Principles of Instrumental Analysis
Principles of Instrumental Analysis
7th Edition
ISBN: 9781305577213
Author: Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher: Cengage Learning
Question
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Chapter 14, Problem 14.12QAP
Interpretation Introduction

(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 = sc=srm1M+1N+(y¯cy¯)2m2Sxx

M − number of replicates

N- number of calibration points.

Expert Solution
Check Mark

Answer to Problem 14.12QAP

x=3.66 ppm

sc=0.229 ppm

If absorbance data are means of 3 measurements, sc=0.170 ppm

Explanation of Solution

y=0.03949x0.001340.143=0.03949x0.001340.03949x=0.14434x=3.66 ppm

sc=0.00740.0394911+16+(0.1430.828)2(0.03949)2×926sc=0.18741+0.167+0.46921.4441sc=0.18741+0.167+0.325sc=0.1874×1.221sc=0.229 ppm

If the experiment was replicated three times,

sc=0.00740.0394913+16+(0.1430.828)2(0.03949)2×926sc=0.18740.333+0.167+0.46921.4441sc=0.18740.333+0.167+0.325sc=0.1874×0.9083sc=0.170 ppm

Interpretation Introduction

(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 = sc=srm1M+1N+(y¯cy¯)2m2Sxx

M − number of replicates

N- number of calibration points.

Expert Solution
Check Mark

Answer to Problem 14.12QAP

x=17.13 ppm

sc=0.204 ppm

If absorbance data are means of 3 measurements, sc=0.135 ppm

Explanation of Solution

y=0.03949x0.001340.675=0.03949x0.001340.03949x=0.67634x=17.13 ppm

sc=0.00740.0394911+16+(0.6750.828)2(0.03949)2×926sc=0.18741+0.167+0.02341.4441sc=0.18741+0.167+0.016sc=0.1874×1.087sc=0.204 ppm

If the experiment was replicated three times,

sc=0.00740.0394913+16+(0.6750.828)2(0.03949)2×926sc=0.18740.333+0.167+0.02341.4441sc=0.18740.333+0.167+0.016sc=0.1874×0.7183sc=0.135 ppm

Interpretation Introduction

(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 = sc=srm1M+1N+(y¯cy¯)2m2Sxx

M − number of replicates

N- number of calibration points.

Expert Solution
Check Mark

Answer to Problem 14.12QAP

x=1.76 ppm

sc=0.294 ppm

If absorbance data are means of 3 measurements, sc=0.178 ppm

Explanation of Solution

y=0.03949x0.001340.068=0.03949x0.001340.03949x=0.06934x=1.76 ppm

sc=0.00740.0394911+16+(0.0680.828)2(0.03949)2×926sc=0.18741+0.167+0.57761.4441sc=0.18741+0.167+0.400sc=0.1874×1.567sc=0.294 ppm

If the experiment was replicated three times,

sc=0.00740.0394913+16+(0.0680.828)2(0.03949)2×926sc=0.18740.333+0.167+0.57761.4441sc=0.18740.333+0.167+0.400sc=0.1874×0.949sc=0.178 ppm

Interpretation Introduction

(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 = sc=srm1M+1N+(y¯cy¯)2m2Sxx

M − number of replicates

N- number of calibration points.

Expert Solution
Check Mark

Answer to Problem 14.12QAP

x=25.58 ppm

sc=0.204 ppm

If absorbance data are means of 3 measurements, sc=0.135 ppm

Explanation of Solution

y=0.03949x0.001341.009=0.03949x0.001340.03949x=1.01034x=25.58 ppm

sc=0.00740.0394911+16+(1.0090.828)2(0.03949)2×926sc=0.18741+0.167+0.03271.4441sc=0.18741+0.167+0.0227sc=0.1874×1.091sc=0.204 ppm

If the experiment was replicated three times,

sc=0.00740.0394913+16+(1.0090.828)2(0.03949)2×926sc=0.18740.333+0.167+0.03271.4441sc=0.18740.333+0.167+0.0227sc=0.1874×0.7229sc=0.135 ppm

Interpretation Introduction

(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 = sc=srm1M+1N+(y¯cy¯)2m2Sxx

M − number of replicates

N- number of calibration points.

Expert Solution
Check Mark

Answer to Problem 14.12QAP

x=38.32 ppm

sc=0.229 ppm

If absorbance data are means of 3 measurements, sc=0.170 ppm

Explanation of Solution

y=0.03949x0.001341.512=0.03949x0.001340.03949x=1.51334x=38.32 ppm

sc=0.00740.0394911+16+(1.5120.828)2(0.03949)2×926sc=0.18741+0.167+0.46781.4441sc=0.18741+0.167+0.324sc=0.1874×1.221sc=0.229 ppm

If the experiment was replicated three times,

sc=0.00740.0394913+16+(1.5120.828)2(0.03949)2×926sc=0.18740.333+0.167+0.46781.4441sc=0.18740.333+0.167+0.324sc=0.1874×0.908sc=0.170 ppm

Interpretation Introduction

(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 = sc=srm1M+1N+(y¯cy¯)2m2Sxx

M − number of replicates

N- number of calibration points.

Expert Solution
Check Mark

Answer to Problem 14.12QAP

x=13.86 ppm

sc=0.207 ppm

If absorbance data are means of 3 measurements, sc=0.139 ppm

Explanation of Solution

y=0.03949x0.001340.546=0.03949x0.001340.03949x=0.54734x=13.86 ppm

sc=0.00740.0394911+16+(0.5460.828)2(0.03949)2×926sc=0.18741+0.167+0.07951.4441sc=0.18741+0.167+0.0551sc=0.1874×1.105sc=0.207 ppm

If the experiment was replicated three times,

sc=0.00740.0394913+16+(0.5460.828)2(0.03949)2×926sc=0.18740.333+0.167+0.07951.4441sc=0.18740.333+0.167+0.0551sc=0.1874×0.7451sc=0.139 ppm

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