2, 4-D, 2, 4, 5-T, and Silvex

Wiese and Davis (158) reported that esters of 2,4-D, 2,4,5-T, and silvex move little in soils. Menges and Hubbard (406) found that DCPA was not leached into soils in detectable amounts. Talbert et al. (157) found that chloramben methyl ester leached much less than chloramben salts because of its low water solubility. 

Figure 3. Direct flow injection TSP NI mass spectra of (1) 2,4-D, (2) 2,4,5-T and (3) silvex. Carrier stream acetonitrile-water...

Figure 5. TSP NI LC-MS using selected ion monitoring of a water sample spiked with 2 ppm of (1) 2,4,-D, (2) 2,4,5-T and (3) silvex using and LC eluent of acetonitrile-water (50 50) + 0.05 M ammonium acetate or aoetonitrile-water-ohloraoetonitrile (49 49 2) + 0.05 M ammonium acetate. Flow rate 1 ml/min. Amount of each compound injeoted 200 ng,...

Lee et al. [187] developed a multi-residue method with a low detection limit for 10 commonly used acid herbicides in non saline waters. The herbicides were Dicamba, MCPA, 2,4-DP, 2,3,6-TBA, 2,4-D, Silvex, 2,4,5-T, MCPB, 2,4,5-DB and Picloram. The method used solvent extraction and the formation of pentafluorobenzyl esters. The derivatives were quantified by capillary column gas chromatography with electron capture detection. The detection limit was 0.05pg L. Recoveries of herbicides from spiked Ontario lake water (0.5-1.Opg L 1) were 73-108% except for Picloram recovery which was 59% at 0.1 pg L 1. 

The nine herbicides studied by these workers were Dicamba, MCPA, MCPB, 2,4-DB, Picloram (4-amino-3,5,6-trichloropicolinic acid), 2,4-D, 2,4,5-T, Silvex and 2,4-DP. 

These herbicides are highly selective for hroadleaved weeds. 2,4-D was the first chlorophenoxy acid herbicide developed. There are several compounds that belong to this group in addition to 2,4-D and they include 2,4-DB, Di-chlorprop, MPCA, MPCB, MCPP, 2,4,5-T, and 2,4,5-TP (Silvex). 

Arodor 1248, Arodor 1254, and Arodor 1260. Quantitation is by comparison of chromatograms with standard concentrations of pure compounds treated in an identical manner. The phenoxy acid herbiddes (2,4-dichlorophenoxy)acetic acid (2,4-D), silvex, and (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) can be determined by dectron-capture detection after extraction and conversion to the methyl esters with BF -methanol. The water sample must be acidified to pH <2 prior to extraction with chloroform. 

Chlorophenoxy acids and their derivatives constitute a major class of herbicides used for controlling weeds in cereal croplands, lawns, turfs, pastures, forests and in non-croplands near water. Some common herbicides of this class include 2,4-D, Silvex, 2,4,5-T,... 

Silvex is moderately toxic to test animals. The toxic effects are comparable to those of 2,4-D and 2,4,5-T. Oral or subcutaneous administration in mice caused embryo toxicity and fetal death. The oral LD50 value in rats is 650 mg/kg. 

Source Although not produced commercially, TCDD is formed as a by-product in the synthesis of 2,4,5-trichlorophenol. TCDD was found in 85% of soil samples obtained from a trichlorophenol manufacturing site. Concentrations ranged from approximately 20 ng/kg to 600 g/kg (Van Ness et al, 1980). TCDD may be present in the herbicide 2,4-D which contains a mixture of dichloro-, trichloro-, and tetrachlorodioxins. TCDD is commonly found as a contaminant associated with pulp and paper mills (Boddington, 1990). In addition, during the manufacture of 2,4,5-T and silvex from trichlorophenol, TCDD was found at concentrations averaging 20 parts per billion (Newton and Snyder, 1978). 

The second case taken from the author s own work uses LLE to initially clean up an aqueous sample taken from the environment that might contain, in addition to the analyte of interest, other organic compounds that may interfere in the determinative step (9). The analytes of interest are the class of chlorophenoxy herbicides (CPFIs) and includes 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4,5-trichlorophenoxypropionic acid (Silvex). CPFIs are... 

---