1、BRITISH STANDARD Water quality - Determination of dissolved anions by liquid chromatography of ions - Determination of chromate, iodide, sulfite, thiocyanate and thiosulfate The European Standard EN IS0 10304-3 : 1997 has the status of a British Standard ICs 13.060.01 BS EN IS0 BS 6068 : Section 2.5
2、9 : 1997 10304-3 : 1997 STD-BSI BS EN IS0 1030Y-3-ENGL L777 Lb2YbbS Ob57015 888 i BS EN IS0 10304-3 : 1997 National foreword This British Standard is the English language version of EN IS0 10304-3 : 1997. It is identical with IS0 10304-3 : 1997. The UK participation in its preparation was entrusted
3、by Technical Conunittee EI%(, Water quaiity, to Subcommittee E”2, Physical, chemical and biochemical methods, which has the responsibility to: - aid enquirers to understand the text; - present to the responsible international/European committee any enquiries on the interpretation, or proposals for c
4、hange, and keep the UK interests informed - monitor related international and European developments and promulgate them in the UK. A iist of organizations represented on this subcommittee can be obtained on request to its secrem. BS EN IS0 103043 is one of a series of standards on water quality, oth
5、ers of which have been, or will be, published as Sections of BS 6068. This standard has therefore been given the secondary identifier BS 6068 : Section 2.59. The various Sections of BS 6068 are comprised within Parts 1 to 7, which, together with Part O, are listed below. Part o Part 1 Part 2 Part 3
6、Part 4 Part 5 Pari 6 Part 7 Introduction Glossary Physical, chemical an - sulfite (clause 5); - chromate (clause 6). An appropriate pretreatment of the sample 1e.g. dilution) and the application of a conductivity detector (CO), UV detector (UV) or amperometric detector (AD) make the working ranges g
7、iven in table 1 feasible. I 0.5 mai to 50 mg/l I UV (A = 205 nm to 220 nm) Thiocyanate (SCN), clause 4 I 0,1 mg/l to 50 mg/l I CD or UV (A = 205 nm to 220 nm) 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this patt o
8、f IS0 10304. At the time of publication, the editions indicated were valid. All standards are subject to revision, and patties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Membe
9、rs of IEC and IS0 maintain registers of currently valid International Standards. IS0 5667-1:1980 Water quality - Sampling - Part I: Guidance on the design of sampling programmes. IS0 5667-21991 Water quality - Sampling - Part 2: Guidance on sampling techniques. IS0 5667-311994 Water quality - Sampli
10、ng - Part 3: Guidance on the preservation and handling of samples. IS0 8466-11990 Water quality - Calibration and evaluation of analytical methods and estimation of performance characteristics -Part I: Statistical evaluation of the linear calibration function. IS0 10304-1:1992 Water quality - Determ
11、ination of dissolved fluoride, chloride, nitrite, orthophosphate, bromide, nitrate, and sulfate ions, using liquid chromatography of ions - Part 1: Method for water with low contamination. IS0 10304-21995 Water quality - Determination of dissolved anions by liquid chromatography of ions - Part 2: De
12、termination of bromide, chloride, nitrate, nitrite, orthophosphate and sulfate in waste water. 1 - STD-BSI BS EN IS0 10304-3-ENGL 1777 = lb24bb7 Ob57023 754 EN IS0 10304-3 : 1997 3 Principle 3.1 Separation of ions is carried out by liquid chromatography using a separating column. A low capacity anio
