1、ES1 BS*EN*ISO 1339.5 96 Lb24669 D57LDL7 054 BRITISH STANDARD Water quality Determination of nitrite nitrogen and nitrate nitrogen and the sum of both by flow analysis (CFA and FIA) and spectrometric detection BS EN IS0 13395 : 1996 * IB * The European Standard EN IS0 13395 : 1996 has the status of a
2、 British Standard ICs 13.060 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BSI BS*EN*ISO 13395 9b W 3624669 0573038 T90 Amd. No. BS EN IS0 13395 : 1996 Date Text affected Committees responsible for this British Standard The preparation of this British Standard was entrusted
3、by Technical Committee Em, Water quality, to Subcommittee Em, Physical, chemical and biochemical methods, upon which the following bodies were represented British Agrochemicals Association Ltd British Ceramic Research British Gas pic British Soft Drinks Association Ltd. Chemical Industries Associati
4、on Convention of Scottish Local Authorities Department of the Environment (Her Majestys inspectorate of Pollution) Department of the Environment (Water Directorate) Department of ?i.ade and Industry (Laboratory of the Government Chemist) GAMBICA (BEAMA) Ltd. Industrial Water Society National Rivers
5、Authority Royal Society of Chemistry Sow and Detergent Industry Association Society of Chemical Industry Swimming Pool and Alied hades Association Ltd. Water Companies Association Water Research Centre Water Services Association of England and Wales This British Standard, having been prepared under
6、the direction of the Health and Environment Sector Board, was published under the authority of the Standards Board and comes into effect on 15 November 1996 O BSI 19% The following BSI references relate to the work on this standard Committee reference EW2 Draft for comment 94601676 DC ISBN O 680 260
7、92 6 * * m BSI BSaENUISO 13395 9b 1624669 0573039 927 W BS EN IS0 13395 : 1996 Contents Committees responsible National foreword Page Inside fi-ont cover u Foreword Method 1 Scope 2 Normative references 3 Principle 4 Reagents 5 APP- 6 Checking the flow system 7 Sampling and sample preparation 8 Inte
8、rferences 9 Procedure 10 Evaluation 11 Expression of results 12 Precision 13 Testreport 2 3 3 3 4 7 7 8 8 8 10 10 10 15 Annexes A (informative) Examples of flow injection systems (5.1) for the determination of nilrite(N) and nitritenitrate(N) 16 B (informative) Examples of continuous flow systms (5.
9、2) for the determination of nitrate(N) and nitritehutsate(N) 17 C (informative) Example of a continuous flow system (socalled macroflow) 19 D (informative) Bibliography 20 (5.2) for the determination of 0,2 mgl to 2 mg/i nitriMm(N) Tables 1 5 2 Preparation of the caiibration solutions for nitrite(N)
10、 6 3 Preparation of the caiibration solutions for nilriWnitrate(N) 6 4 Statistical data for the determination of nitrite(N) with flow injection analysis (FIA) 11 6 Statistical data for the determination of nitrite(N) with continuous flow analysis (CFA) 12 6 statistical data for the determination of
11、nitriWnihte(N) with flow injection anaiysii (F7.A) 13 7 Satistical data for the determination of nitrit see 5.1 and 5.2). 4.13 Imidazole stock solution, c = 0,25 mol/l. 4 Reagents Dissolve, in a beaker of nominal capacity 1 litre, 17,0 g of imidazole (4.6) in approximately 900 ml of water. If not st
12、ated otherwise, only reagents of recognized analytical grade and water according to grade 1 of ISo 3696 agents shall be checked regularly (see 9.3). 4.1 Phosphoric acid (H,PO,). p = 1.71 g/ml. be med. The blank Of the re While stirring with a magnetic stirrer, add hydrochloric acid I (4.7) and adjus
13、t, with the help of a pH electrode, the pH to 7.5. Transfer to a volumetric flask, of nominal capacity 1 O00 ml, and dilute to volume with water. The solution is stable for 4 weeks if kept in a brown glass bottle at room temperature. 4.2 Sulfanilamide (4-aminobenzenesulfonamide, C this solution is s
