The Basis for the Hard-Water Antagonism of Glyphosate Activity

Weed Science ◽  
1995 ◽  
Vol 43 (4) ◽  
pp. 541-548 ◽  
Author(s):  
Kurt D. Thelen ◽  
Evelyn P. Jackson ◽  
Donald Penner
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ammonium Sulfate ◽  
Hard Water ◽  
Calcium Antagonism ◽  
Chemical Effects ◽  
Spray Solution ◽  
Type Complex ◽  
Over Time ◽  
Nuclear Magnetic

Hard-water cations, such as Ca+2and Mg+2, present in the spray solution can greatly reduce the efficacy of glyphosate. These cations potentially compete with the isopropylamine in the formulation for association with the glyphosate anion.14C-Glyphosate absorption by sunflower was reduced in the presence of Ca+2. The addition of ammonium sulfate overcame the observed decrease in14C-glyphosate absorption. Nuclear Magnetic Resonance (NMR) was used to study the chemical effects of calcium and calcium plus ammonium sulfate (AMS) on the glyphosate molecule. Data indicate an association of calcium with both the carboxyl and phosphonate groups on the glyphosate molecule. Initially, a random association of the compounds occurred; however, the reaction progressed to yield a more structured, chelate type complex over time. NH4+from AMS effectively competed with calcium for complexation sites on the glyphosate molecule. Data suggest that the observed calcium antagonism of glyphosate and AMS reversal of the antagonism are chemically based.

Charge distributions and chemical effects. XXVI. Relationships between nuclear magnetic resonance shifts and atomic charges for 17O nuclei in ethers and carbonyl compounds

1982 ◽  
Vol 60 (2) ◽  
pp. 106-110 ◽  
Author(s):  
Marie-Thérèse Béraldin ◽  
Edouard Vauthier ◽  
Sándor Fliszár
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Oxygen Atom ◽  
Carbonyl Compounds ◽  
Electronic Charge ◽  
Atomic Charges ◽  
Chemical Effects ◽  
Opposite Trend ◽  
Nuclear Magnetic ◽  
Oxygen Atoms

The 17O nuclear magnetic resonance shifts of dialkylethers are linearly related to the electron populations on the oxygen atoms, in a range covering L ~ 130 ppm, showing that any increase of electronic charge at the oxygen atom is accompanied by a downfield nmr shift. The opposite trend is observed for the oxygen atoms of ketones and aldehydes.

Utility of Nuclear Magnetic Resonance for Determining the Molecular Influence of Citric Acid and an Organosilicone Adjuvant on Glyphosate Activity

Weed Science ◽  
1995 ◽  
Vol 43 (4) ◽  
pp. 566-571 ◽  
Author(s):  
Kurt D. Thelen ◽  
Evelyn P. Jackson ◽  
Donald Penner
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Citric Acid ◽  
Magnetic Resonance ◽  
Structural Information ◽  
Effective Technique ◽  
H Nmr ◽  
Spray Solution ◽  
Nmr Spectrometry ◽  
Absorption Studies ◽  
Nuclear Magnetic

In the discipline of Weed Science, nuclear magnetic resonance (NMR) has been used extensively for obtaining structural information on herbicide compounds in the areas of herbicide synthesis, metabolism, and environmental degradation. However, little research has been published with regard to the utilization of NMR in determining molecular interactions in the spray solution. The molecular influence of citric add and an organosilicone adjuvant on glyphosate was analyzed with NMR spectrometry.14C-glyphosate absorption studies showed a decrease in glyphosate absorption by sunflower when Ca2+was added to the spray solution. This absorption antagonism was overcome with the inclusion of an organosilicone adjuvant.1H-NMR was used to stow that the organosilicone adjuvant did not directly interact with the glyphosate molecule nor did it prevent the formation of Ca-glyphosate. Citric add was effective in overcoming the Cat2+antagonism of glyphosate activity when the citric add concentration was 2× or 4× the Ca2+molar concentration based on plant fresh weight and plant height, respectively.1H-NMR was utilized to show that citric acid reacted with Ca2+in solution to produce Ca-citrate and prevent the formation of Ca-glyphosate. NMR was an effective technique for characterizing chemical interactions among the spray solution components.

Characterizing the Sethoxydim-Bentazon Interaction with Proton Nuclear Magnetic Resonance Spectrometry

Weed Science ◽  
1995 ◽  
Vol 43 (3) ◽  
pp. 337-341 ◽  
Author(s):  
Kurt D. Thelen ◽  
Evelyn P. Jackson ◽  
Donald Penner
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ammonium Sulfate ◽  
Antagonistic Effect ◽  
Herbicidal Activity ◽  
Proton Nuclear Magnetic Resonance ◽  
H Nmr ◽  
Nuclear Magnetic Resonance Spectrometry ◽  
Magnetic Resonance Spectrometry ◽  
Nuclear Magnetic

The antagonistic effect of Na-bentazon on sethoxydim absorption and herbicidal activity has been documented. The addition of ammonium sulfate (AMS) with a surfactant overcomes the observed loss of sethoxydim activity. Nuclear Magnetic Resonance (NMR) was used to study the chemical effects of commercially formulated Na-bentazon, NaCl, NaHCO3, Na-bentazon plus AMS, and NaHCO3plus AMS on commercially formulated sethoxydim. Technical grade Li-sethoxydim and sethoxydim were analyzed and1H-NMR spectra were used as comparative standards. Data indicate an association of Na+from Na-bentazon, NaHCO3, and NaCl with the sethoxydim molecule. NH4+from AMS appears to associate spatially with sethoxydim but does not exert the same electronic effect on the sethoxydim ring protons as observed with Na+or Li+. The addition of AMS to sethoxydim plus Na-bentazon or NaHCO3treatments prevents the complexation of Na+with the sethoxydim molecule. The data support the hypothesis that the observed Na-bentazon antagonism and ammonium sulfate reversal of antagonism are chemically based.

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