STANDARD OPERATING PROCEDURE FOR THE ANALYSIS OF

ETHYLENE GLYCOL IN WATER BY GC/FID

(DIRECT INJECTION)

CRL METHOD 8000-EGLYCOL

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION 5 CENTRAL REGIONAL LABORATORY

536 SOUTH CLARK STREET (SL0-10C)

CHICAGO, ILLINOIS 60605

DATE: JUNE 3, 1994

CONCURRENCES:

TEAM LEADER:	ERLINDA S. EVANGELISTA
SECTION CHIEF:	CHI M. TANG
QC COORDINATOR:	JAMES ADAMS, JR.
CRL DIRECTOR:	CHARLES ELLY

 

 

TABLE OF CONTENTS

SECTION	REV	DATE
1.0   SCOPE AND APPLICATION	0	6/94
2.0 SAFETY	0	6/94
3.0 SUMMARY OF METHOD	0	6/94
4.0 SAMPLE HANDLING AND PRESERVATION	0	6/94
5.0 INTERFERENCES	0	6/94
6.0 APPARATUS AND MATERIALS	0	6/94
7.0 REAGENTS	0	6/94
8.0 INSTRUMENT CALIBRATION	0	6/94
9.0 PROCEDURE	0	6/94
10.0 QUALITY CONTROL	0	6/94
11.0 REFERENCES	0

1.0 SCOPE AND APPLICATION

1.1 This method describes a procedure for analyzing ethylene glycol in water using a gas chromatograph with flame ionization detector.

1.2 This method is applicable to the analysis of ethylene glycol in water samples collected primarily from sites that are in the vicinity of airports where this compound is commonly  used for de-icing airplanes and which, if improperly discharged, may cause groundwater contamination.

1.3 The detection limit for this method is the lowest  concentration of ethylene glycol that produced a  quantifiable peak. At the CRL, the detection limit is 0.1 ppm.

2.0 SAFETY

2.1 Ethylene glycol reagent is a toxic irritant. The material safety data sheet should be consulted prior to use. The reagent should be handled with caution and stored in a properly vented solvents storage cabinet.

3.0 SUMMARY OF METHOD

3.1 The water sample is directly injected on the GC/FID under optimum operating conditions and the resulting chromatogram compared with that of a standard solution of ethylene glycol.

4.0 SAMPLE HANDLING AND PRESERVATION

4.1 Samples must be collected in amber glass bottles, 1 L capacity, fitted with Teflon-lined screw caps. Sampling practices vary by programs and must be carried out according to approved sampling plans. In all cases the sampler must ensure that contamination is kept to a minimum by thorough rinsing of equipment used and by avoiding the use of  plastics and other potential sources of contamination.

4.2 The samples must be refrigerated at 4 deg C from the time of collection until analysis.

5.0 INTERFERENCES

5.1 Method interferences may be caused by contaminants in solvents, reagents, glassware,

and other sample processing hardware that lead to discrete artifacts or elevated  baselines in gaschromatograms. All of these materials must be routinely demonstrated to be free from interferences under the conditions of the analysis by running laboratory reagent blanks.

5.1.1Glassware must be scrupulously cleaned. Clean all glassware as soon as possible after use by rinsing with the last solvent used in it, followed by detergent washing with hot water and rinses with tap water and distilled water. The dry glassware are then heated in a drying oven at 400 deg C for about 30 minutes or at 130 deg C for 12 hours or more.

NOTE:See the SOP for washing of labware at the CRL.

5.1.2 The use of high purity reagents and solvents will greatly minimize interference problems.

6.0 APPARATUS AND MATERIALS

 

6.1 Glassware

6.1.1 Pipets, Class A, volumetric

6.1.2 Pipets, disposable

6.1.3 Volumetric flasks - 10 ml, 50 ml, 100 ml

6.2 Gas Chromatograph: An analytical system complete with Gas Chromatograph (GC), all required accessories such as column supplies, gases and an autosampler. A data system should be used for data acquisition and processing. The system will consist of an A/D module, a computer and a printer.

6.2.1Gas chromatograph equipped with 2 capillary split/splitless inlet systems. The GC should be equipped with at least one flame ionization detector (FID)and a dual-column capability oven. High purity Helium carrier gas, nitrogen make-up gas, hydrogen and air cylinders should be properly connected to the GC.

6.2.2 Gas chromatographic column-Column is a 30 m X 0.53 mm ID X 0.1 um film thickness fused silica; stationary phase is Crossbond 95 % dimethyl-5 % diphenyl polysiloxane. (E.g. Restek Rtx-5, J & W DB-5 or equivalent)

7.0 REAGENTS

7.1 Ethylene glycol, 99% Reagent grade, HOCH₂CH₂OH

7.2 Standard solutions-Prepare multi-level calibration solutions of ethylene glycol in reagent water, as follows: Weigh out 1.0 g of ethylene glycol in a tared 100 ml volumetric flask and dilute to the mark with reagent water, mixing well during the addition of water. The resulting stock solution (A) concentration is 10 mg/ml. Pipet 1.0 ml of the stock solution and dilute to 100 ml to obtain an intermediate concentration (B) of 0.1 mg/ml or 100 ug/ml (100 ppm). Prepare the following concentration levels of ethylene glycol from the intermediate solution: 1 ppm, 2 ppm, 5  ppm & 10 ppm. From the 5 ppm solution, prepare a 0.1 ppm solution.

