United States
Environmental Protection
Agency
Office of Air Quality        EMB Report 79-OCM-16
Planning and Standards       February 1981
Research Triangle Park NC 27711
Air
 Synthetic Orgar
                lanyfacturii
Dimethyl Terephthalate
                      eport

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         SOURCE TEST  AT HERCOFINA

        DIMETHYL TEREPHTHALATE PLANT

         WILMINGTON,  NORTH CAROLINA
          Contract No. 68-02-2812

            Work Assignment 54
      Technical Manager:  Winton  Kelly
               Prepared for:

    U.S.  Environmental Protection Agency
 Emission Standards and Engineering Division
         Emission Measurement Branch
 Research  Triangle Park, North Carolina  27711
               Prepared by:

                TRW
ENVIRONMENTAL ENGINEERING DIVISION
             P. O. BOX 13000
 RESEARCH TRIANGLE PARK, N. C. 27709

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                            TABLE OF CONTENTS
Section                                                            Page
 1.0      INTRODUCTION	1-1
 2.0      SUMMARY OF RESULTS	2-1
 3.0      PROCESS DESCRIPTION 	  3-1
 4.0      LOCATION OF SAMPLING POINTS .	4-1
 5.0      TEST PROCEDURES	5-1
          APPENDIX A   COMPLETE RESULTS AND SAMPLE CALCULATIONS
          APPENDIX B   LAB RESULTS
          APPENDIX C   FIELD DATA SHEETS
          APPENDIX D   PROCEDURES
          APPENDIX E   TEST LOG
          APPENDIX F   PROJECT PARTICIPANTS

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                           GLOSSARY OF TERMS

TGNMO - Total Gaseous Non Methane Organics
THC   - Total Hydrocarbon
FID   - Flame lonization Detector
TCD   - Thermal Conductivity Detector
GC    - Gas Chromatograph
ppm   - parts per million
RT    - Retention Time
VOC   - Volatile Organic Compound
CM    - Continuous Monitor
                    SAMPLE IDENTIFICATION GLOSSARY

H - Hereofina Plant
T - TGNMO Sample
B - Integrated Bag Sample
0 - Outlet Location
I - Inlet Location

ex.  HTO - 2 is Hercofina TGNMO sample taken at the outlet 2nd Run.

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                           1.0  INTRODUCTION

     During the period  of November 26 through November 30, 1979, per-
sonnel from TRW Environmental Engineering Division conducted tests of a
Dimethyl Terephthalate plant at Hercofina Inc., Wilmington, North
Carolina.  Personnel from the Environmental  Protection Agency's Emission
Measurement Branch (EPA/EMB) were present to monitor and observe the
testing.  The collection and review of process information during
testing was carried out by personnel from Energy  and  Environmental  Analysis,
Inc.  (EEA), Durham, North Carolina under contract to EPA.
     The purpose of the testing was to obtain and analyze samples to
provide data in support of possible New Source Performance Standards
(NSPS) for synthetic organic chemical manufacturing and to develop
background information regarding carbon adsorption techniques used for
VOC emission control.  Sampling was performed at the inlet and outlet of
the carbon adsorber for the determination of the adsorber efficiencies.
The carbon adsorber serves the "C" line, Dimethyl  Terephthalate (DMT)
oxidation vessel.  Levels of Volatile Organic Compounds (VOC) were
monitored utilizing three differing techniques (TGNMO, Method 25; FID
continuous monitor, and GC/FID total hydrocarbon)  to develop information
for selecting an appropriate testing procedure for this type source.
     The emissions were analyzed for total  hydrocarbons, methyl acetate,
methyl alcohol, benzene, toluene, xylenes,  formic acid and acetic acid.
In addition, the gaseous samples were analyzed for CO^, Op, Np, and CO.
     All of the testing took place at the Hercofina plant in Wilmington,
North Carolina by TRW personnel.  The analysis was also conducted at
this site with the exception of the TGNMO cylinders which were sent to
Pollution Control Science, Inc., Miamisburg, Ohio for analysis.

