# (a) Interpretation: Retention time for cinnamaldehyde should be determined using Figure b. Concept introduction: The retention time of a substance can be determined using the chromatogram. The distance between the starting position (0) and the peak of the interested substance. From the x-axis of the chromatogram, retention time of the interested substance can be determined. ### Principles of Instrumental Analysis

7th Edition
Douglas A. Skoog + 2 others
Publisher: Cengage Learning
ISBN: 9781305577213 ### Principles of Instrumental Analysis

7th Edition
Douglas A. Skoog + 2 others
Publisher: Cengage Learning
ISBN: 9781305577213

#### Solutions

Chapter 27, Problem 27.30QAP
Interpretation Introduction

## (a)Interpretation:Retention time for cinnamaldehyde should be determined using Figure b.Concept introduction:The retention time of a substance can be determined using the chromatogram. The distance between the starting position (0) and the peak of the interested substance. From the x-axis of the chromatogram, retention time of the interested substance can be determined.

Interpretation Introduction

### (b)Interpretation:Number of theoretical plates should be calculated using Figure b.Concept introduction:N=16(tRW)2where:N=Number of platestR=Retention timeW=Width of peak base

Interpretation Introduction

### (c)Interpretation:Plate height should be calculated using the information in part a and b.Concept introduction:Plate height can be calculated using the following equation.H=LNwhere:H=Plate heightL=Length of column packingN=Number of plates

Interpretation Introduction

### (d)Interpretation:Calibration curves should be plotted for cinnamaldehyde, eugenol, and thymol. The R2 values for each compound also should be determined.Concept introduction:Standard addition method is an analytical method used in quantitative analysis of unknown samples. Calibration curves can be plotted, concentration vs relative peak area. That plot can be used to determine the unknown sample concentration.

Interpretation Introduction

### (e)Interpretation:Sensitivity levels of the calibration curves should be determined, as highest and lowest.Concept introduction:Linear regression R2 can be used to determine the linearity between two variables, with regard to this question the sensitivity of the calibration curve can be determined by the R2 value.

Interpretation Introduction

### (f)Interpretation:Concentrations of each component in the sample should be calculated. Then the standard deviation also should be calculated.Concept introduction:The equation obtained from the calibration curve in part d can be used in the calculation of concentrations of unknown samples.yCinnamaldehyde = 1.7077x − 0.2074yEugenol = 1.0906x − 0.0741yThymol = 2.2094x + 0.2925Standard devation (s)=∑i=1N(xi−x)2N−1Where:xi=concentration of interested substancex=Mean concentration of interested substance N=Number of samples

Interpretation Introduction

### (g)Interpretation:The statistical effect should be calculated for the decomposition of cinnamaldehyde with the temperature.Concept introduction:Analysis of variance (ANOVA) test can be done in order to determine whether there is a statistical effect on temperature for the decomposition of cinnamaldehyde.

Interpretation Introduction

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