Physicochemical characterization and formation of glyphosate-laden nano-emulsion for herbicide formulation

Abstract

A nano-emulsion system was developed for pesticide formulation. Pseudoternary phase diagrams were constructed consisting emulsion system of long-chain fatty acid methyl esters (LFAMEs)/mixed surfactant/water and a quarternary component, glyphosate isopropylamine (IPA) as a herbicide active. Isotropic (L) regions were formed in the phase diagrams using mixed surfactant long-chain alkylpolyglucosides (LAPG) and ethoxylated -(3hydroxypropyl)-heptamethyltrisiloxane (organosilicone) at the ratios of 9:1, 8:2 and 7:3. Preformulation concentrates were chosen from the L regions with less than 20% (w/w) of inerts (LFAMEs + mixed surfactant) and were characterized with regard to particle size, particle aging rate and thermostability study. A pre-formulation concentrate with the lowest aging rate and stable at high temperature (54 °C) was selected for the mechanisms study of the preformulation concentrate in conjunction with the development of nano-emulsion formulation. The transmission electron microscopy (TEM) result showed that the pre-formulation concentrate appeared as a polymerized multi-connected network. Upon water dilution of the pre-formulation concentrate with gentle stirring (low-energy emulsification method), welldispersed nanoparticles were formed with no needle structure being observed. The nanoemulsion particles were incorporated well with the glyphosate IPA thus inferring that this nano-emulsion system could ameliorate the bioactivity and bioavailability of the herbicide.

Green nanoemulsion‐laden glyphosate isopropylamine formulation in suppressing creeping foxglove (A. gangetica), slender button weed (D. ocimifolia) and buffalo grass (P. conjugatum)

“…A thermostability assessment confirmed that the preformulations had high long‐term stability. After dilution of the preformulations, nanoscale particles appeared as a result of rupturing of the network . The LAPG formulations (NF3 and NF4) had an optically translucent colour with a larger particle size of > 100 nm.…”

“…A phase behaviour study of the preformulations was conducted using the pseudoternary phase diagram design technique . Four herbicide preformulations were selected from the isotropic region as in previous phase behaviour studies . The preformulations F1, F2, F3 and F4 were liquid concentrates with transparent visibility and a monophase state (no phase separation).…”

“…Nanoemulsions have a particle size of less than 200 nm, which makes the systems inherently transparent/translucent and kinetically stable. Pesticides formulated with nanoemulsions having a lower surfactant concentration than microemulsions and surfactants are considerably more environmentally benign and are cost effective and economically viable . Low‐energy emulsification methods are applied to produce nanoemulsions, and the energy stored could promote smaller‐sized nanoparticles of longer life …”

Preparation and characterization of neem oil nanoemulsion formulations against <i>Sitophilus oryzae</i> and <i>Tribolium castaneum</i> adults

“…Afterward, the components were centrifuged at 3500 rpm at 25°C for 30 min. 11,12) The samples were visually investigated to determine their phase transition on the basis of clarity, stability, and transparency. The phase domains of the components were determined to be isotropic (transparent and one-phase) or anisotropic (cloudy or two-phase).…”

Application Of Nanotechnology In Agriculture And Food Industry, Its Prospects And Risks

“…Glyphosate isopropylamine (GIPA) incorporated in nanoemulsion formulation (environmentally friendly nanoemulsion system) prepared from the isotropic liquid phase upon aqueous dilution of the preformulation concentrate with low-energy stirring formed well-dispersed NPs, and the nanoemulsion formulation showed improved physicochemical characteristics [99]. Nanoemulsion system was used to increase penetration and uptake of GIPA by weeds of Eleusine indica, and nanoemulsion formulations of GIPA showed enhanced bioactivity and displayed a significantly lower spray deposition on creeping foxglove (2.9-3.5 ng/cm 2 ), slender button weed (2.6-2.9 ng/cm 2 ) and buffalo grass (1.8-2.4 ng/cm 2 ) than Roundup ® (3.7-5.1 ng/cm 2 ), even though the visible injury rates of weeds treated with the nanoemulsion formulations were statistically equivalent to those relating to Roundup ® [100].…”