Definition and scope of application
In this method, potassium persulfate (or nitric acid perchloric acid) is used as oxidant to digest dissolved nitrogen in water sample and nitrogen in suspension to determine total nitrogen. It includes nitrite nitrogen, nitrate nitrogen, inorganic ammonium salt, dissolved ammonia and nitrogen in most organic nitrogen compounds.
This method is suitable for the determination of total nitrogen in surface water, groundwater, industrial wastewater and domestic sewage.
When the volume of water sample is 10ml and the diameter of 10 mm colorimetric tube is used, the detection limit of this method is 0.05mg/l, the lower limit of determination is 0.2mg/l, and the upper limit of determination is 20.0mg/l (all in n).
A known amount of potassium persulfate (or nitric acid perchloric acid) solution is added to the sample. After digestion in acid medium, the total nitrogen value is determined by spectrophotometry.
The total nitrogen micro reflux test method developed by Shenzhen Changhong science and Technology Co., Ltd. (hereinafter referred to as shenchanghong) is simple, fast and economical in operation, and the test results are accurate and reliable. Shenchanghong can provide a complete analysis scheme of total nitrogen micro reflux test method, and users do not need to prepare their own total nitrogen reagents. The scheme includes total nitrogen analyzer, ds-16b / 20B / 25B / 36B digester and matching total nitrogen reagent. The total nitrogen reagent is used in combination with digester and total nitrogen analyzer. The analytical procedure is simple and convenient, which meets the requirements of national industry standards.
● no need to prepare total nitrogen reagent: the reagent prepared by a certain proportion of chemical components required for total nitrogen analysis can greatly save the preparation time of total nitrogen reagent;
● time saving: the whole analysis process, including water sample digestion, colorimetric determination and other steps, takes much less time than traditional methods;
Compact digestion device: ds-16b / 20B / 25B / 36B, a total nitrogen digester developed by shenchanghong, replaces the traditional device and can digest up to 16-36 water samples at the same time;
● small secondary pollution to the environment: only a small amount of total nitrogen reagent is needed for the micro reflux method, and the carefully designed total nitrogen reagent tube can prevent the volatilization of organic matters and the escape of samples, ensuring the safety of the digestion process;
● simple operation and easy to learn: the operation guide with pictures and texts is convenient for mastering the analysis method of total nitrogen in a short time.
Analysis steps of total nitrogen micro reflux method of shenchanghong:
(1) Preparation of total nitrogen reagent and water sample
Put the reagent required for total nitrogen analysis into each total nitrogen pipe, add a proper amount of water sample according to the instructions, and then tighten the bottle cap.
(2) Water sample digestion
Put the digestion colorimetric tube that has been added with water sample and reagent into ds-16b / 20B / 25B / 36B, select the appropriate digestion temperature and time according to the requirements of reagent for hot reflux. After the digestion process, take out the total nitrogen test tube from ds-16b / 20B / 25B / 36B, and cool it to room temperature.
(3) Determination of total nitrogen by colorimetry
Shenchanghong's total nitrogen analyzer (laboratory: tn-2a, tn-3a, tn-3c / 3D; portable: pwn-810b; Multi parameter (Laboratory / portable): cnpn-401 / 401c / 401d / 401d / mulp-8c / pmulp-8, etc.), select the corresponding total nitrogen test program in the main menu, do not need to re-establish the standard curve, just put the digested total nitrogen reagent test tube into the instrument to read the total nitrogen value expressed in concentration units, and save the record results.
Brief introduction of total nitrogen micro reflux analysis system of shenchanghong
The total nitrogen micro reflux analysis system provided by shenchanghong includes the total nitrogen analyzer host, digester and matching total nitrogen reagents.
(1) Instrument host: according to the needs of different customers, shenchanghong company can provide a variety of models of total nitrogen analyzer for the determination of total nitrogen.
(2) Ds-16b / 20B / 25B / 36B digester is a digestion device developed by shenchanghong. It can be used for digestion of water samples such as total nitrogen, total chromium, total phosphorus and cod. The digestion time and temperature can be selected in the range of normal temperature - 200 ℃ and 1 - 9999 minutes respectively.