Chapter 14, Problem 14.19QAP

Interpretation Introduction

(a)

Interpretation:

The standard addition plot should be constructed.

Concept introduction:

Standard addition method is used to analyze complex samples which matrix effect is significant. One common approach is standard addition technique is spiking of sample. In this method, one or more increments of a standard solution is added to the several aliquots of sample containing same volume. Each solution is then diluted to a fixed volume and experiment is proceeded.

Interpretation Introduction

(b)

Interpretation:

The slope and the intercept should be determined.

Concept introduction:

$\begin{array}{l}{S}_{yy}={\displaystyle \sum {\left(y_i-\overline{y}\right)}^2}\\ S_{xx}={\displaystyle \sum {\left(x_i-\overline{x}\right)}^2}\\ S_{xy}={\displaystyle \sum \left(x_i-\overline{x}\right)}\left(y_i-\overline{y}\right)\end{array}$

The slope of the line, $m=\frac{S_{xy}}{S_{xx}}$

The intercept, $b=\overline{y}-m\overline{x}$

Interpretation Introduction

(c)

Interpretation:

The standard deviation of the slope and the intercept should be determined.

Concept introduction:

Standard deviation about regression, $s_r=\sqrt{\frac{S_{yy}-m^2{S}_{xx}}{N-2}}$

N − number of points used.

The standard deviation of the slope, $s_m=\sqrt{\frac{s_r^2}{S_{xx}}}$

The standard deviation of the intercept, $s_b=s_r\sqrt{\frac{{\displaystyle \sum x_i^2}}{N{\displaystyle \sum x_i^2}-{\left({\displaystyle \sum x_i}\right)}^2}}$

Interpretation Introduction

(d)

Interpretation:

The concentration of Pd(II) in the analyte solution should be determined.

Concept introduction:

Concentration of the analyte in the sample can be determined by the data obtained from standard-addition method and using following formula.

$C_x=\frac{b{C}_s}{m{V}_x}$

C_x − concentration of unknown sample

b- intercept

C_s − concentration of the standard sample

m − slope

V_x−volume of unknown sample.

Interpretation Introduction

(e)

Interpretation:

The standard deviation of measured concentration should be determined.

Concept introduction:

$s_C=C_x\sqrt{{\left(\frac{S_m}{m}\right)}^2+{\left(\frac{S_b}{b}\right)}^2}$