MARCH 3, 1988

	SECTION	REV	DATE
1	SCOPE AND APPLICATION	0	2-88
II	SAFETY AND WASTE HANDLING	0	2-88
III	SUMMARY OF METHOD	0	2-88
IV	SAMPLE HANDLING AND PRESERVATION	0	2-88
V	INTERFERENCES	0	2-88
VI	APPARATUS	0	2-88
VII	REAGENTS	0	2-88
VIII	PROCEDURE	0	2-88
IX	QUANTITATION CALCULATION	0	2-88
X	QUALITY ASSURANCE	0	2-88
XI	INSTRUMENT MAINTENANCE AND TROUBLESHOOTING	0	2-88
	REFERENCES	0	2-88
ATTACHMENTS, TABLES, AND FIGURES
ATTACHMENT I.............................. Photovac 10S10 Portable GasChromatograph and Recorder Operation
ATTACHMENT II.............................Calculation of Air Standard Concentrations
TABLE I.............................................MDL Study Results
TABLE II...........................................Additional Detectable Compounds
TABLE III................................. ........Calibration Curve Parameters
TABLE IV..........................................Trouble Shooting Items
FIGURE I...........................................GAS SAMPLING BULB

STANDARD OPERATING PROCEDURE FOR MANUAL ANALYSIS OF AMBIENT AIR FOR

SELECTED VOLATILE ORGANIC COMPOUNDS BY A PORTABLE GAS CHROMATOGRAPH

1.0 SCOPE AND APPLICATION

This method is used for determining the amount of selected volatile organic compounds (VOC's) in grab samples of air. It is dependent on the target compound being detectable by a photoionization detector (PID) incorporated in the Photovac gas chromatograph (GC) 10S series instrument.

THIS METHOD PRESUPPOSES THE USER HAS PRIOR OR INDEPENDENT KNOWLEDGE (OR THAT A HIGH PROBABILITY EXISTS) OF THE IDENTITY OF SPECIFIC VOC's TO BE DETERMINED AT A SITE, SO THAT THE INSTRUMENT CAN BE CALIBRATED FOR THESE VOC's PRIOR TO USE.

Unambiquous identification of presumptively identified VOC's at a site requires reference to an additional analytical system, because this Photovac instrument uses only one chromatography column and non-specific detector at a time. Possible tentative identification of other unknown VOC's with this Photovac system requires the user to have independent knowledge of the retention time order of VOC's not used for instrument calibration, for the specific chromatography column being used. The ionization potential of a molecule must generally be less than the ionizing energy produced by the PID in order for it to be detected. Aromatic and unsaturated molecules are usually detectable by  The PID. However, other types of molecules may also demonstrate

detectability. Although other compounds may be measurable by this method, the following ones are known to be detectable in air and are used as illustrative examples for calibration of the instrument. They are: vinyl chloride, methylene chloride, trans- 1,2 - dichloroethylene, benzene, trichloroethylene and toluene. The sensitivity of these compounds vary, but the method covers a range of 0.05 ppm (V/V) to 10 ppm (V/V) easily. The detection limits in air for this method are listed in Table I. Any program that requires rapid identification and quantitation of a known group of analytes that are detectable by this instrument could use this procedure in general. However modifications in instrument parameters and analytical column would need to be made to address the need at hand.

A list of some compounds that are detectable by this instrument is attached in Table II. Only personnel trained in the operation and calibration of the Photovac GC as well as the interpretation of the raw data should use this method. Training in the use of this method is the responsibility of the Central Regional Laboratory, Region V, U.S. EPA.

