ASTM D4291 standard test method for trace ethylene glycol in used engine oil
7. Preparation of Apparatus
7.1 Column Preparation - Prepare the column by the following steps:
7.1.1 Prepare the packing, 5 mass % Carbowax 20-M liquid phase on 30/60 mesh Chromosorb T solid support, by any satisfactory method used in the practice of gas chromatography.

NOTE 6 - Care should be taken in handling Chromosorb T solid support because of its static charge and softness. Chilling may be helpful in improving its handling properties.

7.1.2 Add the prepared packing to the copper tubing using only gentle tapping. Do not use vacuum or mechanical vibration to pack the column. Chromosorb T solid support is a resin which will deform under pressure or severe vibration.

7.2 Column Installation - The column must be attached to the injection port in such a way as to allow on-column injection.

7.3 Column Conditioning - The column must be conditioned at the operating temperature to reduce baseline shift due to bleeding of column substrate.

7.4 Chromatograph - Place in service in accordance with manufacturer's instructions. Typical operating conditions are shown in Table 1.

8. Calibration
8.1 Analyze each of the calibration mixtures following the procedure in Section 10, injecting exactly 5 µL and record the area of the ethylene glycol peak.

8.2 Calculate a response factor for each calibration mixtureas follows:
F = C/A
where:
F = response factor for ethylene glycol,
C = concentration in mass ppm of ethylene glycol in water, and
A = peak area for ethylene glycol.

8.3 Calculate an average response factor.

NOTE 7 - A calibration curve may be employed to obtain the response factor.

9. Preparation of Sample
9.1 Weigh approximately 3 g of sample, obtained as recommended in Practice D4057, to the nearest 0.1 mg into the stoppered centrifuge tube. Add approximately 3 g of water, weighed to the nearest 0.1 mg, to the centrifuge tube. Add 5 mL of n-hexane.

9.2 Stopper and vigorously agitate the centrifuge tube for approximately 5 min.

9.3 Centrifuge the tube for 30 min.

9.4 If there is no clear water layer, remove and discard the upper oil layer, taking care not to remove any of the water emulsion. Add another 5 mL of n-hexane and centrifuge for 30 min.

9.5 Remove an aliquot of the clear water layer from the centrifuge tube with a pasteur pipette and place in a 2-mL vial. Crimp a cap on the vial.