In order to avoid cross-contamination when collecting water samples, the oil in water project should be equipped with a special sampler and sampling bottle, the sampling bottle is a brown 500 ml wide-mouth glass bottle, the sampling volume is greater than 500 ml, and the water sample is acidified to pH 2. How to collect water samples for oil in water?The water is collected at a distance of less than 20 cm from the water level, and the water from the surface is collected together when there is a specific request. The next thing to talk about is the infrared method for determining water and the precautions.
This is a routine laboratory testing method, and the detection index of oil substances in water is based on:Infrared oil testerIf the quality of the reagent used in the pretreatment process of the tested sample is unqualified, it will seriously interfere with the accuracy of the measurement results, so it is very important to purchase chemical reagents.
When purchasing reagents for oil detection in water, it is necessary to purchase and dispose of them in strict accordance with the requirements of the national standard HJ637-2018. Perchloroethylene will be purchased from regular manufacturers of environmentally friendly special reagents, and the absorbance of perchloroethylene should be tested at 2930cm-1, 2960cm-1, 3030cm-1, not more than 034，0.07，0.00。Perchloroethylene that meets this standard can be used with confidence. Magnesium silicate adsorbent is purchased from regular manufacturers for 60-100 purposes, activated according to the requirements, and used after passing the test.
But be carefulInfrared oil testerIn the process of oil detection in ordinary water, a lot of utensils need to be used, these utensils will inevitably be polluted to varying degrees in the process of long-term use, and if you do not pay attention to it in the cleaning process, it will seriously affect the accuracy of the oil measurement results in water. In the normal process of use, if you feel that the utensils are dirty, you can use clean perchloroethylene to dry them, and the extraction bottle can be rinsed with tap water. When you feel particularly dirty and need to be cleaned thoroughly, you can soak the utensils in the chrome pickling solution or pour the chrome pickling solution into the container for about 5 minutes, pour out the chrome pickling solution and rinse the utensils with tap water.
However, with the continuous progress of science, this OIL-8000Oil-in-water analyzersIt is specially designed to measure the concentration of oil (hydrocarbons) in water, using ultraviolet fluorescence to measure the concentration of oil molecules in water. This method is used to determine without manual sampling, and the water sample is mainly automatically transferred to the equipment by a pump for measurement.
The principle is that the oil molecule is activated into an excited state when exposed to specific ultraviolet light, which is very unstable and will quickly return to the ground state;Radiation fluorescence occurs during the return to the ground state, and the concentration of oil molecules in the water sample is proportional to the intensity of the emitted radiation fluorescence. The water sample is sent to the cuvette after the pretreatment device, and the light source is irradiated parallel to the oil molecules in the cuvetus water sample, and the resulting fluorescence is irradiated on the fluorescence sensor, and the ultraviolet light emission and fluorescence sensor are installed with a precise filter system before receiving it, which is used to control the emission wavelength of ultraviolet light and select the specific fluorescence wavelength scattered back by the receiving oil molecules. There is a certain correspondence between the received fluorescence intensity and the concentration of oil in the water sample, and this linear relationship can be made more definite by the selection and control of the emission and reception wavelengths by the filtering light system.