Hi, dear prasad

Study this links:

https://www.researchgate.net/post/Why_is_it_used_in_bioassays_studies_with_essential_oils_for_effect_pesticidal_from_acetone_solvent_instead_of_DMSO

you can optimize the dissolution using ultrasound, and you have to test the insecticidal effect of dmso (control)

Dear Preet, can you provide us with the procedure you will use to evaluate the insecticide activity?

José Luis Duque-Rivera

hello

insecticidal tests involved are: larvicidal and adulticidal test. Aedes sp of required stages will be introduced to diluted essential oil types and its Lethal concentration calculated (see the attached). DMSO will be the control for this study

Currently my concern is how will I dissolve essential oil in diluted DMSO (DMSO will be diluted in dis. water)

Samaneh Mahmoudvand

Hello

Thanks

I have read the links as recommended.

Preet Prasad, one last question: will the solutions with which you will impregnate the cottons, according to the methodology described in the document, have a final concentration of DMSO of 2% v/v?

José Luis Duque-Rivera

Yes Sir...the EO concentrations will be prepared using 2% DMSO (v/v) only.

Preet Prasad, you must prepare your solutions by carrying out the following two step procedure:

1. Dissolution in DMSO: dissolve the essential oils in DMSO at a 50X concentration. For example, if the solutions you will apply on cotton balls are 2, 4 and 10 mg/mL, then you should prepare them at 100 mg/mL, 200 mg/mL and 500 mg/mL.

2. Dilution with water: if you want 100 mL of diluted solution, mix 2 mL of the concentrated solution (previous step) with 98 mL of distilled water. If you need a lower final volume, dilute maintaining the proportions.

Note 1: The control is prepared by mixing 2 mL of DMSO in 98 mL of water.

Note 2: If you are going to use volumetric flasks to prepare the solutions of step 2, you do not have to measure the volume of water, simply complete up to the flask mark. If this alternative is possible it would be the best way to ensure that the DMSO dilution is exactly 2% v/v.

As you can see, the essential oil does not dissolve directly in 2% v / v DMSO in water. As I recommend, when diluting the 2 mL aliquots, the DMSO will serve as a vehicle to disperse the oil in the aqueous medium, possibly avoiding emulsification or separation in two phases.

By the way Preet Prasad , I wanted to ask you if you have not considered using acetone instead of DMSO (is the solubility of your oils in acetone good?). You would obtain some advantages: it would not be necessary to dilute to 2% with water and the drying of the cotton balls would be much faster and less possibility of remaining solvent in your assay (acetone is more volatile than water, its boiling point is 56 °C).

@Josè Luis Duque-Rivera

Hmmm initially I wanted to use acetone but then wont it influence the insecticidal property of EO/ acetone itself may lead to mortality of the insect tested

If you use acetone, after one hour of drying it is likely that the cotton balls are free of acetone, due to its volatility and then it would not be possible for the insects to be affected. Anyway, you can do a preliminary test by wetting the cotton and let it dry for 1 hour and examine it at the end of that time. You could weigh the cotton (before impregnation) and after drying to know if the acetone has completely evaporated. This test would allow you to evaluate that your control would be free of the effect of acetone and would give you an idea of the functionality of this change of solvent when incorporating essential oils.

@Josè Luis Duque-Rivera

Thanks I will try with acetone first and if it poses problem then will seek assistance

All right. Then you tell us how you are doing.

@Josè Luis Duque-Rivera

Sure

Currently I am extracting neem EO using clevenger followed by clove n Tulsi. So once my extraction is completed then I will go to the insecticidal activity test.