(a)
Interpretation:
The concentration in samples that yielded absorbance of 0.143 should be expressed in ppm. The relative standard deviation of the result should be calculated. The calculation should be repeated assuming the absorbance data are means of three measurements.
Concept introduction:
Standard deviation of the results obtained from the calibration curve =
M − number of replicates
N- number of calibration points.
Answer to Problem 14.12QAP
If absorbance data are means of 3 measurements,
Explanation of Solution
If the experiment was replicated three times,
(b)
Interpretation:
The concentration in samples that yielded absorbance of 0.675 should be expressed in ppm. The relative standard deviation of the result should be calculated. The calculation should be repeated assuming the absorbance data are means of three measurements.
Concept introduction:
Standard deviation of the results obtained from the calibration curve =
M − number of replicates
N- number of calibration points.
Answer to Problem 14.12QAP
If absorbance data are means of 3 measurements,
Explanation of Solution
If the experiment was replicated three times,
(c)
Interpretation:
The concentration in samples that yielded absorbance of 0.068 should be expressed in ppm. The relative standard deviation of the result should be calculated. The calculation should be repeated assuming the absorbance data are means of three measurements.
Concept introduction:
Standard deviation of the results obtained from the calibration curve =
M − number of replicates
N- number of calibration points.
Answer to Problem 14.12QAP
If absorbance data are means of 3 measurements,
Explanation of Solution
If the experiment was replicated three times,
(d)
Interpretation:
The concentration in samples that yielded absorbance of 1.009 should be expressed in ppm. The relative standard deviation of the result should be calculated. The calculation should be repeated assuming the absorbance data are means of three measurements.
Concept introduction:
Standard deviation of the results obtained from the calibration curve =
M − number of replicates
N- number of calibration points.
Answer to Problem 14.12QAP
If absorbance data are means of 3 measurements,
Explanation of Solution
If the experiment was replicated three times,
(e)
Interpretation:
The concentration in samples that yielded absorbance of 1.512 should be expressed in ppm. The relative standard deviation of the result should be calculated. The calculation should be repeated assuming the absorbance data are means of three measurements.
Concept introduction:
Standard deviation of the results obtained from the calibration curve =
M − number of replicates
N- number of calibration points.
Answer to Problem 14.12QAP
If absorbance data are means of 3 measurements,
Explanation of Solution
If the experiment was replicated three times,
(f)
Interpretation:
The concentration in samples that yielded absorbance of 0.546 should be expressed in ppm. The relative standard deviation of the result should be calculated. The calculation should be repeated assuming the absorbance data are means of three measurements.
Concept introduction:
Standard deviation of the results obtained from the calibration curve =
M − number of replicates
N- number of calibration points.
Answer to Problem 14.12QAP
If absorbance data are means of 3 measurements,
Explanation of Solution
If the experiment was replicated three times,
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Chapter 14 Solutions
Principles of Instrumental Analysis
- You are developing a Ca detection method for a graphite furnace AA instrument. Your analysis of ten blank samples gives a standard deviation of 0.265 ppb. To establish your limit of detection (LOD), what concentration of Ca should be spiked into your blanks?arrow_forwardThe 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_forwardAs part of an analytical chemistry laboratory course, a student measured the Ca2+ content in two water samples, city-supplied drinking water and well-supplied drinking water, using two different analytical methods, flame atomic absorption spectrometry (FAAS) and EDTA complexometric titration. The results of this experiment are given in the table as the mean Ca2+concentration (?¯) and standard deviation (?) in parts per million (ppm). Each sample was measured five times (n=5) by each method. Method City-Supplied Drinking Water (?¯±?x¯±s) Well-Supplied Drinking Water (?¯±?x¯±s) FAAS 57.57±0.68 ppm 64.77±0.70 ppm EDTA titration 58.32±0.96 ppm 65.62±0.97 ppm Method Comparison: For each drinking water sample (city and well), compare the Ca2+ content measured by FAAS and EDTA titration. Calculate the ? value for each sample. Do the methods produce statistically different results at the 95% confidence level when measuring the Ca2+content of the city-supplied drinking water? Do the…arrow_forward
