George Lunn

Ethidium bromide: Destruction and decontamination of solutions

Ethidium bromide in water, TBE buffer, Mops buffer, and cesium chloride solution may be completely degraded by reaction with sodium nitrite and hypophosphorous acid. Only non-mutagenic reaction mixtures were produced. Destruction was greater than 99.8% in all cases; the limit of detection was 0.5 micrograms ethidium bromide per milliliter of solution. Ethidium bromide also may be removed completely from the above solutions by using Amberlite XAD-16 resin. The limit of detection was 0.05 micrograms ethidium bromide per milliliter of solution (0.27 micrograms/ml when cesium chloride solution was used).

Oxidation of 1,1-dimethylhydrazine (UDMH) in aqueous solution with air and hydrogen peroxide

The degradation of 1,1-dimethylhydrazine (UDMH), a component of some rocket fuels, was investigated using atmospheric oxygen and hydrogen peroxide. The reactions were carried out in the presence and absence of copper catalysis and at varying pH. Reactions were also carried out in the presence of hydrazine, a constituent, along with UDMH, of the rocket fuel Aerozine-50. In the presence of copper, UDMH was degraded by air passed through the solution; the efficiency of degradation increased as the pH increased but the carcinogen N-nitrosodimethylamine (NDMA) was formed at neutral and alkaline pH. Oxidation was not seen in the absence of copper. Production of NDMA occurred even at copper concentrations of < 1 ppm. Oxidation of UDMH with hydrogen peroxide also gave rise to NDMA. When copper was absent degradation of UDMH did not occur at acid pH but when copper was present some degradation occurred at all pH levels investigated. The production of NDMA occurred mostly at neutral and alkaline pH. In general, higher concentrations of hydrogen peroxide and copper favored the production of NDMA. Dimethylamine, methanol, formaldehyde dimethylhydrazone, formaldehyde hydrazone, and tetramethyltetrazene were also produced. The last three compounds were tested and found to be mutagenic.

The Safe Disposal of Diaminobenzidine

Abstract Diaminobenzidine is a mutagen and possible carcinogen which is widely used in microscopy. The disposal of unneeded bulk quantities and aged working solutions is a problem for many laboratories. A number of methods for the treatment of diaminobenzidine for safe disposal were evaluated. The methods tested were oxidation with potassium permanganate in sulfuric acid, treatment with hydrogen peroxide in the presence of horseradish peroxidase, treatment with sodium hypochlorite, and treatment with sodium nitrite and hypophosphorous acid. The methods were tested to see that the compound was completely degraded and that only nonmutagenic reaction mixtures were produced. Two methods can be recommended for general use: destruction using potassium permanganate or using hydrogen peroxide in the presence of horseradish peroxidase. These procedures can be used for diaminobenzidine in tris(hydroxymethyl) aminomethane or phosphate buffer or for bulk quantities. The diaminobenzidine is completely destroyed (less ...

Oxidative Destruction of Hydrazines Produces N-Nitrosamines and Other Mutagenic Species

As part of the joint International Agency for Research on Cancer-National Cancer Institute program for the evaluation and development of methods for the degradation of chemical carcinogens, four oxidative techniques for the degradation of hydrazines were investigated. The oxidizing agents used were as follows: sodium hypochlorite, calcium hypochlorite, potassium iodate, and potassium permanganate in sulfuric acid. In each case, at least 99% of the hydrazine initially present was destroyed; however, the potential usefulness of these methods was compromised by the formation (in some reaction mixtures) of carcinogenic N-nitroso compounds and/or unknown mutagenic species. Oxidative degradation of hydrazines is recommended only for the decontamination of glassware and for the treatment of spills, for which reductive degradation methods are not suitable.

Decontamination of Aqueous Solutions of Biological Stains

Aqueous solutions of a number of biological stains were completely decontaminated to the limit of detection using Amberlite resins. Amberlite XAD-16 was the most generally applicable resin but Amberlite XAD-2, Amberlite XAD-4, and Amberlite XAD-7 could be used to decontaminate some solutions. Solutions of acridine orange, alcian blue 8GX, alizarin red S, azure A, azure B, Congo red, cresyl violet acetate, crystal violet, eosin B, erythrosin B, ethidium bromide, Janus green B, methylene blue, neutral red, nigrosin, orcein, propidium iodide, rose Bengal, safranine O, toluidine blue O, and trypan blue could be completely decontaminated to the limit of detection and solutions of eosin Y and Giemsa stain were decontaminated to very low levels (less than 0.02 ppm) using Amberlite XAD-16. Reaction times varied from 10 min to 18 hr. Up to 500 ml of a 100 micrograms/ml solution could be decontaminated per gram of Amberlite XAD-16. Fourteen of the 23 stains tested were found to be mutagenic to Salmonella typhimurium. None of the completely decontaminated solutions were found to be mutagenic.

Destruction of cyanogen bromide and inorganic cyanides.

Cyanogen bromide in water and seven organic solvents and sodium cyanide in water may safely and efficiently (greater than 99.7%) be destroyed using sodium hydroxide (1 M) solution and commercially available sodium or calcium hypochlorite. Details are given of an analytical procedure which can be used to check the final reaction mixture for the presence of residual cyanogen bromide or cyanide.

