Qualitative filter papers

The recipe for the soak solution was obtained from the Journal of Chemical Education s December 1991 issue. You should weigh 10 g of CoCl2 6H20 and dissolve it in 25 mL of water. The material for the wall hanging is Whatman 2 qualitative filter paper. 

Initially, 1.60 g [C(NH2)3] 2 [Pt(CN)4] rxr O is dissolved in 5 mL concentrated HF (28.9 M) in a 50-mL polyethylene beaker. The solution is transferred to an electrolysis cell which is constructed from a polyethylene beaker with two holes drilled 2 cm beneath the top of the solution. Two platinum wires 25 mm long are cemented in the two holes with epoxy cement and separated by 5 mm to form the electrodes. A constant potential is applied to the electrodes using a 1.5-V dc source.10 Crystal growth is observed anytime between 1 and 5 days. One week after initial crystal formation, the crystals are suction filtered through a plastic funnel using Whatman qualitative filter paper. The material is then washed with two 5-mL portions of cold water and allowed to air dry. The yield is 1.46 g (80%) based on [C(NH2)3] 2 [Pt(CN)4] xH20 being anhydrous. 

Catalyst recovery The above catalyst cake was removed from the fluted filter paper with a stream of deionized water (ca. 200 mL). The slurry was filtered on a Buchner funnel (Whatman 1, qualitative filter paper) and washed with water (50 mL) and acetone (25 mL) and initially dried hy suction then by standing in air. 

Table 8.2 compares some commonly available qualitative filter paper types and ranks them according to porosity, retentivity, and speed. Eaton-Dikeman (E D),... 

Table 8.2 Some common qualitative filter paper types and approximate relative speeds and retentivities ...

Qualitative filter papers are available for qualitative analyses and general use quantitative papers are for use in analytical work that is carried out to quantify the composition of materials, where the purity of composition of the filter paper can be crucial. Qualitative cellulose papers are available with or without binders with particle retention capabilities from <3 pm to about 30 pm. Quantitative papers are generally binder free and offer a similar range of particle retentions. 

Procedure. Three drops of sulfuric acid and one drop of the test solution are placed in a micro crucible. The crucible is closed with a piece of qualitative filter paper, sufficiently greater in diameter than the crucible so that the area exposed to hydrogen fluoride can be compared easily with the unexposed portion of the paper. The charged crucible is kept at 60-60° C for five minutes. The paper is then spotted with a chloroform solution of oxine and examined in ultraviolet light. If the sample contained fluoride, the exposed area shows no or only a faint fluorescence compared with the surrounding portions of the paper. 

This reaction will reveal magnesium in tap water (drop). The magnesium in the ash of qualitative filter paper, after treatment with dilute acid, also responds positively. 

In the examination of paper ash, a strip (about 2x3 mm) of the specimen is ashed on a crucible lid until the residue has become as near white as possible. The ash is treated with a drop of the reagent solution, and it turns gray or black at once, or in a few minutes, according to the amount of alkali present. The ash of cigarette paper, newspaper, writing paper, and qualitative filter paper turns black immediately owing to the high alkali content, but the ash of quantitative paper shows almost no reaction. 

The response to the Nessler reaction of quantitative and qualitative filter papers of various porosities and makes is shown in the following ... 

Calcium, magnesium and aluminum compounds can be detected in qualitative filter papers by exposing the samples to oxine vapors fluorescent oxine compounds or complexes are formed. This test can be made at room temperatures if a piece of the paper is suspended over a crucible containing solid oxine. After a few minutes, a weak yellow-green fluorescence can be seen under an ultraviolet lamp and its intensity increases with longer exposure. If the vessel containing the oxine is warmed, the oxine (m.p. 79° C) volatilizes more rapidly and the fluorescence appears more quickly. The action of the oxine vapors cannot be satisfactorily explained by assuming that there is a transformation of the mineral constituents into the respective oxinates. A more probable explanation is that the oxine is chemically adsorbed (lake-formation ) and that this product exhibits the same fluorescence phenomena as those shown by the real inner complex metal oxinates. ... 

If the top supernatant layer is not clear, it should be filtered through qualitative filter paper... 

The crude derivative is collected on qualitative filter paper cut to fit a micro (1 cm) Buchner funnel and washed with 2-3 ml of ice water. The compound is then transferred to a 30 ml beaker, dissolved in 10-12 ml of water by heating to incipient boiling, and the solution is decolorized with 30-35 mg of activated charcoal. The suspension is stirred briefly then filtered as before to remove the charcoal. The filtrate is transferred to a 30 ml beaker, which is placed in an ice bath and the solution is stirred... 

The marihuana suspension was extracted twice with a mixture of CHC1 H20 (10 1, v/v) and blended for four minutes. A total voltune of 125 ml CHCl plus 12.5 ml H O of extraction solvent was necessary to extract 25 g of plant material. The extract ion-solvent volume was adjusted according to the quantity of plant material in each individual sample. The combined-sample supernatants were decanted through coarse, qualitative filter paper (VHiatman No. 4, 18.5 cm), and dried over... 

Fuel Pre-treatment— Filtration through a single layer of general purpose, retentive, qualitative filter paper followed by a 6-min aeration at 1.5 L/min air flow rate for a maximum of 600 mL sample using sparge stone of porosity C (see Test Method E 128). 

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