CHM 653
FINAL EXAM
2008
QUESTION #1
A specialty Chemical Company located in Toronto has hired your environmental
consulting company to do some wastewater sampling at their production facility and test
the samples for levels of zinc, phenolics (not 4AAP method) and ATG 17 (no residual
chlorine present). The company wants to determine if they are compliant with the Sewer
–use Bylaw. The production is set up with one batch reactor and one continuous
production process. The wastewaters from both processes are combined prior to
discharge into a large lagoon prior. The wastewater is then discharged to the sewer. The
company wants assurance that proper sampling protocols are followed and that no
degradation of the sample parameters has occurred during the transport of the samples
from the site to the lab.
The company also wants to determine if concentrations of ATG 17 are lower after the
holding time in the lagoon because of their volatility hence causing an air pollution
problem.
They also require that your lab assures them that no extraneous contamination from the
laboratory has occurred during analysis. Analytical results that the company has received
in the past indicate that the zinc levels in the batch process are elevated but the company
questions the reliability of the analyst at that lab. They want assurance that your
analytical data for all parameters is reliable. There is concern that sample matrix might
interfere with all analysis and you are required to check this potential problem.
You decide to run a control that will indicate the percent recovery for ATG 17 only. Your
lab has limited information concerning percent recovery using the special system for
ATG 17 because it is a relatively new piece of equipment in your lab.
A) Write a complete sampling schedule. For marking purposes explain why samples are
combined, kept separate etc. Present the data in a NEATLY PREPARED TABLE OR
CHART as we have done in the class. Include in your answer all the information
required in a sampling protocol. (15)
1
QUESTION #2 (5 marks)
A) Interpret the following set of controls.
Zinc Analysis (ppm)
MDL= 0.1 ppm
CONTROL
SET#1
SET #2
Traveling blank
Traveling Spike (10 ppm)
<0.1
4.8
2.1
6.8
Method Blank
<0.1
0.1
Duplicate
Bottle a
Bottle b
23.9
24.1
32.8
23.7
Replicate (bottle a)
23.6
21.1
Sample Spike (10 ppm)
Bottle a
33.7
27.2
Blank Spike (10 ppm)
5.0
14.1
QUESTION #3 (6 marks)
SHOW ALL YOUR CALCULATIONS
Given the following data calculate the concentration of anthracene (R.T.= 7.10).
Anthracene standard concentration = 1000ug/ml
Type of sample: soil
wet weight = 1.236 g,
dry weight = 0.9886 g
578.8 g of soil extracted, final volume of extract after sample prep steps = 2 ml
20 ul standard injected and 10 ul of sample injected
2
Integrated data of STANDARD
Peak #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Retention Time
1.90
2.40
4.88
5.66
6.21
7.10
9.08
11.30
15.34
17.30
21.90
23.00
26.56
27.56
32.89
Area
921
210
100
100320
213992
312098
510654
210987
390765
421368
89706
76098
125436
319853
21009
Integration data for SAMPLE
Peak #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Retention Time
2.39
5.69
5.99
6.21
6.89
7.15
9.11
11.35
13.88
15.39
17.35
18.56
21.85
22.95
26.53
27.49
30.78
33.00
33.99
41.00
Area
289
10320
23009
213476
12543
32678
5135
67521
1265
976543
21456
9876
8976
7865
1098
19345
324543
87654
9807
8767
3
QUESTION #4
For each of the following situations: i) briefly explain how you would take the sample
ii) what type of sample and sampling equipment used
iii)and briefly explain how the sampling equipment works. (3 marks each)
a)
b)
c)
d)
e)
f)
g)
soil samples to determine the depth of migration
high volume air particulate sample
air sample with water soluble noxious gases
air sample with extremely high conc of organic vapors
lake sediment samples
ATG 16 for continuous process wastewater sample
stratified liquid sample from a 45 gallon drum
QUESTION #5 (2 marks each)
BREIFLY EXPLAIN:
A) why you would use stratified vs. non stratified sampling protocols
B) why you would use high volume vs. low volume air sampling protocols
C) why you would use plain filter paper vs. sorbent filter paper for air sampling
D) why you add preservatives to the sample
E) why you would implement a blind sample in the analytical run
F) what a background sample is and what is it used for.
QUESTION #6
Name and describe the principle/operation for 2 methods used to concentrate VOCs in
aqueous samples. (6)
QUESTION #7
List the 3 most common column clean-up principles and explain the theory for each. (9)
4
QUESTION # 8 Analysis of Whale Blubber for Environmental Contaminants
(20 marks)
1) A weighed blubber sample (10.2372g) is cut into small pieces and placed in a mortar
and pestle along with sodium sulfate for the first step in processing.
2) The sample was transferred to the thimble in the Soxhlet apparatus and refluxed with
hexane for 4 hours.
3) Nitrogen was bubbled through the sample to a volume of 1 mL.
4) The sample was then applied to a gel permeation column and eluted with hexane.
5) The first fraction was evaporated to dryness. The residue was weighed and then this
part of the sample was discarded and the second fraction was placed in a container and
nitrogen was bubbled through the sample to a volume of 1 mL.
6) The sample was applied to a silica gel containing a top layer of sodium sulfate.
7) The column was eluted with 30 mL of hexane and the fraction was collected. This
fractioned contained the PCBs.
8) The column was then eluted with a 30 mL of a 1:1 mixture of pentane and
dichloromethane. This fraction was collected and contains the DDT and other organochlorinated pesticides.
9) Both fractions were reduced in volume to 1 mL and analyzed by GC.
10) The results from the chromatogram indicate sample concentrations of PCBs at 22.3
ppb and the sample concentration of DDT at 12.9 ppb. What are the concentrations of
PCB and DDT in the bubbler (ug/g) Show all your calculations. (6)
For each of the numbered steps above explain the theory that applies and which 1 of
the 3 sample preparation steps is involved (if applicable) (20)
QUESTION #9
Explain the operation of the Soxhlet apparatus, its’ purpose and the advantages of this
method versus tradition methods. (4)
5
QUESTION #10
BRIEFLY explain each of the following
a) solid phase extraction (2)
b) isolating metals from sample using a chelating agent (3)
c) purpose of each step involved in sample preparation (3)
6