II. SAFETY AND WASTE HANDLING

Good laboratory practices should be the guide in field use of the Photovac GC, standard materials, injection syringes, compressed air, and samples. The exit port of the detector will need to be vented via tubing away from the analytical area so as not to allow standard compounds or contaminants to come into the breathing zone of the analyst and coworkers. Disposal of the remains of air samples from Tedlar bags and sampling bulbs could be done by drawing them through a large charcoal trap or other sorbant material known to retain the compounds of interest. The traps can then be disposed of in a proper fashion. Another safety consideration is handling the compressed air carrier gas. The Photovac lOS10 has an internal reservoir which can be filled via a special high pressure gas filling tube supplied by the manufacturer. It is made specifically for the instrument and must not be altered in any way. The contents gauge should read 1600 psi when the reservoir is filled but must not exceed 1800 psi. The pressure relief valve on the filling tube should prevent this from happening. A further safety measure is a rupture disc inside the instrument which is rated at 3200 psi.

III.SUMMARY OF METHOD

Aliquots of air up to 2 millilites are analyzed using a Photovac 10510 GC with a PID and a portable strip chart recorder.  The GC system can only be operated at ambient temperatures which are recommended to be in a range from 55 F to 900 F. It is important that a proper field environment be provided in order to minimize temperature fluctuation as much as possible. The only gas necessary for operation is compressed air as the carrier gas. It should be zero grade or better. The GC is calibrated using methanolic solutions of the target compounds at three concentrations. Retention time (RT) windows as well as calibration factors (CF) are calculated for each VOC compound. RT's are used for compound identification and CF's are used in quantitating compounds. During the analysis frequent single concentration level calibrations are performed to update RT's and check the fluctuation Of CF's- This information is used to determine if the systems can be used for continuing analyses or requires re-calibration or maintenance. Analytical samples are directly injected into the GC system and results are compared to the standard injection. The amount injected can be varied from 10 ul to 2 ml. depending on the contaminant levels.

IV. SAMPLE HANDLING AND PRESERVATION

Samples may be collected in Tedlar bags that have not been previously used by placing the bag in a rigid vessel, such as a vacuum desicator, and removing the air. Ambient air can then be allowed to fill the vessel at the sampling point. A glass vessel for gas sampling may also be used (Figure 1). It is mandatory that a pump be used to draw air into the vessel (downstream) instead of pushing air into it (upstream). This avoids contamination from the pump or tubing used with it. Finally, a gas tight syringe may be used to collect a small sample of air, if it is to be analyzed immediately. No preservation is necessary since the samples should be analyzed as soon as possible. If the samples are to be held for several hours, they should be kept out of the light to insure that photodecomposition does not occur depending on the target compounds.

V. INTERFERENCES

Many compounds that volatilize in ambient air may be detectable by a PID at widely different concentration levels. Although a chromatographic column may separate compounds according to chemical and physical traits, there is the likelihood that several compounds, if present, could coelute. If this happens to a target compound, an interference occurs.

There may be only partial interferences with a target compound as evidenced by an elevated baseline or peak shape. In such a case its identity and quantity may still be determined depending on the severity of the problem. The data may need to be qualified as "estimated". In such a situation an experienced chromatographer should be consulted.

VI. APPARATUS

1. Photovac lOS10 gas chromatograph with a 4 foot length by 1/8 inch diameter Teflon column packed with 5% SE-30 on 100/120 mesh chromosorb G-AW.

