ANALYSIS OF TARGET ANALYTES IN COSOLVENT FLOOD EFFLUENT SAMPLES FROM THE HILL AFB, UT FIELD STUDY

1.0 PURPOSE

The purpose of this SOP is to ensure reliable and reproducible analytical results of o-xylene, 1,2-dichlorobenzene, naphthalene and tetradecane measurements in cosolvent effluent samples containing less than 1% hexanol for GC/MSD analyses.

2.0 SCOPE

This SOP describes the analytical procedures used by Clemson University (CU) for analysis of target analytes in laboratory and field studies, to quantify the amount of o-xylene, 1,2-dichlorobenzene, naphthalene, undecane and tetradecane in samples containing between 30 and 100% TBA and to quantify the amount of those same analytes, excepting undecane, in samples containing greater than 1% hexanol. This SOP may not be specifically applicable to the activities of other organizations.

This SOP was written by Patrick Haskell and Cindy Lee at Clemson University.

The method described herein was developed to enable the analyst to accurately quantify the concentration of the target analytes at 1 mg/L. Samples are collected in 20 mL vials without headspace and immediately refrigerated. Samples are sub-sampled to determine alcohol content prior to analysis for target analytes.

3.0 RESPONSIBILITIES

All Clemson University project staff, faculty and students assigned to conduct these analyses are responsible for knowing the procedures outlined herein.

4.0 PROCEDURES

4.1 Sample Containers, Collection, Transport and Storage

Sample Containers. Field samples collected from extraction wells are contained in 20-mL vials (Fisher Catalog # 03-339-14E or equivalent) with open-top caps and Teflon®-faced septa. Field samples collected from multi-level samplers are contained in 4-mL vials (Fisher Catalog # 03-393G or equivalent) with open-top caps and Teflon®-faced septa. The glass vials and septa are not reused.

Sample Collection. Each sample vial is completely filled with effluent sample, such that no headspace of air exists, and capped. The vials are not opened until the time of sub-sampling or analysis.

Transportation and Storage. For field studies, samples are stored in coolers containing "blue ice," and later stored in refrigerators in a trailer located on the site. Samples may be subjected to on-site GC analysis, and/or shipped back to CU laboratories. Samples are packed in coolers containing "blue ice" and shipped via overnight air express. The samples are stored in a refrigerator at 4°C until they are ready for GC analysis. After sub-sampling the samples are returned to cold storage. For laboratory studies samples are stored in a refrigerator upon collection.

4.2 Sub-Sampling and Dilution.

For laboratory and field analysis of alcohol content,a 200 mL aliquot of sample is transferred from the sample collection vial to a 250 mL glass insert within a 2 mL autosampler vial. The original sample vial is immediately capped and replaced in cold storage.

A sample dilution is prepared if response for any peak in the sample exceeds the calibration range. The dilution should allow the analyst to obtain the greatest response within the calibration range.

4.3 Apparatus and Materials

Gas Chromatograph/Mass Selective Detector System. An analytical GC is required. It must have a temperature programmable oven, an integrator or PC-based acquisition/data analysis software package, and a mass selective detector (MSD) capable of analysis in a select ion mode. Also required are an appropriate analytical column and ultra-high-purity helium (99.999%) as a carrier gas.

The GC system used at CU is a Hewlett Packard 5890 Series II, equipped with a 5790A mass selective detector and interfaced with an IBM-compatible PC loaded with HP Chemstation software.

· Column: The GC/MSD uses a 30 m long, 0.25 mm ID HP-5MS capillary column with a 0.25 mm thick bonded phase (5%-diphenyl-95%dimethyl-siloxane) (Hewlett Packard Catalog # or equivalent).

· Injector Materials: Pre-drilled ¾" red silicone septa are used in the injector port. Glass wool-containing 800 mL liners are cleaned and silanized prior to use. Silanizing is accomplished according to the SOP GCLINER.

