Green filter

Tables 4 and 5 show properties of ground mica products. For all forms of ground mica the index of refraction is 1.58 wt %, Mohs hardness is 2.5, oil absorption (Brit. Stand. 3483) is 60.75%, water solubihty (Brit. Stand. 1765) is <0.3%, the phericity factor is 0.01, and the softening point in °C is 1538. For Microni2ed and wet ground micas the brightness (green filter), pH, and apparent density in kg/m are 75, 5.2, and 160—224, respectively for dry ground mica, 66—75, 6.2, and 192—561, respectively (1).

Procedure. Transfer the almost neutral sample solution of beryllium (containing 5 to 80jug of the element in a volume of about lOmL) to a 25 mL graduated flask, add 2.8 mL of 2.0M sodium hydroxide (or more if much aluminium is present), 5.0 mL of 0.64M boric acid solution, and 6.0 mL of the dye solution (see Note), dilute to the mark with distilled water, and mix well. Measure the transmittance at 520 nm, or with a green filter preferably using a 2 cm cell. 

Procedure. Prepare a 0.25 per cent solution of diphenylcarbazide in 50 per cent acetone as required. The test solution may contain from 0.2 to 0.5 part per million of chromate. To about 15 mL of this solution add sufficient 3M sulphuric acid to make the concentration about 0.1M when subsequently diluted to 25 mL, add 1 mL of the diphenylcarbazide reagent and make up to 25 mL with water. Match the colour produced against standards prepared from 0.0002M potassium dichromate solution. A green filter having the transmission maximum at about 540 nm may be used. 

Procedure. Dissolve a weighed portion of the substance in which the amount of iron is to be determined in a suitable acid, and evaporate nearly to dryness to expel excess of acid. Dilute slightly with water, oxidise the iron to the iron(III) state with dilute potassium permanganate solution or with a little bromine water, and make up the liquid to 500 mL or other suitable volume. Take 40 mL of this solution and place in a 50 mL graduated flask, add 5 mL of the thiocyanate solution and 3 mL of AM nitric acid. Add de-ionised water to dilute to the mark. Prepare a blank using the same quantities of reagents. Measure the absorbance of the sample solution in a spectrophotometer at 480 nm (blue-green filter). Determine the concentration of this solution by comparison with values on a reference curve obtained in the same way from different concentrations of the standard iron solution. 

Procedure. Place 10.0 mL of the working lead solution in a 250 mL separatory funnel, add 75 mL of the ammonia-cyanide-sulphite solution and then by the cautious addition of dilute hydrochloric acid adjust the pH of the solution to 9.5 (pH-meter). This operation must be carried out slowly if the pH of the solution falls even temporarily below 9.5, HCN may be liberated and so use of a fume cupboard is necessary. Now add 7.5 mL of the dithizone reagent to the separatory funnel, followed by a further 17.5 mL of chloroform. Shake for 1 minute, allow the layers to separate, then remove the chloroform layer. Measure the absorbance of this against a blank solution, using a 1 cm cell and a wavelength of 510 nm (green filter). 

Procedure. Transfer the neutral sample solution (<100 gMg), free from calcium and other metals, to a 100 mL graduated flask with calibrated neck. Add 25 mL of the buffer solution, dilute to just below the 90 mL graduation mark, and shake. Add 10.0 mL of the solochrome black solution carefully. Shake to mix and dilute to the 100 mL mark with water. Measure the absorbance immediately at 520 nm (green filter) against that of a blank solution, similarly prepared but containing no magnesium. 

To 10.0 mL of the solution thus prepared add 0.5 mL of dilute hydrochloric acid (1 1) and proceed as above. Measure the absorbance at 545 nm, or use a green filter with an absorptiometer. 