2. Linear Instruments portable single pen strip chart recorder -Model 142.

3. Various sizes of gas sampling bulbs from 1 liter to 125 ml.

4. Small portable vacuum pump.

5. One liter Tedlar bags with closures.

6. Large vacuum desicator or rigid vessel for collecting samples in Tedlar bags.

7. Various sizes of gas tight syringes from 0.1 ml to 2.0 ml as those supplied by Precision Scientific Co.

8. Liquid syringes from 1.0 ml to 10.0 ul capacity.

9. Lecture size bottles of zero grade or better compressed air.

10. Ruler capable of measuring in millimeter and pocket calculator with standard deviation functions.

VII. REAGENTS

1. Stock standards of target VOC compounds in methanol in 5,000 to 10,000 ug/ml range.

2. Methanol - reagent grade.

VIII.PROCEDURE

The general procedure for settling up the Photovac lOS10 and the recorder is given in Attachment I. The GC conditions are given as a  column flow rate of 25 ml/min through injector #1 and a gain of 50. An initial three point calibration curve is performed to determine a RT window and CF values for target compounds under field conditions. Four of the six target compounds are in a methanol solution so they may be injected simultaneously. They are trans - 1,2 - dichloroethylene, benzene, trichloro-ethylene, and toluene. Table III gives the amounts of the solutions to inject into a 0.5 liter gas sampling bulb to generate the curve. Their concentrations are also given. Allow at least 5 minutes for the solution to vaporize and diffusion in the bulb to occur. A 0.5 ml injection of the increasingly concentrated air standard is made to generate each data point. A similar calibration is carried out for vinyl chloride and methylene chloride simultaneously. However, each is added to the bulb separately. Their amounts and concentrations are also in Table II.

Mixtures of target compounds should be made in the laboratory before going into the field. However, if individual components need to be calibrated at a different level in the field, Attachment II describes a calculation for determining concentrations of components in air.

Before each use the sampling bulb must be purged for at least 5 minutes by drawing clean air through it or by using air from a compressed air cylinder. Also, the 2.0 ml gas tight syringe used for injection should be pumped several times in clean air before each use. To make the 0.5 ml injection, draw about 1 ml of air-standard from the bulb and with the needle still in the bulb depress the plunger to the 0.5 ml mark. Withdraw the syringe and place the needle immediately in the #1 injection port of the GC. Push the needle all the way in until the shoulder of the syringe stops it. Inject in one snappy continuous motion and make a mark on the strip chart to show the injection start time. Since methanol and 2-propanol have been used as the solvent for the target compounds, a broad hump or even an offscale peak may appear near the RT of toluene. These disturbances should be allowed to subside to near the original baseline before another injection is made. This should be in about 20 minutes or less at about 65' F to 700 F ambient temperature.

After all calibration data is gathered, the individual Rt's are calculated by measuring from the injection mark to the apex of the individual peaks in millimeters. A +/- 5% window can then be assigned to the average Rt. The C_F values are calculated using the following equation:

C_F =      Peak height    

          ppb (V/V) of std.

long with the standard The mean C_F ( F) is calculated for each compound a deviation. The percent relative standard deviation is calculated for each compound with:

% RSD = S.D. X 100

                  C_F

The % RSD should be less than 20% for each compound. If it is not, prepare another standard at the level which showed the largest difference from the C_F for that compound and reinject. Recalculate using the new C_F value. If the %RSD is still greater than 20%, consider the quantitation of this compound as estimated. The mid-level calibration should be done after every four samples or after any long delays in analysis in order to update RT windows and check the useability of the calibration curve. The C_F's calculated from this continuing calibration are used to calculate the percent difference from the three point curve using:

% D = C_F - C_F X 100

                C_F

If % D is greater than 30%, a new three point curve must be performed to establish good quantitation.

If % D is less than 30%, the EF- established from the initial calibration curve may still be used. if peak heights decrease during the course of analysis using a fresh standard, the battery may need charging or  a leak may have developed in the GC column fittings, septum, or in the syringe.

Check the battery charge, replace the septum, and check the column fittings so that they are finger tight. Reinject and examine the responses. If it is still not responding properly, change the syringe and try again. Also, change the septum in the sampling bulb. A change in flow rate and ambient temperature may also cause fluctuations in peak height. Before analysis, inject a sample of clean air from a bulb that has been purged. This will check the syringe and total system for contaminants.

Analysis of an aliquot of an air sample may now begin. If the sample is known to large VOC concentrations an injection volume much less than the 0.5 ml standard injection should be used. Start with a 50 ul injection. Any peaks found should have their RT's compared to the RT listed for that compound. If it falls within the +/-5% window, a tentative identification exists.

