The soil thin layer chromatography technique was employed to assess the mobility of 21 chemicals (6 insecticides, 4 herbicides, and 11 of their hydrolysis metabolites) in 6 different soils. The hydrolysis products of the four studied organophosphorus insecticides were significantly more mobile than their parent compounds, but the metabolites of carbamates, s triazines and phenoxy alkanoic acids were less mobile than their parent compounds. For the chemicals for which significant effects of soil variables were observed, greater levels of organic matter, clay, cation exchange capacity and water holding capacity (at one‐third bar) lowered the mobility Soil pH significantly affected mobility of many of the chemicals studied, with increased mobility in soils with higher pH values. Both water solubility and octanol/water partition coefficient (Kow) significantly correlated with the mobility of the chemicals studied, however, Kow was found to be the better predictor of mobility No direct relationship existed between the pKa of the chemicals and their mobility

The soil thin layer chromatography technique was employed to assess the mobility of 21 chemicals (6 insecticides, 4 herbicides, and 11 of their hydrolysis metabolites) in 6 different soils The hydrolysis products of the four studied organophosphorus insecticides were significantly more mobile than their parent compounds, but the metabolites of carbamates, s triazines and phenoxy alkanoic acids were less mobile than their parent compounds For the chemicals for which signifi cant effects of soil variables were observed, greater levels of organic matter, clay, cation exchange capacity and water holding capacity (at one-third bar) lowered the mobility Soil pH significantly affected mobility of many of the chemicals studied, with increased mobility in soils with higher pH values Both water solubility and octanol/water partition coefficient (KOw) significantly correlated with the mobility of the chemicals studied, however, KO, was found to be the better predictor of mobility No direct relationship existed between the pK, of the chemicals and their mobility

No abstract

Potentiometric p [H] measurements are employed to evaluate protonation constants, metal complex stabilities, and Schiff base (SB) formation constants in solutions containing pyridoxal 5'-phosphate (PLP) 5'-deoxypyridoxal (DPL), phenylglycine and its derivatives, and divalent transition-metal ions at 25 O C and at an ionic strength of 0.100 M (KN03). Protonation constants for phenylglycine (PG), (4-methoxyphenyl)glycine (MPG), and (4-sulfophenyl)glycine (SPG) indicate that these synthetic amino acids are more acidic than glycine and other natural amino acids. Stability constants are reported for 1:l and 1:2 complexes of Mn2', Co*', Ni2', Cu2+, and Zn2+ with PG, MPG, and SPG. Hydrolysis of these metal ions complicates the study of the nature of the metal complex formed at high p [H]. The vitamin B6 derivatives, pyridoxal 5'-phosphate and 5'-deoxypyridoxal, were found to form only 1:l metal complexes. The equilibrium constants for the formation of Schiff bases by PLP and DPL with PG, MPG, and SPG are reported. The monoprotonated form of the Schiff base was found to be the most stable species in each of the systems studied. The equilibrium constants are reported for protonated 1:l Cu(I1)-Schiff base complexes, CuSBH,"+ and for 1:l and 2:1 Schiff base complexes of Mn(II), Co(II), Ni(II), and Zn(I1). The formation of a number of hydroxometal Schiff base chelates in alkaline solutions is observed. The equilibrium constants determined are employed to calculate the distribution of complex species as a function of p [H] in solutions containing these ligands and the metal ions identified above.The transfer of a nitrosyl ligand between neutral and oxidized iron and cobalt metalloporphyrins in dichloromethane solutions was investigated by electrochemistry and FTIR or ESR spectroelectrochemistry. The transfer of NO from (P)Co(NO) to (P)Fe, from [(P)Co(NO)]' to (P)FeC104, and from [(P)Fe(NO)]+ to (P)Co was demonstrated for complexes where P = the dianion of tetraphenylporphyrin (TPP), meso-tetrakis(2,4,6-trimethylphenyl)porphyrin (TMP), or octaethylporphyrin (OEP). The driving force in these reactions is related to both the nature and oxidation state of the central metal in (P)M(NO) or [(P)M(NO)]+, where M = Fe or Co, and follows the order (P)Fe(NO) > (P)Co(NO) > [(P)Fe(NO)]' > [(P)Co(NO)]'.

No abstract