14、table. Prior to use, solutions C and B for FIA shall be 4.10 Copper sulfate solution II, p(CuS04.5H20) = 20 g/l; this solution is stable. degassed, for example by membrane filtration (vac- uum). Table 1 - Options for preparing the solutions C and B in figures A.l, B.l and C.l Method Parameter Conten
15、t of Content of solution C solution B (see figures (see figures A.l, B.l and A.l, B.l and C.1) C.1) FIA 1 Nitritelnitrate I necessary ” is not Nitrite Buffer (4.1412) Water Water) Buffer (4.14) No solution BI) I Nitrite/nitratel Buffer (4.14) I Buffer (4.14) I CFA I I 1) Three different alternatives
16、. 2) If, in the case of CFA, water or buffer (4.14) is used as solution B and 1 ml of surfactant (4.1 1) per 1 litre of solution is added. If solution B is omitted, the surfactant (4.1 1) has to be added to the reagent solution R1 (4.17, see figures A.l, B.l and C.1). 4.16 Buffered copper sulfate so
17、lution. Mix 20 ml of the copper sulfate solution II (4.10) and 20 ml of the imidazole stock solution (4.13) in a beaker of nominal capacity 50 ml. Page 5 EN IS0 13395 : 1996 also be made separately and dosed into the equipment by different lines. Prior to use, solution RI for FIA shall be degassed,
18、for example by membrane filtration (vacuum). 4.18 Nitrite(N1 stock solution, pN = 100 mg/l. Dissolve 492,6 mg of sodium nitrite (4.4) in water, in a volumetric flask of nominal capacity 1 O00 ml, and dilute to volume. This solution is stable for at least 2 weeks if kept in a stoppered glass bottle a
19、t 4 “C. 4.19 Nitrite(N1 solution I, pN = 20 mg/i. Pipette 20 ml of the stock solution (4.18) into a volumetric flask of nominal capacity 1 O0 ml, and dilute to volume with water. Prepare the solution freshly before use. 4.20 Pipette 1 ml of the stock solution (4.18) into a volumetric flask of nomina
20、l capacity 1 O0 ml, and dilute to volume with water. Nitrite(N1 solution II, pN = 1 mg/l. Prepare the solution freshly before use. 4.21 Dissolve 144,4 mg of potassium nitrate (4.5) in water, in a volumetric flask of nominal capacity 100 ml, and dilute to volume. Nitrate(N) solution 1, pN = 200 mg/l.
21、 The solution is stable for at least 1 month. Prepare the solution freshly before use. 4.22 Nitrate(N1 solution II, pN = 20 mg/l. to volume with water. L. I J. Dissolve, in a volumetric flask of nominal capacity 500 ml, 5 g of sulfanilamide (4.21, 0.5 g of N-(l-naphthyl)ethylenediaminedihydrochlorid
22、e (4.3) in water, add 50 ml of phosphoric acid (4.11, and dilute to volume. Stored in a brown glass bottle, the solution is stable for at least one week. NOTE 4 For the preparation of this reagent solution, hydrochloric acid (4.7, 4.8) may be used instead of phosphoric acid, provided equivalent perf
23、ormance charac- teristics are obtained. The solutions of sulfanilamide (4.2) and N(1-naphthyl)ethylenediaminedihydrochloride (4.3) can Prepare the solu:ion freshly before use. 4.23 Calibration solutions The calibration solutions are prepared by diluting the respective solutions described in 4.19 to
24、4.22. These solutions may be used in any combination for the preparation of calibration solutions for the determi- nation of nitrite(N1, nitrite/nitrate(N or nitrate(N1. At least five calibration standards per working range are recommended. The following working ranges are provided: BSI BS*EN*ISO 13
25、395 96 1624667 0573026 Ob7 Page 6 EN IS0 13396 : 1996 mg/l 02 0,4 Proceed, for example, as recommended in tables 2 and 3 (if 10 standards are used). All calibration solutions shall be prepared immediately before measurement. For nitrite(N): Working range II: 0.01 mg/i to 0,l mg/l Working range I: 0,
