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1、BRITISH STANDARD BS 2690-102: 1979 Methods of testing Water used in industry Part 102: Hydrazine: spectrophotometric method (4-dimethylaminobenzaldehyde) IMPORTANT NOTE. It is essential that this Part be read in conjunction with the information in Part 100 of this standard, “Foreword, scope and gene
2、ral requirements”, which is published separately. UDC 628.1:663.63.01:543.3:546.171.5 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 12:57:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2690-102:1979 This British Standard, having been prepared under the direction of the Environment and Pol
3、lution Standards Committee, was published under the authority of the Executive Board on 31 January 1979 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference EPC/37 Draft for comment 77/50234 DC ISBN 0 580 10613 6 A British Standard does not purport to inc
4、lude all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, page
5、s i and ii, pages 1 and 2 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffiel
6、dun sheffieldun, na, Mon Nov 27 12:57:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2690-102:1979 BSI 08-1999i Contents Page 1Scope1 2Range1 3Maximum size of test portion1 4Principle1 5Interferences1 6Reagents1 7Sampling1 8Preparation of calibration graph1 9Procedure1 10Calculation2 Licensed Copy
7、: sheffieldun sheffieldun, na, Mon Nov 27 12:57:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 12:57:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2690-102:1979 BSI 08-19991 1 Scope The method described is for the determination of hyd
8、razine in industrial waters. 2 Range 0.5 4g to 5 4g hydrazine. 3 Maximum size of test portion The maximum size of test portion is 20 ml. 4 Principle Hydrazine reacts with 4-dimethylaminobenzaldehyde to give acid salts of the azine that are intensely red in strong solutions and yellow in dilute solut
9、ions. 5 Interferences Under the conditions described in the method the presence of 100 4g of ammonia, cyclohexylamine, morpholine, octadecylamine, iron, copper and nickel and 5 000 4g of chloride, sulphate and phosphate either separately or collectively do not cause significant interference. 6 Reage
10、nts The following reagents are required. 6.1 4-dimethylaminobenzaldehyde solution. Dissolve 4.0 g of 4-dimethylaminobenzaldehyde (grade for hydrazine determination) in 200 ml of methanol and 20 ml of concentrated hydrochloric acid, 36 % (m/m) (11N). Store in a dark bottle out of direct sunlight. 6.2
11、 Hydrochloric acid solution, 0.5N. 6.3 Hydrochloric acid/methanol solution. Mix 20 ml of concentrated hydrochloric acid, 36 % (m/m) (11N), with 200 ml of methanol. 6.4 Hydrazine standard solutions 6.4.1 Hydrazine stock solution. Dissolve 0.082 g of hydrazine dihydrochloride in 0.5N hydrochloric acid
12、 and dilute with this acid to 1 litre. 6.4.2 Hydrazine working solution. Dilute 1 ml of hydrazine solution with 0.5N hydrochloric acid to 100 ml. 1 ml N 0.25 g N4g N2H4. 7 Sampling If the temperature of the sample is above 25 C it is necessary to use an efficient stainless steel cooling coil so that
13、 the temperature of the sample is reduced to about 15 C to 25 C. Insert the outlet tube from the cooling coil into a 250 ml stoppered bottle so that it almost reaches the bottom. Allow the water to flow until a representative sample is obtained. Withdraw the outlet slowly and immediately stopper the
14、 bottle avoiding trapping any air bubbles in the bottle. The sample should then be analysed without delay. 8 Preparation of calibration graph Measure accurately volumes of the hydrazine working solution containing 0, 1, 2, 3, 4 and 5 4g of N2H4 into a series of previously dried 50 ml one-mark volume
15、tric flasks, each containing 15 ml of 0.5N hydrochloric acid. Then add enough water to each flask to make the total volume approximately 38 ml. Stopper and mix. Adjust the temperature of the contents of each flask to between 20 C and 25 C, add 10 ml of 4-dimethylaminobenzaldehyde solution to each, m
16、ake-up to the mark with water, stopper and mix. Allow to stand for 10 min. Measure the absorbance of each solution using 40 mm cells at a known temperature between 20 C and 25 C in a spectrophotometer at the wavelength corresponding to maximum absorption (approximately 458 nm but the exact wavelengt
17、h shall be checked for each spectrophotometer). Use water in the compensating cell. Deduct the reading for the blank solution containing no added hydrazine from those obtained for the standard solutions. Plot a graph of the net absorbance against corresponding micrograms of hydrazine. 9 Procedure Me
18、asure a suitable volume of the sample (not greater than 20 ml) into a 50 ml one-mark volumetric flask containing 15 ml of the 0.5N hydrochloric acid. Add enough water to make the total volume approximately 38 ml. Stopper and mix. Adjust the temperature to within 1 C of the calibration temperature, a
19、dd 10 ml of the 4-dimethylaminobenzaldehyde solution and make up to the mark with water. Stopper and mix. Measure 20 ml of water into a second 50 ml one-mark volumetric flask containing 15 ml of the 0.5N hydrochloric acid to serve as a blank. Stopper and mix. Adjust the temperature to within 1 C of
20、the calibration temperature, add 10 ml of the 4-dimethylaminobenzaldehyde solution, make up to the mark with water. Stopper and mix. Allow to stand for 10 min. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 12:57:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2690-102:1979 2 BSI 08-1999 Me
21、asure the absorbance of the sample solution and the blank solution using 40 mm cells in the spectrophotometer at a temperature within 1 C of that at which the calibration graph was prepared and at the same wavelength. Use water in the compensating cell. If it is necessary to compensate for the colou
22、r of the sample, take a volume equal to that of the test portion and proceed as before but substituting 10 ml of the hydrochloric acid/methanol solution for the 4-dimethylaminobenzaldehyde solution and making up to a volume of 50 ml with water. Measure the absorbance of this compensating solution ag
23、ainst water. 10 Calculation Deduct the reading obtained for the blank solution and the colour compensating solution, if used, from that obtained for the sample solution and read off from the calibration graph the hydrazine content of. the test portion. Hydrazine (as N2H4), mg/l of test sample = wher
24、e m is the mass of hydrazine in the test portion (4g) v is the volume of the test portion (ml). m v - - Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 12:57:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 3 blank Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 12:57:22 GMT+00:00 2006, U
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