An impurity in water has an extinction coefficient of 3.45 * 103 M-1 cm-1 at 280 nm, its absorption maximum(A Closer Look, p. 576). Below 50 ppb, the impurity is not a problem for human health. Given that most spectrometers cannot detect absorbances less than 0.0001 with good reliability, is measuring the absorbance of a water sample at 280 nm a good way to detect concentrations of the impurity above the 50-ppb threshold?

An impurity in water has an extinction coefficient of 3.45 * 103 M-1 cm-1 at 280 nm, its absorption maximum(A Closer Look, p. 576). Below 50 ppb, the impurity is not a problem for human health. Given that most spectrometers cannot detect absorbances less than 0.0001 with good reliability, is measuring the absorbance of a water sample at 280 nm a good way to detect concentrations of the impurity above the 50-ppb threshold?

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 validation process comprises four main steps that are : hardware validation, software validation, method validation and system suitability. To evaluate a spectrophotometer’s accuracy by measuring absorbance, a solution of 60.06 mg/L K2Cr2O7 in 0.0050M H2SO4 was carefully prepared together with a 0.0050 M H2SO4 as a reagent blank. If the spectrometer’s signal is properly calibrated, it has been reported that this solution should provide an absorbance of 0.640 +- 0.010 at wavelength 350 nm. Which one of the validations mentioned above had been involved in this process? Explain your choice
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.
The measurement of Li in brine (salt water) is used by geochemists to help determine the origin of this fluid in oil fields. Flame atomic absorption of Li is subject to interference by other elements. Atomic absorption of analysis of replicate sample of Li in a brine sample gave results in the table. a. Suggest a reason for the increasing apparent concentration of Li from sample 1 to 2. b. Suggest a reason for the increasing apparent concentration of Li from sample 1 to 3 c. Why do samples 4-6 give a nearly constant result? (What type of interference you think is being eliminated?
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.
To 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?
A student prepared four standard solutions of (NH4)2Fe(SO4)2 and measured their absorbance at 505 nm. She created a calibration plot with the best-fit line of y = 9372 x + 0.0539. She measured the absorbance of her diluted unknown sample solution as (4.69x10^-1) nm. If she prepared her diluted sample solution by diluting 10.00 mL of the original solution to a total volume of 50.00 mL with deionized water, what is the concentration of Fe2+ in her original solution? Answer in units of M. Note: Your answer is assumed to be reduced to the highest power possible.
Calculate the specific absorbance ratio (SAR), where A620 = 0.166 and A280 = 0.557