CE 772 29 October 1997

 

MID-TERM EXAM

 

Open Book, Open Notes

 

 

Answer any three of the following four questions:

(each is worth 33%)

 

1. Atomic Absorption Spectrophotometry

Discuss the various steps in preparing and atomizing a sample for analysis by graphite furnace atomic absorption spectrophotometry.

 

 

2. UV-Vis Spectrophotometry

Summarize the types of errors that can be encountered in UV-Vis spectrophotometry. Explain why there exists an optimal range for molecular absorption measurements.

 

 

3. Total Organic Carbon Analysis

Describe three different schemes for distinguishing organic from inorganic carbon using a modern TOC analyzer. Comment on their relative merits.

 

 

4. General

You have made the following measurements using electrothermal AA. These are replicate analyses of the same sample, filtered and unfiltered. The values are in units of g/L. Determine the mean and standard deviation of the particulate iron concentration for this sample.

 

Replicate #

1

2

3

Total Iron

55.6

53.4

57.2

Dissolved Iron

50.3

51.1

52.4