ASTM D1319 Test Method for Hydrocarbon Types in Liquid Petroleum Products
ASTM D1319 Standard Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption
6. Apparatus
6.1 Adsorption Columns, with precision bore ("true bore" IP designation) tubing, as shown on the right in Fig. 1, made of glass and consisting of a charger section with a capillary neck, a separator section, and an analyzer section; or with standard wall tubing, as shown on the left in Fig. 1. Refer to Table 1 for column tolerance limits.
6.1.1 The inner diameter of the analyzer section for the precision bore tubing shall be 1.60 to 1.65 mm. In addition the length of an approximately 100-mm thread of mercury shall not vary by more than 0.3 mm in any part of the analyzer section. In glass-sealing the various sections to each other, long-taper connections shall be made instead of shouldered connections. Support the silica gel with a small piece of glass wool located between the ball and socket of the 12/2 spherical joint and covering the analyzer outlet. The column tip attached to the 12/2 socket shall have a 2-mm internal diameter. Clamp the ball and socket together and ensure that the tip does not tend to slide from a position in a direct line with the analyzer section during the packing and subsequent use of the column. Commercial compression-type connectors may be used to couple the bottom of the separator section (which has been cut square), to the disposable 3-mm analyzer section, provided that the internal geometry is essentially similar to the aforementioned procedure and provides for a smooth physical transition from the inner diameters of the two glass column sections. Similar commercial compression-type connectors may be employed at the terminal end of the 3-mm analyzer section, having an integral porous support to retain the silica gel.
6.1.2 For convenience, adsorption columns with standard wall tubing, as shown on the left in Fig. 1, can be used. When using standard wall tubing for the analyzer section, it is necessary to select tubing of uniform bore and to provide a leakproof connection between the separator and the analyzer sections. Calibrations of standard wall tubing would be impractical; however, any variations of 0.5 mm or greater, as measured by ordinary calipers, in the outside diameter along the tube can be taken as an indication of irregularities in the inner diameter and such tubing should not be used. Prepare the glassware to retain the gel. One way to accomplish this is to draw out one end of the tubing selected for the analyzer section to a fine capillary. Connect the other end of the analyzer section to the separator section with a suitable length of vinyl tubing, making certain that the two glass sections touch. A 30 more or less 5 mm length of vinyl tubing has been found to be suitable. To ensure a leakproof glass-to-vinyl seal with the analyzer section, it is necessary to heat the upper end of the analyzer section until it is just hot enough to melt the vinyl, then insert the upper end of the analyzer section into the vinyl sleeve. Alternatively, this seal can be made by securing the vinyl sleeve to the analyzer section by wrapping it tightly with soft wire.
6.2 Zone-Measuring Device - The zones may be marked with a glass-writing pencil and the distances measured with a meter rule, with the analyzer section lying horizontally. Alternatively, the meter rule may be fastened adjacent to the column. In this case, it is convenient to have each rule fitted with four movable metal index clips (Fig. 1) for marking zone boundaries and measuring the length of each zone.
6.3 Ultraviolet Light Source, with radiation predominantly at 365 nm is required. A convenient arrangement consists of one or two 915 or 1220-mm units mounted vertically along the apparatus. Adjust to give the best fluorescence.
6.4 Electric Vibrator, for vibrating individual columns or the frame supporting multiple columns.
6.5 Hypodermic Syringe, 1 mL, graduated to 0.01 or 0.02 mL, with needle 102 mm in length. Needles of No. 18, 20, or 22 gage are satisfactory.
6.6 Regulator(s), capable of adjusting and maintaining the pressure within the 0 to 103 kPa delivery range.
7. Reagents and Materials
7.1 Silica Gel, manufactured to conform to the specifications shown in Table 2. Determine the pH of the silica gel as follows: Calibrate a pH meter with standard pH 4 and pH 7 buffer solutions. Place 5 g of the gel sample in a 250-mL beaker. Add 100 mL of water and a stirring bar. Stir the slurry on a magnetic stirrer for 20 min and then determine the pH with the calibrated meter. Before use, dry the gel in a shallow vessel at 175°C for 3 h. Transfer the dried gel to an air tight container while still hot, and protect it thereafter from atmospheric moisture.
NOTE 3 - Some batches of silica gel that otherwise meet specifications have been found to produce olefin boundary fading. The exact reason for this phenomenon is unknown but will affect accuracy and precision.
7.2 Fluorescent Indicator Dyed Gel - A standard dyed gel, consisting of a mixture of recrystallized Petrol Red AB4 and purified portions of the olefin and aromatic dyes obtained by chromatographic adsorption, following a definite, uniform procedure, and deposited on silica gel. The dyed gel shall be stored in a dark place under an atmosphere of nitrogen. When stored under these conditions, the dyed gel can have a shelf life of at least five years. It is recommended that portions of the dyed gel be transferred as required to a smaller working vial from which the dyed gel is routinely taken for analyses.
7.3 Isoamyl Alcohol, (3-methyl-1-butanol) 99 %. (Warning - Flammable. Health hazard.)
7.4 Isopropyl Alcohol, (2-propanol) minimum 99 % purity. (Warning - Flammable. Health hazard.)
7.5 Pressuring Gas - Air (or nitrogen) delivered to the top of the column at pressures controllable over the range from 0 to 103 kPa gage. (Warning - Compressed gas under high pressure.)
7.6 Acetone, reagent grade, residue free. (Warning - Flammable. Health hazard.)
7.7 Buffer Solutions, pH 4 and 7.
8. Sampling
8.1 Obtain a representative sample in accordance with sampling procedures in Practice D4057. For samples that would meet volatility conditions of Group 2 or less of Test Method D86, ensure that the sample is maintained at a temperature of not more than 4°C when opening or transferring the sample. (Warning - Flammable. Health hazard.)
9. Preparation of Apparatus
9.1 Mount the apparatus assembly in a darkened room or area to facilitate observation of zone boundaries. For multiple determinations, assemble an apparatus that includes the ultra-violet light source, a rack to hold the columns, and a gas manifold system with spherical joints to connect to the desired number of columns.