26、l mg/l to 1,0 mg/l 0.2 mg/l to 2 mg/l Working range I: 2 mg/l to 20 mg/l For nitrite/nitrate(N): Working range II: to 100 ml water to 100 ml ml mg/l ml 1 2 1 2 4 2 Table 2 - Preparation of the calibration solutions for nitrite(N1 concentration Nitrite(N) concentration 0.6 0.8 1 ,o 1.2 3 6 3 4 8 4 5
27、10 5 6 12 6 nitrate(N1 solution I I concentration I (4.21) diluted with I solution II (4.22) Nitrate(N1 concentration diluted with water 1.6 1.8 8 16 8 9 18 9 2.0 I 10 20 10 7 14 7 BSI BS*EN*ISO 1339.5 96 1624667 0571027 TT3 = Page 7 EN IS0 13396 : 1996 5 Apparatus Usual laboratory apparatus and 5.1
28、 Flow injection system (FIA), normally compris- ing the following components (see figure A.1). Reagent reservoirs. Low pulsation pump. Suitable pump tubing, if required. Sample injector with an injection volume of 10 pl to 300 pl. If nitrite/nitrate(N) or nitrate(N) is to be determined: cadmium redu
29、ctor with a minimum reduction ef- ficiency of 90 %, e.g. packed cadmium column with granulate (4.1 21, of internal diameter 4,O mm, for example, and minimum length 5 cm. Transport tubes and reaction coils of internal di- ameter 0,5 mm to 0,8 mm, with tube connections and T-connections of chemically
30、inert plastics. Dialysis cell, if required, with, for example, a cellulose membrane, suitable for the predilution of the sample or the elimination of interfering compounds. NOTE 5 The dialysis cell should be placed after the injector (see figure A. 1). The carrier solution C may serve as a donor and
31、 also as a recipient solution. The flow rates of these two streams should be equal. Photometric detector with flow cell, wavelength range 520 nm to 560 nm. Recording unit (e.g. strip chart recorder, integrator or printerlplotter). In general, peak height signals are evaluated. Autosampler, if requir
32、ed. 5.2 Continuous flow analysis (CFA), normally comprising the following components (see figure B.1): - Autosampler or any other device allowing a repro- ducible application of the sample. - Reagent reservoirs. - Low pulsation pump with suitable, chemically inert pump tu bec. - If nitrite/nitrate(N
33、) or nitrate(N1 is to be determined: cadmium reductor with a minimum reduction ef- ficiency of 90 %, e.g. cadmium tube 1101 of internal diameter 1,l mm or cadmium column (see 5.1). - Manifold with highly reproducible gas-bubble feeding (nitrogen is recommended), sample and reagent feeding, with appr
34、opriate transport sys- tems and connection assemblies of chemically inert plastics or metal. The application of the cad- mium reductor requires oxygen-free gas. Before entering the cadmium column the flow stream has to be debubbled, if air is used for segmenting the flow stream. - Dialysis cell, if
35、required, with, for example, a cellulose membrane, suitable for the prediiution of the sample or the elimination of interfering compounds. - Photometric detector with flow cell, wavelength range 520 nm to 560 nm. - Recording unit (e.g. strip chart recorder, integrator or printer/plotter). In general
36、, peak height signals are evaluated. NOTE 6 Figure B.l describes two flow systems with an internal diameter of approximately 1 mm. Figure C.1 shows a flow system (for the determination of nitritelnitrate(N1 with an internal diameter of 2,2 mm. 5.3 Volumetric flasks, of nominal capacity 100 MI, 500 m
37、l and 1 O00 ml. 5.4 Pipettes, of nominal capacity 100 pl, 1 ml to 10 ml, 20 ml, 50 ml and 100 ml. 5.5 Beakers, of nominal capacity 25 ml, 50 ml and 1 litre. 5.6 Syringe, of nominal capacity 25 ml. 5.7 Membrane filter assembly, with membrane fil- ters of pore size 0,45 pm. 5.8 pH electrode 6 Checking
