A series of eight absorbance measurements using an atomic absorption spectrophotometer are as follows: 0.855, 0.836, 0.848, 0.870, 0.859, 0.841, 0.861, and 0.852. According to the instrument manufacturer, the precision of the absorbance measurements using this instrument should not exceed 1% relative standard deviation. Does it in this case?

A series of eight absorbance measurements using an atomic absorption spectrophotometer are as follows: 0.855, 0.836, 0.848, 0.870, 0.859, 0.841, 0.861, and 0.852. According to the instrument manufacturer, the precision of the absorbance measurements using this instrument should not exceed 1% relative standard deviation. Does it in this case?

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter26: Molecular Absorption Spectrometry

Section: Chapter Questions

Problem 26.1QAP

See similar textbooks

Similar questions

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.
A graphite furnace atomic absorption spectrophotometer (AAS) was used to determine the arsenic (As) concentrations in drinking water. A large set of blank samples yielded an average blank signal of 0.013 and a blank standard deviation of 0.0030. The following data were obtained for a calibration curve. [As] (ppm) 2.0 4.0 6.0 8.0 10.0 Absorbance 0.17 0.28 0.48 0.53 0.72 Using a spreadsheet on an Excell, create a graph of the data using symbols only for the data points. Plot the line on the same graph and include the graph to this question. (a). What is the sensitivity of the method? (b). Calculate the LOD and LOQ for As. (c). A sample of water yielded an absorbance of 0.43. What is the concentration of As in the water?
Standard solutions of a chemical species with different concentrations are analyzed using a UV-Vis spectrophotometer. The absorbance values obtained are plotted against concentration and the slope of the drawn calibration line is calculated as 55400. Since a 0.5 cm cuvette is used in this analysis, calculate the molar absorptivity coefficient of the analyzed species.
Maria 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?
In UV and visible spectrophotometry, the specimen is generally dissolved in a solvent, and determinations are made at room temperature using a path length of 1 cm. Give the most common solvents suitable for UV or visible spectrophotometry.
You are developing a procedure for determining traces of copper in biological materials using a wet digestion followed by measurements by atomic absorption spectrophotometry. In order to test the validity of the method, you obtain a NIST orchard leaves standard reference material and analyze this material with your procedure five times and obtain a mean of 12.27 ppm with a standard deviation of 0.097 ppm. The NIST sample is listed as 11.7 ppm. Does your method give a statistically valid value at the 95% confidence level?
In 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) Sensitivity
Chemistry Atomic absorption analysis of Zn gave a calibration best fit line of A=0.670(ppm Zn) The detection limit was determined for this analysis using a 0.020 ppm Zn solution. The standard deviation of the absorbances for 11 samples of the solution was found to be 1.560 x 10-3 and the slope of the calibration curve was 0.026. Calculate the detection limit, Cq, (in units of ppm) for this instrument. Give your answer to 3 places after the decimal place.
A spectrophotometer method for the quantitative analysis of Pb2+ in blood uses Cu2+ as an internal standard. A standard containing 1.75 ppb Pb2+ and 2.25 ppb Cu2+ yields a signal of 0.832 for Pb2+ and a signal of 0.351 for Cu2+. A sample of blood is spiked with the same concentration of Cu2+, giving a signal of 0.520 for Pb2+ and 0.289 for Cu2+. Determine the concentration of Pb2+ in the sample of blood.
1 mL was taken from the sample filtrate and mixed with 13 mL pure water and 4 mL sulfomolybdic acid and 2 mL dilute SnCI2 solution by adding it, and after waiting for 15 minutes, the absorbance of the resulting solutions against pure water was read at 520 nm. if the function of the calibration graph obtained with standard phosphorus solutions of 0.5-2.5 mg/mL is y= 0.245x + 0.107 and the absorbance of the serum sample is 0.342, how many grams of phosphorus is the amount in the sample?
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?
An unknown sample of Mn2+ gave an absorbance of 0.392 in an atomic absorption analysis. Then 2.00 mL of solution containing 100.0 ppm of Mn2+ (=μg/mL) was mixed with 90.0 mL of unknown, and the mixture was diluted to 100.0 mL in a volumetric flask. The absorbance of the new solution was 0.600. The blank reading for this experiment is 0.010. Denoting the initial, unknown concentration as [Mn2+]i, write an expression for the final concentration, [Mn2+]f, after dilution. Units of the concentration are ppm. In a similar manner, write the final concentration of added standard Mn2+, designated as [S]f. Find [Mn2+]i in the unknown.