LD50 is an important factor for determination the toxicity of any substance.
This depends very much on the number of doses tested. In case the dose-response curve is well covered, non-linear logistic regression may provide you with a good LD50 estimation, which even comes with confidence intervals. If non-linear regression is not applicable, e.g. because only a few doses have been tested, a simple solution is to calculate the LD50 by linear interpolation between the response of the dose below the LD50 and the dose above the LD50.
Plot a dose response curve (different doses and response (dead or alive) based on your experimental species (shrimp/rat/mice) and look for the dose at which 50% of the your organism are dead. This dose is the LD50 dose.
You can use this protocol and software.
http://www.epa.gov/oppfead1/harmonization/
Dear Ali Aldallal
Answering lots of doses administered is not linear. There can be interpolated.
The advice given by Abolfazl Dashti is excellent. INSTRUCTIONS follows the links attached. They are very well made.
This is the way you should go.
Good luck with that
Each chemical or physical variable determined a different LD50 reaction depending on the studied subject. First you have to select your subject and then the substance or environmental condition you want to investigate. Once you have defined both, you can use any of the techniques pointed out previously by Abolfazi Dashti
The guidelines supplied by Abolfazl Dashti pertains to up and down procedure and the AOT software is exclusively built for that procedure. If you need a LD50/LC50 calculator, it is freely available at the following site: This calculator also provides estimation of 95% fiducial confidence limits for LD/LC values and is downloadable
http://probitanalysis.blogspot.in/2016/07/free-excel-calculator-for-estimating.html
https://probitanalysis.wordpress.com/2016/07/07/first-blog-post/
For toxicity tests, in case of dose-mortality relationship, LD50 can be calculated by means of probit analysis.
Hi Sir.....you could depend a Miller LC, Tainter ML. Estimation of LD50 and its error by means of log-probit graph paper. Proc Soc Exp Bio Med 1944;57:261