13、n exchanger is used as the stationary phase, and usually aqueous solutions of salts of weak monobasic and dibasic acids as mobile phases (eluent, see 4.1.16, 5.1.4,6.1.9). 3.2 The addition of organic agents, such as 4-hydroxybenzonitrile (see 4.1.16.2.2, 4.3.4), or organic solvents to the eluent can
14、 be used to speed up the elution or reduce the tailing effects, especially for the analysis of the more strongly polarizable ions iodide, thiocyanate and thiosulfate. 3.3 Detection is by conductivity (CD), UV and amperometric detectors (AD). 3.3.1 When using conductivity detectors it is essential th
15、at the eluents have a sufficiently low conductivity. For this reason, conductivity detectors are often combined with suppressor devices (cation exchangers) which will reduce the conductivity of the eluents and transform the sample species into their respective acids. 3.3.2 UV detection measures eith
16、er the absorption directly (see table 1) or, in the case of anions which are transparent in the UV-range, the decrease in the background absorption caused by a UV-absorbing eluent is measured (indirect measurement). If indirect UV-detection is used, the measuring wavelength depends on the compositio
17、n of the eluent. 3.3.3 Amperometric detectors measure the quantity of current caused by the oxidation of anions. The oxidation voltage required for the anions in question depends on the pH value of the eluent. 3.4 The concentration of the respective anions is determined by a calibration of the overa
18、ll procedure. Particular cases may require calibration by means of standard addition (spiking). 4 Determination of iodide, thiocyanate and thiosulfate Follow the instructions given in clause 4 to make the working ranges given in table 1 feasible. 4.1 Reagents Use only reagents of recognized analytic
19、al grade, if commercially available. Carry out weighing with an accuracy of 1% of the nominal mass. The water shall have an electrical conductivity of 0,45 pm. An increase of the electrical conductivity due to an uptake of carbon dioxide does not interfere with the determination. 4.1.1 Sodium hydrog
20、en carbonate, NaHCO, 4.1.2 Sodium carbonate, Na,CO, 4.1.3 Phthalic acid, C,H,O, 4.1 A Disodium teiraborate, Na,B,O, 4.1.5 Gluconlc acid, sodium sait, C,H,NaO, 4.1.6 Methanol, CH,OH 4.1.7 Bodc acid, H,BO, 4.1.8 Glycerol, C,H,O, 2 STD-BSI BS EN IS0 1030q-3-ENGL 1997 m Lb24bb9 Ob57024 890 D EN IS0 1030
21、4-3 1997 4.1.9 Acetonitrile, CH,CN 4.1.10 Sodium hydroxide solution, dNaOH) = 0,l mol/l 4.1.1 1 4-hydroxybenzonitrile, C,H,NO 4.1.12 Tils(hydroxymethyi)ainomethane, C,H,NO, 4.1.13 Sodium thiosulfate, pentahydrate, Na,S,O, .5 H,O 4.1.14 Sodium Iodide, Na1 4.1.1 5 Potassium thiocyanate, KSCN 4.1.16 El
22、uents 4.1.16.1 General Different eluents are used, their choice depending on the type of separating column and detector. Therefore, follow the column manufacturers instructions for the exact composition of the eluent. The eluent compositions described in 4.1.16.2 and 4.1.16.3 are examples only. A se
23、lection of reagents for some commonly used eluents is presented in 4.1.1 to 4.1.12. Degas all eluents or prepare eluents using degassed water (4.1). Take steps to avoid any renewed gas pick-up during operation (e.g. by helium superposition). In order to minimize the growth of bacteria or algae, stor
24、e eluents in the dark and renew every 2 to 3 days. 4.1.16.2 Examples of eluents for ion chromatography using the suppressor technique For the application of the suppressor technique, sodium hydroxide and solutions of salts of weakly dissociated acids, such as sodium carbonate/sodium hydrogen carbona
