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LAAN-A-LC-E273







            Application                  Supercritical Fluid Extraction /  Chromatography

            News                         Using the Nexera UC Online SFE-SFC-MS System to


                                         Analyze Residual Pesticides in Agricultural Products
            No.L497





            The Nexera UC online SFE-SFC-MS system combines    n Sample Preparation
            supercritical fluid extraction (SFE) and supercritical fluid   The QuEChERS is a well-known method that prioritizes
            chromatography (SFC) in one online system, so that the   simplicity and speed and is commonly used to pretreate
            entire process from extraction of target components to   agricultural products for residual pesticide analysis. However,
            acquisition of data can be performed completely    the method involves many steps, such as adding reagents,
            automatically. Furthermore, the system can add polar   solvent extraction, purification by dispersive solid phase
            organic solvents (modifiers) to the supercritical carbon   extraction, and centrifugal separation. In contrast, the online
            dioxide fluid during SFE and SFC, so that the system   SFE-SFC-MS system requires only mixing 1 g of agricultural
            can be used to extract and analyze components with a   product crushed with a mixer with 1 g of a dehydrating
            wide range of polarities.                          agent* and placing the mixture in the extraction vessel, as
            Meanwhile, ever since the positive list system was   shown in Fig. 2. Consequently, the system improves
            enacted in 2006 in Japan for residual pesticides in   analytical productivity, reduces the environmental impact,
            foods, which applies to more than 800 types of     and also avoids human errors involved in the pretreatment
            pesticides, there has been increasing demand for a   steps. Using a dedicated rack changer, the system can
            system able to simultaneously analyze multiple     continuously extract and analyze up to 48 samples at a time.
            pesticides with a wide range of properties, including
            pretreating samples.                               * "Miyazaki Hydro-Protect" Patent No. 3645552
            This article describes an example of using the Nexera          Extraction vessel
            UC online SFE-SFC-MS system to analyze residual      (A)                    Analytical column
            pesticides in agricultural products.                                                Back pressure   Mass
                                                                                                Back pressure
                                                                                               regulator (BPR-B)
                                                                           Valve  Valve        regulator (BPR-A)  spectrometer
                                                                             SFE unit
            n Online SFE-SFC-MS System                                               Back pressure
                                                                                     Back pressure
                                                                                    regulator (BPR-B)
                                                                                    regulator (BPR-B)
            The operating principle of the Nexera UC online SFE-       Modifier         Make-up
            SFC-MS system is shown in Fig. 1. The extraction vessel   CO2 cylinder
            filled with the sample is placed in the SFE unit and   (B)     Extraction vessel
            heated to an internal temperature of 40 °C (Fig. 1A).                       Analytical column
                                                                                                Back pressure
                                                                                                Back pressure
                                                                                                        Mass
            Then supercritical carbon dioxide fluid is pumped into         Valve  Valve        regulator (BPR-A)  spectrometer
                                                                                               regulator (BPR-B)
            the extraction vessel. After filling the vessel, the flow is     SFE unit
                                                                                     Back pressure
            stopped to allow static extraction of target components                 regulator (BPR-B)
            (Fig. 1B). After static extraction, the fluid is pumped   CO2 cylinder  Modifier  Make-up
            through the extraction vessel for dynamic extraction
            (Fig. 1C). During dynamic extraction, extracted                Extraction vessel
            substances flow from the extraction vessel and into the   (C)
            analytical column. However, due to the high level of                        Analytical column  Back pressure   spectrometer
                                                                                                        Mass
                                                                                                Back pressure
                                                                                               regulator (BPR-A)
            contaminant components in agricultural products,               Valve SFE unit Valve  regulator (BPR-B)
            passing all the extract substances through the analytical                Back pressure
            column or mass spectrometer could damage the                            regulator (BPR-B)
            column or contaminate the mass spectrometer.        CO2 cylinder  Modifier  Make-up
            Therefore, the Nexera UC online SFE-SFC-MS system              Extraction vessel
            splits the flow to send only a portion of the substances   (D)
            extracted from dynamic extraction through the                               Analytical column  Back pressure   spectrometer
                                                                                                        Mass
                                                                                                Back pressure
                                                                                               regulator (BPR-A)
            analytical column. After dynamic extraction, fluid is only     Valve  SFE unit Valve  regulator (BPR-B)
            sent through the analytical flow line, where the                        regulator (BPR-B)
                                                                                    Back pressure
            analytical column is used for gradient separation and
            the mass spectrometer for detecting the target      CO2 cylinder  Modifier  Make-up
            components (Fig. 1D).
                                                                       Fig. 1  Analysis Flow by Online SFE-SFC-MS
                        Pretreatment process for conventional (QuEChERS) method
                              Pulverize  Add solvent  Stir  Add reagent  Stir  Centrifuge Acquire supernatant  Add reagent  Stir  Centrifuge
                                                           Mix agricultural products  Rack changer
                        Pretreatment for Nexera UC system  and dehydrating agent
                                  Add dehydrating  Fill extraction
                             Pulverize    Mix
                                  agent       vessel
                                                   Fig. 2  Sample Preparation
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