CN1200264C - Method for measuring seawater chemical oxygen demand by photometry - Google Patents
Method for measuring seawater chemical oxygen demand by photometry Download PDFInfo
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- CN1200264C CN1200264C CN 03143223 CN03143223A CN1200264C CN 1200264 C CN1200264 C CN 1200264C CN 03143223 CN03143223 CN 03143223 CN 03143223 A CN03143223 A CN 03143223A CN 1200264 C CN1200264 C CN 1200264C
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- seawater
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- oxygen demand
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- 239000013535 sea water Substances 0.000 title claims abstract description 71
- 239000000126 substance Substances 0.000 title claims abstract description 48
- 238000000034 method Methods 0.000 title claims abstract description 28
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 24
- 239000001301 oxygen Substances 0.000 title claims abstract description 24
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 24
- 238000005375 photometry Methods 0.000 title description 2
- 238000002835 absorbance Methods 0.000 claims abstract description 26
- LBSANEJBGMCTBH-UHFFFAOYSA-N manganate Chemical compound [O-][Mn]([O-])(=O)=O LBSANEJBGMCTBH-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000012286 potassium permanganate Substances 0.000 claims abstract description 23
- 238000005259 measurement Methods 0.000 claims abstract description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 10
- 238000006243 chemical reaction Methods 0.000 claims abstract description 8
- 239000012490 blank solution Substances 0.000 claims abstract description 7
- 239000000243 solution Substances 0.000 claims description 39
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- IWZKICVEHNUQTL-UHFFFAOYSA-M potassium hydrogen phthalate Chemical compound [K+].OC(=O)C1=CC=CC=C1C([O-])=O IWZKICVEHNUQTL-UHFFFAOYSA-M 0.000 claims description 9
- 238000007781 pre-processing Methods 0.000 claims description 8
- 229920005989 resin Polymers 0.000 claims description 8
- 239000011347 resin Substances 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 7
- 239000013522 chelant Substances 0.000 claims description 6
- 238000005342 ion exchange Methods 0.000 claims description 6
- 150000001455 metallic ions Chemical class 0.000 claims description 5
- HLBBKKJFGFRGMU-UHFFFAOYSA-M sodium formate Chemical compound [Na+].[O-]C=O HLBBKKJFGFRGMU-UHFFFAOYSA-M 0.000 claims description 5
- 239000004280 Sodium formate Substances 0.000 claims description 4
- 230000003647 oxidation Effects 0.000 claims description 4
- 238000007254 oxidation reaction Methods 0.000 claims description 4
- 235000019254 sodium formate Nutrition 0.000 claims description 4
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 claims description 3
- 238000013459 approach Methods 0.000 claims description 3
- 150000002894 organic compounds Chemical class 0.000 claims description 3
- 238000003912 environmental pollution Methods 0.000 abstract description 3
- 238000010521 absorption reaction Methods 0.000 abstract description 2
- 239000005416 organic matter Substances 0.000 abstract 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 238000003556 assay Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- NLKNQRATVPKPDG-UHFFFAOYSA-M potassium iodide Chemical compound [K+].[I-] NLKNQRATVPKPDG-UHFFFAOYSA-M 0.000 description 3
- 229920001429 chelating resin Polymers 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 2
- 229910021645 metal ion Inorganic materials 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000007348 radical reaction Methods 0.000 description 2
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 2
- 235000019345 sodium thiosulphate Nutrition 0.000 description 2
- 239000012086 standard solution Substances 0.000 description 2
- 241000370738 Chlorion Species 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- QLBHNVFOQLIYTH-UHFFFAOYSA-L dipotassium;2-[2-[bis(carboxymethyl)amino]ethyl-(carboxylatomethyl)amino]acetate Chemical group [K+].[K+].OC(=O)CN(CC([O-])=O)CCN(CC(O)=O)CC([O-])=O QLBHNVFOQLIYTH-UHFFFAOYSA-L 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- PNDPGZBMCMUPRI-UHFFFAOYSA-N iodine Chemical compound II PNDPGZBMCMUPRI-UHFFFAOYSA-N 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- -1 organism is oxidized Substances 0.000 description 1
- 239000002957 persistent organic pollutant Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000012925 reference material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
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- Investigating Or Analysing Materials By The Use Of Chemical Reactions (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
本发明公开了一种对海水化学需氧量进行测定的光度测定法，该方法首先将海水样品进行预处理，再以碱性高锰酸钾为反应体系，这样海水中的有机物在强碱性介质中与过量的高锰酸钾迅速反应，高锰酸钾被有机物定量还原后生成锰酸盐，以纯水或空白溶液作参比，在锰酸盐的最大吸收波长430nm处测其吸光度A，该吸光度A与海水样品中的有机物的含量具有正相关关系。绘制A～COD值工作曲线，通过工作曲线根据吸光度值可求得海水中有机物的浓度，即海水COD值。该方法操作简便，快速准确，减少环境污染，而且很容易实现对海水COD测量的自动化。
The invention discloses a photometric method for measuring the chemical oxygen demand of seawater. In the method, the seawater sample is pretreated firstly, and then the alkaline potassium permanganate is used as the reaction system, so that the organic matter in the seawater is Rapid reaction with excess potassium permanganate in the medium, potassium permanganate is quantitatively reduced by organic matter to form manganate, with pure water or blank solution as reference, measure its absorbance A at the maximum absorption wavelength of manganate at 430nm , the absorbance A has a positive correlation with the content of organic matter in the seawater sample. Draw the working curve of A～COD value, through the working curve, the concentration of organic matter in seawater can be obtained according to the absorbance value, that is, the COD value of seawater. The method is easy to operate, fast and accurate, reduces environmental pollution, and can easily realize the automation of seawater COD measurement.
