Syringe membrane filters

The sampling of solution for activity measurement is carried out by filtration with 0.22 pm Millex filter (Millipore Co.) which is encapsuled and attached to a syringe for handy operation. The randomly selected filtrates are further passed through Amicon Centriflo membrane filter (CF-25) of 2 nm pore size. The activities measured for the filtrates from the two different pore sizes are observed to be identical within experimental error. Activities are measured by a liquid scintillation counter. For each sample solution, triplicate samplings and activity measurements are undertaken and the average of three values is used for calculation. Absorption spectra of experimental solutions are measured using a Beckman UV 5260 spectrophotometer for the analysis of oxidation states of dissolved Pu ions. 

At least five test vessels, containing the metal or metal compound (e.g. 100 mg solid/1 medium), are agitated as described in A 10.5.1.9 at a temperature 2 °C in the range 20 - 25 °C, and triplicate samples are taken by syringe from each test vessel after 24 hours. The solid and solution are separated by membrane filter as described in AIO.5.1.10, the solution is acidified with 1% HNO3 and analysed for total dissolved metal concentration. 

AIO.5.3.1.2 The metal compound is added to the test vessels at a loading of 100 mg/1 and the test vessels are covered and agitated rapidly and vigorously. After the 24 hours agitation, the pH, temperature and dissolved O2 concentrations are measured in each test vessel, and two to three solution samples are drawn by syringe from each test vessel and the solution is passed through a membrane filter as described in A10.5.1.10 above, acidified (e.g. 1 % HNO3) and analysed for total dissolved metal concentration. 

Figure 14.2. Operational problems in size fractionation by membrane filters, (a, b, c) Size distributions of iron oxyhydroxyphosphate particles obtained by transmission electron microscopy (true distribution) and syringe filtration on Nucleopore polycarbonate filters and Schleicher-Schuell cellulose ester depth filters. Iron particles formed at the oxic-anoxic interface of eutrophic Lake Bret (Switzerland), (d) Fraction of iron particles retained on 3.0-pim membranes, as a function of flow rate (j) Nucleopore polycarbonate, and (2) Schleicher-Schuell cellulose nitrate. In the absence of coagulation or adsorption, no particle should be retained. (From Buffle et al., 1992.)...

Various designs of the stirred-flow reactor are possible. Carski and Sparks (1985) developed a relatively simple stirred-flow reactor constructed from a plastic syringe and membrane filter holder (Fig. 2-8). The volume of the reactor is adjustable to allow one to add and maintain a known amount of solution to a known amount of solid phase. Mixing is accomplished by a magnetic stirrer. 

Decant the supernatant liquid and filter through a disposable membrane filter (0.45 pm, nylon 66) attached to a syringe. Collect each in a 100 mL volumetric flask and dilute to volume with 20 mM H2SO4. 

Procedure manually shake the sample bottle for 1 min to homogenize contents and take sample for analysis directly from the bottle. Weigh accurately 40 g soil and extract in extraction bottle with 100 mL of 0.1 mol L NaN03 solution at 20 2 °C for 2 h at 120 rpm. Centrifuge for 10 min at 4000 g remove the supernatant by syringe fit the membrane filter and filter into 50 mL bottle add 2 mL cone. HNO3 to 50 mL volumetric flask and make up to volume with filtered extract (prevention of microbial growth) analyse immediately (note that solutions are stable for 1 week at 20 5 °C). 

From time to time throughout the experiments the pH was recorded, and a sample of precipitate and supernate was withdrawn from the stirred mixture by means of a syringe, and filtered through a 0.10-/xm pore-diameter membrane filter. The filtrate was analyzed for manganese by atomic absorption. The filter membrane with the precipitate was transferred to a small beaker and the oxide was dissolved in a measured excess of standardized oxalic acid and 0.2 mL of concentrated H2SO4. This solution was diluted to 100 mL the manganese was determined on... 

Prepare the necessary mobile phase according to the method description, membrane filter buffer, degas, connect to inlet tube, if necessary remove air bubbles with syringe or purge. 

Adsorption of heavy metal ions on the ETS-10 sample was conducted using a batch-type method at room temperature (23 C). For kinetic measurement, I g of air-dried ETS-10 was added to 100 ml of solution pre-acidified by nitric acid under shaking so as to generate a solution of pH = 5.8. Then, 100 ml of 20 mmol/L Pb(N03)2 (or Cu(N03)2) solution was added to obtain a mixture with an initial Pb (or Cu concentration of approximately 10 mmol/L, a final pH value of about S.O and a batch fiictor (ratio of liquid volume to solid mass) of about 0.2 L/g. S ml of the mixture was withdrawn at an appropriate time interval by using a 5 ml syringe and rapidly filtered through a 0.2 pm nylon membrane filter. The filtrate was collected in a sample valve and analyzed for Pb (or Cu), Na and K concentrations using a spectrometer (Perkin-Elmer Analyst 300). The amount of metal adsorbed at time t (s), (mmol/g), was deduced from the mass balance between the initial concentration (Q) and concentration at time t (C,). The experimental data were fitted to pseudo-second-order equation ((/g, =1/Vq +//gj [8], where k (g/mmol/s) is the adsorption... 

The integrity of membrane filters with a pore size of 0.2 and 1.2 pm should be verified using a bubble-point test after use as an in-process control. During this test a 0.2 pm membrane filter should resist the air pressure produced by moving the plunger over 80-85 % of the total syringe volume and in the case of a 1.2 pm membrane filter over 50-60 % without continuous bubble formation on the opposite of the membrane (see also Sect. 30.6.5). 

To get defect-free membranes, organic solvent-based polymer solutions should be filtered before casting. For large volumes, a glass filter or membrane filter can be used. For smaller volumes (<50 mL) the losses may be too high, and filtration through a syringe filter (0.45 pm)... 

Filter the rainwater sample with a membrane filter having a pore size of 0.45pm, Use the filtrate as the sample for the test. Inject approximately 2ml of the sample into a microloop with a syringe. Table 2.8 lists the determination conditions. Obtain the peak areas of the chromatogram by the half value width method (width mm) in half value of peak height x peak height (mm) and prepare a calibration curve. 

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