IX. QUANTITATION CALCULATIONS

The measured peak height in millimeters must be within the range of the calibration curve peak heights for

proper quantitation. If it is, the following formula is used to quantitate the concentration:

C(ppb) =        peak height of sample X amt. of std. injection (ul)   

                  C_F for the identified std.      amt. of sample injection (ul)

For example, by injecting 50 ul of air sample with a C_F of 0.058 and assuming a peak height would be:

C (ppb) = 30 mm X   500 ul

            0.58mm/ppb    50 ul

C (ppb) = 5,120 or 5.1 ppm (V/V)

Detection limits are based on a 1 ml injection. If no peaks are seen with a 50 ul injection, up to a 1 ml injection should be made. If no compounds are seen with a 1 ml injection and no interferences are present that would compromise their identification, the detection limit value would be used as listed to quantitate the compounds. The sampling bulb should be purged with clean air for five minutes before reuse. If a very high positive response has been seen using the bulb, a blank should be injected from it after cleaning to insure it is suitable for reuse.

X. QUALITY ASSURANCE

Consideration of sample integrity, method monitoring, and record keeping needs to be made as parts of a quality assurance program. Precautions should be taken to assure that a sample is not contaminated by the vessel in which it is collected or by the injection syringe. Clean air, either ambient air filtered through a sorbient material or from a compressed air cylinder, should be used to decontaminate any vessel or syringe that has been used for sampling. This step is alleviated by using Tedlar bags only once for the sample collection vessel.

After purging with clean air for 5 minutes, inject 1 ml of the air contained in the bulb as a blank to determine if the vessel is suitable for continued use. If peaks are seen that will interfere with analysis, continue the purging process and try again. This should always be done before analysis begins and after any positive hits prior to the next analysis of a sample. Monitoring the method and the system ruy be done by injection of the mid level calibration standard that is freshly prepared after every four injections or an extended period of delay between analyses. The % D is checked to assure good quantitation and the retention times are checked and updated to account for the possible changes in the instrumental environment that may lead to incorrect identification of compounds. This is done as stated in the calibration procedures. Record keeping is important in accounting for analytical data collected in the field and to allow for further consideration of data validity. Chromatograms should be labeled with a date, sample description and number, amount injected, instrument gain, and analyst's initials.

All problems relating to the operation and analysis must be kept in a notebook. All analytical events must be traceable and linked to the chromatographic data. All of the above tasks must be considered and done even if the data quality objective is only to identify the presence or absence of a target compound.

XI. INSTRUMENT MAINTENANCE AND TROUBLESHOOTING

If the GC and recorder are to be used with battery power, the charge should be checked before going into the field and all recharging instructions should be followed in the manufacturer's manuals. A proper supply of expendable items such as chart paper and pens, septa for GC and bulbs, syringes, sampling bulbs an even an extra GC column should be taken into the field. Also, extra cylinders of compressed air and regulators should be taken. As stated in Attachment I, air should continuously flow through the column at a low rate, especially in the field. Since the column is Teflon and therefore somewhat permeable, exposure to a contaminated atmosphere will allow some contaiminats to collect on the packing material. A carrier gas flow will continually sweep them from the column and prevent a build up.

The GC septum should be changed after every 10 to 15 injections to minimize the change of leakage at the injection port. This is one of the first things to check if calibration standards suddenly loose sensitivity or there are large variations noticed from one injection to another. All sampling bulb septa should be changed after every 5 to 10 injections. The column connections should be finger tight. This should also be checked if a leak is suspected.  The syringe should be checked for leaks at the removeable needle connection by injecting air while holding part of the syringe submerged in clean water. This will also check to see if an injection is actuall being made by observir?g any bubbles coming out of the needle tip. If the needle is clogged, simply change it.The instrument will operate out its optimum, if it is located in a stable temperature environment. Retention times will remain stable and fewer continuing calibrations will be needed.

Table IV has a list of common troubleshooting items and their probable cause.

REFERENCES

Photovac 10S10 Operator's Manual Linear Instruments Model 142 Operator's Manual "Ambient Monitoring for Specific Volatile Organics Using a Sensitive Portable PID GC", Spittler, T.M.