Description
Technical field
The present invention relates to the assay method of chemical oxygen demand (COD) (Chemical Oxygen Demand, below abbreviate COD sometimes as), relate in particular to a kind of method of utilizing photometry to measure seawater cod.
Background technology
Seawater cod is to characterize the composite target that the seawater water body is subjected to organic pollutants, is a basic environmental ecology key element weighing the ocean water body quality.The standard determination method of China's sea water COD is basic potassium permanganate method (GB17378.4-1998) at present, this method is in alkaline medium, seawater sample and excessive potassium permanganate are reacted under heating condition, make the organism in the seawater quantitatively potassium permanganate is reduced to manganate.Add sulfuric acid acidation afterwards, add the solid potassium iodide again and reduce the manganate of remaining potassium permanganate and generation, generate quantitative iodine molecule, then with starch as indicator, carry out titration with sodium thiosulfate standard solution, make blank assay simultaneously.The consumption difference of sodium thiosulfate standard solution in experiment and the blank assay is passed through the chemical oxygen demand (COD) (COD value) that calculates seawater more per sample.This method complex operation as can be seen, time and effort consuming, severe corrosive of reaction system etc. in addition, be not suitable for the on-the-spot fast monitored of sea water COD, therefore research is used for easy, the fast and accurate method of sea water COD, for the labour intensity that alleviates oceanographic survey and monitoring personnel, improve working environment, especially set up China's offshore pollution/ECOLOGICAL ENVIRONMENTAL MONITORING net, satisfy the needs of national digital marine technology support system, keep the sustainable development of marine economy all significant.
Summary of the invention
Purpose of the present invention just provides a kind of method with the spectrphotometric method for measuring sea water COD, and this method is easy, quick, accurate, and the minimizing environmental pollution also can realize the fast automatic measurement to sea water COD.
The technical solution adopted in the present invention is for achieving the above object:
First step sea water preprocessing
At first seawater sample is filled with the sea water preprocessing device of ion-exchange type or chelate resin by inside, removes the metallic ion in the seawater;
The second step oxidation of organic compounds
The pretreated seawater sample of learning from else's experience, add strongly basic medium and excessive potassium permanganate, to the last alkaline concentration of solution be 2mol/L, reaction is oxidized rapidly with excessive potassium permanganate in strongly basic medium for the organism in the seawater, potassium permanganate is quantitatively reduced the back by organism and generates manganate;
Absorbance A is decided in the 3rd pacing
With spectrophotometer 430nm place, make reference with blank solution or pure water, the absorbance A of manganate in the seawater sample behind the generation manganate that second step of measurement obtains;
The 4th step drawing curve
Be taken in the reaction system stable, the solution with reductibility that the chemical oxygen demand value is determined is as standard substance solution, its chemical oxygen demand (COD) is measured according to the basic potassium permanganate method in the seawater quality analytical approach, the standard substance solution of getting the different chemical oxygen demand afterwards reacts with excessive potassium permanganate in the strongly basic medium of 2mol/L, with spectrophotometer at the 430nm place, make the absorbance A of manganate in the standard substance solution after reference measurement generates manganate with blank solution or pure water, according to the corresponding relation between this absorbance A and the reference material solution chemistry oxygen demand, draw absorbance～chemical oxygen demand value working curve;
The 5th step was asked chemical oxygen demand (COD)
The working curve that the absorbance A that gets according to the 3rd pacing drew from the 4th step is found the pairing point of this absorbance A, thereby obtains the chemical oxygen demand (COD) into seawater.
