EVALUATING THE QUALITY OF DATA FROM A COMMERCIAL LAB
Youve recently graduated with a bachelors degree in environmental engineering sciences from the University of Florida and got hired by AECOM a multinational engineering firm that provides design consulting and management services. After a few months in your tenure at AECOM the company receives funds to develop a remediation strategy for soil contaminated by high levels of chromium (Cr) copper (Cu) and arsenic (As) due to historic use of woods preserved with a pesticide containing the above listed chemicals – and known as CCA-treated wood. The project requires some basic knowledge of analytical chemistry applied to environmental matrices. Based on your academic transcripts you have been asked to act as Project Manager. However to meet the projects objectives you need the services of commercial laboratories for different analyses you cannot conduct in house. The following is an example scenario you are facing.
Experiments. Your research team has been conducting batch sorption studies to identify efficient sorbent materials for the removal of Cr Cu and As from soil water. Using corroded metallic iron (CMI) particles as example sorbent material experiments mixed contaminated soils with CMI in specific ratios and each treatment conducted in triplicates. Next water was added to the sorbent-soil mixtures to simulate acid rain and to induce metal leaching from soils particles to soil solutions. Leached Cr Cu and As would then get adsorbed onto CMI and at the end of the experimental contact time the CMI particles and metal bound to them retrieved by magnetic separation using magnets. Samples of used soils were taken before and after treatment with CMI and sent to a commercial lab for the determination of the concentrations of Cr Cu and As.
The following is a table of relevant information your research team submitted with the samples to the commercial lab.
Table 3.1. Sample treatment types masses of untreated soils (control) and of CMI-treated soils.
Sample ID
Triplicates
Tested CMI/Soil ratios
(g of CM/g of soil)
Mass of soil submitted for analysis
(g)
Observations
Control
C1
N/A
10
These are non-treated contaminated soils
C2
N/A
10
C3
N/A
10
Treatment-1
T1A
1/20
10
These soils samples were reacted with CMI and after a 2-hour contact time to allow metal adsorption the CMI were retrieved by magnetic separation
T1B
1/20
10
T1C
1/20
10
Traetment-2
T2A
5/20
10
T2B
5/20
10
T2C
5/20
10
Treatment-3
T3A
10/20
10
T3B
10/20
10
T3C
10/20
10
After one week you get the data back from the commercial lab and the report reads as follows (See next page).
VOODOOSCIENCELAB
Michael Reyes Manager
Isabella Robby Analyst
April 16 2017
Dear Customer:
We have completed the analysis of your samples. Please find below the analytical results and relevant quality assurance (QA) and quality control (QC) information. If questions arise please feel free to get in touch with our chemical analysis team.
We appreciate your business and look forward to your patronage in the future.
Sincerely
For the Voodoo Science Lab Team
M.R.
MiChael Reyes
Table 3.2. Concentrations of chromium copper and arsenic in submitted soil samples. All samples were acid digested at sub-boiling temperature for 12 hours diluted with ultrapure water filtered through a 0.45 mm filter membrane to remove solid particles and analyzed by inductively coupled plasma (ICP-MS). A certified reference material was used for verification of digestion recovery efficiency. In addition reagent blanks and standard solutions were analyzed for QA/QC purposes.
Sample ID
Triplicates
Tested CMI to Soil ratios
(g of CM/g of soil)
Chromium
(Cr)
Copper
(Cu)
Arsenic
(As)
Control
C1
N/A
250.21
1122.01
75.89
C2
N/A
275.33
1075.99
81.02
C3
N/A
260.27
1201.22
79.99
Treatment-1
T1A
1/20
100.15
200.12
250.77
T1B
1/20
99.03
201.52
149.88
T1C
1/20
101.78
199.02
151.00
Traetment-2
T2A
1/4
30.22
20.13
415.17
T2B
1/4
31.33
19.71
312.99
T2C
1/4
29.79
18.99
353.45
Treatment-3
T3A
1/2
1.89
8.13
51.03
T3B
1/2
2.05
9.75
62.99
T3C
1/2
1.75
7.01
61.50
QUESTION:
First you need evidence of good quality control/quality assurance (QA/QC) information so you can trust the data. Second you need these results to establish differences between controls and treatments on one hand and between any two of the 3 treatments on the other – so that best experimental conditions can be determined. Therefore based on the above data report:
1. Based on your current knowledge in environmental analysis provide a bulleted list of all flaws you can identify in these results.
2. Write a technical letter (not to exceed 2-pages) to the Commercial Lab to request necessary data and relevant information for an adequate QA/QC evaluation. In your letter and for each one of the requested items clearly state how the latter would be used to help with data interpretation and/or for publication purposes. Be brief and straight to the point. (Hintyou should show that you have a good understanding of the analytical process in general and that you know what it takes in terms of QA/QC for analytical data to be considered acceptable).