 

ATTACHMENT I

Photovac lOS10 Portable Gas Chromatograph

The Photovac IOS10 is a self contained portable gas chromatograph (GC) approximately 18"Xl3"X6". It can be operated at ambient temperatures either by external 115 volt AC power or internal battery power for up to eight hours before recharging. The operating temperature range is between 50F (100C) and 100F (38C). There are two analytical columns attached to one photoionization detector via a two-way valve. All of this is located beneath the electronic panel in the center of the instrument. . Two flow controllers regulate the carrier gas which is compressed air. The carrier gas can come from an external tank or from a refillable internal tank. Two pressure gauges are mounted on the instrument to monitor the gas used.

Set Up

Gas Connections

1. External

There is one quick disconnect port for a 1/8 inch stainless gas line which can be attached to the regulator of a lecture sized bottle of compressed air. Set the secondary gauge on the regulator to 40 psi and open the inlet valve to allow the gas to flow into the GC. Reset the gauge to 40 psi if necessary and note that the delivery gauge on the GC will finally indicate 40 psi also.

2. Internal

Compressed air is put into the reservoir via a high pressure filling slation hose from a large cylinder. The contents pressure gage should be at about 1600 psi when the reservoir is filled. This should be enough for eight hours of operation.

Both internal and external gas supplies are regulated with the two flow controllers attached to each column of the instrument. Counterclockwise turning deceases the flows in each column. The flow rate should be kept at 10 ml/min even when the column is not in use as a method of keeping the   columns free of contamination. The port labelled "detector out" may be connected to a flow meter to determine the flow rate through the column as the flow controller are adjusted. The flow in each column in turn may be measured by turning the flow diverter valve located under the mid compartment 90 degrees to allow gas flow to each column.

Electrical Connections

For external power operation connect power cord from instrument receptacle to an AC outlet. Internal battery powered operation requires only the power on" button be depressed. The recorder plug goes from the recorder outlet on the instrument to the recorder with the two pronged plug placed so that the pen on the recorder remains at the left side of the strip chart when it is in operation.

Start Up

With the carrier gas flowing through a column at the desired flow rate (40cc/min for SE-30 column and locc/min for CSP-20m column) for 20 t 0 30 minutes, press the "power on" button. If the power is AC, black bars above the AC mark on the LCD screen will appear. Press the "Diagnostics Batt" button. Black bars should appear at the top of the screen and extend into the "check" range. If it does not, the battery will need charging for off line work. If changing the battery is desired, press the "charge on" key and the LCD will indicate "charge". Keep this on for about 12 hours then press "charge off"'. The gain may now be put on the desired setting dicatated by the method and the amount of sensitivity needed. Black bars appearing at the top of the screen indicate the level of background seen by the detector. The offset knob can be used to reduce the background to an acceptable level. The bars should not extent more then 10 to 20 percent of the distance accross the screen. The bars also will appear as a component elutes into the detector. The initial gain setting is 50.

The recorder should be operated on the I volt full scale setting with the attenuator off. Keeping the zero switch on the recorder depressed, adjust the zero knob until the penh is at about the 5 unit line on the paper. Release the switch and readjust the pen position with the offset knob.

The background may fluctuate causing the pen to drift up or down. This may be adjusted with the offset knob to keep the pen on scale. The chart speed should be set to 0.5 cm/min. The system is now operational for analysis of air or vapor samples ONLY.

 

ATTACHMENT II

The following formula is used to calculate the concentration of each component in the air mixture:

C =                 m                 

       (4. 1 X 10^-8) X M X V

    C is the concentration of compound in air in ppm (V/V)

    m is the mass of compound added to bulb in grams.

    M is the molecular weight of the compound in a.m.u.

    V is the volume of the sampling bulb in liters.

    4.1 X 10-8 is the number of moles, derived from the ideal gas equation, for 1 ul of gas.

 

For example, if 1 ul of 10,000 ug/ml solution of benzene is added to 500 ml of air, what will be its concentration? 10,000 ug/MI is 10 ug/ul therefore,

C =             10 X 10^-6 g  

     4.1 x l0 ^-8 X 78 X 0.5 liters

C = 0.062 ppm (62ppb) of benzene

TABLE I

Compound	MDL (ppb) (V/V) in Air
Vinyl chloride	7.0
Methylene chloride	240.
Trans - 1,2 - dichloroethylene	21
Benzene	25
Trichloroethylene	23
Toluene	55

MDL's were determined using microliterquantities of methonolic solutions of the compounds injected into a 0.5 liter gas sampling bulb. A 1 milli-liter injection was made at a gain of 50 and aflow rate of 25 ml/min. They are based on statistical estimates of seven replicate determinations.

