EN 12673-1998 en Water Quality - Gas Chromatographic Determination of Some Selected Chlorophenols in Water《水质 水中一些选择氯酚的气相色谱测定》.pdf
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1、BRITISH STANDARD Water quality - Gas BS EN 12673:1999 BS 6068-2.65 : chromatographic determination of some selected chlorophenols in water The European Standard EN 126731998 has the status of a British Siandard ICs 13.060.50 U- NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW S
2、TD-BSI BS EN 12b73-ENGL 1999 m 1b29bb 07BL751 3T5 BS EN 12673:1999 Environment Sector Committee, Amd. No. D - present to the responsible internatio - 2,6dibromophenol, C - 2,3,6trichlorophenol (see 6.24), C - 2,4,Mbromophenol, CgH3OBr3. For mass selective detection similar labelled compounds can be
3、used NOTE The two internai standards are used as a control for the analytical procedure. The choice of the two intenial standards should reflect the anticipated occurrence of the chlorophenols in the sample (e.g. if dichiorophenols are expected 2,rl-dibromophenol and 2,6dibromophenol should be used)
4、. Prepare a mixed standard of two component solutions in such a concentration that if a smal volume is added to a sample, the amount of the internai standards gives peak heights on the chromahgram in the upper part of the linear workmg range. for electron capture detection at least two with stationa
5、ry phases of Werent polariw, for mass spectsometsic detection one column sunices. dace water Is0 5667-6; sea water IS0 5667-9; rainwater IS0 5667-8; waste water IS0 5667-10; groundwater IS0 5667-11. The bottles sha be filled to the brim with the water sample and stoppered. On sample collection, take
6、 care that no interfering substances enter the water sample, and no losses of the determinands occur. This is especially important in the use of any plastic tubing used within the sampling apparatus. If necessary, it shall be proved by control tests that no losses by adsorption occur. Glass and stai
7、nless steel devices are preferable. Some chlorophenois may degrade in an aqueous environment. Therefore, unless experimental stability triais indicate otherwise, extract samples wih two days of sampling. If extraction is extended beyond two days this shall be noted in the test report. If the interva
8、l between sampling and extraction exceeds one day, keep the samples at 4 OC in the dark. If free halogens are suspected, add, at the time of sampling, some crystals of Na2S203-5H20 or 0,l ml of a 10 % (dm) NazS203 solution (6.12) per 125 ml of sample. Otherwise, do not add any preservation agent. 9
9、Procedure 9.1 Sample pretreatment In this section two procedures are given: - a method including acid-base partition which may be applied for dugr samples or when enrichment of the sample is required (9.1.1); - a procedure employing direct acetylation suitable for relatively clean samples (9.1.2). I
10、t is permissible for sample volumes to be increased if required The volumes of d other reagents (except the internai standard) shail be usted accordingly. Moreover, as the calibration is based on the totai procedure, the volumes used for the prepamtion of calibration solutions shall also be austed a
11、ccordingly. Apply one of the following procedures. salts. Shake the collected toluene extract with a 3 X 20 mi 0,l mom potassium carbonate solution (6.6), for 3 minutes each time, in a 250 ml separaijng funnel. Collect the water layers and proceed with 9.2.2. 9.1.2 Pretreatment if no clean ufienrich
12、ment procedure is followed Take a sample of 50 mi or an aiquot diluted with distilled water to a volume of 50 mi. Neutraiize acidic samples with sodium hydroxide (6.11) to a pH value of about 7 and alkaJine samples with phosphoric acid (6.9) to a pH of about 10. Add 200 pJ of internai standard (6.32
13、.1). 9.2 Acetylation procedure 9.2.1 Acetulatwn of the working standards That each of the working standards (6.32.4) as follows. Zt-ancfer with a pipette into a 100 ml open flask (7.3): - 50 mi of med water, - 2,00 ml of the working standard (6.32.4); - 200 1 of the internal standard (6.32.1). The f
14、ollowing steps shall be carried out in the exact times given and without interruption. Add 5 ml of the 1 moM potassium carbonate solution (6.6) and subsequently 1 rd of the acetic anhydride (6.7) and stir vigorously for 5 min to allow the release of carbon dioxide. NOTE 1 This procedure can also be
15、canied out using a separating funnel or a microseparator (see annex C). Allow to stand for 10 min and then add 5,O ml of n-hexane (6.4). Close the flask with the stopper and stir for 5 min Allow the two phases to separate. Transfer as large a portion as possible of the hexane phase to a vial. Dry th
16、e hexane phase with anhydrous sodium sulfate (6.10) or by freezing. Store at 4 OC. These acetylated solutionc are the calibration solutions. Calculate the content of each substance (p.g/ml) in each of the calibration solutions. NOTE 2 The efficiency of the derivatization step may be checked with a s
17、election of chiorophenolacetates. Generally these compounds are not suitable for calibration purposes because sufficiently pure chiorophenolacetates are not always available. O BSI 06-1999 STD-BSI BS EN 32b73-ENGL 1779 E Lb2qbb7 0783757 AL3 Page 6 EN 12673:1998 i e 9.2.2 Acetylation of the sample li
18、.ansfer the collected aqueous phases or an aliquot of 9.1.1 or the (neutralized) sample of 9.1.2 int a 100 ml open flask (7.3) and add 5 ml of the 1 mou potassium carbonate solution (6.6). Cany out the following steps in the exact times given and without interruption. NOTE 1 This procedure can also
19、be canied out using a separating funnel or a microseparator (see annex C). Add 1 ml of acetic anhydride (6.7). Stir vigorously for 5 min to allow the release of carbon dioxide. Mow to stand at room temperature for 10 min and add 5,O mi of n-hexane (6.4). Close the flask with the stopper and stir for
20、 5 min. Allow the phases to separate. Remove the water iayer and dry the hexane phase with anhyrous sodium sulfate (6.10) or by fkezing. NOTE 2 If an emulsion forms during the extraction process, the emulsion can be broken by e.g. violent shaking, deep freezing, uitrasonification or separating out b
21、y means of the addition of salts. In case of emulsification recoveries should be checked. 9.3 Calibration 9.3.1 Gas chromatograph calibration Set up the gas chromatographic instrument, equipped with the columns (7.6), according to the manufacturers instructions. Optimize gas flows. Ensure it is in a
22、 stable condition Guidance on the initiai gas chromatographic conditions is given in annex D. Calibrate by direct injection of the acetylated working standards (9.2.1) and in addition run a blank. Measure the gas chromatographic signais for each substance against concentsation. This gives informatio
23、n on retention times and relative responses of the determinands and the linear working range of the gas chromatogmph and detector. NOTE 1 Chromatograms of standards should be checked for retention time and peak resolution changes, and losses caused by decomposition within the injection liner. NOTE 2
24、 Separation can be considered as satisfactory if the height measured from the base line of the trough between the two adjacent peaks is no more than 20 % of the height of the highest peak; the peaks in this instance need to be of comparable height. Separation between 2,3,4,5tetrachiorophenol acetate
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