The determination of residues of 2,4‐D in post‐emergence‐treated triticale

Abstract

A B S T R A C TA gas chromatographic method, using electrolytic conductivity detection, is presented for the determination of 2,4-0 as its methyl ester in triticale ( X Triticosecale Wittmack). The method was used to monitor the dissipation of 2,4-0 residues in triticale over a growing season at two sites following postemergence application of the dimethylamine salt of 2,4-0 at 0.56 kkg ha-'. Initial residues, in the order of30 mg kg -' on the day a f e r application (3-to 4-leaf stage of the crop), decreased to non-detectable levels in the mature straw and seed. Recoveries of 2,4-0 were greater than 90 % fiom green tissue fortified at 0.1 my k g -' , and in the order of 75% from seed fortified at 0.05 mg kg -' .

Comparison of extraction/hydrolysis procedures for the determination of acidic herbicides in plants: residues of mecoprop in barley following postemergence application

“…Detector response at the retention time for mecoprop methyl ester in the chromatograms of treated seed samples was not significantly different from that of the check samples. Rapid dissipation of residues leading to nondetectable residues in the seed as observed in the present study has also been reported for other chlorophenoxy acids in cereals, for example, 2,4-D in triticale (Cessna, 1990) and wheat (Cessna, 1980;Grover et al, 1985).…”

“…Severe emulsions were also encountered during the diethyl ether partitioning of the resulting decántate. [Similar problems occurred with triticale (Cessna, 1990) and wheat (unpublished data) seed.] Such emulsions generally required centrifugation to effect partitioning.…”

Residues of the Herbicides MCPA and Bromoxynil in Postemergence-Treated Triticale (×Triticosecale)

“…On the basis of a 17% cumulative vapor loss reported for 2,4-D ist?-octylester [vapor pressure =0.48 mPa (6)] from wheat (11), some MCPA iso-octyl ester would have also dissipated by volatilization. Sufficient rain fell ( Figure 2) within a few days of application at both experimental sites to have effected some washoff of plant surface herbicide deposits (4). Both herbicides are susceptible to photode- gradation.…”

“…Residues of MCPA, as its methyl ester, were determined using a Tracor Model 560 gas chromatograph equipped with a Hall electrolytic conductivity detector which, when operated under conditions described previously 4 Fortification. Fortification procedures, using MCPA acid and bromoxynil phenol, were as described previously (4). Recoveries of MCPA and bromoxynil were determined by the extraction of chopped untreated green tissue fortified at 0.1 mglkg and milled untreated seed fortified at 0.1 and 0.05 mglkg.…”

Comparison of total vaporisation and dynamic headspace techniques combined with direct mass spectrometric detection for the on-line analysis of liquid process streams

“…A range of analytical instrumentation has been employed for on-line analysis applications in the chemical industry, 1 including gas chromatography 3 and infrared spectroscopy. 4 Mass spectrometry has been employed in the iron making, 5 semiconductor 6,7 and chemical 8,9 industries since the 1950s 10,11 for the analysis of gaseous process streams or environmental monitoring. Only in the previous three decades have the benefits 12 that the technique can provide been fully realised, which has led to an increase in the number of applications.…”