Definitive test. (i) The purpose of the definitive test is to determine the 24, 48, 72, and 96—hour LC50 values and the concentration-response curves.
(ii) A minimum of 20 gammarids per concentration shall be exposed to five or more concentrations of the test sub- stance chosen in a geometric series in which the ratio is between 1.5 and 2.0 (e.g., 2, 4, 8, 16, 32, 64 mg/L). The range and number of concentrations to which the organisms are exposed shall be such that in 96 hours there is at least one concentration resulting in mor- tality greater than 50 and less than 100 percent, and one concentration causing greater than zero and less than 50 per- cent mortality. An equal number of gammarids may be placed in two or more replicate test xxxxxxxx. Solvents should be avoided, if possible. If sol- vents have to be used, a solvent con- trol, as well as a dilution control, shall be tested at the highest solvent con- centration employed in the treatments. The solvent should not be toxic or have an effect on the toxicity of the test substance. The concentration of sol- vent should not exceed 0.1 ml/L.
(iii) Every test shall include a con- current control using gammarids from the same population or culture con- tainer. The control group shall be ex- posed to the same dilution water, con- ditions and procedures, except that none of the test substance shall be is added to the chamber.
(iv) The dissolved oxygen concentra- tion, temperature and pH of the test solution shall be measured at the be- ginning of the test and at 24, 48, 72 and 96 hours in at least one replicate each of the control, and the highest, lowest and middle test concentrations.
(v) The test duration is 96 hours. The test is unacceptable if more than 10 percent of the control organisms die during the test.
(vi) In addition to death, any abnor- mal behavior or appearance shall also be reported.
(vii) Gammarids shall be randomly assigned to the test xxxxxxxx. Test xxxxxxxx shall be positioned within the testing area in a random manner or in a way in which appropriate statis- tical analyses can be used to determine whether there is any variation due to placement.
(viii) Gammarids shall be introduced into the test xxxxxxxx after the test substance has been added.
(ix) Observations on compound solu- bility shall be recorded. The investi- gator should record the appearance of surface slicks, precipitates, or material adhering to the sides of the test cham- bers.
Definitive test. The purpose of the definitive test is to determine the concentration response curves, the EC10’s, EC50’s, and EC90’s for algal growth for each species tested, with a minimum amount of testing beyond the range-finding test.
Definitive test. ( i) T h e p ur pose of t h e defi n i t ive t es t i s t o de t e r m i n e t h e co n ce n t r a t io n r espo n se c ur ves, t h e EC10’s, EC50’s, a n d EC90’s fo r a lg a l g r ow t h fo r e a c h species t es t ed, wi t h a m i n i m u m a m o un t of t es t i n g be y o n d t h e r a n ge-fi n di n g t es t .
Definitive test. (i) The purpose of the definitive test is to determine the 24, 48, 72, and 96—hour LC50 values and the concentration-response curves.
Definitive test. The purpose of the definitive test is to determine the concentration response curves, the EC ’s, EC ’s, and EC ’s for algal test containers with appropriate vol- 10 50 90 umes of nutrient medium and/or test solution. Start the test by introducing algae into the test and control con- tainers in the growth xxxxxxxx. Envi- ronmental conditions within the growth xxxxxxxx are established at predetermined limits.