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     The initial  test request included obtaining  samples  of the  liquid
from the stripping steam condensate.   This  sampling  location was inac-
cessible at the time of the test and  therefore no samples were col-
lected.
                               1-2

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                 2.0  SUMMARY AND DISCUSSION OF RESULTS

     Sampling at the Hereofina plant took place at the inlet and outlet
of the carbon absorber.   Samples were collected by placing a steam
heated manifold at the two locations and extracting three gas streams.
The first stream was pumped through a long length of polypropylene
tubing to the continuous monitoring shed where it was monitored by a
continuous Flame lonization Detector (FID) for total hydrocarbons.   The
second stream was metered into a tedlar bag (EPA Method 110) and provided
a one-hour integrated sample for GC/FID analysis.   The manual procedure
for EPA Method 25 (TGNMO) was utilized on the third stream..  These
samples were taken at the inlet (Figure 2.1, point A) and at the outlet
(Figure 2.1, point B) simultaneously.
     Three sets of samples were taken and are represented graphically in
Figure 2.2.   Both  the inlet and outlet of the absorber are listed.
Carbon absorber bed A and bed B alternated to provide better absorption
efficiencies.  Each bed built up with hydrocarbons and at a certain
level the bed was reactivated with steam purging.   This relationship is
evident graphically in the total hydrocarbon analysis plotted versus
time.  Figure 2.3 represents the integrated bag sample analysis and the
TGNMO analysis.  The relative times these samples were obtained are
shown on the top of Figure 2.2.  The individual component analyses of
the integrated bag samples are presented in Table 2.1.  The TGNMO analysis
is presented in Table 2.2.
     The apparent efficiencies of the carbon absorber are listed in
Table 2.3.  As can be seen from this table, there is a great variation
in results.   The percent moistures are listed below the table which
would account for most of this deviation in the TGNMO analysis.  The
moisture problem is detailed in the sample line problems in Section 5.

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The continuous monitor data has not taken into account the varying
response factors of differing compounds.  The response factors are
calculated in the bag analysis and are presented in Appendix A.
     The data gained from this test shows inconsistency of results
between test runs and test methods.  No attempt was made to determine
the specific reasons for these variations by additional testing and/or
experiments as to the validity of the individual methods used.  The
results as achieved by this one test cannot be used to select and support
an appropriate test procedure for this type source.
                                 2-2

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             TABLE 2.1  GAS ANALYSIS
COMPONENT RUN

METHYL ALCOHOL
METHYL FORMATE
METHYL ACETATE
OTHER
^


[BENZENE
TOLUENE
XYLENE
TOTAL HC PPM

JJM " " .

FIXED GASESC

TOTAL %
HBI - 1

4.90
Q17
632
20


119
982
6736
9411

5.66%

97.10

103.70
HBO - 1

190
Q?l
127
128


6.4
36
385
1793

3.76%

99.73

103.67
HBI - 2d

















HBO - 2

i
0
75?
85
15
i
1
6
34
455
1347

i
3.76%

100.78

104.67
?PPM AS METHANE; SHIMADZU MINI - 2 DUAL FID (POROPAK - Q)
°PPM AS METHANE; SHIMADZU MINI - 1 DUAL FID (SP - 1000)
Ttv/v; SHIMADZU 3BT (MOLECULAR SEIVE, CHROMOSORB 102)
dSAMPLE BAG EXPLODED
                      2-3

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       TABLE 2.1  GAS ANALYSIS (CONTINUED)
COMPONENT RUN

METHYL ALCOHOL
/ METHYL FORMATE
METHYL ACETATE
OTHER
V


{BENZENE
TOLUENE
XYLENE
TOTAL HC PPM

%M >

FIXED GASESC

TOTAL %
HBI - 3

3.8
1921
83.5
1286


63
540
8695
12592

5.0

91.76

98.02
HBO - 3A

206
848
66
181


1.6
0
57
1359.6

2.21

93.11

95.45
HBO - 3B

4.2
396
42
174


31
20
73
740

2.21

99.85

102.13
!
»
i
1

j

I

|









*PPM AS METHANE; SHIMADZU MINI - 2 DUAL FID (POROPAK - Q)
     AS METHANE; SHIMADZU MINI - 1 DUAL FID (SP - 1000)
     , SHIMADZU 3BT (MOLECULAR SEIVE, CHROMOSORB 102)
                      2-4

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       TABLE 2.1  GAS. ANALYSIS (CONTINUED)
COMPONENT RUN

f METHYL ALCOHOL
/ METHYL FORMATE
METHYL ACETATE
OTHER
V


( BENZENE
{ TOLUENE
[ XYLENE
TOTAL HC PPM

%M

FIXED GASESC

TOTAL %
HBI - 4

13.4
324
276
14


58.8
0
304
990.