7.3 Reagent water - B & J, or equivalent

8.0 INSTRUMENT CALIBRATION

8.1 Establish gas chromatographic operating conditions as follows:

(Note: Any changes in these conditions must be properly validated and documented.)

Gas chromatographic conditions:

Injector A Temperature -	250 deg C, splitless
Detector A Temperature -	300 deg C
Oven Temperature Program
Initial Temp -	100 deg C
Initial Time -	2 min
Rate -	10 deg C/min
Final Temp -	200 deg C
Final Time -	5 min
Equilibrium Time -	3 min
Purge A OFF at 0 min, ON at 1 min
Carrier gas -	Helium, ultra-high purity, at about6 ml/min
Make-up gas -	Nitrogen, ultra-high purity
FID gases -	Hydrogen, prepurified Compressed Air, dry grade
Column head pressure -	5 psi
Total flow through DET A -	55 ml/min

8.2 Calibrate the gas chromatographic system initially by injecting 1 ul each of 0.1, 1, 2, 5 and 10 ppm ethylene glycol into the GC. Use the Turbochrom 3.0 software to  acquire and process the data. Generate a calibration curve of peak area (or height) versus concentration. This curve will then be utilized by the system to quantitate the amount of ethylene glycol in the samples. The calibration curve is acceptable if the correlation coefficient is 0.995 or better.

8.3 Verify the calibration curve on each day of analysis by running one or more calibration standards. If the response varies by more than 10% (RPD) from the predicted response, generate a new calibration curve.

8.4 Run a continuing calibration by injecting a mid-level standard evey 5 sample extract injections. Check the response against the initial calibration curve. The RPD should be less than 10%. If the RPD is >10% but <20 %,  recalibrate and reanalyze the samples with positive hits. If the RPD is >20%, recalibrate and reanalyze all samples.

9.0 PROCEDURE

9.1 Transfer 1 ml of the water sample into autosampler vials, seal and label with the complete sample name.

9.2 Transfer 1 ml of reagent water in a vial. This will serve as method blank as well as instrument blank.

9.3 Spike duplicate 50 ml portions of a sample designated for spiking with 1 ml of the 100 ppm ethylene glycol solution. The spike level is at 2 ppm. Transfer 1 ml of the MS/MSD solutions into autosampler vials, seal and label properly.

9.4 Generate a method for data acquisition using the Turbochrom 3.0 software. Prepare to acquire data by generating a sequence starting with a method blank and 5-calibration levels, followed by the samples and MS/MSD. Run a 2 ppm standard after every 5 injections.

9.5 Load the vials on the autosampler tray in exactly the same  order as they appear in the sequence prepared in 9.4 Download the sequence and start data acquisition by pushing the AStart@ button of the autosampler.

9.6 Process the data and generate reports according to standard Turbochrom 3.0 procedure. The data system utilizes the  calibration curve to calculate the amount of the analyte in the sample.

9.7 If manual calculations need to be done for reasons, such as to check the computer-generated values or if peak splitting occurs, use the following equation:

 

Conc _{cpd in spl}, ug/ml  = Conc _{cpd in std}, ug/ml X Area _{cpd in spl}

                                                                      Area _{cpd in std}

10.0 QUALITY CONTROL

10.1 The laboratory is required to operate a formal quality control program. The minimum requirements of this program consists of an initial demonstration of laboratory capability and an ongoing analysis of method blanks, spiked samples, and laboratory control standards to evaluate and document data quality. Ongoing data quality checks are  compared with established performance criteria to determine if the results of the analysis meet the criteria.

10.1.1 Method blank: The method blank is carried through the entire procedure. It should be free of contamination by the parameters of interest. A method blank is run with every set of 10 samples or each day of extraction. If there is no extraction involved, as in this case, where the water sample is directly injected on the GC, then The method blank also serves as the instrument blank.

10.1.2 Matrix spike/matrix spike duplicate: The matrix spike and matrix spike duplicate are carried through the entire procedure and the recovery results are compared with established limits. The relative percent difference (RPD) between duplicate spikes is calculated and is a measure of method precision. MS/MSD samples are run for every data set and matrix type in the data set. For a large study (same site) consisting of several data sets, MS/MSD are run for every 20 samples.

10.1.3 Spike the sample selected as MS/MSD as follows: Take duplicate 50 ml portions of the water sample and add 1 ml of the 100 ppm solution of ethylene glycol for a final ethylene glycol concentration of 2 ppm.

11.0 REFERENCES

 

1. 1994 - 95 J & W Chromatography catalog and Reference Guide

 

2. 1994 - 95 Restek Corp. Chromatography Products Catalog