Syringe filter

Disposable syringe filter, 0.2-pm or 0.45-pm Round-bottom flasks, KIMAX Glass-wool... 

Precondition a Cig (EC) SPE column (l-g/6-mL) with methanol (5mL) followed by another 5 mL of acetonitrile-water (3 7, v/v). Transfer the sample on to the column and allow it to percolate through the column under vacuum, discarding the column eluate. Wash the column with 5 mL of acetonitrile-water (3 7, v/v). Dry the column under high vacuum for 15 min and wash it with hexane (5 mL). Elute the azoxystrobin from the column with 5 mL of ethyl acetate-dichloromethane (11 9, v/v), and evaporate the eluate to dryness under a stream of air in a heating block at 50 °C. Dissolve the sample in 1 mL of acetonitrile-water (1 1, v/v) and filter the solution through a 0.45-p.m syringe filter, transferring the filtrate to an autosampler vial ready for LC/MS/MS analysis. 

Plant material is homogenized in acetone followed by addition of water. The filtered extract is diluted with acetone-water (2 1 v/v) and filtered through a syringe filter. The sample extract is diluted 1 1 with a deuterated azinphos-methyl internal standard and analyzed using LC/MS/MS in the positive-ion selected reaction monitoring (-I-SRM) mode. 

Analysis of soluble Pd by ICP. A series of reactions was initiated according to the procedure described above. After 20 s, 1 min, 3 min or 1 h, the hot reaction mixture was passed quickly through a 0.45 pm syringe filter to remove solid BaCei cPd c03.x, then the solvent was removed under reduced pressure. A mixture of BaCei cPdx03. cand K2CO3 in IPA/H2O, heated at 80 °C for 1 h, was subjected to the same workup procedure. Each of the solid residues was suspended in 12 mL 10 M aqueous HCl. The mixtures were filtered to produce clear solutions for subsequent analysis on a Thermo Jarrell Ash (TJA) High Resolution ICP spectrometer. A ICP standard solution of Pd (Aldrich) was diluted to 10 ppm for use as the high standard. 

Soil solution samples from saturated soils can be obtained by simple filtration. Simple gravity filtration is preferable to vacuum filtration methods because vacuum filtration can lead to distortions in the composition of analyte composition in filtrates. Syringe filters are usually not capable of handling soil and so are not recommended. Also, some filters can retain analytes of interest. 

If a syringe filter is to be used, it must be checked to make sure that it is not retaining the analyte of interest or, if it is, how much is being retained. 

Obtain the sample from your instructor and filter it into a small vial using a syringe filter (instructor may choose to demonstrate). The sample is a solution of methyl, propyl, and butyl paraben in methanol. Record any identifying label in your notebook. 

Filter each calibration standard, using the syringe filtering equipment, into small labeled vials. 

For high-performance liquid chromatography (HPLC) analysis samples (0.5 mL) were clarified by centrifugation at 14000 Gav for 5 min and the supernatant was decanted, filtered through a 0.2 yim in-line syringe filter and analysed directly by chiral HPLC (see below). 

Mix thoroughly the working sample solution via flask inversion and filter aliquots of the solution through a Whatman 25-mm GD/X 0.45-nm PP membrane syringe filter. Discard the first few milliliters of the filtrate and then transfer the subsequent filtrate into a capped HPLC vial for analysis. Inject 20 J,L of the filtrate into the HPLC. 

Filter the protein sample through a 0.22-pm syringe filter, and inject the sample onto the column (see Note 19). 

Remove any precipitated proteins by centrifugation at 10,000g for 30 min at 4°C. Filter the sample through a 0.22- j,m syringe filter. 

Pass the suspension through a syringe filter (0.45 pm sterile filter) to remove the gel, add an equal volume of a saturated solution of phenol in 0.3 M NaOAc pH 5.2, and vortex hard. 

For GC analysis, the emulsion samples are diluted in THF or acetone (1.5 ml). For SEC samples, the emulsions are dissolved in THF (3-5 ml, containing 0.06% toluene as an internal SEC standard).The solution SEC is filtered over aluminum oxide (to remove the copper residues) and then through a syringe filter prior to the injection into the SEC. 

Syringe filter (e.g. 0.2 mm, CHROMAFIL Type 020/15, Macherey-Nagel) Procedure... 

After stirring for 2 h, the pressure was released and the solvent was evaporated in a slow stream of nitrogen gas. The residue was extracted with heptane (3mL) and the resulting suspension filtered through a syringe filter. The filtrate was directly analyzed by GC and chiral HPLC to determine the conversion and enantiomeric excess (for analytical procedures and data, see ref. [1]). 

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