volumetric flask; the absorbance of this sample was measured to be A = 0.294. Calculate the % spike recovery for the analysis and report to the nearest whole number. Hint: A=mC of the type y=mx, so C=A/m %Spike=100%((Cspike-Coriginal)/Cadded)) Cadded can be found from C1 V1=Cadded V2.arrow_forwardThe intensity of light passing through a 1.00-cm sample of a solution of polystyrene in methyl ethyl ketone was observed to decrease by O.9%. The concentration of the solution was 10.6 kgm-3. Given A =546.1 nm, no= 1.377, and dn/dC" = 2.20x 10-4 %3D m3/ kg. calculate the molar mass of the polystyrene in kg/mol. The relative displacement (r/ro) of bovine serum albumin was observed as a function of time: t (s) 700 3580 4540 5020 r/r. 1.0129 1.0679 1.0871 1.0965 6 260 /s, find the sedimentation coefficient. Assuming Given w = v = 7.34x 10 3 m3 kg and p = 9.93 x 102 kg/m3, diffusivity = 6.97 x 1011 m2/s at 25 °C, determine the molar %3D mass of the sample in kg/mol.arrow_forwardAtomic Spectroscopy (a) In terms of spectral shape, how are atomic spectra different from molecular spectra? What is the source of this difference? (b) Describe the decision-making process for picking a line for atomic emission analysis of a given analyte. (c) For quality assurance, spike recovery is not sufficient to establish confidence in an analytical procedure. Explain this statement. What should be done instead to demonstrate satisfactory performance of an instrumental method (including elemental analysis). (d) Find a literature example of atomic spectroscopy used for elemental analysis. State the operating conditions with sufficient detail to reproduce the analysis; Please answer very soon will give rating surely All questions complete Answer needed Please help mearrow_forward
- Prepare a calibration curve to determine the Pb content in a well water sample using atomic absorption spectrophotometry; the following data were recorded: % T 100 75.2 56.6 42.5 31.9 24.6 13.8 ppm Pb 0 0.2 0.4 0.6 0.8 1.0 1.4 A 50 mL aliquot of well water is taken and diluted twice, the% T reading is taken and a value of 40.6% is recorded. Calculate the ppm of Pb in the well water.arrow_forwardMercury(II) forms a 1:1 complex with triphenyltetrazolium chloride that exhibits an absorption maximum at 255 nm. The mercury(II) in a soil sample was extracted into an organic solvent containing an excess of TTC , and the resulting solution was diluted to 100.0 mL in a volumetric flask. Five-milliliter aliquots of the analyte solution were then transferred to six 25-mL volumetric flasks. A standard solution was then prepared that was 5*10^-6 M in . Volumes of the standard solution shown in the table were then pipetted into the volumetric flasks, and each solution was then diluted to 25.00 mL. The absorbance of each solution was measured at 255 nm in 1.00-cm quartz cells. Please solve and explain these questions: A.) Enter the given data pictured above into a spreadsheet and show the correct standard additions plot B.) Determine the slope and the intercept of the line C.)Determine the standard deviation of the slope and the intercept. D.) Calculate the concentration of Hg(II) in the…arrow_forward(5) A sample of sodium phosphate is dissolved in water to give 100.00 mL of solution (Solution A). Then this solution is diluted 5 times to give the final solution (Solution B). Solution B is Known to contain 3.920 x 1022 number of PO43- ions, which has an absorption peak at 460 nm and absorbance value of 0.355 in a 1.000 cm cuvette. (i) Calculate the molar absorptivity of Solution B. (ii) What mass of sodium phosphate (MM 163.94 g/mol) dissolved in Solution A.arrow_forward
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