Efficiency of hexane extraction of napropamide from Aldrich humic acid andsoil solutions

Dissolved organic matter (DOM) has been shown. to form a stable complex wit h Napropamide [2(alpha-naphthoxy)-N,N-diethyl propionamide] and to facilita te its transport through soil columns. Liquid-liquid extraction of organics is a common method to transfer napropamide from water into an organic phas e for gas chromatography analysis. A study was conducted to determine the e ffect of Aldrich hunic acid, soil-derived dissolved organic matter, electri cal conductivity, and hydrogen ion activity on the ability of hexane to ext ract napropamide from solutions and from soil extracts. The electrical cond uctivity of Aldrich humic acid solutions (0.0, 48, and 100 mg C L-1) were a djusted to 0.01, 0.97, and 1.69 dS m(-1) by adding NaCl and CaCl2, and pH ( 8.2, 7.4, and 5.6) was adjusted using HCl and NaOH. Electrical conductivity had no effect on extraction efficiency. In the absence of DOM pH had no ef fect on extraction efficiency. Extraction efficiency decreased with increas ing DOM concentration. Maximum reduction in extraction efficiency occurred in the presence of DOM when solution pH was near neutrality. A maximum extr action efficiency of 100% was observed in the absence of DOM and a minimum of 68% when napropamide was added to DOM solutions at pH 8.2 and then lower ed to pH 5.6. Management practices such as liming and allowing napropamide to dry on the soil may increase environmental transport. Also quantificatio n of napropamide in environmental samples can be affected by DOM.