Second step, described strongly basic medium of the 4th step are NaOH solution.
Described standard substance solution of the 4th step be Potassium Hydrogen Phthalate with sodium formate with the amount of substance mixture solution more formulated than 1: 1 or by Potassium Hydrogen Phthalate and EDTA with the amount of substance mixture solution more formulated than 1: 1.
Below, the assay method to sea water COD of the present invention describes in order:
1, at first with seawater sample by the sea water preprocessing device, purpose is in order to remove the metallic ion in the seawater, be filled with ion-exchange type resin or chelate resin in the sea water preprocessing device, metallic ion in the seawater is exchanged by the hydrogen ion in the ion-exchange type resin, or generate chelate with certain radical reaction in the chelating resin, the concentration of metal ions of make handling in the seawater of back significantly reduces, and seawater sample can not form precipitation of hydroxide and influence the mensuration of sea water COD value in alkaline medium like this.
2, oxidation of organic compounds, ultimate principle is:
React rapidly with excessive potassium permanganate in strongly basic medium through the organism in the pretreated seawater, organism is oxidized, and potassium permanganate is generated manganate by quantitative reduction back.Strongly basic medium can be selected the 2.0mol/L sodium hydroxide solution for use, and being chosen in the strongly basic medium is for fast reaction speed, also is in order to prevent that chlorion in the seawater and other reductibility ions are by the oxidation of potassium permanganate institute.
3, measure absorbance, the maximum absorption wavelength of manganate solution is 430nm, and with the absorbance of manganate in the seawater sample of spectrophotometer after the generation manganate is measured at the 430nm place, organic content has positive correlation in this absorbance and the seawater sample.
4, drawing curve, should be chosen in the system stable during the choice criteria substance solution, the solution with reductibility that the COD value is determined, the present invention selects is Potassium Hydrogen Phthalate with sodium formate with the amount of substance solution more formulated than 1: 1 or Potassium Hydrogen Phthalate and EDTA with the amount of substance mixture solution more formulated than 1: 1 as standard substance solution.
5, obtain the COD value, behind the drawing curve, obtain COD value into seawater thereby the absorbance A that gets according to the 3rd pacing finds its corresponding point from working curve.
Compare with background technology, technique effect of the present invention is tangible, adopt spectrphotometric method for measuring sea water COD of the present invention easy and simple to handle, quick and precisely, in the mensuration process, do not use sulfuric acid, the chemical reagent kind of using is few, reduces environmental pollution, and whole mensuration process is easy to realize the robotization of sea water COD measurement.
Description of drawings
Fig. 1 is a process flow diagram of the present invention.
Embodiment
The present invention will be further described below in conjunction with embodiment.
Figure 1 shows that the process flow diagram of spectrphotometric method for measuring sea water COD of the present invention, at first get seawater sample, with it by the sea water preprocessing device, described sea water preprocessing device is a cylindrical shape cylinder, two ends screw-cap shutoff, and leave intake-outlet, portion is filled with ion-exchange type resin or chelate resin within it, seawater is by behind the pretreatment unit, metallic ion wherein or exchanged by the hydrogen ion in the ion-exchange type resin, or generate chelate with certain radical reaction in the chelating resin, make that the concentration of metal ions in the outlet seawater significantly reduces.To place the 25mL color comparison tube through pretreated seawater sample, the sodium hydroxide solution 8mL that adds 6.25mol/L, 0.01mol/L liquor potassic permanganate 5.0ml, add water to scale, shake up or in water-bath the heating 3-5 minute after, make reference with pure water or blank solution, the absorbance A of manganate in the seawater sample after the 430nm place surveys the generation manganate; Draw A～COD value working curve then: be taken in the reaction system stable, the solution with reductibility that the chemical oxygen demand value is determined is as standard substance solution, get mixture solution that Potassium Hydrogen Phthalate and sodium formate form than configuration in 1: 1 with amount of substance in the present embodiment as standard substance solution, certainly the mixture solution that also desirable Potassium Hydrogen Phthalate and EDTA form than configuration in 1: 1 with amount of substance is as standard substance solution, its chemical oxygen demand (COD) is measured according to the basic potassium permanganate method in the seawater quality analytical approach, the standard substance solution of getting the different chemical oxygen demand afterwards reacts with excessive potassium permanganate in the NaOH of 2mol/L solution, with spectrophotometer at the 430nm place, make the absorbance A of manganate in the standard substance solution after reference measurement generates manganate with blank solution or pure water, according to the corresponding relation between the chemical oxygen demand (COD) of this absorbance A and standard substance solution, draw absorbance～chemical oxygen demand value working curve; Absorbance A according to manganate in the seawater sample behind the generation manganate that records above finds its corresponding point from A～COD value working curve, thereby obtains being seawater cod.
