Determination of 3,6-dichloropicolinic acid residues in soil by gas chromatography of the 1-butyl ester

Gas chromatography‐mass spectrometry analysis of the herbicide clopyralid in differentially cultivated soils

“…In order to investigate the reproducibility of the method, two different soils (soil 1 and soil 2) were employed. Recovery rates at concentrations of 50, 100, and 500 g/kg soil were 73 Ϯ 11, 69 Ϯ 12, and 68 Ϯ 9 for conventional and 83 Ϯ 6, 75 Ϯ 5, and 76 Ϯ 4 for ultrasound-enhanced extraction, resulting in means of 70 Ϯ 10% for conventional [5,[10][11][12] extraction by shaking with solvent and 78 Ϯ 5% for ultrasound-enhanced extraction (n ϭ 10 each concentration). Application of ultrasound enhances the dissociation of clay-humic acid complexes in soil and increases reliability and recovery of clopyralid extraction [5,10,11].…”

“…Chem. 15,1996 S. Schütz et al shifts the pH into the acidic range and NaCl helps to transfer the undissociated clopyralid acid into the organic phase [5,[10][11][12]. After phase separation, the organic phase was extracted with 2 ml 10% sodium phosphate buffer (pH ϭ 8).…”

“…Trace analysis of aliphatic carboxylic acids was performed by derivatization with pentafluorobenzylbromide (PFBB) using gas chromatography with an electron capture detector (GC-ECD) [4]. This method resulted in highly sensitive but poorly reliable clopyralid analysis [5]. Although the published HPLC-UV methods [6,7] suffer from a general lack of sensitivity, the GC-ECD methods [4,5,8,9] fall short in reliability because of instabilities of baselines due to numerous unidentified by-products formed in the derivatization step.…”

“…This method resulted in highly sensitive but poorly reliable clopyralid analysis [5]. Although the published HPLC-UV methods [6,7] suffer from a general lack of sensitivity, the GC-ECD methods [4,5,8,9] fall short in reliability because of instabilities of baselines due to numerous unidentified by-products formed in the derivatization step. Another published gas chromatography-mass spectrometry (GC-MS) method employing clopyralid methyl ester [10,11] has not been considered because of the toxic, carcinogenic, and explosive properties of the diazomethane needed for the derivatization reaction.…”

Journal of Range Management, Volume 55, Number 3 (May 2002)

“…Barley Mill Plaza, Wilmington, Del. 19898. ester derivative of the clopyralid was formed by adding 1 ml 1-butanol and 6 drops H2504 to the residue and heating for 30 min in boiling water (Cotterill 1978). The mixture was cooled and 20 ml H2O and 5 ml hexane were added to the test tube.…”