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February 1, 2005
Data Validation for PFOS/PFOA Oakdale Project
(MDH Sample Numbers 200501211-200501219)
Sample receipt: Samples were received in good condition. Samples were delivered directly from the field but were not on ice. Samples were stored at 4C 2C until analysis.
Holding Times: Samples were collected January 25, 2005 and were delivered to the laboratory on January 25, 2005. Analysis of the samples took place on January 27, 2005. The analysis date was within 14 days of sample collection. No data were qualified.
LC/MS/MS Parameters:
HPLC System Mobile Phase Sample Prep
Agilent 1100 Ammonium hydroxide in water, methanol All unknown, calibration, and QC samples were diluted by a factor of two with methanol prior to injection.
Mass Spec Ionization Mode Polarity Transitions Monitored
Micromass Quattro Micro Electrospray Negative PFOS (499>80; 499>99) PFOA (413>369; 413>169)
Method Detection Limit: MDLs of 0.100 ppb for PFOS and of 0.097 ppb for PFOA were determined by the analysis of 12 replicate samples over three days.
Instrument Calibration
Initial Calibration of Method: The PFOS/PFOA method utilizes a six point calibration curve. A new curve is analyzed for each batch of samples. Each calibration level must be accurate within + 20% of the true value, except the lowest calibration point must be within + 30% of the true value.
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Environmental Health Oakdale Project Page 2 of 2
The six-point calibration curve spans a concentration range from 0.25-ug/L to 25-ug/L. Using linear regression with 1/x weighting, the correlation coefficient (r) for PFOS and PFOA were 0.999 and 0.999 respectively. A calibration curve is acceptable if r > 0.990 (r2 > 0.980).
Continuing Calibrations:
Continuing calibration checks are run after a maximum often field samples. Two levels of continuing calibration (0.5 ppb and 10 ppb) are analyzed to verify the curve. Continuing calibration checks must be within 30% accuracy (70% - 130%) of the true value. Two sets of continuing calibration check standards were analyzed with this batch.
Continuing Calibration Results:
Analyte
Spike Amt % Recovery Spike Amt % Recovery
PFOS PFOA
0.5 ppb 0.5 ppb
95 111
10 ppb 10 ppb
117 99
PFOS PFOA
0.5 ppb 0.5 ppb
79 97
10 ppb 10 ppb
123 100
Blanks
Method Blank: PFOS and PFOA were not detected in the method blank at > 4 of the reporting limits. No data were qualified. .
Instrument Blanks: Instrument blanks were run after every sample. PFOS and PFOA were not detected in the instrument blanks at > % of the reporting limits. No carryover was observed.
Trip Blank: PFOS and PFOA (200501218) were not detected in the trip blank at > % of the reporting limits. No data were qualified.
Surrogates: No surrogates were used for this method.
Internal Standards: No internal standards were used for this method.
Environmental Health Oakdale Project Page 3 of 3
Matrix Spikes/Matrix Spike Duplicates: A 500 uL aliquot of each sample was spiked with 10 ppb of PFOS and PFOA after receipt in the laboratory. The recovery must be within + 30%. All matrix spikes were within the acceptable range. PFOS sample spike recoveries ranged from 105% to 116%. PFOA sample spike recoveries ranged from 88% to 113%.
Sample 200501215 (Field ID 105009 - Well #7) was used to generate accuracy and precision data. The spike recoveries for PFOS were 111% and 115% with an RPD of 3.8 %. The spike recoveries for PFOA were 97% and 99% with an RPD of 2.7 %. The recoveries met the QC criteria range of 70% to 130% with an RPD limit of less than 30%.
Laboratory Control Samples/Laboratory Control Sample Duplicates: Laboratory control waters were spiked with PFOS and PFOA for laboratory control samples at a concentration of 8 ppb. The accuracy of the LCS/LCSD samples must be within + 20% and the RPD within 30% to accept the sample batch. The PFOS spike recoveries were 108% and 108% respectively with an RPD of 0.1%. The PFOA spike recoveries were 85% and 88% respectively with an RPD of 3.4%.
Prepared By: Julia Jiang and Paul Swedenborg
William H. Scruton Quality Assurance Officer Minnesota Department of Health Public Health Laboratory Environmental Laboratory
Method 553: PFOS/PFOA
Collected: 1/25/05
Analyzed: 1/27/05
Site: Oakdale
Sample ID Field ID 200501211 105005, E01
PFOS
Dataset
Measured Value
012705sa
ND
200501212 105006, E02 012705sa
ND
200501213 105007, E03 012705sa
ND
200501214 105008, E04 012705sa
1.125
200501215 (duplicate)
105009, E06
012705sa
0.187 0.117
200501216 105010, E07 012705sa 200501217 105011, E08 012705sa
0.936 0.613
200501218 trip blank 200501219 105012, E01
012705sa 012705sa
ND ND
After Spike (%) Reported Oakdale
Spike Recovery Value (ppb) W ell#
10.651
106.5
< 0.5
1
11.131
111.3
< 0.5
2
11.561
115.6
< 0.5
3
12.174
110.5
1.1 5
11.270
110.8
11.629
115.1
<0.5 7
11.982
110.5
0.9 8
12.136
115.2
0.6 9
10.602
106.0
< 0.5
10.486
104.9
< 0.5 Whisp. Oaks
Sample ID Field ID
200501211 200501212 200501213 200501214 200501215 (duplicate) 200501216 200501217 200501218 200501219
105005, E01 105006, E02 105007, E03 105008, E04
105009, E06
105010, E07 105011, E08 trip blank 105012, E01
Dataset
PFOA Measured
Value
012705sa
ND
012705sa
ND
012705sa
ND
012705sa
0.799
0.211
012705sa
0.235
012705sa
0.628
012705sa
0.737
012705sa
ND
012705sa
ND
After Spike (%) Reported Oakdale
Spike Recovery Value (Dob)
11.291
112.9
< 1.0
W ell#
1
11.036
110.4
< 1.0
2
10.737
107.4
< 1.0
3
11.091
102.9
< 1.0
5
9.891
96.8
10.176
99.4
< 1.0
7
9.699
90.7
< 1.0
8
10.247
95.1
< 1.0
9
8.789
87.9
< 1.0
8.859
88.6
< 1.0 Whisp. Oaks
Note: 1. All unknown samples are spiked with 10 ppb of PFOS and PFOA, and the measured value of a certai sample is accepted only if the spike recovery is within 70% to 130%.
2. One sample (200501215) was analyzed twice (laboratory duplicate) and each aliquot
was spiked and analyzed. 3. The report level is 0.5 ppb for PFOS and 1.0 ppb for PFOA. 4. ND: Not Detected
Prepared by Julia Jiang Research Scientist 2/2/2005 Page 1 of 2
