Liquid Chromatographic Determination of Glyphosate in Water-Soluble Granular Formulations: Collaborative Study

A liquid chromatographic (LC) method for the determination of glyphosate in various water-soluble granular formulations was tested by 28 laboratories. Samples were dissolved in mobile phase and injected directly into an LC system with a 25 cm SAX column and a mobile phase of 96% aqueous buffer solution, 0.0062M KH2PO4, and 4% methanol. Detection was by UV absorption at 195 nm. Manual or automated injections were made via fixed-volume loops. Calculations were based on peak area comparisons with external standards. The collaborative study analyzed 5 matched pairs of 4 water-soluble granular formulations, with one determination per sample. The study generated 138 matched pairs, which were analyzed by using the AOAC spreadsheet and Youden’s matched-pair calculations. Coefficients of variation for the 4 formulations ranged from 0.65 to 1.37%. The LC method for the determination of glyphosate in water-soluble granular formulations has been adopted first action by AOAC INTERNATIONAL.

Assimilation in visibility: additional evidence

The present research tested the theory that a less visible target increases in similarity to a more visible simultaneous context, and that therefore the target increases in visibility. This assimilation-in-visibility theory was tested using context + targets that were either 3-line brackets or 2-line right angles, contexts and targets that were the component lines of these context + targets, with the target always the identical single top line. Experiments with a total of 204 participants indicated that the 3-line context + targets resulted in better context + target versus context discriminations than target versus background discriminations than did the 2-line context + targets. This was so for both over-all errors and misses but not false alarms. It is concluded that only the 3-line context + targets increased the visibility of the 1-line target. Additional analysis indicated that the 2-line contexts of the 3-line context + targets were more visible than all the 1-line stimuli. So, the 1-line target assimilated to a simultaneous more visible 2-line context and thereby increased in visibility, thus improving the context + target versus context discrimination. This support for the assimilation-in-visibility theory is of interest because assimilation and contrast in visibility may play a large role in perception.

Health effects classification and its role in the derivation of minimal risk levels: developmental effects

Agency for Toxic Substances and Disease Registry (ATSDR) utilizes chemical-specific minimal risk levels (MRLs) to assist in evaluating the public health risk associated with exposure to hazardous substances. The MRLs are derived based on the health effects data compiled from current literature searches and presented in ATSDR's toxicological profiles. Health effects are categorized according to their degree of severity (e.g., serious, less serious, minimal, and not adverse). This evaluation is important, because each respective category can be assigned a different amount of uncertainty, thus affecting the final value of the calculated MRL. From the total of 272 MRLs derived as of December 1997, 21 were based on developmental effects. ATSDR's ranking of developmental health effects as described in the Guidance for Developing Toxicological Profiles and specific examples of how the categorized health effects were used in MRL derivations are provided in this paper.

Context-produced increase in visibility

It has not been clearly shown that context (e.g., three lines of a square) increases the visibility of a feature (e.g., the fourth line of the same square). To investigate this possibility, four sets of context+feature, context, feature, and BLANK (empty field) stimuli were used. For three out of the four sets, the context+feature stimulus was less likely to be falsely identified as the context and BLANK stimuli (i.e., the stimuli without the feature) than was the feature stimulus. For the same three sets, discriminating between the context+feature and context stimuli produced fewer false identifications (FIs) than discriminating between the feature and BLANK stimuli.

THE CONCLUSION

the context components of context+feature stimuli increased the visibility of the feature components of the same stimuli.