1、German Standard Methods for the Analysis of Water, Waste Water and Sludge Determination of Borate ions (D 17) Anions (Group D) As it is current practice in standards published by the International Organization for Standardization (ISO), the comm, has been used throughout as a decimal marker. DIN 38
2、405 - Part 17 This Standard has been jointly prepared with the Technical Group Water Chemistry in the Gesellschaft Deutscher Chemiker (Association of German ChemistsJ, see Explanations. It is essential that qualified personnel or specialized equipment be used for the analyses according to this Stand
3、ard. 1 General The natural amount of boron compounds occuring in groundwater and surface water is small. Because boron compounds are ingredients of domestic washing agents, the boron content of surface water can be significantly increased due to waste water inputs. 2 Scope The method is suitable for
4、 determining borate ions in the mass concentration range between 0,Ol and 1 mg/i if the boron content is higher than this, the water sample must be diluted. The boron contained in the sodium perborate (sodium perborate-peroxhydrate) is fully determined by this method. 3 Basis of the method Borate io
5、ns, in a buffered solution with azomethine-H, yield a yellow pigment, the solution obeying the Bougert- Lambert-Beer Law. Azomethine-H is the condensation product of the H-acid (4-amino-5-hydroxynaphthaline-2,7- disul- phonic acid) and the salicylic aldehyde: H OH HO3 S CO3 H Azomethine-H 4 interfer
6、ence The determination of borate ions is not disturbed by the following ions: Mn2+, Zn2+, Ca2+, Mg*+, Na+, K+,PO 4 3-, SO 43 2- NO ions of the following elements, simulate borate ions: Zr, Cr, Ti, Cu, V, AL, Be, Fe. Thus, in water containing 0.25 mg/l of borate ions (as 6) and 5 mg/l of Fe2+ and 20
7、mg/l of Cu2+ as weil as 20 mg/l of Al3+, these metal ions lead to a borate ion overestimate of about 5%. The water to be examined must be colourless and free of any undissolved substances. The latter can be removed by filtering the water across a diaphragm filter (pore size 0,45 pm). Slight discoiou
8、rations can be compensated for by sub- jecting the sample to photometry, on the one hand with, and on the other hand without the addition of azomthine-H solution (see Section 7.121, and compara- tive measurement against doubledistilled water. If the water sample has too high a content of disturbing
9、substances, the boron can be,removed from the solution by extraction using 2-ethylhexane-l,3diol, and converted to the organic phase from which it can be returned to the aqueous phase again by means of a sodium hydroxide solution (see Section 7.6). l However, in all instances it must be established
10、whether this extraction stage is itself the cause of further interference . Other disturbing substances must be removed by using suitable methods, e. g. metal ions by precipitation or by cation exchange, turbidity and discolouration by precipitation using an aluminium salt. 5 Designation The designa
11、tion of the method employed for the photo- metric determination of borate ions (D 17) by means of azomethine-H (11, is: Method DIN 38 405 - D17 6 Apparatus - Plastic separating-funnel, nominal volume 100 ml - Polyethylene bottles, nominal volumes 1000, 500, - Volumetric pipettes nominal volumes 25 m
12、l, - Quartz glass or plastic measuring flasks, nominal - Spectrophotometer or filterphotometer, cuvettes, 100 ml e.g. pipette DIN 12 691 - VPAS 25 volumes 1000 ml, 100 ml layer thickness 1 ; 2; 5 cm. Continued on pages 2 and 3 Sole sale rights of German Standards (DIN-Normen) are with Beuth Verlag G
13、mbH. Berlin 30 DIN 38 405 Part 17 Engl. Price group 5 03.82 Sales No. 0105 Page 2 DIN 38 405 Part 17 7 Chemicals Only chemicals of the highest reagent quality must be used, and only double-distilled water or water of the same degree of purity. 7.1 Azomethine-H, sodium salt, Cl,H12NNa08 20 g of sodiu
14、m hydroxide, NaOH, are dissolved in 1OCi ml of water. 7.7 Sulfuric = 1,21 mg/l : 20 ml of sulfuric acid, H2S0, 0 = 1,84 mg/(, and 80 ml of water are carefully mixed with each other. 7.8 Phosphoric acid, H,PO, 020 = 1,71 mg/l 7.9 Citric acid, C6H807 . H,O 7.10 Ammonium acetate, C2H702N 7.1 1 Disodium
15、 sait of ethylenediaminotetraacetic acid (EDTA), C10H14N2N08 . 2H20 7.12 Azomethine-H solution: 1 ,O g of azomethine-H sodiumsalt (seeSection7.1) and 3,Ogof L(+) -ascorbic acid (see Section 7.2) are dissolved in water. After topping the solution up with water to a volume of 100 mi, it is stored in a
16、 plastic bottle in a refrigerator; its shelf life is about 1 week. 7.13 Buffer solution, pH value 5,9: 250 g of ammonium acetate (see Section 7.10), 250 ml of water, 80 ml of sulfuric acid (see Section 7.7), 5 ml of phosphoric acid (see Section 7.8), 1 ,O g citric acid (see Section 7.9) and 1,0 g of
17、 EDTA (see Section 7.1 i), are mixed to form a solution. 7.14 Reaction solution: equal volumes of azomethine-H solution (see Section 7.1 2) and buffer solution (see Section 7.13) are mixed together on the day of analysis. The solution must be kept in a refrigerator. 7.15 Extractant: 20 ml of 2-ethyl
18、hexane-l,3-diol (see Section 7.3) and 80 ml of isobutylmethylketone (see Section 7.4) are mixed together. 7.16 Borate stock solution: 0,143 g of boric acid, H,BO, in crystallized form, are dissolved in water; the solution is topped up with water in the measuring flask (the latter is made of a boron-
