Sampling through-glass

Standard Method 2540C determines total dissolved solids (IDS) by filtering a water sample through glass fiber disks, then drying the sample at 180 °C for 1 h. The sample is cooled in a dessicator and weighed, then redried at 180 °C. This process is repeated until a constant weight is obtained. Coefficient of variation of test values is 7%. 

Filtration Air is filtered for collection of aerosols by drawing the air sample through glass fiber, cellulose, sintered glass, or membrane or granular filters. On accumulation of the aerosol the flow through the filter is restricted, and collection is influenced by... 

Figure 2.27. Cooling (1) and reheating (2) a glassy sample through glass transition. The cooling rate is less than heating rate on subsequent heating (endotherm is up).

Particulate gravimetry is commonly encountered in the environmental analysis of water, air, and soil samples. The analysis for suspended solids in water samples, for example, is accomplished by filtering an appropriate volume of a well-mixed sample through a glass fiber filter and drying the filter to constant weight at 103-105 °C. 

Add to the sample solution (containing 1 -25 g of Mo) 4 mL of 1 3 sulphuric acid, 3 drops of 85 per cent phosphoric(V) acid, and 0.5 g of citric acid. Dilute with water to 20 mL and add 2 mL of dithiol solution. Allow to stand at room temperature for 2 hours. Extract the molybdenum complex with 13 mL and 10 mL portions respectively of re-distilled butyl acetate, and make up to 25.0 mL with this solvent in a graduated flask filter through glass wool if not entirely clear. Determine the absorbance of the solution at 670 nm. Prepare a calibration curve as detailed in Section 6.14. 

Weigh 2.5 or 5 g of crop matrix into a blending vessel. Fortify samples at this point with the appropriate analytical standards. Allow the solvent to evaporate. Add 100 mL of acetone-water (4 1, v/v) and blend the mixture using an Omni mixer equipped with a macro generator for 5 min at 6000-7000 rpm. Filter the sample through a Whatman 934 AFI glass-fiber filter paper on a Buchner funnel/vacuum flask setup. Rinse the blending cup and filter cake with 100 mL of acetone. Transfer the filtrate into a 200-mL TurboVap vessel. 

Air is sampled through a glass-fiber filter disk for 6 h at a rate of 2 L min. The filter is placed in a vial containing acetonitrile and the vial is heated at 70 °C for 40 min. After cooling, the vial is ultrasonicated for 15 min. An aliquot of the acetonitrile is filtered and analysed by gas chromatography/mass spectrometry (GC/MS). 

Test 2 Mandelin s Test Dissolve 0.5 g of ammonium vanadate in 1.5 mL of water and dilute to 100 mL with sulfuric acid. Filter the solution through glass wool. Add a drop of the reagent to the primaquine phosphate sample on a white tile. A orange — violet color is produced [2]. 

Gas chromatography makes use, as the stationary phase, a glass or metal column fdled either with a powdered adsorbent or a non-volatile liquid coated on a non-adsorbent powder. The mobile-phase consists of an inert-gas loaded with the vapourised mixture of solutes flowing through the stationary phase at a suitable temperature. In the course of the passage of the vapour of the sample through the column, separation of the components of the sample occurs in two ways, namely ... 

In cases where water is turbid, samples are generally filtered through glass fiber Alters (GEE) prior to percolation through sorbents. This step recovers waterborne particulates and microorganisms with average diameters >0.7 pm, which are analyzed separately. However, chemicals associated with colloid-sized particulates and DOC are not removed by GFFs. 

Carrier-gas is transferred from the column through a heated metal capillary, which minimizes the dead volume at the end of the column and prevents condensation of the column effluent prior to its entry into the scrubbing unit. The tube carrying the liquid stream is joined to the gas stream tube, at a T-junction that is joined to the mixing coil by a glass-to-metal seal. Furfural is transferred from the gas stream into the liquid stream and the colour develops the two phases are then separated by the debubbling unit and the liquid stream is re-sampled through the flow cell of the colorimeter. A Technicon peristaltic... 

The samples for gramine analyses were frozen and macerated with 20 ml of MeOH NHi,0H (100 1 v/v). The extract was filtered through glass wool. Solvent and endogenous water were evaporated to dryness. The chlorophyllous residue was dissolved in 5 ml 0.1 M HCl, and the solution filtered (Whatman N°1 paper). The aqueous filtrate was adjusted to pH 9 with concentrated NHi,0H and shaken twice with... 

Experimental Technique. The solid material (1-3 g) with known particle size and standard water (30-50 ml) containing the radionuclide of interest were shaken in glass bottles for 8-12 hours at constant temperature (25°C or 65 C). The phases were separated by centrifugation (50 min, 7000 rpm) and the distribution coefficient of the radionuclide was determined from measurements of the remaining activity of the water. Filtration of the samples through 0.2 pm membrane filter did not change the values. 

Margarine Dissolve sample in heptane containing 500 mg BHT and 200 mg a-tocopherol per L. Pass emulsion through glass column containing 10 g Na2S04 and 20 g NaCl. LiChrosorb Si-60 5 pm 250 X 4.6 mm Heptane/ diisopropyl ether, 95 5 Retinyl palmi-tate or retinyl acetate UV 325 nm 144... 

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