38、 the flow system A calibration solution (4.23) with a nitrite(N) concen- tration of 0.05 mg/l, or a nitrate(N) concentration of 1 mg/l, measured in the system (FIA or CFA, respectively) which is adjusted to the lower working range, should give an absorbance of at least 0,04 per 10 mm path length. BS
39、I BS*EN*ISO 33395 96 3624669 0573028 93T Page 8 EN IS0 13395 : 1996 NOTE 7 If the photometric detector (see 5.1 or 5.2) does not give any absorbance readings, the absorbance may then be determined by comparing with an external absorbance- measuring photometer. 7 Sampling and sample preparation Befor
40、e use, all containers coming into contact with the sample shall be cleaned thoroughly with water and shall be rinsed several times with the samples. (See IS0 5667-3.) If only nitrite is to be determined, collect the sample in a glass or polyethylene bottle and analyse it at once. Proceed in the same
41、 way, if nitrate is to be de- termined and if the nitrite(N) concentration is at least in the same working range as the nitrate(N1 concen- tration. If only nitrite/nitrate(N) is to be determined, or nitrate(N1 in samples with nitrite(N1 concentrations below the respective nitrite/nitrate(N) working
42、range, sample containers made of polyalkylene and poly- tetrafluoroethylene (PTFE) are also suitable. Acidify these samples with hydrochloric acid (4.7 and 4.8) to approximately pH 2, store at 2 “C to 5 “C and analyse within 24 h. As an exception, the samples may be stored in the freezer at approxim
43、ately - 20 “C for 8 d, provided the applicability of this preservation has previously been checked. Provided that significant loss of nitratelnitrite is ex- cluded, filtration of the sample is necessary if it con- tains particulate matter oY a particle size 0,l mm (risk of clogging the transport tub
44、es). 8 Interferences 8.1 Interferences of a general nature Nitrite cannot be stabilized and shall immediately be analysed see clause 7). Particulate matter present in the sample may lead to clogging of the transport tubes and will interfere with the photometric measurement. Larger particles ( 0,l mm
45、) can be removed by membrane filtration, smaller particles can be removed suitably by dialysis. In order to remove an interfering organic matrix (compounds with a higher molar mass), the sample may be dialysed, if need be in an online process. As an alternative, the sample may be filtered through ac
46、tivated carbon, provided changes of the nitrite or nitrate mass concentration in the sample can be ruled out. The self-absorption of the sample can be compen- sated by measuring, in addition to the sample signal (9.51, the signal of the sample without the admixture of the reagents. In this case, the
47、 difference of the two responses is used for the evaluation (according to clause 10). Prior to the measurement, dilute samples with a total salt concentration of 30 911. 8.2 Interference with the reduction of nitrate to nitrite Interferences may occur if the sample, after the ad- mixture of the buff
48、er solution, does not reach a pH of 6,5 to 7.5. This may happen with strongly acid, basic or buffered samples. In this event, the sample shall, prior to the measurement, be treated appropri- ately with bases or acids so as to reach the above mentioned pH in the solution streaming through the cadmium
49、 reductor see 5.1 and 5.2). 8.3 Interferences with the formation of the azo dye Surfactant concentrations 1 O mg/l may interfere with the determination; this interference can be pre- vented by a dialysis of the sample, if need be in the online process. (See 9 in annex D.) 9 Procedure 9.1 Preparation, activation and checking of the cadmium reductor 9.1.1 Cadmium column with granulate Place a sufficient quantity of the cadmium granulate (4.12) to fill the column (see 5.1) in a beaker (5.5) of nominal capacity 25 ml. Stir with hydrochloric aci
