# Intro to Analytical Chemistry and Calibration

Mary Kate DonaisLevelBasic

Intro, Calibration, External Calibration, Standard addition

## Intro to Analytical Chemistry (Video)

Classical methods versus instrumental methods. What is an instrument?## Calibration

General description of instrument calibration.## External Calibration

Description and equations for external calibration.## Standard Addition

Description and equations for standard addition calibration.## Exercise 1

What is Analytical Chemistry1) Analytical methods can be described as…

a. Classical versus instrumental

b. Qualitative versus quantitative

Set up a comparative chart, one side being classical and the other being instrumental. Then provide specific examples of analytical methods based on the readings and your previous experiences as a science student. Thinking about WHY analyses are done may help you in thinking of examples. For each example, be sure to indicate whether it provides qualitative information, quantitative information, or possibly both.

2) Make a block diagram showing the general parts of an instrumental measurement. Then provide a revised version of this diagram for a specific instrument you have working with in one of your science courses. What physical property does this instrument measure? In what domain is the measurement taken? What kind of readout is used for the instrument?

## Exercise 2

Calibration1) External Calibration Example: The following results were obtained when each of a series of standard silver solutions was analyzed by flame atomic absorption spectrometry.

Concentration (ng/mL) 0 5 10 15 20 25 30

Absorbance 0.003 0.127 0.251 0.390 0.498 0.625 0.763

a) Produce a calibration plot for this data. Think about how you would produce a plot if you collected three replicate values for each standard solution.

b) Determine the equation for a linear fit to the data provided.

c) Determine the standard deviation on the slope and the standard deviation on the intercept. From these values calculate the 95% confidence intervals for the slope and intercept.

d) Calculate the silver concentration for a sample giving an absorbance of 0.456 in a single determination. What is the absolute standard deviation on this result (Use equation 1-2)? Report the silver concentration with the correct number of significant figures together with the absolute standard deviation on the result.

e) Calculate the silver concentration for a sample giving absorbance values of 0.308, 0.314, 0.347, and 0.312 in four separate analyses? What is the absolute standard deviation on this result (Use equation 1-2)? Report the silver concentration with the correct number of significant figures together with the absolute standard deviation on the result.