Fate of [14C]Emamectin Benzoate in Cabbage. 2. Unextractable Residues

Cabbage plants were treated with seven weekly applications of [14C]emamectin benzoate followed by a final application of [14C/3H]emamectin benzoate at two rates; the maximum expected commercial use rate of 0.015 lbs a.i./acre (1×) or an exaggerated rate of 0.075 lbs a.i./acre (5×). Methanol homogena...

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Bibliographic Details
Published in:Journal of agricultural and food chemistry 1997-07, Vol.45 (7), p.2758-2762
Main Authors: Feely, William F, Crouch, Louis S
Format: Article
Language:English
Subjects:
AVERMECTINAS
AVERMECTINE
AVERMECTINS
Biological and medical sciences
Biological control
CABBAGES
CHOU POMME
Control
EXTRACCION
EXTRACTION
Fundamental and applied biological sciences. Psychology
ISOTOPE LABELING
Medical sciences
METABOLISM
METABOLISME
METABOLISMO
PESTICIDE
PESTICIDES
Pesticides, fertilizers and other agrochemicals toxicology
Phytopathology. Animal pests. Plant and forest protection
PLAGUICIDAS
Protozoa. Invertebrates
REPOLLO
RESIDU
RESIDUES
RESIDUOS
TECHNIQUE DES TRACEURS
TECNICAS DE TRAZADORES
Toxicology
TRACER TECHNIQUES
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Summary:Cabbage plants were treated with seven weekly applications of [14C]emamectin benzoate followed by a final application of [14C/3H]emamectin benzoate at two rates; the maximum expected commercial use rate of 0.015 lbs a.i./acre (1×) or an exaggerated rate of 0.075 lbs a.i./acre (5×). Methanol homogenates of cabbage heads were extracted with methanol/water containing ammonium acetate. Approximately 14−26%, or 58−95 ppb for 1× plants and 188−492 ppb for 5× plants, of the total residues remained unextractable. The unextractable residues were characterized by serial treatment with buffer, cellulase, α-amylase, pectinase, and protease, solubilization with hot dimethyl sulfoxide (DMSO), and reflux with 0.5 N sodium hydroxide (NaOH). A portion of the amylase hydrolysate was treated with maltase. All samples, including final uncharacterized residues, were analyzed for radioactivity. Selected fractions were assayed for glucose and protein. Generally, recovered radioactivity was released in the following order:  protease (23−29%) > DMSO (15−29%) > NaOH (12−18%) > cellulase (9−17%) > buffer (9−16%) > α-amylase (7−9%) > pectinase (3−5%). Only about 1% of the initial unextractable residues remained uncharacterized after the procedure. The results suggest incorporation of radioactivity into natural products such as protein, cellulose, lignin, and starch. Keywords: Emamectin benzoate; unextractable; natural products
ISSN:0021-8561
1520-5118
DOI:10.1021/jf960907+