3.7

94.4

98.2
HBO - 4

94
425
87
12


5.2
10.8
143
777

4.9

92.75

97.73














'





















?PPM AS METHANE; SHIMADZU MINI - 2 DUAL FID (POROPAK - Q)
°PPM AS METHANE; SHIMADZU MINI - 1 DUAL FID (SP - 1000)
c%v/v; SHIMADZU 3BT (MOLECULAR SEIVE, CHROMOSORB 102)
                      2-5

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TABLE 2.2:   TGNMO ANALYSIS
WEIGHTED
PCS
SAMPLE
t
93816
93816
93817
93817
93818
93818
93819
93919
93820
93820
93821
93821

SAMPLE
I.D.
HTI-1
HTI-1
HTO-1
HTO-1
HTI-2
HTI-2
HTO-2
HTO-2
HTI-3
HTI-3
HTO-3
HTO-3
SAMPLE
VOLUME
(L)
3.549
3.990
3.800
3.758
4.092
3.773
3.885
3.671
5.471
5.449
4.684
4.830
PPM TANK
OL AVG.
TRAP PPM Ci
76720 5102
1658 2638
32757 2074
11027 1568
38945 660
1123 762
PPM
Cl
TANK
5906
3165
2106
806
3450
1950
402
920
408

TOTAL
PPM Ci
81838
4307
37288
12595
39605
1885

TOTAL
MG/L q
40.862
2.150
18.618
6.289
19.775
0.941

TANK TRAP
# #
71 ^
% «
77 n
F306 12
F117 9
4
          2-6

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                Table 2.3.   CARBON ABSORBER EFFICIENCIES



Inlet
Outlet
Efficiency (%)
Moisture (%)

Inlet
Outlet
Efficiency (%)
Moisture (%)

Inlet
Outlet
Efficiency (%)
Moisture (%)

Inlet
Outlet
Efficiency (%)
Moisture (%)
N/D - Not detected.
*
TGNMO*

81838
4307
94.7
3.76

37288
12595
66.2
4.35

39605
1885
95.2
5.0

N/S
N/S
N/S
4.3


Bag*
Run #1
9631
1737
82.0
3.76
RUN n
N/D
1370
—
4.35
RUN #3
12634
1145
91.0
5.0
RUN #4
3576
790
77.9
4.3


CONT*

N/D
1037
--
3.76

8036
1019
87.3
4.35

6462
1369
78.8
5.0

7918
1641
79.3
4.3


 All units in ppm as methane.
N/S - Not sampled.
                                 2-7

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ro
i
oo
                                      A )  INLET GAS




1
OX I DAT
REACTO
r
I
rvi
t-SJ
STE/
ION
R
                                                               OUTLET
CARBON ADSORBER

     BED A
                                                 I
HX)
                                                  CARBON ADSORBER

                                                      BED B
                                                                                TO ATMOSPHERE
                                                                               STACK
                   STRIPPING  STEAM
                      CONDENSER
                                                                             \/ CONDENSATE TO
                                                                                 ORGANIC RECOVERY
                                                                                                         CONDENSER
                                                                                                         VENT TO
                                                                                                         ATMOSPHERE
                                  FIGURE 2.1:  Sample Locations, Hereofina Plant

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         •7T    9000-f-
              8000 4-
         S
              7000 +
              6000-f-
              5000-1-
             4000-1-
        -   3000

         c
         10
         Ol
                                    SAMPLE HBI-2
                            14:20
                                                BAG EXPLODED
                                           SAMPLE HBO-2
                                 14:40
                                                              16:50
 IMPROPER

* FLOW "*~
             1000 -f-
(Test Day - 11/28/80)    1/hOO  14:30   15:00  15.:30  16:0tr  16:30
                                       Time (CLOCK)
     FIGURE 2.2:    Inlet  vs Outlet CM/FID  Data  (Run  2)
                                2-9

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(Test Day - Il/30/79)ii2::00        13:00        14:00         15:00        16:00
                                               Time (CLOCK)
    FIGURE 2.2:   Inlet vs  Outlet  CM/FID Data (Run  3  and 4)  (Continued)
                                         2-10

