ISO 10478-1994 Petroleum products - Determination of aluminium and silicon in fuel oils - Inductively coupled plasma emission and atomic absorption spectroscopy.pdf

1、INTERNATIONAL STANDARD IS0 10478 First edition 1994-08-01 ANI Internnat Dsc Set Petroleum products - Determination of aluminium and silicon in fuel oils - Inductively coupled plasma emission and atomic absorption spectroscopy methods Prod and a light detector with a 2 Q IS0 IS0 10478:1994(E) suitabl

2、e measuring and readout system. The scale shall be linear in absorbance or in light intensity, or shall be directly in concentration units with curve cor- rection. 5.8 Volumetric flasks, 100 ml and 1 000 ml, com- plying with IS0 1042, class A. 5.9 Pipettes, 1 ml, 2 ml, 5 ml, 10 ml, 20 ml and 25 ml,

3、complying with IS0 648, class A. 5.10 Pipettes, 1 ml and 2 ml, graduated in 0,l ml subdivisions, complying with IS0 835-2. 5.11 Measuring cylinders, 10 ml, 25 ml, 50 ml and 100 ml, with subdivided graduations, complying with IS0 4788. 5.12 Beaker, 400 ml squat form, complying with IS0 3819. 5.13 Fil

4、ter paper, “ashless”, 0,Ol % (m/m) ash maximum. 5.14 Plastic bottles, unfilled virgin plastic, suitable for long-term storage of dilute acid solutions, 100 ml and 1 000 ml. 5.15 Balance, capable of being read to the nearest 0,2 mg. 6 Sample preparation The sample shall be homogenized thoroughly befo

5、re the test portion is taken. Place the sample container in an oven at a temperature between 50 “C and 60 “C and maintain the sample at this temperature until all the sample has melted and reached a uniform viscosity. Insert the shaft of the mixer (5.3) into the sample so that the head of the shaft

6、is immersed to approximately 5 mm from the base of the container. Homogenize the sample for approximately 5 min. In the case of fluid samples which have stood undis- turbed for several months, use a plastic rod to dis- lodge any sediment adhering to the base of the sample container before homogeniza

7、tion. NOTE 2 Failure to use this homogenization procedure will invalidate results, 7 Procedure 7.1 Test portion The mass of test portion taken from the sample (clause 6) shall weigh between 20 g and 50 g, and preferably contain approximately 1,3 mg of alu- minium. NOTE 3 The mass of test portion pro

8、posed, based on the aluminium content, will also suffice for the silicon determi- nation, as both elements are usually found in fuel oils as- sociated with each other. 7.2 Preparation of test solution 7.2.1 Immediately after homogenization transfer the test portion from the homogenized sample to the

9、 weighed platinum basin (5.1); reweigh the basin and contents to the nearest 0,l g to obtain the mass of the test portion taken. 7.2.2 Warm the basin and contents gently with a Bunsen flame until the sample ignites. Maintain the contents of the basin at a temperature such that most of the combustibl

10、e material is removed and only car- bon and ash remain. NOTE 4 If the sample contains considerable amounts of moisture, foaming and frothing may cause loss of sample. If foaming and frothing occur, discard the sample and to a fresh portion add 1 ml to 2 ml of propan-2-01 (4.3) before heating. If foa

11、ming and frothing are not sufficently reduced, add 10 ml of a mixture of toluene/propan-2-01 (4.5) to a further test portion and mix thoroughly. Place several strips of ashless filter paper (5.13) in the mixture and warm gently (when the paper begins to burn, the greater part of the water will have

12、been removed). 7.2.3 Place the basin and contents in the muffle furnace (5.5) preheated to a temperature of 550 “C f 25 “C. Maintain the muffle furnace at this temperature until all the carbon has been removed and only ash remains. NOTE 5 This may require heating overnight. 7.2.4 Cool the basin to r

13、oom temperature and to the contents of the basin add 0,4 g of the flux (4.2) and mix it with the ash. Place the basin and contents for 5 min in a muffle furnace preheated to a temperature of 925 “C f 25 “C. Remove the basin and ensure contact of the flux with the ash. Replace the basin in the muffle