- The nitrate in water was analyzed using a spectrophotometric method. The absorbances of the standards and the unknown sample were obtained at 550 nm.Solution Absorbance 2.00 µM 0.0656.00 µM 0.20510.00 µM 0.33814.00 µM 0.47418.00 µM 0.598Unknown 0.402 Write the equation of the lineWhat is the standard deviation of the calibration curve?arrow_forwardInternal standard (As , Cs ), analyte with known concentration (Ax , Cx ) In a chromatographic equipment, a solution containing 0.006727 X and 0.008331 M S give peak area of Ax= 2316 and As= 207. To analyze an unknown sample, 5.0mL of 0.008331M S was added to 5.0mL of X, and the mixture was diluted to 50.0mL. This mixture gave a chromatography spectrum with area Ax= 3206 and As= 200. Find Cx.arrow_forwardMaria was tasked to determine the concentration of a Fe2(SO4)3 solution. She prepared 5 different standards of Fe2(SO4)3 using the table below as her guide. She ran the standards and the unknown solution through UV-VIS spectroscopy and recorded the absorbances of each solution. HINT: use the dilution equation to determine the concentration of Fe2(SO4)3 in each test tube before preparing the standard curve. NOTE: No need to force the line to pass through zero. Just graph the data as is. What is the slope of the line of the standard curve from the given data? What is the concentration of the unknown solution?arrow_forward
- You are developing a procedure for determining traces of copper materials using a wet digestion followed by measurement by atomic absorption spectrophotometry. In order to test the validity of the method, you obtain an NIST orchard leaves standard reference material and analyze this material. Five replicas are sampled and analyzed, and the mean results are found to be 10.8 ppm with a standard deviation of plus or minus 0.7. ppm. The listed value for the standard reference is 11.7 ppm. Does your method give a statistically correct value at the 95% confidence level?arrow_forwardIn the analysis conducted with flame AAS, standard solutions of the X-type are analyzed individually and the absorbance values obtained are plotted against concentration (ppm). It was seen that the slope of the calibration line obtained was 0.0925. The standard deviation of the absorbance values obtained by reading the blank 10 times under the same conditions was calculated as 0.00183 ppm. According to this; For the X-type calculate the following: a) LOD b) LOQ c) Sensitivityarrow_forwardFluoride determination can be performed photometrically with alizarin red and Zirconium acid solution, obtaining the following data in the calibration: (View Table) 100.0 mL of well water are measured and concentrated to 50 ml by evaporation, the alizarin and zirconium reagents are added (in quantity proportional to the standards) and after the appropriate time, the reading of the instrument (under the same conditions instrumental) reports an absorbance of 0.182. How much fluoride in mg / L does the well water sample contain?arrow_forward
- 0.1120 g of a solid sample containing copper was dissolved by acid and transferred to a 250.00 mL volumetric flask and volume was made up with distilled water. The solution was then diluted by a factor of 25. The final solution was analyzed by atomic absorption spectrophotometry and the concentration was found be 2.982 ppm, What is the weight percentage of copper in the original solid sample? Keep four significant figures in your final answer.arrow_forwardA Dubosq colorimeter consists of a cell of fixed path length and a cell of variable path length. By adjusting the length of the latter until the transmission through the two cells is the same. the concentration of the second solution can be inferred from that of the former. Suppose that a plantdye of concentration 25 μg dm-3 is added to the fixed cell. the length of which is 1.55 em. Then a solution of the same dye. but of unknown concentration. is added to the second cel l. It is found that the same t ransmittance is obtained when the length of the second cel l is adjusted to 1.18 em. What is the concentration of the second solution?arrow_forwardUsing the absorbance of [FeSCN]+2 at the wavelength of maximum absorption which you obtained in part B, and the diameter of the tube, obtained in part A,calculate the molar extinction coefficient. given info: Concentration of Fe3+ stock solution, C1 = 0.001 M Volume of stock Fe3+ solution pipetted, V1 = 25mL Concentration of diluted stock solution, C2 = 0.0004 M Volume of Fe2+ solution and KSCN (upon mixing) = 10mL Weight of KSCN = 1g The reaction taking place is given as: The reaction taking place is given as: F e 3+ (aq) + SC N − (aq) ⇔Fe [SCN] 2+ (aq) the concentration of [FeSCN]2+ after the mixing of Fe3+ and SCN- is 2.5 x 10-3 M. Moles of [FeSCN]2+ = 2.5 x 10-5 moles Diameter:1.2cm The wavelength at which maximum absorption takes place is = 480 nmarrow_forward
- Principles of Instrumental AnalysisChemistryISBN:9781305577213Author:Douglas A. Skoog, F. James Holler, Stanley R. CrouchPublisher:Cengage Learning