Comparison of One‐Step Acidic Extraction Versus Two‐Step Basic and Acidic Extraction Procedures for Semivolatile Analysis of Wastewater

Abstract

The feasibility of using the U.S. Environmental Protection Agency's (U.S. EPA's) contract laboratory protocol method for analyzing semivolatile compounds in industrial wastewater pretreatment program samples was investigated because of time and labor savings involved. Various laboratory evaluation studies were conducted to determine whether this alternate one‐step acidic extraction method would give comparable results to U.S. EPA Method 625. These studies consisted of comparisons of method detection limits, spike recoveries in reagent water and actual field samples, and the precision between Method 625 and the alternate one‐step acidic extraction. More than 60 base‐neutral and acid extractables (55 target compounds and 6 surrogates) were used in the comparative study of method detection limits and spike recoveries of the two procedures. Using reagent water, one‐step acidic extraction gave consistently better recoveries than two‐step basic and acidic extraction. Similar results were obtained with representative field sample matrices. Based on results of this investigation, the Metropolitan Water Reclamation District of Greater Chicago, Illinois, submitted an application to U.S. EPA to have one‐step acidic extraction accepted as a site‐specific alternate test procedure for analyzing industrial wastewater samples. After thorough review, U.S. EPA Region V approved the use of this alternate one‐step acidic extraction method. It is recommended that other municipal analytical laboratories apply to U.S. EPA for similar approval.

MNDO and DFT Computational Study on the Mechanism of the Oxidation of 1,2-Diphenylhydrazine by Iodine

“…May and Halpern [11] did provide an alternative one step mechanism in which "cyclic" activated complex was formed which disproportionates to give products that are consistent with (6). The authors [11] were of the opinion that both the chain multistep mechanism proposed in (1)-(4) and the onestep mechanism, as shown in (8) in Scheme 1, were plausible mechanisms. It is the desire of this study to investigate whether the popular multistep mechanism [11,12] or the latter proposed one-step mechanism is the most plausible one and/or if both routes are possible, which would be the most favored:…”

“…The effort of study to shift the chemistry in a different direction was only partially successful. Several others [5][6][7][8][9] have also reported that the reactions of 1,2-diphenylhydrazine and its derivatives were pH dependent and would yield different products depending on the PH of the reaction medium. These studies [4][5][6][7][8][9] concluded that 1,2-diphenylhydrazine and its derivatives enjoy complicated chemistries that include structural rearrangement and disproportionation and that their interactions with metal ions or inorganic substances are complex and incompletely understood.…”

“…Several others [5][6][7][8][9] have also reported that the reactions of 1,2-diphenylhydrazine and its derivatives were pH dependent and would yield different products depending on the PH of the reaction medium. These studies [4][5][6][7][8][9] concluded that 1,2-diphenylhydrazine and its derivatives enjoy complicated chemistries that include structural rearrangement and disproportionation and that their interactions with metal ions or inorganic substances are complex and incompletely understood. Although 1,2diphenylhydrazine is known to be oxidized readily by many oxidants [10][11][12][13][14][15][16][17], only in a few other cases have the reaction mechanisms been examined, especially its reaction mechanisms with iodine [14].…”

Chemical Species

“…A kinetic model of the process was discussed. Khalil et al (1999) compared the two-step basic and acidic extraction procedure of US EPA method 625 with the one-step acidic extraction of the US EPA's contract laboratory protocol for analysis of semivolatile constituents in wastewater.…”