14、 furnace and maintain at a temperature of 925 “C f 25 “C for a further 10 min. 7.2.5 Remove the basin, cool the fusion melt to room temperature and add 50 ml of tartaric acid/hydrochloric acid solution (4.7.1) to the basin. Place the basin and contents on a hotplate (5.6) and maintain at a moderate

15、temperature without boiling. 3 IS0 10478:1994(E) 0 ISC NOTES 6 Excessive evaporation of the solution could lead to pre- cipitation of an insoluble form of silica. 7 Prolonged heating may be required to dissolve the solidified melt completely and obtain a solution. Agitation or the use of magnetic st

16、irring may be employed to speed dissolution of the solidified melt. 7.2.6 Allow the solution to cool and transfer it to the 100 ml volumetric flask (5.8) with water, washing the basin several times to ensure transfer is quantitative. Make up to the mark with water. Transfer to a plastic bottle, 100

17、ml (5.14). NOTE 8 Transfer to a plastic bottle is thought to be de- sirable, as the dilute acid solution will contain tetrafluoroboric acid from solution of the flux. However, storage tests have shown that there is no attack of glass- ware in the short term (up to one week); and that the sol- ution

18、does not contain free fluoride “ion” above the 5 mg/l level. 7.3 Preparation of blank solution Prepare a zero-concentration solution containing only 0,4 g flux and 50 ml of the tartaric acid/hydrochloric acid solution (4.7.1) diluted to 100 ml and transfer to a plastic bottle, 100 ml (5.14). 7.4 Pre

19、paration of calibration solutions 7.4.1 Aluminium Prepare a 250 mg/l aluminium working solution by di- luting 25 ml of the 1 000 mg/l standard solution (4.8.1) to 100 ml with water. To each of four clean 100 ml volumetric flasks (5.8) add 0,4 g of the flux and 50 ml of the tartaric acid/hydrochloric

20、 acid sol- ution (4.7.1). To successive flasks add 2 ml, 4 ml, 10 ml and 20 ml of the 250 mg/l aluminium working solution and dilute to 100 ml with water. The calibration solutions then contain 5 mg/l, 10 mg/l, 25 mg/l and 50 mg/l of aluminium respect- ively. The calibration solutions then contain 5

21、 mg/l 10 mg/l, 25 mg/l and 50 mg/l of silicon respectively. 7.4.3 Storage Transfer all standards to 100 ml plastic bottles (5.14). NOTE 9 When both aluminium and silicon are being de- termined together, the 5 mg/l to 50 mg/l calibration sol utions of each may be combined, providing there are nc inco

22、mpatibility problems caused by the reagents used in the preparation of the standard solutions 4.8.1 and 4.8.2. 7.5 Setting up and operating the inductively coupled plasma atomic emission spectrometer 7.5.1 General Consult and follow the manufacturers instructions for the operation of the instrument.

23、 NOTE 10 Design differences between instruments, ICP excitation sources and different selected analytical wave lengths for individual spectrometers make it impracticable to specify the required manipulations in detail. 7.5.2 Peristaltic pump If using a peristaltic pump, inspect the pump tubing and r

24、eplace it, if necessary, before starting each day. Verify the solution uptake rate and adjust it to the desired rate. 7.5.3 ICP excitation source Ignite the ICP excitation source at least 30 min before performing an analysis. During this warmup period nebulize distilled or deionized water through th

25、e plasma torch. NOTE 11 Some manufacturers may recommend even longer warmup periods. 7.5.4 Wavelength profiling Perform any wavelength profiling that is called for in the normal operation of the instrument. 7.4.2 Silicon 7.5.5 Operation parameters Prepare a 250 mg/l silicon working solution by dilut

26、ing 25 ml of 1 000 mg/l standard solution (4.8.2) to 100 ml with water. To each of four clean 100 ml volumetric flasks (5.8) add 0,4 g of the flux and 50 ml of the tartaric acid/hydrochloric acid solution (4.7.1). To successive flasks add 2 ml, 4 ml, 10 ml and 20 ml of the 250 mg/l silicon working s

27、olution and di- lute to 100 ml with water. Assign the appropriate operating parameters to the instrument task file so that it is possible to determine the desired elements. Include the following par- ameters: element, wavelength, background correction points (optional), inter-element correction factors lop- tional), integration time and three consecutive repeat integrations.