Nitrocellulose procedures

The two procedures primarily used for continuous nitration are the semicontinuous method developed by Bofors-Nobel Chematur of Sweden and the continuous method of Hercules Powder Co. in the United States. The latter process, which uses a multiple cascade system for nitration and a continuous wringing operation, increases safety, reduces the personnel involved, provides a substantial reduction in pollutants, and increases the uniformity of the product. The cellulose is automatically and continuously fed into the first of a series of pots at a controlled rate. It falls into the slurry of acid and nitrocellulose and is submerged immediately by a turbine-type agitator. The acid is deflvered to the pots from tanks at a rate controlled by appropriate instmmentation based on the desired acid to cellulose ratio. The slurry flows successively by gravity from the first to the last of the nitration vessels through under- and overflow weirs to ensure adequate retention time during nitration. The overflow from the last pot is fully nitrated cellulose. 

The centrifuge is a horizontal basket designed to operate so that the cake formed on the screen is pushed as an increment from the loading end of the basket to the discharge end by a pusher plate operating on a timed cycle. On completion, the nitrocellulose cake is discharged into water in a slurry tub on a lower floor, and purified by conventional procedures. 

If chloride is present, saturated aqueous silver acetate solution should be added in amounts slightly more than the calculated quantity prior t o the addition of concentrated sulphuric acid. The procedure may be applied to the routine analysis of mixtures of nitric and sulphuric acids, and to the determination of nitrogen in esters such as nitroglycerine and nitrocellulose the latter are easily hydrolysed by strong sulphuric acid after dispersal in glacial acetic acid. 

Preparation o f NitroisobutyIglycerin. Several procedures for the preparation of this compd are given in the literature. Of those tried, that described by Stettbacher [Nitrocellulose 5, 162 (1934)] gave the best results. The method of prepn follows ... 

The reagent is similar to another maleimide-containing biotinylation reagent, 3-(N-maleimi-dopropionyl) biocytin, a compound used to detect sulfhydryl-containing molecules on nitrocellulose blots after SDS-electrophoresis separation (Bayer et al., 1987). Biotin-BMCC should be useful in similar detection procedures. 

Transfer proteins onto a nitrocellulose membrane using any appropriate procedure, including dot blotting the protein solution onto the surface. 

Towbin H, StaeheHn T, Gordon J. 1979. Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets procedure and some applications. Proc Natl Acad... 

In protein microarrays, capture molecules need to be immobilized in a functional state on a solid support. In principle, the format of the assay system does not limit the choice of appropriate surface chemistry. The same immobilization procedure can be applied for both planar and bead-based systems. Proteins can be immobilized on various surfaces (Fig. 1) (12). Two-dimensional polystyrene, polylysine, aminosilane, or aldehyde, epoxy- or thiol group-coated surfaces can be used to immobilize proteins via noncovalent or covalent attachment (13,14). Three-dimensional supports like nitrocellulose or hydrogel-coated surfaces enable the immobilization of the proteins in a network structure. Larger quantities of proteins can be immobilized and kept in a functional state. Affinity binding reagents such as protein A, G, and L can be used to immobilize antibodies (15), streptavidin is used for biotinylated proteins (16), chelate for His-tagged proteins (17, 18), anti-GST antibodies for GST fusion proteins (19), and oligonucleotides for cDNA or mRNA-protein hybrids (20). 

Fig. 1. Different types of surface modification, (a) Two-dimensionai surface, e.g., poiystyrene, poiy-iysine, aminosiiane, or aidetiyde, epoxy- or thioi group-coated surface, etc. (b) Three-dimensionai surface, e.g., nitrocellulose or hydrogel-coated surface, (c) Surfaces with a special type of spacer and immobilization procedures such as PEG-epoxy, streptavidin, and N 2+ chelate, etc.

On-blot digestion is another method used for proteins blotted onto nitrocellulose or PVDF membranes. Procedure is similar to in-gel digestion with the exception of elution from the membrane surface. 

In this method sulfur is determined by carbon tetrachloride extraction of the residue remaining after the ether, water, and acid extractions of the sample. The sum of the sulfur found here and by the ether extraction procedure (Standard Method No 30) represents the total sulfur content. The sulfur removal is followed by acetone extraction for the determination of NC (Nitrocellulose)... 

Various uses of acetic acid are discussed in Refs 5 7- Its principal use in explosives industry is the manuf of cyclonite(RDX) by the Bachmann process. It can also be used for the prepn of high-nitrogen(ca 14%N) nitrocellulose. US specification JAN-A-465, covers the requirements for acetic acid used in Ordnance (see Acetic Acid, Analytical Procedures)... 

In Great Britain instead of hot poaching, the pulped nitrocellulose is subjected to repeated washing. This consists in thoroughly stirring the nitrocellulose with water, decanting the water and repeating the procedure with fresh water. 

Screen selected colonies for desired DNA fragment. In one procedure a small sample from each of the selected colonies is placed onto spots on a nitrocellulose filter. Several colonies can be placed on one filter and the bacteria lysed, hybridized with a radio-... 

Western blotting has become an important, modern technique for analysis and characterization of proteins. The procedure consists of, first, the electrophoretic transfer (blotting) of proteins from polyacrylamide gels to synthetic membranes. The transferred blots are then probed using immunological detection methods to identify proteins of specific structure and/or function. In this experiment, bovine serum will be fractionated by SDS-PAGE and the proteins blotted onto a nitrocellulose membrane. Serum glycoproteins will be identified by their specific interaction with the lectin concanavalin A. 

This is a crucial point in the procedure If too much PBS is added, the pieces of nitrocellulose will swirl around the probe and disintegration does not occur. In this case, the nitrocellulose pieces should be allowed to settle to the bottom of the tube before sonication and the excess buffer drawn off with a syringe or other suitable instrument (70-80 pL of PBS is sufficient for about 0 4 cm2 of nitrocellulose) For these quantities, one or two 10-s cycles suffice to get powdered nitrocellulose We mention the volume as a reference since the surface of nitrocellulose-bound antigen may vary In every case the volume of PBS must be adjusted. 

Proteins, blotted from polyacrylamide gels onto nitrocellulose sheets (Western blots) can be stained nonspecifically with a variety of dyes, or they can be identified individually by probing with appropriate antibodies. These procedures may be performed on duplicate blots, staining the total protein pattern on one blot and using the second blot for the immune reaction (1,2) This chapter describes how to combine both methods on one blot, i.e., staining the blot first for total protein, followed by an indirect immune reaction (3). 

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