Considerations for analytical supercritical fluid extraction of sulfonyl ureas employing a modified fluid

Abstract

Important considerations are discussed for analytical SFEmethod development employing methanolmodified carbon dioxide and solid-phase trapping.The focus of this study was to break the method development procedure into distinct steps so that the origins of low recoveries could be determined conclusively. Sulfonyl urea herbicides were used as probe analytes. Analyte solubility, analyte trapping, analyte trap removal (solidphase), and extract analysis were all shown to be equally important in achieving quantitative SFE recoveries.

Evaluation of Hydromatrix and Magnesium Sulfate Drying Agents for Supercritical Fluid Extraction of Multiple Pesticides in Produce

“…For the 7680T, the 1 ml Hypersil octyldecylsilane (ODS) trap was rinsed to waste with 2 ml of ethyl acetate followed by 2 ml of acetonitrile at 1 ml min 21 each to clean and regenerate the trap between extractions. For the Autoprep-44, the 1 ml trap consisted of a 1 + 1 ODS-Unibeads sorbent prepared by Suprex, and the trap was flushed with 4 ml of acetonitrile at 1.8 ml min 21 between extractions (60 psi N 2 gas pressure to blow the trap dry, 1 psi = 6894.76 Pa). After 8-16 extractions, the 7680T tubing (after the vessel) and trap were flushed with ≈ 10 ml of 1 + 1 methanol-water.…”

“…9 The use of modifiers also complicates the optimization of extraction and trapping conditions. 6,[19][20][21] Derivatization is another option to improve SFE recovery of polar pesticides, such as 2,4-D, [22][23][24][25] but in multiresidue analysis, derivatization methods are not desirable.…”

“…However, HMX can retain certain polar pesticides, such as methamidophos, omethoate, and sulfonyl urea herbicides. 1,11,21 Burford et al evaluated several other drying agents, including inorganic salts, in the SFE of organic pollutants from moist samples, 27 but pesticide analytes or food matrices were not included in the study. Valverde-García et al demonstrated that methamidophos, chlorpyrifos, endosulfans, methiocarb, and chlorothalonil, were extracted from vegetables when using anhydrous MgSO 4 as the drying agent.…”

Supercritical CO2Fluid Extraction of Imazaquin From Soil

“…The pellet was resuspended with 40 ml methanol, shaken for 5 min, and centrifuged for 5 min at 4080 x g. The methanol and NaOH supematants were combined and the pH was adjusted to 2 with 6 N HC1 to precipitate the humic acids. The combined NaOH-methanol supernatant was centrifuged for 5 min at 4080 x g and filtered using a Buchner funnel with two filter papers 7 . The 50-g soil pellet was resuspended with 40 ml 0.1 N HC1 in 25% by vol aqueous methanol and centrifuged for 5 min at 4080 x g. The supernatant was filtered and combined with NaOH-methanol extract.…”

Optimization of experimental parameters for the quantification of polymer additives using SFE/HPLC

“…To overcome this problem, CO 2 is often used with a modifier. [7][8][9][10] Poor analyte recoveries are often attributed to poor extraction efficiencies, although in some cases, they are caused by incomplete analyte collection after the extraction. 11 The aim of this article is to develop an efficient, rapid method for the quantitative analysis of antioxidants in polypropylene.…”