25、te, sodium hydrogen carbonate, and sodium tetraborate are used. 4.1.16.2.1 Sodium carbonate/sodium hydrogen carbonate concentrate The addition of the following eluent concentrate to the sample has proved to be successful for sample pretreatment and eluent preparation (see 4.1.16.2.2). -Place 36 g of
26、 sodium carbonate (4.1.2) and 36,l g of sodium hydrogen carbonate (4.1.1) in a graduated flask of nominal capacity 1 O00 ml, and dilute to volume with water (4.1). The solution contains 0,34 mol/l of sodium carbonate and 0,43 mol/l of sodium hydrogen carbonate. This solution is stable for several mo
27、nths if stored at 4 “C to 6 OC. 4.1.16.2.2 Sodium carbonate/sodium hydrogen carbonate eluent The following eluent has proved to be applicable for the determination of iodide, thiocyanate, thiosulfate: - Place 50 ml of the concentrate (4.1.16.2.1) in a graduated flask of nominal capacity 5 O00 ml, ad
28、d water (4.11, add 750 mg of 4-hydroxybenzonitrile (4.1.11) and dilute to volume with water (4.1) The solution contains 0,0034 mol/l of sodium carbonate, 0,0043 mol/l of sodium hydrogen carbonate and 0,0013 mol/l of 4-hydroxybenzonitrile. Renew the eluent every 2 to 3 days (4.1.16). The concentratio
29、ns of iodide, thiocyanate and thiosulfate in these calibration solutions are 1 mg/i, 2 mg/l, 3 mg/l, 4 mg/i, 5 mg/i, 6 rng/I, 7 mg/i, 8 mg/l, 9 mg/i and 10 mg/l respectively. Prepare the calibration solutions on the day of use. 11 4-hydroxybenzonlrile can be added to speed up the elution or reduce t
30、he tailing effects, for the analysis of iodide, thiocyanate and thiosulfate (4) but it can cause interferences with the determination of iodide, thiocyanate and thiosulfate when the UV detector is used (4.3.41. 21 To improve the solubility of 4-hydroxybenzonitrile the substance can be dissolved in a
31、 small quantity of methanol or ethanol and, after addition to the eluent concentrate the solution should be stirred overnight. 12 1. 3 4.1.16.3 Examples of eluents for ion chromatography without using the suppressor technique For ion chromatography without suppressor devices, use salt solutions, e.g
32、. potassium hydrogenphthalate, 4-hydroxybenzoate, sodium borate/gluconate, and sodium benzoate. The concentration of the salts is usually in the range of 0,0005 to 0,Ol mol/l. Concentrate and eluent solutions are prepared as described in 4.1.16.2.1 or 4.1-16.2.2 respectively. 4.1.16.3.1 Phthalic aci
33、d concentrate The addition of the following eluent concentrate to the sample has proved to be successful for sample pretreatment and eluent preparation (see 4.1.16.3.2). - Place 4,485 g of phthalic acid (4.1.3) in a graduated flask of nominal capacity 1 O00 ml, dissolve in approximately 800 ml of wa
34、ter (4.11, add 100 ml of acetonitrile (4.1.9) and dilute to volume with water (4.1). Adjust to a pH of 4 with tris(hydroxymethy1)aminomethane (4.1.12; can be added either in solid form or as solution, e.g. 1 mol/l). The solution contains 0,027 mol/l phthalic acid and approximately 10 % of acetonitri
35、le. 4.1 .I 6.3.2 Phthalic acid eluent The following eluent can be used for the determination of iodide, thiocyanate and thiosulfate: -Pipette 100 ml of the concentrate (4.1.16.3.1) into a graduated flask of nominal capacity 1 O00 ml and dilute to volume with water (4.1). The solution contains 0,0027
36、 mol/l of phthalic acid and approximately 1 % of acetonitrile. The pH of the solution should be in the range of 4,O to 4.5 3). Renew the eluent every 2 to 3 days (4.1.16). 4.1.16.3.3 Borate/gluconate concentrate The following eluent concentrate has proved useful for the preparation of the eluent (4.
