TurboVap concentrator

The TurboVap Concentration Workstation series, which includes models II, LV, 500 and 96, all of which are equipped with shearing technology and differ mainly in the number of samples they can handle simultaneously. 

Sample extracts may be concentrated by nitrogen evaporation. Turbovap concentrators direct a steam of nitrogen over the extract surface. Vessels are housed in a temperature-controlled water bath. Although some losses of volatiles occur, this technique is suited to semi-volatile analysis such as DRO. 

Concentrate the sample (remove acetone) under nitrogen to ca 20-25 mL using a TurboVap (water-bath at 50 °C). Transfer the sample into a 50-mL polypropylene centrifuge tube. Rinse the TurboVap vessel with 5 or lOmL of pFI 6 buffer solution. The amount of pH 6 buffer required depends on the matrix being analyzed and should be determined as needed. All matrices need 5 mL of the buffer solution to adjust the sample to pH 6, except for sweet corn (ears, forage, and stover), which requires 10 mL. Add the rinse buffer to the sample. Rinse the TurboVap vessel with 10 mL of hexane and add the hexane to the sample. 

Concentrate the hexane fraction (20 mL) from the previous hexane-aqueous partition to 3 mL in a TurboVap at ca 50 °C. 

Concentrate the sample to 0.1 mL in a TurboVap at ca 50 °C and adjust the sample to a final volume of 1.0 mL with acetonitrile. Note there is the potential for loss of analyte if the samples go to dryness at this step. Analyze the sample for parent carfentrazone-ethyl by GC/ECD. 

Partition the sample in methanol twice with 2mL of dichloromethane (DCM), remove the DCM after each partition step and pass the sample in DCM through a 6-mL filtration tube containing a polyethylene frit and packed with 1 g of anhydrous sodium sulfate. The use of the anhydrous sodium sulfate can be eliminated if great care is taken when removing the DCM from each partition step so that no water is included with the DCM. If water droplets are present in the DCM fraction, carefully remove them with a small pipet. The DCM is then concentrated in a Turbovap to 0.1 mL at 50 °C. Note there is the potential for loss of analytes if the samples go to dryness at this step. 

Cool the sample extract to room temperature and filter the extract through a Whatman No. 1 (11-cm) filter paper (pre-rinsed with 5mL of acetone) into a filter flask using a Buchner funnel and vacuum (15 inHg). Rinse the boiling flask with 2 x 25 mL of acetone and pass the rinsate through the post-reflux solid and filter paper. Transfer the filtrate into a 200-mL TurboVap vessel. Rinse the filter flask with 5 mL of acetone and add the rinsate to the TurboVap vessel. Concentrate the filtrate to <25 mL (not to dryness) using a TurboVap Evaporator (water-bath at 50 °C increase the pressure up to 30 psi as the volume decreases). All traces of acetone must be removed. 

Figure 10.4 Schematic of a typical gas blow-down system (Turbovap ) system used for the pre-concentration of compounds in organic solvents.

Sample preparation before HPLC analysis differs for juice and peel oil samples. Juice samples were extracted 1 1 on a weight basis with solvent (10% w/w dichloromethane + 90% hexane) (40 g juice + 40 g solvent), the solvent was separated and evaporated to 0.5 g using a Turbovap 11 model concentration This concentrated mixture was injected into the HPLC. Extraction recovery for the PMFs was determined to be 89 %. Oil samples were diluted to 10% (w/w i in ethanol and injected directly. In both cases, injection volumes of 5 jL were used. All oil samples in this study were winterized for at least 30 days at a temperature of 4 C or less. 

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