To same seawater sample replicate determination 9 times, and contrast with standard method (basic potassium permanganate method GB17378.4-1998) measurement result, analysis result sees the following form.
Seawater measurement result (COD:mg/L is a standards system with Potassium Hydrogen Phthalate+sodium formate)
The seawater sample COD mean value relative standard deviation standard law relative error recovery
(mL) x(n＝9)(mg/L) RSD(％) (mg/L) RE(％) (％)
5.00 1.01 20.8 1.10 -8.2
10.00 1.13 15.6 1.10 2.7 91-108
Claims (3)
1, the spectrphotometric method for measuring of seawater cod is characterized in that it comprises following operation steps:
First step sea water preprocessing
At first seawater sample is filled with the sea water preprocessing device of ion-exchange type or chelate resin by inside, removes the metallic ion in the seawater;
The second step oxidation of organic compounds
The pretreated seawater sample of learning from else's experience, add strongly basic medium and excessive potassium permanganate, to the last alkaline concentration of solution be 2mol/L, reaction is oxidized rapidly with excessive potassium permanganate in strongly basic medium for the organism in the seawater, potassium permanganate is quantitatively reduced the back by organism and generates manganate;
Absorbance A is decided in the 3rd pacing
At the 430nm place, make reference with spectrophotometer, the absorbance A of manganate in the seawater sample behind the generation manganate that second step of measurement obtains with blank solution or pure water;
The 4th step drawing curve
Be taken in the reaction system stable, the solution with reductibility that the chemical oxygen demand value is determined is as standard substance solution, its chemical oxygen demand (COD) is measured according to the basic potassium permanganate method in the seawater quality analytical approach, the standard substance solution of getting the different chemical oxygen demand afterwards reacts with excessive potassium permanganate in the strongly basic medium of 2mol/L, with spectrophotometer at the 430nm place, make the absorbance A of manganate in the standard substance solution after reference measurement generates manganate with blank solution or pure water, according to the corresponding relation between the chemical oxygen demand (COD) of this absorbance A and standard substance solution, draw absorbance～chemical oxygen demand value working curve;
The 5th step was asked chemical oxygen demand (COD)
The working curve that the absorbance A that gets according to the 3rd pacing drew from the 4th step is found the pairing point of this absorbance A, thereby obtains the chemical oxygen demand (COD) into seawater.
2, the spectrphotometric method for measuring of seawater cod according to claim 1 is characterized in that: second step, described strongly basic medium of the 4th step are NaOH solution.
3, the spectrphotometric method for measuring of seawater cod according to claim 1 is characterized in that: described standard substance solution of the 4th step be Potassium Hydrogen Phthalate with sodium formate with the amount of substance mixture solution more formulated than 1: 1 or by Potassium Hydrogen Phthalate and EDTA with the amount of substance mixture solution more formulated than 1: 1.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 03143223 CN1200264C (en) | 2003-07-22 | 2003-07-22 | Method for measuring seawater chemical oxygen demand by photometry |
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| CN 03143223 CN1200264C (en) | 2003-07-22 | 2003-07-22 | Method for measuring seawater chemical oxygen demand by photometry |
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007016740A1 (en) * | 2005-08-11 | 2007-02-15 | Aqua Diagnostic Pty. Ltd. | Water analysis using a photoelectrochemical method |
| CN103163088B (en) * | 2011-12-14 | 2017-04-05 | 北京普源精仪科技有限责任公司 | For spectrophotometric measurement apparatus and its measuring method |
| CN103278501B (en) * | 2013-06-26 | 2015-07-22 | 北京桑普生物化学技术有限公司 | COD quick detection solution, test box and determination method |
| US9476866B2 (en) * | 2013-10-23 | 2016-10-25 | Hach Company | COD/TOC analyses using ferrate oxidation |
| CN103592242B (en) * | 2013-11-11 | 2016-01-06 | 天津大学 | A kind of method measuring seawater cod |
| CN104535398A (en) * | 2015-01-28 | 2015-04-22 | 国家海洋技术中心 | Method for preparing seawater pH standard buffer solution |
| CN108122647A (en) * | 2017-12-18 | 2018-06-05 | 苏州人为峰软件科技有限公司 | A kind of super-thin oxidation resisting copper braided wire and its manufacturing method |
| CN115127879A (en) * | 2022-01-24 | 2022-09-30 | 坛墨质检科技股份有限公司 | Preparation method of chemical oxygen demand standard substance in natural seawater |
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