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    9000 - -
o.
D.
    8000 - -
    7000 - -
    6000 - -
    5000 - -
    4000 - -
    3000 - -
    2000 - -
    1000 - -
                HBI-1
        12 00
                   HTI-1  (X 10)
                       HTO-1
                     HBO-1
             HTI-2  (X 10)
                                                       HBO-2
                                                     HTO-2 (X  10)
                                                              +
                     13:00         14:00         15:00         16:00
(Test Day - 11/28/80)
Time (CLOCK)
       FIGURE  2.3:   TGNMO vs  Integrated  Bag  Analysis
                               2-11

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c
+J

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VI

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3.0  PROCESS DESCRIPTION
 (to be supplied by EPA)

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                   4.0  LOCATION OF SAMPLING POINTS

     Sampling locations are presented schematically in the flow diagram
(Figure 2.1).  The locations are described in the following sections:
     •  4.1  Carbon Adsorber Inlet
     •  4.2  Carbon Adsorber Outlet
The sample points are shown specifically in Figure 4.1.

4.1  CARBON ADSORBER INLET
     The carbon adsorber inlet position in the Hercofina process was
located after the oxidation reactor and before the carbon bed systems.
The sample pollutants of interest were defined as those emissions from
the p-xylene and p-methyl toluate oxidation.  The carbon adsorber sample
inlet position (Figure 4.1) diagrams the sample point above the carbon
beds.  This position was on the second level of the process super-
structure beside the top of the carbon beds.  The sample port consisted
of a ball valve port which had to be adapted with teflon tubing to the
sample chamber.  A steam line from the plant process was used to heat
the sampling apparatus initially.  However, sufficient control  of
heating could not be achieved, and tests two, three and four were run
with no sample line heating.

4.2  CARBON ADSORBER OUTLET
     The carbon adsorber outlet in the Hercofina process was located
after the carbon bed system and before the stack.  The sample stream was
defined as the effluent of the carbon adsorption bed of unreacted p-
xylene and low molecular weight hydrocarbons.  This position is dia-
grammed in Figure 4.1 to be located below the carbon absorbers.  The
sample point was a ball valve port from the carbon bed exit pipe which
was approximately five (5) feet from the ground level.  The sample port

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ro
          FROM
          OXIDATION
          REACTOR
                                              q    P
          TO STACK
                                                            CARBON ABSORBERS
                                  STEAMLINE
                                  FROM
                                  PLANT
•OUTLET


  -^.STEAMLINE EXHAUST
                           FIGURE  4.1:   Carbon Absorber  Sample  Positions,. Hercofina Plant

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had to be adapted with teflon tubing to the sample chamber.   A steam
line from the plant process was used for the jacket of coils  on the
sample chamber.  However, sufficient control  of heating could not be
achieved, and tests two, three and four were run with no sample line
heating.
                              4-3

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                 5.0  SAMPLING AND ANALYSIS PROCEDURES

5.1  SAMPLING AND ANALYSIS PROCEDURES
     Three sampling systems were utilized for the detection of VOC's at
the Hereofina plant and are represented schematically in Figure 5.1.
Each system consisted of different modes for the collection of gaseous
sample.  The collection systems were (1) the Integrated Bag Method, (2)
the Manual Sampling Method for EPA Method 25, and (3) the Continuous
Monitor System.  Each of the three systems were installed at the inlet
and outlet of the carbon adsorber.  The sample lines from each system
were connected into a sample chamber (see Figure 5.2) from the sample
location of the inlet and outlet; therefore, permitting the three sys-
tems to sample simultaneously.  A fourth outlet of the sample chamber
was used for the extraction of an EPA Method 4 sample for moisture
determination taken during each run.

5.1.1  Integrated Bag Method (EPA Method 110)
     Figure 5.3 illustrates the sampling apparatus used during testing.
This system was chosen due to the explosion risk and safety requirements
of the plant.  The collection system consisted of a can which seals at a
vacuum of 15" of mercury (Hg), a bag evacuated to 29" Hg, a flowmeter
for metering gas, and teflon tubing to serve as a sample line.
     The procedure was to evacuate the can with the outside self-sealing
valve.  After a vacuum was achieved, the can vacuum would be checked by
placing a vacuum guage on the outside valve and monitoring the pressure.
The can would be considered leak free if less than a 1" Hg pressure
change was observed.  The second step was to evacuate the bag to 29" Hg.
The same leak check was made on the bag as the can.  The flowmeter and
can were then transported to the sample site and connected to the sample
chamber and the sample system fabricated.  The sample valve was opened

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at the appropriate time and the sample extracted from the sample point.
Proper flow was maintained with adjustment of the flowmeter.