19、free material) to 1000 ml. 1 ml of this solution contains 25 pg of boron in the form of borate ions. 7.17 Borate standard solution: 10 ml of the borate stock solution (see Section 7.16) are topped up with water in the measuring flask (which is made of boron- free material) to 1000 mi. 1 ml of this s
20、olution contains 0,25 pg of boron in the form of borate ions. The standard solution must be renewed weekly. 8 Procedure 25 ml of the water sample which must be free of undissolved substances, and colourless (it will possibly have been diluted to reduce an excess Concentration or have been pretreated
21、 in accordance with Section 4 because of other interference), are pipetted into a dry poly- ethylene bottle of nominal volume 100 ml. 10 ml of the reaction solution (see Section 7.14) are added to the sample. In the same way, a blank sample containing double- distilled water instead of the water sam
22、ple is prepared. Compared with double-distilled water, at 414 nm and a layer thickness of 1 cm, the blank value has a spectral absorption coefficient (extinction) of 0,lO to 0.17. At values 0.2, the chemicals must be tested for purity. Likewise, 25 ml of the borate standard solution (see Section 7.1
23、7) are treated as a reference sample. The bottles, with their contents, are turned over and stored for 2 hours in the dark. Thereafter, the spectral absorp- tion coefficient (extinction) of each of the 3 samples is determined at a wavelength of 414 nm. The layer thickness in the cuvettes depends upo
24、n the borate concentration. 9 Evaluation The mass concentration of the water sample in terms of borate ions, is dertermined by the equation: e= where E E, f it is the reciprocal of the slope of the calibration straight line. is the volume of the water sample according to Section 8, in ml 10 Statemen
25、t of the result Where the water sample has a borate ion content (ex- pressed as 6) which is less than 1 mg/l, the values are roundet off to 0,Ol rng/l, and where it is equal to or greater than 1 mg/l the values are rounded off to 0.1 mg/l. Examples: a) borate ions (expressed as B) 0,51 mg/l b) borat
26、e ions (expressed as B) 6.3 mg/L DIN 38 405 Part 17 Page 3 Bibliography Hofer, A., Brosche, E., Heidinger, R.: Spektralphotometrische Bestimmung von wasserlslichem Bor in Komplex- dngern mit Azomethin-H nach vorheriger Isolierung durch Extraktion mit 2-Ethylhexandiol-( 1.3) (Spectrophoto- metric det
27、ermination of water-soluble boron in complex manures using azomethine-H, after previous isolation by extraction using 2-ethylhexandiol-(l.3). 2. Anal. Chem. 253, 117-1 19 (1971). Graffmann, G., Kuzel, P., Nsler, H., Nonnemacher, G.: Spurenbestimrnung von Bor in Oberflchengewssern und Trinkwssern. (D
28、etermination of boron traces in surface water and drinking water). Chem. Zeitg. 98,499-504 (1974). Capelle, R.: Versuche zur Mikrobestimmung von Bor mit 19 Farbstoffen, die Azo- oder Irningruppen enthalten. (Tests for the microscopic determination of boron in 19 pigments containing azo or irium grou
29、ps). Anal-chim.Acta (Amsterdam) 24, 555-572 (1 962) Ref.: Z. Anal. Chem. 187,446447 (1962) Dietz, F.: Die Borkonzentration in Wssern als Indikator der Gewsserbelastung. (The boron concentration in water, as an indicator of the impurity level.) Gas- und Wasserf. 116,301-308 (1975). Explanations This
30、Standard incorporates the German Standard Method developed jointly by the Normenausschuss Wasserwesen (NAW) (Standards Committee Water Practice) in the DIN and of the Technical Group Water Chemistry of the Gesellschaft Deutscher Chemiker (Association of German Chemists) Additional Standard Methods d
31、eveloped by the Technical Group Water Chemistry and hitherto contained in the loose- leaf publication “Deutsche Einheitsverfahren zur Wasser-, Abwasser- und Schlarnmuntersuchung“ (German Standard Methods for Analysis of Water, Waste Water and Sludge), will be gradually incorporated into the body of
32、German Standards so that after a certain transition time, all the Standard Methods will be available in the form of DIN Standards. The Standard Methods published as DIN Standards are obtainable individually or grouped in volumes from Beuth Verlag GmbH. The above-mentioned loose-leaf publication, pub
33、lished by Verlag Chemie GmbH, will continue to be issued as well, and will incorporate the standardized Standard Methods. Existing and future Standard Methods for the analysis of water, waste water,and sludge will in future be elaborated jointly by the Normenausschuss Wasserwesen (NAW) (Standards Co
34、mmittee Water Practice) in DIN and the Technical Group Water Chemistry of the Gesellschaft Deutscher Chemiker and published as DIN Standards. Standards or draft standards with the group title “German Standard Methods for the Analysis of Water, Waste Water and Sludge“ ar subdivided into the following
35、 groups (main titles): Physical and physico-chemical characteristics (Group C) Anions (Group D) Cations (Group E) Jointly determinable substances (Group F) Gaseous components (Group G) Summary action and material characteristic parameters (Group H) (DIN 38 409) Microbiological methods (Group K) (DIN
36、 38 41 1) Test methods with water organisms (Group L) (DIN 38412) Individual components (Group P) Sludge and sediments (Group S) (DIN 38 414) Information on the parts of these standards which have already been published can be obtained from the office of the Normenausschuss Wasserwesen (NAW) (Standards Committee Water Practice) in DIN Deutsches Institut fr Normung e.V. (German Institute for Standardization), telephone (030) 2 60 14 21, or from Beuth Verlag GmbH, Postfach 11 07, 1 O00 Berlin 30. “Determination of borate ions (D17)“ (DIN 38 404) (DI N 38 405) (DIN 38 406)