37、1.16.3.4) and the pretreatment of the samples. -Weigh 16 g of gluconic acid, sodium salt (4.1.51, 18 g of boric acid (4.1.71, and 25 g of disodium tetraborate (4.1.4) into a graduated flask, nominal capacity 1 O00 ml, dissolve in approximately 500 ml of water (4.11, add 250 ml of glycerol (4.1.8) an
38、d dilute to volume with water (4.1). The solution contains 0,073 mol/l of gluconic acid, 0,291 mol/l of boric acid, 0,124 moVI of disodium tetraborate, and approximately 25 % of glycerol. The solution is stable for several months if stored at 4 OC to 6 “C. 4.1.16.3.4 Borate/gluconate eluent The foll
39、owing eluent can, for example, be used for the determination of iodide, thiocyanate and thiosulfate. - Place 500 ml of water (4.1) in a graduated flask of nominal capacity 1 O00 ml, add 23,5 ml of the concentrate (4.1.16.3.31, 120 ml of acetonitrile (4.1.9) and dilute to volume with water (4.1). The
40、 solution contains 0,0017 molll of gluconic acid, 0,0068 molll of boric acid, 0,0029 mom of disodium tetraborate, approximately 0,6 % of glycerol, and approximately 12 % of acetonitrile. The pH of this solution should be in the range of 8.3 to 8.7 1. Renew the eluent every 2 to 3 days (4.1.16). 4.1.
41、17 Stock solutions Prepare stock solutions of concentration 1 O00 mg/i for each of the anions iodide, thiocyanate and thiosulfate. - Dissolve the appropriate mass of each of the substances, prepared as stated in table 2, in a small quantity of water in graduated flasks of nominal capacity 1 O00 ml.
42、Dilute to volume with water. The solutions are stable for several months if stored at 4 OC to 6 OC in polyethylene bottles. Alternatively, use commercially available stock solutions of the required concentration. 3) pH values 4,5 can increase retention times or cause a peak resolution R 1,3 (for cri
43、teria for R see 4.2.2). 13) The salt ollen contains some sulfate and is stable in dry air up to temperatures of 100 OC. Low concentrated sulfite solutions will quickly react with atmospheric oxygen. lhe solution is therefore made alkaline and stabilized by the addition of formaldehyde solution. 14)
44、lhe iodometric titration of suIffie is subject to interference by formaldehyde. Calibrate the sulfite content before adding formaldehyde solution. 13 STD-BSI BS EN IS0 1030Y-3-ENGL 1777 W Lb24bb b57035 b7b D - EN IS0 10304-3 : 1997 Prepare the solution on the day of use. Alternatively use commercial
45、ly available stock solution or a solution formed from hydroxymethane sulfonic acid of the required concentration. Prepare the solution according to 5.1.6.1 if necessary. 5.1.6 Standard solutions 5.1.6.1 General remarks When preparing the sulfite standard solution (5.1.6.2) or the sulfite calibration
46、 solutions respectively (5.1.7) always add the reagents in the following sequence: 1) water 2) sodium hydroxide solution 3) formaldehyde solution 4) sodium sulfite stock solution, or sodium sulfite standard solution respectively. Prepare the standard solutions, in the concentrations required, from t
47、he standard stock solution (3.1.5) when needed. The lower the anion concentration, the higher the danger of alterations in concentration caused by interaction with the vessel material or reaction with atmospheric oxygen. The standard solutions shall be stored in polyethylene vessels. Always use the
48、same vessels for the same concentration ranges in order to avoid the danger of cross-contamination. 5.1.6.2 Sulfrte standard solution See 5.1.6.1. The mass concentration of this solution is: p(S0,) = 100 mg/l - Into a graduated flask of nominal capacity DO ml, pipette approximately 80 ml of water (4
49、.11, 1 ml of sodium hydroxide solution (4.1.10), 0.1 ml of formaldehyde solution (5.1.21, 10 ml of the stock solution, prepared as described in 5.1.5, and dilute to volume with water (4.1). Prepare the solution freshly before use. Prepare further standard solutions by appropriate dilutions of this standard solution. 5.1.7 Suffite callbratlon solutions Depending on the anion concentration expected, use the standard solution (5.1.6.2) to prepare 5 to 10 solutions covering the expected working range as evenly as possible; for example, proceed as follows for the