Reagents. All solvents and reagents used in standard preparation are of maximum purity and show no interference with other analytes at the lowest practical quantitation limit for any analyte. Field solvents have no guaranteed purity and are checked for interference with each target analyte and appropriate practical quantitation limits are thereby developed. Laboratory reagent water is distilled, deionized tap water which shows no interference with the target analytes.

Standard Solutions. Analytical standard solutions are prepared from pure materials in the laboratory. At CU, the following reagents are used in the preparation of standard solutions:

Reagent Minimum Purity Manufacturer

o-xylene 95 % Burdick & Jackson

1,2-dichlorobenzene 98 % Mallinkrodt

undecane 99 % Aldrich

naphthalene 98 % Aldrich

d8-naphthalene 98 % Aldrich

tetradecane 99 % Aldrich

TBA 99 % J. T. Baker

n-hexanol 98 % Aldrich

isopropyl alcohol 99. 5 % Mallinkrodt

tetrahydrofuran 99 % Mallinkrodt

The primary stock standard is prepared in isopropyl alcohol (IPA). A Class A volumetric flask is filled to the neck with IPA, placed on an analytical balance accurate to 0.1 mg, and appropriate masses of pure compounds are added to bring their approximate concentration to 5000 mg/L. Analytes are added in reverse order of their volatility; naphthalene, tetradecane, undecane, 1,2-dichlorobenzene and o-xylene. Secondary stock solutions are prepared by diluting the primary stock to concentrations of 200, 100, 50, 25, 10, and 5 mg/L by adding 400, 200, 100, 50, 20 and 10 mL each of the primary standard to 10 mL class A volumetric flasks containing either 95 % TBA and water or 81 % TBA, 15 % hexanol and water. Secondary standards at 2 mg/L and 1 mg/L are prepared by adding 10 and 5 mL respectively of the primary standard to 25 mL class A volumetric flasks containing either the TBA or TBA/hexanol solution. Microliter quantities are measured with microliter syringes such that each volume measured equals at least 40 % of the total volume of the syringe.

Secondary stock solutions are prepared in both the TBA and TBA/hexanol solutions in order to account for matrix effects exhibited by the presence of the semi-volatile solvent, n-hexanol, in certain samples. Primary and secondary stock solutions are stored at 4°C when not in use and are allowed to warm to room temperature prior to subsampling in order to allow the solvent density to return to where it was at the time of standard solution preparation.

A primary stock solution of deuterated-8 (d-8) naphthalene (MW 136) is prepared in a 50 mL class A volumetric flask filled to the neck with IPA. This standard is prepared in the same manner as other primary standards at a concentration of approximately 500 mg/L.

Old stock solutions are discarded and a fresh batch prepared every two months. Working standards are prepared from secondary standards immediately before analysis of samples. During sample analysis, if a comparison with a check standard indicates a problem, a new batch of working standards must be prepared and analyzed and a new calibration curve developed.

4.4 Calibration

Working Calibration Standards: Working calibration standards are prepared by subsampling 200 mL of a secondary stock solution of target analytes into a 250 mL insert within a 2 mL autosampler vial and adding 5 mL of the internal standard stock solution.

Calibration Check Standards: Calibration check standards are any working calibration standards used to verify that an instrument is functioning within established calibration parameters.

Calibration is by an internal standard calibration technique, to specific mass ions, employing the following equation:

where

RRF = relative response factor,

Area (x) = area of the analyte (A) peak or internal standard (IS) peak,

Mass (x) = mass of the analyte (A) or internal standard (IS) in the sample (ng).

The linear calibration range for each analyte is defined as that concentration range showing a single relative response factor for the analyte with a relative standard deviation for duplicate injections of each calibration standard of less than 15 %.

4.5 Quality Control

Quality control procedures that will be followed include:

· GC injector septa will be changed every 30 to 40 injections and must be changed if the current septa has been a high temperature (> 200°C) for two days or more. Inlet liners are changed every 60 injections or every 30 injections when there is dissolved NAPL in the samples.

· An acceptable solvent blank must be performed prior to and subsequent to each 12-hour period of analysis.

