Surfactants are still considered to be agents which either increase spray coverage of leaves with herbicidal solutions and/or increase herbicide penetration into the leaves. Experiments where the method of application largely eliminates leaf wetting as a factor in paraquat uptake show that this is an over‐simplification. Its efficiency in the plant is influenced by penetration and most of all by the degree of movement down the plant into untreated leaves. Results on the uptake, movement and biological activity of paraquat are reported using cocksfoot and wheat. A relation is found between paraquat movement and the hydrophilic nature of the surfactant. It moves most when the number of ethylene oxide residues is less than six and it is minimal when the number is 10 to 15. Leaf penetration, however, is at a maximum when movement under the influence of surfactant is least. Partition studies in which surfactants are distributed between leaf wax and water are described. There is a direct correlation between the degree of partition of the surfactant into the wax and the degree of movement of paraquat in cocksfoot and wheat. Surfactants are essential components of a paraquat formulation to wet the leaf surface and increase penetration but, when the surfactant also penetrates into the leaf, it reduces the mobility of paraquat and hence its efficiency.

A method is described for the determination of brodifacoum in technical and formulated material by high pressure liquid chromatography (HPLC). Samples of technical or formulation are dissolved in a solution of 1,3,5-triphenyl benzene in dichloromethane and methanol. The solution is injected into an HPLC system fitted with 25 cm Zorbax ODS column and an ultraviolet detector. The solution is eluted with a mixture of methanol, water, and acetic acid. Quantitative data are obtained by comparing peak areas of the compound and triphenyl benzene with those obtained by injecting a standard solution. Bait formulations are extracted into dichloromethane-formic acid, filtered, and concentrated by evaporation before chromatography. Nine collaborators made replicate determinations on 4 samples including technical material, a 0.1% powder, a 0.25% liquid, and a 0.005% pelleted bait formulation. They also carried out a recovery experiment on the bait product. Coefficient of variation (%) were 1.21 on the technical product, 13.49 on the powder, 2.40 on the liquid, and 11.06 on the bait. Insufficient data were generated to adequately quantitate the recovery factor. The method has been adopted official first action for the analysis of technical material, liquid, and bait formulations.

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A method is described for the determination of pirimicarb (2-(dimethylamino)-5,6-dimethyl-4-pyrimidinyl dimethylcarbamate) in formulated products by gas-liquid chromatography (GLC). Samples are dissolved in a chloroform solution of an internal standard and injected into a gas chromatograph equipped with a flame ionization detector. Quantitative data are obtained by comparing peak areas of the compound and internal standard with those obtained by injecting a standard solution. Eleven collaborators made replicate determinations on 6 samples including a technical product, a granular product, and 4 powder products. The average coefficient of variation was 1.14% for the technical product, 1.82% for the granular product, and 0.73% for the powder products.

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