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Monsanto
COMPANY
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W. B. Papageorge
800 N. Lindbergh Boulevard St-Louie. Missouri 63166 (314) OXford 4-t000
May 9, 1973
Mr. Louis DIBello W. R. Grace and Company Cryovac Division
Duncan, South Carolina 29334
'
Re: Task Group for PCB Analysis . on Flexible Barrier Materials -
Sub Committee F2.30
Dear Mr. DiBello:
J Enclosed are the results of our analyses of the four task group samples for polychlorinated biphenyls (PCBs). The samples were analyzed, as requested, using the tentative procedure and our usual laboratory procedure. The Instrumental conditions are shown on attachments I and II.
Comparisons of the Aroclor 1242 and Aroclor 1254 standards sent to us with our standards are shown in Chromatograms I-IV (tentative procedure) and in Chromatograms V-VIII (Monsanto procedure). Minor differences were noted in the homolog distributions of the standards sent vs ours. The Aroclor 1242 and Aroclor 1254 standards sent contained less of the lower chlorinated homologs than ours, as witnessed by ratioingthe early peak areas to the late peak areas. However, these differences were not significant enough to affect
quantitation of the samples.
Shown on attachments III and IV are sample calculations for the
tentative procedure and the Monsanto procedure, respectively. The
tentative procedure calculation was modified to compensate for the . different sample sizes injected into the instrument and our dilution of the sample to 25 ml. These changes were necessary because of the sensitivity of our detectors and the fact that we, as a matter of
practice, use the mid-range of the syringe.
The results of our analyses are summarized in Table I. It appeared that some of sample #4 was lost during shipment. We assumed that the loss was due to volatility, and that the bulk of the PCBs remained in the vial. Chromatograms of the samples are enclosed: IX-XII (tentative procedure), XIII-XVI (Monsanto procedure).
In our opinion, the method of calculation used in the tentative procedure causes a small, but clearly observable, positive bias (see Table I). This bias occurs because the calculation ignores n.l0-25it of the area from the standards. Furthermore, when dealing
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Mr. Louis DIBello May 9, 1973 Page No. 2
with a sample containing only Aroclor 1242, It Is Incorrect to ask how much Aroclor 1254 is present and vice versa. However, when one is clearly dealing with samples which contain detectable levels of more than one Aroclor, splitting the chromatogram into parts is a legitimate means of estimating the total amount of PCBs present.
For a number of good reasons, we also recommend the use of calibra tion curves prepared with one or more of the commercial PCB mixtures (Aroclor) which most closely match the residue, since the suggested ratio technique can, under certain conditions, lead to serious errors.
db Attach.
Very truly yours.
<5~! ^
--
E. S. Tucker US.M W. M. Mees
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ATTACHMENT I
INSTRUMENTAL CONDITIONS ASTM F2.30 Tentative Method for the Analysis of Polychlorinated Biphenyls
Instrument: H&P 5750 Research Gas Chromatograph equipped with a High Temperature N1-63 Electron Capture Detector
Column: 6` X 1/8" Stainless Steel, 10% DC-200 . (12,500 cs) on 80/100 Mesh Chromosorb W H.P.
Column Temp: 260C i^>o
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Injection Temp: ^325*0
Detector Temp: yt%0 '^06
' Carrier Gas: Helium - 60 ml/min Purge Gas: 10% Methane/Argon - 60 ml/min Pulse Interval: 50 nsec Chart Speed: l/2"/min
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ATTACHMENT II
INSTRUMENTAL CONDITIONS Monsanto, Analytical Chemistry Method 71-35
Instrument: H&P 5750 Research Gas Chromatograph equipped with a High Temperature Ni-63 Electron Capture Detector
Column: 2M X 4 mm Glass, 4% XE-60 on 80/100 Mesh Chromosorb W H.P.
Column Temp: 170C - Aroclor 1242 185C - Aroclor 1254
Injection Temp: 220C
Detector Temp: 250C
J
Carrier Gas: Helium - 60 ml/min Purge Gas: 10% Methane/Argon - 60 ml/min Pulse Interval: 50 usee Chart Speed: l/2"/min
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ATTACHMENT III
SAMPLE CALCULATION
'
ASTM F2.30
Tentative Method for the Analysis of Polychlorinated Biphenyls
Aroclor 1242
Arocl or
1254
TFFB #4
Area 96-234 sec 235-888 sec
pt Injected Std cone
1794 659
203 2888
5 p
4 pfc
1.014 pg/mt 0.977pg/mS, j
231 2862
7 pt -
pg Aroclor 1242
1 .014 pq/mS, X 25 ml X 5 ut X 231 1794 X 7 vl
2.3 pg
pg Aroclor 1254
0.977 pq/mS, X 25 X 4 pS, X 2862 _
2888 X 7 vt
"
13.8 pg
Total pg of PCB = 16.1 pg
tr 0777135
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ATTACHMENT IV
SAMPLE CALCULATION
ASTM F2.30
Monsanto, Analytical Chemistry Method 71-35
See Calibration Curve Area of Sample TFFB #4 - 3462 ng of Aroclor 1254 In Sample TFFB #4 from Calibration Curve - 2.9 ng
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Y_m x lOljiA X
X 25 mt = 14.5 pg of Aroclor 1254
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Total pg of PCB = 14.5
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Sample No. 1
2
3 4
TABLE I
Task Group's Tentative Procedure
31.8
31.2
Monsanto Analytical Chemistry Method 71- 35
26.7
26.6
25.6 25.2
35.0 35.5
31.9 30.8
16.7 16.1
14.3 14.5
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