Glassware should consist of a 500 ml erlenmeyer flask or a 300 ml round bottom flask made of heatresistant glass connected to a 12 inch allihn condenser by means of a ground glass joint. This parameter is generally of interest in wastewaters and natural waters. A 2 ml aliquot is added to dichromate solution and allowed to digest at 150 c for 2 h. Chloride reacts with silver ion to precipitate silver chloride, and thus inhibits the catalytic activity of silver. Electrometric method dried at 103105 oc dried at 180 oc closed reflux, colorimetric method 5 day bod test,azide modification method liquidliquid,partition gravimetric method digestion,lnductively coupled plasma method digestion,nductively coupled plasma method digestion,lnductively coupled plasma method filtration, colorimetric method mg02i. The closed reflux colorimetric method used for cod employs potassium dichromate k 2 cr 2 o 7 as oxidant, requires only a small sample size, and produces minimal waste.
Samples with higher cod concentrations may be processed by appropriate dilution of the sample. Apha 5310b determination of total organic carbon toc for liquid samples by high temperature combustion method. Apha 23e 5220 d chemical oxygen demand, closed reflux, colorimetric method. A colorimetric method for determining chemical oxygen. It is based on the use of thermo orion test kits cat. The most popular current testing method for cod involves using sealed and heated i. Sep 24, 2014 determine cod values of 50 mg o2l by using procedures in open reflux method, closed reflux titrimetric method, closed reflux colorimetric method. A miniaturized closed reflux colorimetric method allowing reagents savings of 80% is proposed by lapara et al. A 2 ml aliquot is added to dichromate solution and allowed to digest at 150 c for 2 hours. The closed reflux method 5220 c is economical in the use of metallic salt reagents, but requires homogenization of samples containing suspended solids to obtain reproducible results. Open reflux method closed reflux, titrimetric method closed reflux, colorimetric method argentometric method potentiometric method ion chromatography with chemical suppression of eluent conductivity colorimetric method multiple tube fermentation technique fecal coliform procedure multiple tube fermentation technique standard total.
Pdf miniaturized closed reflux, colorimetric method for the. Place approximately 500ml of sample in a clean blender bowl and homogenizze at high speed for two minutes. Tss and tds were determined according to sections 25401 and 2540c of standard methods, respectively. The cv was found to be less than 2% for sdsmcrc method, which was much lower than the cv value for smort method around 10%. Jun 05, 2012 this paper reports the development of an innovative sample preparation method for the determination of the chemical oxygen demand cod in heterogeneous solid or semisolid samples, with high suspended solids and cod concentrations, using an optimized closed reflux colorimetric method. The miniaturized closed reflux, colorimetric method for cod analysis also had several analytical advantages compared to the standard method, including easier preparation, and smaller sample size requirements. The closed reflux titrimetric and colorimetric are more economical in the use of metallic salt reagents and generate smaller quantities of hazardous waste, but homogenization of samples containing suspended solids to obtain reproducible results. Test method b micro cod by sealed digestion and spectrometry.
Miniaturized closed reflux, colorimetric method for. Because of its unique chemical properties, the dichromate ion cr2o7. Standard operation procedure chemical oxygen demand closed reflux, titrimetric. Selection of method the open reflux method b is suitable for a wide range of wastes where a large sample size is preferred. Results and discussion overall runoff quality characteristics the overall bods, cod, and tss values during the period from june to november. May 23, 2010 cods of the synthetic samples containing varying cod and chloride concentrations were measured by closed reflux colorimetric method using three digestion solutions having different strengths. Hach 8000 1979 chemical oxygen demand is considered a methoddefined parameter per the definition in the code of federal regulations, part 6. Jul 01, 2000 read miniaturized closed reflux, colorimetric method for the determination of chemical oxygen demand, waste management on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Standard test methods for chemical oxygen demand dichromate. Methods c and d were used for samples with chemical oxygen.
Standard methods online standard methods for the examination of water and wastewater. The reagents were prepared as described in the standard method for the open and closed reflux titrimetric methods. Full text full text is available as a scanned copy of the original print version. Closed reflux, colorimetric method of standard methods were used to measure bod, and cod, respectively. Scope and application chemical oxygen demand cod measures the oxygen equivalent of that portion of the organic matter in a sample that is easily oxidised by a strong chemical oxidant. Standard operation procedure total chemical oxygen demand closed reflux, spectrophotometric method, cell test cat.
This method is based on the requirements of the two main official sources for chemical analysis in water and wastewater. It is applicable to both organic compounds and inorganic compounds and may be used with or without an enzymatic stage. Determinations can be made titrimetrically by several approved methods, or photometrically colorimetrically with epa method 410. By john stone metals digestions, epa method 1664 oil and gr. Miniaturized closed reflux, colorimetric method for the. It is indicated in this study that a constant ratio of mercury sulphate can only prevent chloride interference up to a specific chloride concentration. The procedure described hereafter is applicable to low cod values. The analysis of total organic carbon toc by the american public health association apha closed tube reflux colorimetric method requires potassium dichromate k2cr2o7, silver sulfate agso4. Modified apha closedtube reflux colorimetric method for toc. This means that the method may not be modified per part 6. Cod closed reflux, titrimetric method mgl apha 5220 c 100 ml 3 days chemical oxygen demand cod closed reflux, colorimetric method mgl apha 5220 d 100 ml 3 days chloride, as cl ion chromatograph mgl apha 4110 100 ml 2 days. In cases of turbid or highly colored samples, prefer titrimetric than colorimetric closed reflux method. The analysis of total organic carbon toc by the american public health association apha closedtube reflux colorimetric method requires potassium dichromate k 2cr 2o 7, silver sulfate agso 4, and mercury hgso 4 sulfate in addition to large volumes of both reagents and samples. Test method a macro cod by reflux digestion and titration.
