Re: How to make 10-120ppm of Chlorpyrifos (Technical grade insecticide) to chec

Nasty problem, dangerous material.  How is the commercial insecticide
formulated for delivery, like crop-spraying?  Those additives are obviously
not phytotoxic.  N-methylpyrrolidinone (1-methyl pyrrolidinone, NMP) can be
a very nice, low toxicity, water-miscible solvent for problem organics. 
Let us do some guessing.

1) Is chlorpyrifos aqueous-dispersible (ultrasonic dispersion) and
adequately stable in detergent micelles like lecithin,
octyl-glucopyranoside, Brij or Tergitol, sorbitan esters, polysorbates,
poloxomers, etc?  There may be biocompatiblity problems with detergent.

2) Continuouously add it in organic solvent at high dilution with stirring,
 http://www.alzet.com/
US Patent 5279608, 6464688 http://www.syringepump.com/

3) Diffuse it through a solution interface, with stirring, with a Gore-Tex
membrane, Anopore filter, or Nucleopore filter.

4) Dissolve it in two-component silicone rubber and cure.  Then let it
diffuse out or bloom out of the membrane or patch within the culture medium.

5) Dissolve in solvent, disperse onto fine silica gel or fumed silica, or
bentonite clay, dry.  Use that as a suspendable wettable powder for gradual
release. 

6) Lyophilize some cyanobacteria, dose them with chlorpyrifos in solvent,
dry again.  Use that as the trace carrier. 

In all cases you must run controls.  One set to look at chlorpyrifos
degradation in its carrier, another for carrier effect upon the
cyanobacteria without chlorpyrifos, and a third for the carrier plus
chlorpyrifos in water without the cyanobacteria.  Others may suggest
themselves.