5.1.2  Manual Sampling for EPA Method 25
     The manual method for EPA 25 was used in the detection of Total
Gaseous Non-Methane Organics (T6NMO).  This method utilized at Hercofina
is discussed in Attachment 2 of the Guideline Series:  Measurement of
Volatile Organic Compounds (EPA - 450/2-78-041).  The equipment was
prepared and provided by EPA personnel to the TRW field crew before the
test.  The sample system was fabricated in the  TRW    van and trans-
ported to the two sample locations.  The system was connected into the
sample chamber and the valve opened at the appropriate time.  If the
pressure of a sampling tank fell to zero, the tank would be changed
immediately.

5.1.3  Continuous Monitor Flame lonization Detector
     The continuous monitor system was located in a room provided by  the
plant which was located approximately 100 feet from the carbon absorber
inlet and outlet sample locations.  A steam heated sample line from each
sample point was set-up but could not be maintained throughout the test,
due to the high steam temperature.  Therefore, the sample lines were
reconstructed without the steam heated hose for the remaining portion of
the test.  The continuous monitor set-up was according to EPA standards
outline in the EPA document 450/2-78-041.  This system (see Figure 5.1)
utilized two separate FID's for the two sample locations.  A Beckman  402
FID was positioned for analysis of the Carbon Absorber Inlet and a
Horiba FID for the analysis of the Carbon Absorber Outlet.

5.1.4  The Sample Chamber
     The sample chamber was constructed by TRW personnel  before the test
trip.  This chamber was designed (see Figure 5.2) to permit four sam-
pling systems to operate simultaneously at a single point.   This was
accomplished by connecting a line from the sample point into the
chamber; therefore, the sampling systems could be connected into the
chamber at the four outlets and operated simultaneously.   The outlet
allowed for the EPA Method 4 moisture determination train to be capped
                                 5-2

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          FROM
          OXIDATION
          REACTOR
          (POSITIVE PRESSURE)
tn
i
oo
                                                               CARBON ABSORBER BED
                                                 •TGNMO
                         ^-INTEGRATED
                               BAG
                                CONDENSATION
                                   COIL
                      EXHAUST
                                                       LOW SPAN
 BECKMAN
ANALYZER
                                                                   ZERO AIR
                  FLOWMETER
                                                                                       TGNMO*
                                                                                                                       TO
                                                                                                                      STACK
                                                                         (AMBIENT
                                                                         RESSURE).
                                HIGH SPAN
                                                                                                          INTEGRATED-^
                                                                                                            BAG
                                                                                                              PUMP-
             CONDENSATION
                 COIL
 HORIBA
ANALYZER
                                                                                                              EXHAUST
                                    FIGURE  5.1:   Sampling Systems  Schematic, Hercofina Plant

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    en
     i
Sample Line Into A
h" Threaded Pipe —
(On the back side
of sample chamber)
                                                  4  Pipe
                                                  Threaded   8"
1"
4 Pipe
Threaded
                                                                                      1"
                                                                                      •% Pipe Threaded
                                                FIGURE  5.2 :    Sample Chamber

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off whenever this method was not being sampled.  The temperature of the
sample chamber was controlled with a steam line of copper tubing coiled
around the chamber.  The coils were insulated with abestos and sealed
with tape.

5.1.5  Moisture Determination By EPA Method 4
     The Method 4 train was assembled in the sampling van according to
EPA Method 4.  The system was then transported to the sample location
and connected to the sample chamber.  The sample was withdrawn from the
sample chamber for 30 minutes and the data recorded.  The sample was
returned to the van and immediately processed.

5.2  ANALYTICAL PROCEDURES
     The gas emissions from the carbon absorption unit were analyzed for
seven (7) components.  Methyl alcohol, methyl formate, methyl acetate,
Benzene, toluene, ethyl benzene and xylenes.

