Domestic Bleach Research Articles

Household bleach products as high-performance and cost-effective cleaning agents for membrane fouling

It has been widely known that polymeric membrane such as polyvinylidene fluoride (PVDF) is very prone to fouling that occurs during the filtration process. In the same light, membrane cleaning has also been popularly used as a mean to remove foulants which accumulated on or inside the membrane. In this paper, the utilization of domestic bleach, which is affordable and easily found in the nearest markets, as the membrane cleaning agent is discussed. The performance evaluation is conducted on three kinds of commercial domestic bleaches, namely Bayclin, Proclin, and Soclin. In order to study deeper about those product potentials, the performance is compared with the pure sodium hypochloride (NaOCl) which has been known as a common chemical cleaning agent, and distillate water. The results show that the bleach products work excellence in cleaning the fouled membrane which confirmed by the scanning electron microscopy (SEM) analysis results, in which membranes cleaned with the bleaches have cleaner surface compared to that cleaned with distillate water. Interestingly, the positive outcome can also be seen in the flux recovery ratio (FRR) of the membranes after cleaning which managed to recover up to 95% of the lost flux. Overall, all three bleach products showed closely similar performance as the original NaOCl, and showed far better performance than distillate water. This result emphasizes that the domestic bleaches are highly promising to be membrane chemical cleaning agents, replacing the common chemicals. This work makes a significant contribution toward giving reasonably priced options for alternative methods of cleaning membranes.

Colorimetric and fluorescence analysis of percarbonate and oxygen bleach by perhydrolysis of resorufin ester

Percarbonate is an important oxidant that is widely used in industrial applications and daily life. In this study, a simple colorimetric and fluorescence method for percarbonate determination using resorufin-based probe 1, carrying a pivaloyl protection group as a signaling switch, was developed. Probe 1 exhibited selective and sensitive signaling behavior for percarbonate via perhydrolysis of the pivaloyl group by hydrogen peroxide that was produced from percarbonate, in the presence of commonly encountered metal ions and anions. Among the esters tested as signaling switches, pivalate was optimal owing to its resistance to spontaneous hydrolysis and high signaling speed under the employed conditions. The detection limit for percarbonate was estimated to be 0.45 μM. The probe was applied to the analysis of percarbonate in domestic bleach using a scanner as a field-oriented signal-capturing device.

Synthesis of Highly Crystalline Graphite from Spontaneous Ignition of In Situ Derived Acetylene and Chlorine at Ambient Conditions.

We exploited a classic chemistry demonstration experiment based on the reaction of acetylene with chlorine to obtain highly crystalline graphite at ambient conditions. Acetylene and chlorine were generated in-situ by the addition of calcium carbide (CaC2) in a concentrated HCl solution, followed by the quick addition of domestic bleach (NaClO). The released gases reacted spontaneously, giving bursts of yellow flame, leaving highly crystalline graphite deposits in the aqueous phase. This was a rather benign alternative towards synthetic graphite, the latter usually being prepared at high temperatures. The synthetic graphite was further utilized to obtain graphene or conductive inks.

First Report of Stem Spots of Ephedra intermedia Caused by Neodidymelliopsis longicolla

Ephedra intermedia Schrenk (Gnetaceae, Gymnospermae) is a traditional Chinese medicinal plant used to treat asthma and cough and as a diaphoretic (Committee of China Pharmacopoeia 2005). It grows in rocky or sandy dry areas. Gansu Province is a main production area. Wild E. intermedia plants occupy ∼600 ha in Yumen City (continental temperate arid climate, ∼1,400 to 1,700 m altitude). However, wild Ephedra has been excessively harvested. Since 1990, ∼100 ha of cultivated Ephedra has been planted in Yumen City. Cultivation of Ephedra is controlled by the government of China, and its cultivation has not changed much since our 2007 disease survey. Stem spots were first found on wild E. intermedia in Huanghua Hacienda in Donghu Village, Yumen City. Early lesions on the stems were small, circular, pale brown spots; they became elliptical, fusiform lesions and finally faded to grayish brown in the center, with numerous black pycnidia distributed on each stem spot. Our surveys in 2007, 2012, and 2016 revealed disease incidence of 40 to 60%. When the disease was serious, lesions became connected, 5 to 10% of stem tissues were damaged, and the plants were stunted. Conidiomata on the stem lesions were pycnidial, immersed or semi-immersed, light brown to olive brown, 192.6 to 327.6 × 179.2 to 277.7 μm. Ostioles papillate or developing into elongated neck, 20 to 35 μm wide and 20 to 100 μm tall. Conidia were hyaline, smooth, cylindrical to clavate, straight to slightly curved, mainly one-septate, slightly constricted at the septa, 10.6 to 16.5 × 5.9 to 8.2 (avg. 13.9 × 6.3) μm, and occasionally aseptate and 7.5 to 15 × 1.25 to 6.25 (avg. 9.95 × 3.42) μm. Symptomatic stems were surface sterilized in 1% NaOCl (diluted domestic bleach) for 1 min and rinsed three times in sterilized distilled water, and the tissues from the lesion periphery were plated onto PDA to obtain pure cultures (the causal agent was designated AM2H). The isolation frequency of AM2H was 100%. Colonies on PDA were white at first and then turned vinaceous with black confluent pycnidia in ∼2 weeks. Conidial dimensions were within the range of those from the field samples. Representative samples were deposited in the Herbarium of Gansu University of Chinese Medicine. Pathogenicity tests were performed by spraying ten 6-month-old Ephedra plants with suspension of conidia harvested from 14-day-old colonies of AM2H growing on PDA; another ten plants sprayed with water served as controls. All plants were placed in a growth chamber and covered with a polyethylene bag for 48 h to maintain >95% humidity. Five days after inoculation, red-brown spots were observed on inoculated stems, but no symptoms appeared on control plants. After another 2 weeks similar spot symptoms on the inoculated plants were observed, and Koch’s postulates were verified by reisolating AM2H from stems with typical spots. DNA of AM2H was extracted, and ITS, LSU, BTUB, and RPB2 regions were sequenced with primers ITS1/ITS4, LROR/LR5, fRPB2-5F/fRPB2-7Cr, and T1/β-Sandy-R, respectively (Verkley et al. 2013); segments (535, 912, 1,102, and 401 bp) were submitted to GenBank (KF263920, MF476109, KM074044, and MF476108, respectively). The phylogenetic tree was constructed with Mega 6.0 using the neighbor-joining method from the combined multilocus database. Strain AM2H clusters with all accepted species in Neodidymelliopsis and forms a single clade with the maximum support rate (100%) with sequences of Neodidymelliopsis longicolla (CBS 382.96); Chen et al. (2017) proposed it as a new species that can cause lesion blight on Papaver dubium in Iran (Razaghi and Zafari 2018). Morphologically, the conidia size of AM2H (10.6 to 16.5 × 5.9 to 8.2 μm) is almost the same as N. longicolla (CBS 382.96) (12 to 15 to 16.5 × 4 to 7 μm). This is the first report of stem spots on Ephedra caused by N. longicolla in the world. Identification of the pathogen will help to work out methods to control the disease.

