KOSEN 한인과학기술자네트워크

뇨중 프탈레이트 대사체 mono methyl, ethyl, ... octyl phthalate를 추출하려고 하는데 SPE 추출에 대해서 잘 이해가 가지 않아서요. 알킬그룹이 짧은 메틸, 에틸 프탈레이트가 검출이 되는지 주시해야 한다고 조언을 들었는데.. 이들이 카트리지에 잘 붙어있지 못해서 그러는것인지요? 카트리지는 Oasis HLB, waters사의 제품입니당. 또 로딩하기전에 산성분위기를 만들어주기 위해 pH 2.0 버퍼를 더해줘야 한다는데 그 이유도 정확히 모르겠습니다. 친수 소수성과 관련이 있는거 같은데 누구 잘 아시는분 설명 좀 .. 아래 페이퍼에서 발췌한 내용을 명확히 이해를 못하고 있습니당. anal. chem. 2000. 72. p4127 First, an SPE cartridge was equilibrated with 1.0 mL of acetonitrile followed by 2.0 mL of basic buffer. This SPE cartridge was used to retain compounds that are hydrophobic at basic pH while allowing the more acidic analytes to elute. Next, the deconjugated urine samples were diluted with 1.0 mL of basic buffer solution and vortex mixed for 5 s. These samples were then added to an equilibrated SPE cartridge (3 mL/60 mg of Oasis HLB, Waters). The eluate was collected in borosilicate glass tubes. Residual analyte on the first cartridge was eluted by adding a second 1.0 mL of basic buffer to the cartridge. The combined basic buffer eluates were acidified by adding 3.0 mL of acidic buffer and mixed thoroughly. SPE solvent flows were monitored while samples were on the cartridges to maximize sorbent-analyte interaction (<2 mL/min). A second SPE cartridge (10 mL/60 mg of Oasis HLB, Waters) was equilibrated by washing with acetonitrile (1.0 mL) followed by water (1.0 mL) and acidic buffer (2.0 mL). We further purified the acidified sample by adding it to the second SPE cartridge and washing this cartridge with acidic buffer (3.0 mL, Figure 2). We removed residual salts by washing the second cartridge with water (9 mL). The analytes were eluted with acetonitrile (2 mL) followed by ethyl acetate (2 mL, 99.8%, Caledon, Georgetown, ON). This pooled eluate was evaporated to dryness under a stream of dry nitrogen (15 psi, UHP grade, Holox, Norcross, GA) at 55 °C (Turbovap, Zymark, Hopkinton, MA). The residue was resuspended in water (200 ？L), transferred to a glass autosampler vial insert, and analyzed by HPLC-MS/MS. Prepared samples could be stored at 4 °C for up to two weeks before analysis without degradation; no significant loss of analyte signal was observed until after 10 days of room-temperature storage. Long-term storage of unextracted urine specimen at -40 °C for six months showed no decrease in phthalate monoester levels. We chose a bifunctional, polymeric SPE sorbent (Oasis HLB, Waters) for several reasons. Previous experience with silica-based reversed-phase columns indicated that low and variable recoveries resulted when cartridges unintentionally ran dry. The Oasis HLB SPE sorbent contains both hydrophilic monomer units (Nvinylpyrolidine) and hydrophobic monomer units (divinylbenzene). The lipophilic monomer retains analytes while the hydrophilic monomer improves wetability so the sorbent remains solvated even when the cartridge momentarily runs dry. This sorbent also allows the pH of the eluates to vary widely.