Reversed phase organochlorine pesticides

The determination of OCP residues in milk has always presented problems, because the most common approach has required the total extraction of fat, together with lipophilic compounds, including organochlorine pesticide residues. Only one procedure for the extraction and separation of OCPs directly into an HPLC system has been described (11). The direct procedure injects the samples into an internal-surface reversed-phase C18 column connected online with the analytical column. 

The trace enrichment of pesticides from groundwater is a straightforward problem for reversed-phase SPE. The following example uses the EMPORE disk (C-18) to isolate organochlorine pesticides including aldrin, chlordane, endrin, heptachlor, lindane, methoxychlor, pentachlorophenol, and toxaphene from groundwater (Fig. 4.15). 

Figure 1.2 Overview of the EPA s organics protocol. VOCs, volatile organics SVOCs, semivolatile organics OCs/PCBs, organochlorine pesticides/poly-chlorinated biphenyls HS-GC-FID, static headspace coupled to gas chromatography and flame ionization detection LLE, liquid-liquid extraction LSE, liquid-solvent extraction or solvent leaching from solid matrices GC-ECD, gas chromatography and electron-capture detection GC-MS, gas chromatography and mass spectrometry RP-SPE, reversed-phase solid-phase extraction.

Reversed-phase SPE is applied principally in two areas of TEQA. The first application is in the determination of organochlorine pesticides (OCs) in connection with the determinative technique of GC using a chlorine-selective detector. The second application is in the determination of priority pollutant semivolatile organics that are adequately recovered from drinking water. Off-line RP-SPE coupled to a determinative technique such as GC using an element-selective detector is a very powerful combination with which to achieve the objectives of TEQA. To illustrate, this author s study of various organophosphorous pesticides (OPs) from spiked water using RP-SPE will now be discussed. 

Octadecyl surface phases (Cig) are used for the reversed-phase extraction of nonjxtlar substances from aqueous solutions. Typical applications include the extraction of organochlorine pesticides 1199]-[201], organophosphorus pesticides [202], chlorinated and unchlorinated hydrocarbons, triazines [200], 20l], PAHs and nitro-PAHs [200], carbamates [200], chlorophenols [200], [20. ], aflatoxins [204], plasticizers [205], vitamins [206], and medicaments such as barbiturates and antibiotics [207], [208],... 

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