5.2.1  Integrated Bag Analysis
     A portable gas chromatograph (Shimadzu, Mini 2 Series) was used for
the analysis of low molecular weight (Cj-Cg) compounds.  The gas chro-
matograph was equipped with dual column-FID's for background correction
and a two position gas injection valve.  Separations were accomplished
on a 6' X 1/8" stainless steel analytical column packed with Poropak Q.
Column conditions are listed below:
                Carrier:  Helium, 20 ml/min.
              Oven Temp:  Isothermal at 75°C
          Detector Temp:  175°C
          Injector Temp:  25° 1 ml sample loop

An analyzed gas mixture in nitrogen (Scott Environmental) was used to
establish the retention times of Cj-Cg alkanes.  The retention times as
well as responses of methyl alcohol, methyl formate and methyl acetate
were established by preparing standards of each individual compound at
known concentrations.  Response factors were determined for each com-
pound relative to methane (Appendix B).
                                5-5

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     Probe 5'
Teflon Tubing
From Sample
Chamber
                     Pinch
                         Lid

                   Air Tight
                   Steel Drum
                  Sample Bag
                                           Flowmeter
                                        Directional Needle
                                                Valve  —
                                            V.
                                                                   L=J
                                                ...... ..
                                                         ~ *
         FIGURE 5.3:   Integrated Bag  Sampling System
                            5-6

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     A second GC (Shimadzu, Mini 1 Series) equipped with an FID detector
was used for the analyses of the aromatic compounds, benzene, toluene,
ethyl benzene and xylene.  The column was a 6'  X 1/8" stainless steel
packed with SP-1000 on Supelcoport.  Sample injection was accomplished
with a sample injection valve with a 2 ml sample loop.  Benzene stan-
dards covering the range of 10 to 500 ppm were prepared to check the
detector linearity.  Retention times and response of the substituted
benzenes were established by preparing individual standards.  Concen-
trations were determined by responsive factors related to benzene.
Column conditions are given below:
                Carrier:  Helium, 20 ml/min.
              Oven Temp:  Programmed from 100 to 225°C @ 15°/min.
          Detector Temp:  175°C
          Injector Temp:  25°C

     A third GC (Shimadzu 3BT) equipped with a portable thermal con-
ductivity detector was used for the analyses of formic and acetic acids
and N2, Op, CO, and COp-  Sample injection was accomplished with a gas
injection valve with a 1 ml sample loop.  The column used was a 6' X
1/8" stainless steel packed with 15% SP 1220, 1% H3P04 on Chromosorb
WAW, 100/120 mesh and operated at 30°C isothermally.  Standards for the
organic acids were prepared in-house while the fixed gas standards were
commercially prepared (Scott Environmental).

5.2.2  Total Gaseous Non-Methane Organics Analysis (TGNMO)
     The equipment for the TGNMO (Method 25) sampling was provided by
EPA.  The initial conditions of the tanks and regulators are provided  in
Appendix B.  The tanks and traps were stored after sampling by TRW.  The
traps were transported in dry ice to maintain the low temperature.  The
traps were transported in dry ice to maintain the low temperature.  The
traps and tanks were shipped by TRW to Pollution Control Science, Inc.
(PCS) in Miamisburg, Ohio.  David Robinson of PCS analyzed the samples
according to EPA Method 25 presented in the Guideline Series:  Measure-
ment of Volatile Organic Compounds (EPA-450/2-78-041).  This method is
presented in Appendix D and the results from PCS presented in Section  2.
                                5-7

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5.2.3  Continuous Monitor/Flame lorn'zation Detector Analysis (CM/FID)
     The CM/FID system was set-up based on Attachment 3.   Alternate Test
Method for Direct Measurement of Total  Gaseous Organic .Compounds using
a Flame lonization Analyzer from EPA-450 2-78-041.   This  procedure is
presented in Appendix D and was operated accordingly except for certain
modifications.  These modifications and an overall  schematic of the
CM/FID sample system is presented in Figure 5.1.

5.2.4  Moisture Determination
     The moisture determination runs were conducted and analyzed according
to EPA Method 4.  The field sheets and  calculations are presented in
Appendix C.

5.2.5  Problems Encountered with Analyses
     Two major problems were encountered in the analytical portion of
this test.  The first problem was the result of the analytical  lab being
set-up next to an electrical transformer room.  This caused severe noise
in one of the instruments (see Appendix B).  This made analysis of
samples very slow, hence, some of the samples were preserved and ana-
lyzed upon return to the lab in Raleigh.  The major problem in  this
procedure results from the fact that the sample apparently degrades as a
function of time.
     The second problem was a result of cold ambient temperatures.
Xylene constituents in a sample are affected by temperature, therefore,
to minimize the effect, the samples were kept in a heated room  until
analysis, however, transfer from the sampling point to the analysis room
could have resulted in a loss of xylene.  The xylene standard was kept
in a shed with the continuous FID and the temperature dropped below
freezing during the night.  This resulted in a 93% loss in the  standard
due to the cold temperature.
                               5-8

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