 

TABLE II

Additional Detectable Compounds

RELATIVE RETENTION TIMES (Relative to Benzene)

ON SE-30 COLUMN

COMPOUND	RELATIVE RETENTION TIME	SHAPE OF PEAK
Benzene	1.0000	A
Diethylether	0.5082	B
Chloroform	0.6557	A
Toluene	2.4426	B
DMDS	1.9911	B
Ethylmercaptan	0.3182	A
TBM	0.5455	A
n-Hexane	0.6084	A
2,4-dimethylpentane	0.8182	A
2,3-dimethylpentane	1.1818	B
2,2,4-trimethylpentane	1.3182	B
n-Heptane	1.4545	B
2,4 & 2,5-dimethylhexane	2.0909	C
2,3,4-trimethylpentane	3.5000	C
n-octane	3.3521	C
p-cymene	6.1220	C
Cis-1,2-Dichloroethylene	---	--
Tetrachloroethylene	---	--
Ethyl Benzene	---	--
Dichlorobromo Methane	---	--
Chlorodibromo Methane	---	--
o-xylene	---	--

A - sharp symmetric peak

B - broad peak shape

C - broad and skew peak shape

 

TABLE III

Example calculations of VOC standard concentrations for calibration curve. A. Amounts of standard mixture solution to be used for calibration curve. Standard mixture solution contains 115 ug/ml trans-1,2-dichloroethene, 250  ug/ml benzene, 250 ug/ml trichloroethene, and 500 ug/ml toluene. Amounts  of standard mixture are added to a 0.5 liter bulb - 0.5 ml is then injected  in Photovac GC.

	Amount of Standard Mixture (Resulting VOC conc. in 0.5 liter bulb (ppb-V/V))
	1 ul	2 ul	4 ul
Trans-1,2-dichloroethene	58	116	232
Benzene	156	312	624
Trichloroethene	94	188	376
Toluene	266	532	1064

B. Amounts of individual standard solutions to be used for calibration  curve. One standard solution contains 450 ug/ml vinyl chloride, and   one has 10,000 ug/ml methylene chloride. Each standard solution is  added to a 0.5 liter bulb - 0.5 ml is then injected in Photovac GC.

	Amount of Standard Solution (Resulting VOC conc. In 0.5 liter bulb (ppb-V/V))
	0.2 ul	0.5 ul	0.8 ul	1.0 ul	1.5 ul	1.6 ul
Vinyl Chloride	70	---	280	---	---	560
Methylene Chloride	---	2900	---	5800	8700	---

 

