Fisher Filtrator

Figure 2. Fisher Filtrator Assembly for Quantitative DDT Estimations...

Determination of Aluminum. Weigh accurately a sample calculated to contain 0.4g of TNT into a tared sintered glass filtering crucible, medium porosity, 30-ml capacity. Extract on a Fisher filtrator with ethylene chloride (purified... 

Determination of Hot Melt — Visually. Weigh accurately a 1 g sample of HBX into a tared sintered glass filtering crucible, medium porosity, 30-ml capacity. Using approx 5ml of ethylene chloride, divided into 5 equal portions, 1 min contact time each, extract sample on a Fisher filtrator with water vacuum. Collect filtrate in a 50-ml volumetric flask and dilute to the mark with ethylene chloride. Compare the color of the filtrate visually with previously prepd standards to det the weight of hot melt present. The prepn of the hot melt standard solns are described in 4.4.3.5.14... 

Certain media components are susceptible to heat it is going to be denatured if it is heated. Therefore they must be added to the media after autoclaving. To do so, it is necessary to cany out filtration, the components using a 0.22 pm pore size filter that is appropriate to the solvent used. Filters are normally available from Whatman, or Fisher Scientific. It is recommended you consult filter experts or suppliers about the solvent and the special application you are intending to implement for the desired filters for die process. Normally filtration of... 

Remove excess reagent and reaction by-products by dialysis or gel filtration using 0.1M sodium phosphate, 0.15M NaCl, lOmM EDTA, pH 7.5. For chromatographic separation, use a desalting gel filtration support such as the Zeba desalting spin columns (Thermo Fisher) or the equivalent. The SAMSA-modified protein may be stored at -20°C until needed. 

Separate excess cystamine and EDC (and reaction by-products) from the modified protein by dialysis or gel filtration using 10 mM sodium phosphate, 0.15M NaCl, pH 7.2. A desalting column may be used for the gel filtration procedure (i.e., Zeba spin columns from Thermo Fisher). 

Purify the modified protein from reaction by-products by dialysis or gel filtration using 50 mM sodium phosphate, 0.15 M NaCl, 10 mM EDTA, pH 7.2. Alternatively, centrifugal spin columns containing a desalting resin may be used for rapid purification (Thermo Fisher). 

Purify the derivative by gel filtration using a PBS buffer or another suitable buffer for the particular protein being modified. The use of a desalting resin (e.g., Excellulose, Thermo Fisher) or similar matrices with low exclusion limits work well. To obtain complete separation, the column size should be 15-20 times the size of the applied sample. Fluorescent molecules often nonspecifically stick to gel filtration supports, so reuse of the column is not recommended. 

The gel filtration column described in step 3 should be prepared and equilibrated prior to starting the modification reaction. Enzymes preactivated with sulfo-SMCC are available from Thermo Fisher. 

Re(0)Cl3(PPh3)2 (10 g, 0.011 mol) is placed in a 500-mL round-bottomed flask in benzene (250 mL) with a magnetic stirring bar. Concentrated hydrochloric acid (Fisher 44 mL, 12 M) is added slowly to the suspension followed by dimethylsulfoxide (Fisher 10 g, 0.13 mol). The suspension is stirred for 5 days closed to the atmosphere. The resulting hght green solid is collected by suction filtration, and then washed with (2 x 30 mL) acetone and then with cold dichloromethane (2 x 30 mL). After drying in air, the yield is 7.5 g (95%). 

Lac sulfur 1s prepared by boiling a suspension of 33 g of calcium oxide and 50 g of sublimed sulfur (Fisher Scientific Company) in 200 mL of water for 30 min, then filtering the hot solution and acidifying the clear filtrate to pH 5 with hydrochloric acid. The precipitated sulfur is collected, washed with water, and dried in a vacuum desiccator. 

Into a 25-mL round-bottomed flask was weighed 2.5 g of Merck 10181 silica gel or Fisher A540 alumina that had been equilibrated with the atmosphere at 120°C for at least 48 h. The flask was stoppered, and the content was allowed to cool to 25 °C. The amine was added without solvent and the resulting mixture tumbled until uniformly free-flowing. The oxidant was then added and the mixture again tumbled. After being heated, the mixture was allowed to cool to 25 °C and was stirred overnight with 100 mL of MeOH. The adsorbent was collected by vacuum filtration and washed with an additional 50 mL of MeOH, and the combined filtrates were concentrated under reduced pressure. 

Equipment. Silver filters of 0.45-pm pore size and 47-mm and 142-mm diameter were obtained from Osmonics, Inc., Minnetonka, MN. Stainless-steel pressure filtration equipment (47-mm and 142-mm plate filtration units) was obtained from Millipore (Bedford, MA). XAD-8 resin was purchased from Supelco, Inc. (Bellefonte, PA) and cation-exchange resin was purchased from Fisher Scientific (Ag-MP-5, Springfield, NJ). A Millipore XX80 peristaltic pump was used in the isolation of humic substances (Bedford, MA), and the freeze drying unit was a FTS Systems Flex Dry freeze drier, an FTS Systems shell freezer, and an FTS model VP62A vacuum pump (Stone Ridge, NY). The specific conductance meter (model 604) was obtained from Amber Science, Inc., Eugene, OR. 

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