A standard solution was prepared containing 10.0 ppm of an analyte and 15.0 ppm of an internal standard. Analysis of the sample gave signals for the analyte and internal standard of 0.155 and 0.233 (arbitrary units), respectively. Sufficient internal standard was added to an unknown sample to make it 15.0 ppm in the internal standard. Analysis of the unknown sample yielded signals for the analyte and internal standard of 0.274 and 0.198, respectively. Calculate the concentration of analyte in the unknown sample.

A standard solution was prepared containing 10.0 ppm of an analyte and 15.0 ppm of an internal standard. Analysis of the sample gave signals for the analyte and internal standard of 0.155 and 0.233 (arbitrary units), respectively. Sufficient internal standard was added to an unknown sample to make it 15.0 ppm in the internal standard. Analysis of the unknown sample yielded signals for the analyte and internal standard of 0.274 and 0.198, respectively. Calculate the concentration of analyte in the unknown sample.

Principles of Instrumental Analysis

7th Edition

ISBN:9781305577213

Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Chapter1: Introduction

Section: Chapter Questions

Problem 1.9QAP

See similar textbooks

Similar questions

The student was supposed to measure the pH of a 0.1 M hydrochloric acid solution. For this purpose, he used a pH-meter and obtained the following results: 0.90, 0.93, 1.04, 1.02. Present the appropriate graphic and statistical elaboration of the performed analysis and confirm whether the applied pH-meter worked properly.
3) The solution taken from a factory waste sample to prepare an internal standard contains Pb + 2 and Ag + 2, and the analysis peaks were determined as 298 mAU and 324 mAU. To analyze the unknown, a solution containing 0.150 M, 50.0 mL of Ag + 2 is put into the unknown liquid and completed to 100.0 mL. When the peaks are measured again, 670 mAU and 856 mAU signals are read from the samples. What is the concentration of Pb + 2 in the unknown liquid?
A 10.00 g sample containing an analyte was transferred to a 250 mL volumetric flask and diluted to volume. When a 10.00 mL aliquot of the resulting solution was diluted to 25.00 mL it was found to give a signal of 0.235 (arbitrary units). A second 10.00 mL aliquot was spiked with 10.00 mL of a 1.00 ppm standard solution of the analyte and diluted to 25.00 mL. The signal for the spiked sample was found to be 0.502. Calculate the weight percent of analyte in the original sample.
A 10.00-g sample containing an analyte was transferred to a 250-mL volumetric flask and diluted to volume. When a 10.00-mL aliquot of the resulting solution was diluted to 25.00 mL it was found to give a signal of o.235 (arbitrary units). A second 10.00-mL aliquot was spiked with 10.00 mL of a 1.00- ppm standard solution of the analyte and diluted to 25.0o mL. The signal for the spiked sample was found to be o.502. Calculate the weight percent of analyte in the original sample.
The response of the instrument must be lincar in the sample matrix. Systematic errors can occur due to sample or standard preparation. It consists of a series of standard analyte solutions separate from the unknown. A blank is used to correct the response from the instrument. Known quantities of a standard solution of the analyte are added to the unknown. It is the method of choice when the matrix of the sample may affect the signal. Matrix effects can cause the same analyte concentration in an unknown and standard to give different responses. It is used to measure the instrument response as a function of a known analyte concentration under a set of conditions.
4) 1.580 g soil sample was analyzed for its copper content. The soil sample was completely digested with HNO3-H2O2 mixture and diluted to 50.0 mL with distilled water. 2.0 mL of this solution was taken into a volumetric flask and diluted to 10.0 mL with distilled water. It was analyzed by FAAS system and its average absorbance was calculated as 0.2564. Calibration plot for copper is shown below. Absorbance 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 10 y = 0,0291x-0,0082 R² = 0,9993 15 Copper, mg/L 20 Calculate the percentage of copper in the soil sample as ppm. 25
A standard method for analyzing aspirin tablets has a known variance of 20. A sample of 10 aspirin tablets is selected and analysed for the amount of aspirin using a modified method, yielding the following results: 254, 249, 252, 252, 249, 249, 250, 247, 251, 252. Determine whether the precision of the modified method is significantly different from that of the standard method at, alpha(a) = 0.10
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.
a sample of butyl benzoate is prepared to use as an internal standard. The results of a preliminary run, which used a solution known to contain 1.53 mg/mL of methyl benzoate (peak A) and1.68 mg/mL of butyl benzoate (peak B), are shown. The area of peak A is determined to be 352 and the area of peak B is determined to be 416 measured in arbitrary units by the computer. To measure the sample, 1.00 mL of a standard sample of butyl benzoate containing 2.19 mg/mL is mixed with 1.00 mL of the plant stream material. Analysis of the mixture gave a peak area of 449 for peak A and 411 for peak B. What is the concentration of methyl benzoate in the plant stream? concentration of methyl benzoate = ____________________ mg/mL
7) A 25.0 ml sample containing Cu gave an instrument reading of 23.6 units (corrected for a blank). When exactly 0.500 ml of 0.0287M Cu(NO3)2 Was added to the solution,the signal increased to 37.9 units. Calculate the molar concentration of Cu" in the sample +2,
why is it better to generate a calibration plot than to perform a determination using a single measurements for a standard solution?
Anionic surfactants in wastewater are measured spectrophotometrically as methylene blue active substances (MBAS). A volume of a water sample is first reacted with methylene blue, a cationic dye, in a basic buffered aqueous solution. The resulting solution is agitated after the addition of chloroform. The organic layer is then extracted, and the absorbance is read at 655 nm. A standard calibration curve is produced by plotting absorbance vs. concentration for the concentration range between 0 ppm to 2.50 ppm. The line had the following equation: y = 0.286x + 0.009 a. The limit of surfactant content in Philippine class B water is 300 ppb. If a 5 mL aliquot of a 50 mL water sample had an absorbance of 0.084 after MBAS analysis, is the sampled water body suitable for bathing? Support your answer