Table IV

Problem	Probable Cause	Remedy
Air cylinder runs out too fast	a) Flow rate is high	Check flow. As a guide, cylinder charged to 1600 psi should last easily 2 days at flow rate 10 mL/min
	b) Leak	Check o-ring between cylinder/regu- lator. Check all external fittings with sparing application of soap solution. Check septum by changinginjection port fitting. Tighten/re-flange.
Batteries run out too fast	a) Inadequate charge	Charge overnight on high and try again.
	b) Electronic problem	Requires skilled service.
Peaks eluting too fast	a) Flow rate too high	Reduce.
	b) Improper column choice	Consult Photovac and/or try a different column
Peaks eluting too slowly	a) Flow is too slow.	Increase.
	b) Possible leak at septum or Column to injection port fitting.	Same remedy as for No Flow.
	c) Improper column choice	Consult Photovac and/or try a different column
Baseline drifts constantly and unacceptably up or down.	a) Unit is undergoing acclimatiz-ation to a large    temperaturechange	Allow to stabilize, move to more equitable temperature zone e.g. into shade.
	b) Column is recovering from earlier contamination	Allow to stabilize with accelerated flow, remove and replace column with newly-conditioned one.
	c) At each injection, a portion of some heavy contaminant is being inadvertently added.	This shows up as a step-wise baseline increment with each successive injec- tion. Use faster chromatography or consider adding backflush option. Sometimes caused by dirty syringe.
	d) If carrier gas has just been changed, possibility new batch is contaminated.	Switch to alternate carrier.
Baseline constantly drifts up, down during chomatography. The effect is slow, takes place over a space of three to ten minutes.	Peaks are appearing from earlier injection(s) and interfering with current analysis.	Allow to stabilize, so as to confirm diagnosis. Consider either speeding up the chromatography or addition of backflush option. Sometimes caused by contaminated syringe.
Baseline moves up and down with a regular pulsation every 1 minute or so.	Flowmeter left hooked up to vent.	Did you forget?
No flow of carrier measured at vent even though 40 psi is indicated on delivery gauge.	a) Septum leak.	Tighten retainer and check flow.
	b) Leak at column to injection port fitting.	Tighten polypropylene fitting, check with soap solution sparingly used. If persisting, check qulaity of column-end flange. Re-flange.
With detector on, gain 2 and offset fully counterclockwise, display indicator is off.	a) UV Source not on.	Confirm: proceed to detailed remedy (end of this Section).
	b) Electronic problem.	Requires skilled service but is not a common problem.
With detector on, gain 2 and offset fully clockwise, display reads full scale and no chromatographic response can be obtained.	a) Detector is saturated.
	b) Column dirty.	Leave to flush with high carrier flow or condition column.
	c) Carrier gas or regulator contaminated.	Switch over to alternate supply, nitrogen or helium can be used in emergency to determine if this is cause.
	d) Electronic problem.	Requires skilled service but is not a common problem.
Peak is Misshapen and non- symmetric.	a) Improper column choice; compound is too polar for existing column.	Use less polar column. Consult Photovac.
	b) Column is defective.	Change column.
	c) Flow is too low.	Increase.
Deterioration of sensitivity	a) Syringe has leak/blockage	Check or change.
	b) Leak at septum or column to   injection port fitting.	Tighten retainer and check flow. Tighten polypropylene fitting, check with soap solution sparingly used. If persisting, check quality of column-end flange. Re-flange.
	c) UV Lamp requires tuning.	Tune as in detailed summary.
	d) UV Lamp defective.	Check and change as in detailed summary.
	e) High voltage low.	Check field indicator.
	f) Column choice incorrect.	Consult Photovac or try a different column.
	g) Recorder not set to 1V FS.	Check.
	h) Electronic problem.	Extremely unlikely but if so, requires skilled service.
	j) Possible miscalculation or defective syringe in standard preparation.	Recheck, assuming everything could have gone wrong!

 

See QC Coordinator for Hard copy of Figure 1

 

PARAMETER:	Selected Halogenated and Aromatic VOC's
MATRIX:	AIR
METHOD:	Manual Analysis of Ambient Air Grab Samples For Selected VOC's By Field GC.
WORKING RANGE
WITHOUT DILUTION:	0.1 ppm to 100 ppm
METHOD DETECTION LIMIT	To Be Determined
SAMPLE HANDLING:	Container -	Tedlar Bags or Glass
	Sampling Bulbs Preservation -	N/A
	Holding Time -	As Soon As Possible
REGULATORY LIMIT:	To Be Determined

In addition to Field Controls, the following will be analyzed within each analytical run:

Laboratory calibration of system for target compounds. Field continuing calibration for all target compounds by vapor injection either bracketing analytical runs or on a cylic basis depending on analytes. This is used to update retention times for identification purposes and to update response factors. An unknown spike solution will be used to check system daily.

REFERENCES:

1. Photovac lOS10 Operators Manual

2. Field Investigation Team (FIT) Screening Methods and Mobile Laboratories Complementary to Contract Laboratory Program (CLP), October 17, 1986. (DRAFT)

3. Field Screening Methods Catalog, User's Guide, October 30, 1987.

4. Various Remedial Investigation QAPP'S.