Preparation of general solution reagents and precautions required for water quality testing

When using an online water quality analyzer, it is often necessary to prepare some reagents into the required concentration solution. The solutions used in practical applications can be divided into three types: general solution, standard solution and buffer solution. If the exact concentration is not specified, the solution used only for general experiments is called general solution or commonly used solution. The mass of the reagent can be weighed with a tray balance during preparation, and the volume of the solution can be measured with a graduated cylinder or a measuring cup. The key to preparing such solutions is to calculate the correct mass of solute that should be weighed, and the volume of solute that should be measured. Today we will introduce some preparation methods for general solutions of online water quality analyzers. Preparation of general solution reagents required for water quality testing: (1) Preparation method of general solution for water quality testing Take a certain volume of concentrated acid and pour it into water. After the acid solution is cooled, transfer it to a reagent bottle and dilute to the required volume. When preparing an acidic solution, be sure to pour the concentrated acid into the water slowly and stir while pouring. Do not pour the water directly into the concentrated acid to prevent the concentrated acid from splashing and hurting people. ② Commonly used alkaline solution configuration, preparation of solid alkali solution: use a beaker to weigh out the mass of the required solid alkali on a tray balance, dissolve it in an appropriate amount of water, and then dilute to the required volume. ③Preparation of commonly used saline solution, weigh the required amount of reagents on a tray balance, dissolve in an appropriate amount of water, and then dilute with water to a predetermined volume. For salts that are not easily soluble or easily hydrolyzed, it is necessary to add an appropriate amount of acid, and then dilute with water or dilute acid. Salts that are prone to redox should be prepared extemporaneously before use. Classify and store the prepared water quality testing solutions: (2) Precautions when preparing general solutions for water quality testing The level of the balance, the representation of effective figures, and the container. ② For solutions that are used frequently or in large quantities, testing personnel can first prepare a stock solution with a concentration 10 times the predetermined concentration. Appropriate dilution can be used when needed. ③ For solutions that are easy to corrode glass, be sure to avoid placing them in glass containers. ④Reagents that volatilize and decompose the solution when preparing the solution, such as KMnO4, AgNO3, etc., should be placed in brown reagent bottles, and then placed in a cool and dark place to avoid direct light exposure. ⑤ After the solution required for the online water quality analyzer is placed in the reagent bottle, the category name label should be affixed immediately, indicating the name, concentration, configuration date, preparation personnel of the solution, and making relevant preparation records. The records should include the specifications, manufacturers and preparation process of the reagents used.