This part of GB/T 31270 specifies the basic requirements for materials, conditions, operation, quality control, data processing, test reports, etc. for alga growth inhibition test.
This part applies to alga growth inhibition test for the registration of chemical pesticides. It may be used as reference for other types of pesticides.
This part does not apply to volatile and insoluble chemical pesticides.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
median effective concentration
concentration of test substance that makes the yield or growth rate of test organism to be decreased by 50% compared with that of control group in the growth inhibition test, which is expressed by EC50. In this part, the median effective concentration obtained by calculating the inhibition percentage of alga yield is expressed by EyC50, while that obtained by calculating the inhibition percentage of alga growth rate is expressed by ErC50
Note: the unit is mg a.i./L.
2.2
average growth rate
logarithm of unit yield of alga within certain exposure duration, expressed by μ
2.3
yield
increasing amount of unit biomass of alga within certain exposure duration, i.e. the amount of unit biomass at the end of exposure deducted by the unit biomass at the beginning of exposure, expressed by Y
2.4
test substance
substance to be tested
2.5
chemical pesticide
pesticide made of chemical substances through artificial synthesis, for some, the active substances in natural products are used as the mother body, and then subjected to imitation, structural transformation and innovation, they are bionic synthetic pesticides
Synonym: synthetic organic pesticide.
[Definition 2.3.1, NY/T 1667.1-2008]
2.6
technical material
final product consisting of the active ingredients and impurities obtained during the manufacturing process, which shall not contain visible foreign substances or any additives, and if necessary, a small amount of stabilizer may be added
[Definition 2.5.1, NY/T 1667.2-2008]
2.7
formulation product
product stable in use and made of technical material (or technical concentrate) of pesticides and auxiliaries
[Definition 3.1, NY/T 1667.2-2008]
2.8
active ingredient; a.i.
specific chemical ingredient that is biologically active in a pesticide product
[Definition 3.1, NY/T 1667.2-2008]
2.9
reference substances
chemical substance or mixture used in a test to confirm or deny certain characteristics of a test substance or to judge the effectiveness of a test system
3 Test overview
In this test, prepare a series of test liquids with different concentrations using a test substance, then observe the growth inhibition of test alga for consecutive 72h after mixing the test liquids with alga liquid, and calculate the median effective concentration EC50 (72h) and 95% confidence limit.
