BS EN ISO 9377-2:2000 pdf – Water quality Ð Determination of hydrocarbon oil index Ð Part 2: Method using solvent extraction and gas chromatography.
1 Scope This part of ISO 9377 specifies a method for the determination of the hydrocarbon oil index in waters by means of gas chromatography. The method is suitable for surface water, waste water and water from sewage treatment plants and allows the determination of a hydrocarbon oil index in concentrations above 0,1 mg/l. The method is not applicable to the quantitative determination of the content of volatile mineral oil. However, on the basis of the peak pattern of the gas chromatogram, certain qualitative information on the composition of the mineral oil contamination can be derived. NOTE 1 For the determination of the mineral-oil content of soils and sediment, see ISO/TR 1 1 046. NOTE 2 The mass concentration of animal and vegetable fat in the test sample should not exceed 1 50 mg/l, because at higher values the adsorption capacity of the clean-up column packing may not be sufficient. NOTE 3 In the case of highly polluted waste water, especially if containing a high amount of surfactants, a loss in recovery may occur. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of ISO 9377. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of ISO 9377 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 5667-3:1 994, Waterquality— Sampling — Part3: Guidance on the preservation andhandling ofsamples. ISO 8466-1 :1 990, Water quality— Calibration and evaluation ofanalytical methods and estimation ofperformance characteristics — Part1: Statisticalevaluation ofthe linearcalibration function.
3.1 hydrocarbon oil index by GC-FID the sum of concentrations of compounds extractable with a hydrocarbon solvent, boiling point between 36 ? C and 69 ? C, not adsorbed on Florisil 1 ) and which may be chromatographed with retention times between those of n-decane (C 1 0 H 22 ) and n-tetracontane (C 40 H 82 ) NOTE Substances complying with this definition are long-chain or branched aliphatic, alicyclic, aromatic or alkyl- substituted aromatic hydrocarbons. 4 Interferences Compounds of low polarity (e.g. halogenated hydrocarbons) and high concentrations of polar substances can interfere with the determination. Surface-active substances interfere with the extraction step. 5 Principle The water sample is extracted with an extracting agent. Polar substances are removed by clean-up on Florisil. The purified aliquot is analysed by capillary chromatography using a non-polar column and a flame ionization detector (FID). The total peak area between n-decane and n-tetracontane is measured. The concentration of mineral oil is quantified against an external standard consisting of two specified mineral oils, and the hydrocarbon oil index is calculated. It is absolutely essential that the test described in this part of ISO 9377 be carried out by suitably qualified staff. It should be investigated whether and to what extent particular problems will require the specification of additional marginal conditions. 6 Reagents All reagents shall be reagent grade and suitable for their specific purpose. The suitability of the reagents and solutions shall be checked by carrying out a blank test. 6.1 Water for the preparation of solutions. Distilled water, or water from a generator of purified water capable of removing organic traces, for example using activated carbon, shall be used.
6.8 Mixture of mineral oils. 6.8.1 Standard 2) mixture. Weigh accurately equal amounts of two different types (type A and type B, both containing no additives) of mineral oil and add enough extraction solvent (6.1 1 .2) to give a total hydrocarbon concentration of about 1 0 mg/ml. Type A should show discrete peaks in the gas chromatogram. An example is diesel fuel without any additives. See EN 590 for further information. Type B should have a boiling range higher than that of type A and should have unresolved signals in the gas chromatogram. An example of this type is a lubricant without any additives, boiling range 325 ? C to 460 ? C. 6.8.2 Calibration mixture. Prepare at least five different calibration solutions by diluting aliquots of standard mixture (6.8.1 ) with the extraction solvent (6.1 1 .2). The following concentrations may be suitable: 0 (blank), 0,2 mg/ml, 0,4 mg/ml, 0,6 mg/ml, 0,8 mg/ml and 1 ,0 mg/ml. Higher concentrations may be advisable for other applications. Store the calibration mixture tightly sealed in a refrigerator (4 ? C to 8 ? C). The calibration mixtures are stable for up to six months. 6.8.3 Quality Control (QC) standard. Prepare a standard solution according to 6.8.1 in acetone (see 6.6) with a mass concentration of e.g. 1 mg/ml. The exact concentration should be about a thousand times the desired application range. NOTE When using a lubricant for QC, the stock solution is easily prepared in extracting agent (6.2), which is further diluted in acetone about tenfold before spiking the QC water. Store the solution tightly sealed in a refrigerator (4 ? C to 8 ? C). It is stable for up to six months.