API MPMS 10.7 pdf download.Standard Test Method for Water in Crude Oils by Potentiometric Karl Fischer Titration
6.1 Karl Fischer Apparatus, using electrometric end-point. A suggested assembly of the apparatus is described in Annex A2. 6.1.1 Presently there is available on the market commercial Karl Fischer titration assemblies, some of which automatically stop the titration at the end-point. Instructions for operation of these devices are provided by the manufacturer and not described herein. This test method is not intended for use with coulometric Karl Fischer titrators. 6.2 Mixer, to homogenize the crude sample. 6.2.1 Non-Aerating, High-Speed, Shear Mixer, 6 capable of meeting the homogenization efficiency test described in Annex A1. The sample size is limited to that suggested by the manufacturer for the size of the probe. 6.3 Syringes: 6.3.1 Samples and base liquid are most easily added to the titration vessel by means ofaccurate glass syringes with LUER fittings and hypodermic needles of suitable length. The bores of the needles used should be kept as small as possible, but large enough to avoid problems arising from back pressure/ blocking whilst sampling. Suggested syringe sizes are as follows: 22.214.171.124 Syringe, 10 µL, with a needle long enough to dip below the surface of the base solution in the cell during the standardization procedure (see Section 9). 126.96.36.199 Syringes, 2.5 mL, 5 mL, and 10 mL for crude oil samples (see Section 10). 188.8.131.52 Syringe, 20 mL or larger for sample solvent.
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Commit- tee on Analytical Reagents of the American Chemical Society, where such specifications are available. 7 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 7.2 Purity ofWater—Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Type IV of Specification D 1193. 7.3 1-Ethylpiperidine (99 + percent). (Warning—Irritant. Flammable.) 7.4 Karl Fischer Reagents, Standard reagent containing pyridine (7.4.1) or pyridine-free reagent (7.4.2). 7.4.1 Karl Fischer Reagent Ethylene Glycol Monomethyl Ether Solution, stabilized, containing pyridine, (1 mL = 5 mg of water)—Fresh Karl Fischer reagent must be used. Must be used with solvent in 7.6.1. (Warning—Combustible. Harmful if swallowed, inhaled, or absorbed through the skin.) 7.4.2 Pyridine-Free Karl Fischer (one-component) reagent diluted with xylene—Dilute three parts pyridine-free Karl Fischer (one-component) reagent 8 (1 mL = 5 mg water) to 1 part xylene. Fresh Karl Fischer reagent must be used. (Warning—See 7.4.1) Must be used with solvent in 7.6.2. 7.5 Methanol (anhydrous), Maximum 0.1 % water but pref- erably less than 0.05 % water. (Warning—Flammable. Vapor harmful. May be fatal or cause blindness if swallowed or inhaled. Cannot be made nonpoisonous.) 7.6 Sample Solvent—Use 7.6.1 for standard Karl Fischer reagent containing pyridine and 7.6.2 for pyridine-free Karl Fischer reagent. 7.6.1 Sample Solvent—Mix 40 mL of 1-ethylpiperidine, 20 mL of methanol, and 40 mL of Karl Fischer reagent in a sealable glass bottle. Allow this mixture to sit overnight before adding 200 mL of xylene. Additional methanol may be required in some cases for the proper function of the elec- trodes. (Warning—see 7.3.) 7.6.2 Sample Solvent for Pyridine-Free Reagents—Mix 3 parts chloroform to 1 part pyridine-free solvent using solvent part of two-component reagent 8 (contains SO 2 and odorless amine dissolved in methanol) and store in a sealable glass bottle. An evaluation of a number of crude oils has demon- strated that xylene can be substituted for chloroform with no apparent change in accuracy of this test method. (Warning— Flammable. Vapor harmful.) (Also, see 7.4.1.) 7.7 Xylene, reagent grade. Less than 0.05 % water. 7.8 Chloroform, reagent grade. (Warning—Harmful if in- haled or swallowed. Carcinogen (animal positive). Skin and eye irritant. May produce toxic vapors if burned.