· Standard calibration must be verified prior to and subsequent to any analysis. Deviation of a calibration check standard of greater than 20 % for any analyte requires that all samples analyzed between the last verified calibration and the deviant check standard be reanalyzed.

4.6 Instrument Procedures

Gas Chromatography. Quantification is obtained by GC/MSD operating in select ion mode operating with the following parameters:

Inlet Temperature 280 °C

Detector Temperature 320 °C

Initial Oven Temperature 60 °C for 3 minutes

Oven Temperature Ramp 10 °C/minute

Ramp Change at 160 °C

2nd Oven Temperature Ramp 30 °C/minute

Final Oven Temperature 300 °C for 5 minutes

MSD On at 2 minutes

Column Head Pressure 8 psi

Liner Purge On at 0.75 minutes

Injection Volume 1 mL

Samples with greater than 0.1 % hexanol are analyzed using a slightly different method, wherein the MSD is turned off between 4.2 minutes and 5.9 minutes to prevent MSD shutdown due to overload by the elution of the hexanol solvent during that time window.

4.6 Sample Analysis

Preparation. Analytical samples and working standards are created identically from field samples and secondary stock solutions, respectively. A 200 mL aliquot of sample is introduced to a 250 mL glass insert in a 2 mL autosampler vial, 5 mL of the d8-naphthalene internal standard solution is added, and the vial is capped and inverted at least ten times to mix thoroughly.

Analysis. If using an autosampler, working samples and calibration check standards are placed in the autosampler tray along with necessary solvent blanks, and the HP Chemstation software is allowed to control the injection sequence. Care must be made to ensure that appropriate matrix identification has been accomplished for each sample prior to target analysis. Failure to do so could result in using the wrong GC method for analysis of hexanol-containing samples, resulting in the MSD being on during the elution of the hexanol cosolvent and damage occuring to the MSD filament. Between each injection the syringe is rinsed five times each in GC grade acetone and methylene chloride.

Analyte Identification. Analyte identification is based on an absolute retention time window for a specific mass ion. Retention time windows and mass ions are as follows:

Analyte Retention Time Mass Ion

o-xylene 3.2 - 4.5 min 91 or 106

1,2-dichlorobenzene 5.9 - 7.5 min 146

naphthalene 8.6 - 9.8 min 128

tetradecane 11.8 - 12.3 min 198

Care must be given to identification of the analyte peaks. Because the samples are present in a low grade solvent, a great deal of shouldering and even some peak splitting can occur. It is important that the analyst familiarize him or herself with the method in these low grade solvents in order to ensure accurate identification of the analyte.

Analyte Quantitation. Target analytes in the effluent are to be quantitated by comparing total area of sample peaks to total area of appropriate calibration standards using the internal standard reference peak and the relative response factor obtained during calibration by rearranging the equation for relative response factor as follows.

Interferences. Gasoline-grade solvents can produce significant interference with ions of interest. Solvent blanks must be checked for the presence of target analytes. It has already been determined that the hexanol cosolvent used in the Hill AFB, UT study contains approximately 150 mg/L undecane, and thus, undecane will not be quantified in samples containing significant amounts of hexanol.

5.0 Environmental, Health and Safety Management.

5.1 Personal Protection and Safety

General safety and health policies are summarized in the ESE Student Handbook, which delineates the laboratory operating policies and includes sections regarding eye and face protection, body protection and appropriate footwear. As several of the reagents used in this SOP are respiratory irritants, it is further recommended that all sample preparation be done in a fume hood, whenever possible. Furthermore, as methylene chloride is both a latex and skin permeant, gloves receiving spills of methylene chloride should be immediately removed and discarded.

5.2 Hazardous Waste Management

The Hazardous Waste Management plan is also included in the ESE Student Handbook to ensure that laboratory wastes are managed to prevent harm to public health and the environment and to conform with the public's expectations and the government's requirements for proper waste management. The plan denotes the responsibilities and requirements of the individual waste generator; identification of hazardous wastes; a categorization, storage, marking and documentation system for wastes; and a pickup and removal procedure. Hazardous wastes generated from this SOP will be handled according to the requirements of the plan.