VALIDATED METHODS FOR DEGRADING HAZARDOUS CHEMICALS: SOME HALOGENATED COMPOUNDS

Two techniques were investigated for degrading a number of halogenated compounds of commercial and research importance. Reductive dehalogenation with nickel-aluminum alloy in potassium hydroxide solution was used to degrade iodomethane, chloroacetic acid, trichloroacetic acid, 2-chloroethanol, 2-bromoethanol, 2-chloroethylamine, 2-bromoethylamine, 1-bromobutane, 1-iodobutane, 2-bromobutane, 2-iodobutane, 2-bromo-2-methylpropane, 2-iodo-2-methylpropane, 3-chloropyridine, fluorobenzene, chlorobenzene, bromobenzene, iodobenzene, 4-fluoroaniline, 2-chloroaniline, 3-chloroaniline, 4-chloroaniline, 4-fluoronitrobenzene, 2-chloronitrobenzene, 3-chloronitrobenzene, 4-chloronitrobenzene, benzyl chloride, benzyl bromide, alpha,alpha-dichlorotoluene, and 3-aminobenzotrifluoride. The products were generally those obtained by replacing the halogen with hydrogen although concomitant reduction of the other groups was also observed. Bibenzyl was produced during the reduction of benzyl chloride, benzyl bromide, and alpha,alpha-dichlorotoluene. Refluxing with ethanolic potassium hydroxide was used to degrade iodomethane, chloroacetic acid, 2-fluoroethanol, 2-chloroethanol, 2-bromoethanol, 1-chlorobutane, 1-bromobutane, 1-iodobutane, 2-bromobutane, 2-iodobutane, 2-bromo-2-methylpropane, 2-iodo-2-methylpropane, benzyl chloride, benzyl bromide, 1-bromononane, 1-chlorodecane, and 1-bromodecane. The products were the corresponding ethyl ethers. 2-Methylaziridine was cleaved with nickel-aluminum alloy in potassium hydroxide solution to a mixture of isopropylamine and n-propylamine. In all cases, the compounds were completely degraded and only nonmutagenic reaction mixtures were produced.

Removal of Biological Stains from Aqueous Solution Using A Flow-Through Decontamination Procedure

Chromatography columns filled with Amberlite XAD-16 were used to decontaminate, using a continuous flow-through procedure, aqueous solutions of the following biological stains: acridine orange, alcian blue 8GX, alizarin red S, azure A, azure B, brilliant blue G, brilliant blue R, Congo red, cresyl violet acetate, crystal violet, eosin B, eosin Y, erythrosin B, ethidium bromide, Giemsa stain, Janus green B, methylene blue, neutral red, nigrosin, orcein, propidium iodide, rose Bengal, safranine O, toluidine blue O, and trypan blue. Adsorption was most efficient for stains of lower molecular weight (< 600). Adsorption of stain increased as the flow rate decreased; column diameter had little effect on adsorption. Adsorption of stain was greatest when finely ground resin was used, but if the resin particles were too small, column clogging occurred. Limited grinding of the resin gave increased adsorption while retaining good flow characteristics. Amberlite XAD-16 saturated with methylene blue was regenerated to its initial adsorption capacity by passing methanol through the column. The technique described provides an economical, rapid means of removing stains from aqueous solution.

Validation of Techniques for the Destruction of Dimethyl Sulfate

It has been reported that dimethyl sulfate (DMS) can be degraded with sodium hydroxide solution (1 mol/L), sodium carbonate solution (1 mol/L), or ammonium hydroxide solution (1.5 mol/L). This has now been confirmed. Complete destruction of undiluted DMS or DMS in solvents miscible with water (methanol, ethanol, DMSO, DMF, acetone) or solvents partially miscible or immiscible with water (toluene, p-xylene, benzene, 1-pentanol, ethyl acetate, chloroform, carbon tetrachloride, acetonitrile) could be obtained using any of the above methods. Reaction times were 15 min after homogeneity was obtained for undiluted DMS, 15 min for solutions in methanol, ethanol, DMSO, and DMF, one hour for solutions in acetone, three hours for acetonitrile, and one day for the other solvents listed above. The final reaction mixtures were tested for mutagenicity, and when the solutions were not cytotoxic, no mutagenic response was obtained. DMS in solution was determined by a colorimetric method. The products of the reactions were found to be methanol when NaOH and Na2CO3 were used and methylamine, dimethylamine, trimethylamine, and methanol when ammonium hydroxide was used. The stability of DMS in various solvents was also determined.

Safe disposal of diisopropyl fluorophosphate (DFP)

Diisopropyl fluorophosphate (DFP), a volatile highly toxic enzyme inhibitor, in buffer (pH 3, pH 5, pH 7, pH 9, pH 11, Hank’s, Dulbecco’s, PBS, TBE, and HEPES) or water (10 mM), in DMF solution (200 mM), and bulk quantities can be degraded by adding 1M NaOH. The DFP was completely degraded, as determined by enzymatic assay, and the final reaction mixtures were not mutagenic.