Spectrotitration of ethane-1-hydroxy-1,1-diphosphonic acid (EHDP(tm)) with thorium diaminocyclohexanetetra-acetate.
An automatic spectrotitration procedure for EHDP has been developed. It is applicable to samples containing 50mug or more of EHDP, with a relative standard deviation of 3% if no interfering materials are present. The sensitivity can be extended down to about 5mug, but titration blanks become significant and the standard deviation increases markedly. Thorium diaminocyclohexanetetra-acetate (Th-DCTA) is used as the titrant, to give a ternary species (Th-DCTA)(2)-EHDP. The end-point in the spectrotitration is due to deprotonation of Xylenol Orange indicator when it is incorporated into a weaker ternary species after all the EHDP has reacted. Salts such as NaCl, NaClO(4), Na(2)SO(4) and NaNO(3) interfere if present at concentrations of 0.1-0.5M. The method is much more sensitive to orthophosphate, but this interference can be averted by isolating the EHDP before titration by selectively adsorbing the phosphonate on calcium hydroxyapatite.
Synthesis of osseous specific 32P‐labeled disodium ethane‐1‐hydroxy‐1,1‐diphosphonate
High specifie activity 32P-Iabeled disodium ethane-1-hydroxy-1,1-diphosphonate has been prepared for specific use as a radiotherapeutic ameliorative treatment of osseous tumors by reacting 32P-labeled phosphorus trichloride, acetic acid and water. This compound has been purified by crystallization of the disodium salt from a water-ethanol solution. Product identity and purity were established by reverse isotope dilution analysis. Spectrochemical quantitation, thin layer chromatography, radionuclide beta energy and half-life determinations are presented as essential procedures for establishing chemical and radiochemical purity when human distribution studies are planned.
Interaction of Diclofop-Methyl and MCPA on Wild Oats (Avena fatua)
Diclofop-methyl {methyl 2-[4-(2,4-dichlorophenoxy)phenoxy] propanoate} loses part of its activity on wild oats (Avena fatua L.) when it is applied in combination with ester or amine formulations of MCPA {[4-chloro-o-tolyl)oxy] acetic acid.} Uptake of diclofop-methyl is reduced in the presence of commercial formulations of MCPA, particularly amine formulations, which are only partly compatible with the diclofop-methyl formulation. With added MCPA, regardless of formulation, hydrolysis of diclofop-methyl to the acid diclofop is slowed down, both in intact wild oat plants and in a crude leaf extract. At the same time, conversion of any acid formed to inactive conjugates is accelerated in the presence of MCPA. It is concluded that the loss of activity of diclofop-methyl by MCPA can be accounted for by the effects of MCPA on uptake and metabolic conversion of diclofop-methyl.