A calibration curve for the range 0.2-10 mg fluoride ion per 100 mL is constructed as follows. Add the appropriate amount of standard sodium fluoride solution, 25 mL of 2-methoxyethanol, and 10 mg of a buffer [0.1 Af in both sodium acetate and acetic (ethanoic) acid] to a 100 mL graduated flask. Dilute to volume with distilled water and add about 0.05 g of thorium chloranilate. Shake the flask intermittently for 30 minutes (the reaction in the presence of 2-methoxyethanol is about 90 per cent complete after 30 minutes and almost complete after 1 hour) and filter about 10 mL of the solution through a dry Whatman No. 42 filter paper. Measure the absorbance of the filtrate in a 1 cm cell at 540 nm (yellow-green filter) against a blank, prepared in the same manner, using a suitable spectrophotometer. Prepare a calibration curve for the concentration range 0.0-0.2 mg fluoride ion per 100 mL in the same way, but add only 10.0 mL of 2-methoxyethanol measure the absorbance of the filtrate in a 1 cm silica cell at 330 nm. 

Procedure. To 100 mL of the neutral sample solution (containing not more than 0.4 mg nitrite) add 2.0 mL of solution A and, after 5 minutes, 2.0 mL of solution B. The pH at this point should be about 1.5. Measure the absorbance after 10 minutes in the wavelength region of 550 nm (yellow-green filter), in a spectrophotometer against a blank solution prepared in the same manner. Calculate the concentration of the nitrite from a calibration plot prepared from a series of standard nitrite solutions. 

Procedure. Dissolve 0.1 g of the sample in 10 mL purified methanol and transfer 1.0 mL of this solution to a stoppered test-tube. Add 1.0 mL of solution A and one drop of concentrated hydrochloric acid, then place the stoppered tube in a beaker of boiling water for 5 minutes. Cool, and then add 5.0 mL of the potassium hydroxide solution. Measure the absorbance of the solution at 480 nm (blue-green filter) against a blank obtained by subjecting 1.0mL of purified methanol to the above procedure. 

Photoelectric-Colorimetric Method. Although the recording spectrophotometer is, for food work at least, a research tool, another instrument, the Hunter multipurpose reflectometer (4), is available and may prove to be applicable to industrial quality control. (The newer Hunter color and color difference meter which eliminates considerable calculation will probably be even more directly applicable. Another make of reflection meter has recently been made available commercially that uses filters similar to those developed by Hunter and can be used to obtain a similar type of data.) This instrument is not a spectrophotometer, for it does not primarily measure the variation of any property of samples with respect to wave length, but certain colorimetric indexes are calculated from separate readings with amber, blue, and green filters, designated A, B, and G, respectively. The most useful indexes in food color work obtainable with this type of instrument have been G, which gives a... 

Apart from the delta filter discussed here, one can define other filters using the same Chebyshev operators. In fact, any analytic function of the Hamiltonian can be expressed as an expansion in terms of the Chebyshev operator.148 For instance, the Green filter can be expressed as follows 126,127 149... 

Indeed, the Green filter and the delta filter operator are related ... 

The filtering, namely the construction of energy local bases, can also be carried out using the Lanczos recursion or similar recursive methods. However, filtered vectors at E/ can only be obtained using the Green filter ... 

Figure 1. Analytical isoelectric focusing of cellulases from Trichodtrma ree-sei. Detection of CBH I and EG I activities using MeUmbLac, in the absence (A) and presence (B) of 10 mM cellobiose. Lane 1, EG I lane 2, EG I (iso-components) lane 3, CBH I (pi 3.9 component) lane 4, EG I-CBH I mixture). Gels were flooded with the fluorogenic substrate (pH 5.0) and after 5-10 min (room temperature) photographed (Polaroid 57, green filter) on a long wavelength UV-transilluminator (8).

Prior to and between washes, the green filter cake cracks and should be pushed down" with a spatula to form a uniform surface prior to any subsequent washes. 

Fig. 1.12. Assembly of a filter cannula or Green filter. (a) A piece of glass capillary tubing, which has been blown open and fire-polished to form a lip on one end, is attached to the cannula with epoxy cement, (b) Filter paper is folded over the glass capillary and secured with wire.

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