The closed reflux methods c and d are more economical in the use of metallic salt reagents and generate smaller quantities of hazardous waste, but require homogenization of. A new approach for chemical oxygen demand cod measurement. Roe from the department of biochemistry, school of medicine, george wash ington university, washington received for publication, july 6, 1934 in 1926 campbell and hanna 1 published a method for the. The design was evaluated using the closed reflux cod method 47. The novel method, named solid dilution sd, is based on a different technique of sample preparation.
The method determines chemical oxygen demand see definitions, section. Colorimetric determination of manganese chemistry 51 version. Measure cod of wastewater using closed reflux method. Miniaturized closed reflux, colorimetric method for the determination of chemical oxygen demand. Steady state tracer trial results three steady state tracer trials were conducted, two that included two pulper batches and one that included four pulper batches. The closed reflux colorimetric method used for cod employs potassium dichromate k 2 cr 2 o 7 as oxidant, requires only a small sample size and produces minimal waste. Category test parameter technique units method ref min. Figure 4 shows the potassium concentration of the clarified effluent over time for the. It has also been shown that procedures involving closed tubes, as opposed to opentube procedures, have resulted in the reporting of higher cod values. Determine cod values of 50 mg o2l by using procedures in open reflux method, closed reflux titrimetric method, closed reflux colorimetric method. Determination of chemical oxygen demand in heterogeneous solid or semisolid samples using a novel method combining solid dilutions as a preparation step followed by optimized closed reflux and colorimetric measurement. Cod samples are prepared with a closedreflux digestion followed by analysis.
Request pdf miniaturized closed reflux, colorimetric method for the determination of chemical oxygen demand the standard technique for the closed reflux. Colorimetric analysis is a method of determining the concentration of a chemical element or chemical compound in a solution with the aid of a color reagent. Add sulfuric acid to ph colorimetric method for the determination of chemical oxygen demand, waste management on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Any equivalent reflux apparatus may be substituted provided that a groundglass connection is used between the flask and the condenser. May 30, 2018 the analysis of total organic carbon toc by the american public health association apha closed tube reflux colorimetric method requires potassium dichromate k 2 cr 2 o 7, silver sulfate agso 4, and mercury hgso 4 sulfate in addition to large volumes of both reagents and samples. The quantity of oxidant consumed is expressed in terms of its oxygen equivalence. Initially, methods c, d and e of this booklet were developed in 1986 as alternative methods to the use of method a, which, over a prolonged period of time, utilises significant quantities of mercury. Closed reflux titrimetric and colorimetric method using cod digester 84. Cod samples are prepared with a closedreflux digestion. Methods c and d were used for samples with chemical oxygen demand cod values of up to 400 mg l1. Modified apha closedtube reflux colorimetric method for. Milestone ethos one operator manual ma 3, rev002010. Cod measurement is based on the wellestablished closed reflux colorimetric method over 3 different ranges.
Chemical oxygen demand chemistry physical sciences. The novel method, named solid dilution sd, is based on a different technique of sample preparation, diluting. Colorimetric determination of manganese chemistry 51 version the objective of this experiment is to determine the percentage of manganese in a steel sample, using colorimetric methods of analysis. Rapid determination of chemical oxygen demand cod using. This method covers the determination of chemical oxygen demand cod in ground and surface waters, domestic. This paper reports the development of an innovative sample preparation method for the determination of the chemical oxygen demand cod in heterogeneous solid or semisolid samples, with high suspended solids and cod concentrations, using an optimized closed reflux colorimetric method. Principles this analysis is accomplished by dissolving the steel sample, converting all of the manganese to the intensely colored mno 4. Apha 23e 4500so42 c sulphate, gravimetric method with ignition of residue. The method relies on the release of oxygen from dichromate on heating which is consumed. The analysis of total organic carbon toc by the american public health association apha closedtube reflux colorimetric method requires potassium dichromate k 2 cr 2 o 7, silver sulfate agso 4, and mercury hgso 4 sulfate in addition to large volumes of both reagents and samples.
Colorimetric analysis works because the two chromium ions absorb in the visible. Precautions vial caps temperature should be low enough to avoid cap damage a potential source of sample contamination in case of colorimetric method a blank must be run with each lot of samples. This method is economical in the use of metallic salt reagents and generate smaller quantity. Use procedures in open reflux method to determine, with lesser accuracy, cod values from 5 to 50 mg o2l. Get a printable copy pdf file of the complete article 296k, or click on a page image below to browse page by page. The determination of chemical oxygen demand in waters and. Determination of chemical oxygen demand in heterogeneous. Pdf miniaturized closed reflux, colorimetric method for. The modified method, the potassium monochromate closedtube. Simply put, the miniaturized technique reproduced the chemistry of the standard method, but with smaller amounts. The theoretical cod was considered to be the assigned cod value for each sample raposo et al. The method is widely used in medical laboratories and for industrial purposes, e.
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