Fragrances and Aerosol during Office Cleaning

Fragrance compounds emitted during and after the use of cleaning products in an office were monitored. Mopping the floor with a general purpose cleaner and a domestic bleach and cleaning the windows with an aerosol glass cleaner, as well as a combination of these cleaning activities, were carried out. The following compounds were found in detectable amounts: d-limonene, α-pinene, α-terpineol, 2-butoxyethanol, 1,3,5-trimethylbenzene, eucalyptol, tetrahydrolinalool and diphenyl ether. Along with the fragrances, the number concentrations of airborne particles with an aerodynamic diameter range between 0.2 μm and 10 μm were monitored continuously. Cleaning affected the number concentrations of all particle sizes, but particles with an aerodynamic diameter above 0.4 μm were the most affected. The largest increase above background concentrations was observed during mopping the floor with a solution of general purpose cleaner in combination with cleaning the windows with a glass-cleaning spray. In this case, for particles larger than 0.4 μm, indoor number concentrations were 19 times larger than the background concentrations. Conversely, for particles below 0.4 μm, number concentrations increased only 4 times above the background concentrations during the same event. Auxiliary measurements included carbon dioxide (CO_2) concentrations and the indoor micro-climatic conditions (air velocity, light intensity, temperature and relative humidity).

Immuno-gold replica technique for ultrastructural localization of antigens

We developed a simple method for immunolabelling viral glycoproteins on surface of infected ceil monolayers. Cells 9 hours post-infected with Sendai virus were fixed and treated with polyclonal antibody anti HN glycoprotein (Rabbit IgG), labelled with goat immunoglobulin anti rabbit IgG conjugated with colloidal gold particles. Then, the cells were shadowed with platinum-carbon, covered with nitrocellulose glue, and digested with domestic bleach, washed, and replica fragments were caught with uncovered grid.

ChemInform Abstract: One‐Pot Hydrogen Peroxide and Hydrohalic Acid Induced Ring Closure and Selective Aromatic Halogenation to Give New Ring‐Fused Benzimidazoles.

A new series of selectively dichlorinated and dibrominated five- to eight-membered-ring [1,2-a]-fused benzimidazoles and [1,4]oxazino[4,3-a]benzimidazoles are synthesized in mostly high yields of >80% using the reaction of hydrogen peroxide and hydrohalic acid with commercially available o-cyclic amine substituted anilines. Domestic bleach with HCl can also be used for a one-pot ring closure and chlorination.

One-pot hydrogen peroxide and hydrohalic acid induced ring closure and selective aromatic halogenation to give new ring-fused benzimidazoles.

A new series of selectively dichlorinated and dibrominated five- to eight-membered-ring [1,2-a]-fused benzimidazoles and [1,4]oxazino[4,3-a]benzimidazoles are synthesized in mostly high yields of >80% using the reaction of hydrogen peroxide and hydrohalic acid with commercially available o-cyclic amine substituted anilines. Domestic bleach with HCl can also be used for a one-pot ring closure and chlorination.

Operational Use of Household Bleach to “Crash and Release” <I>Aedes aegypti</I> Prior to <I>Wolbachia</I>-Infected Mosquito Release

Dengue (family Flaviviridae, genus Flavivirus, DENV) remains the leading arboviral cause of mortality in the tropics. Wolbachia pipientis has been shown to interrupt DENV transmission and is presently being trialled as a biological control. However, deployment issues have arisen on methods to temporarily suppress wild mosquito populations before Wolbachia-infected mosquito releases. By suppressing wild populations, fewer Ae. aegypti releases are required to achieve a sustainable Wolbachia density threshold. Furthermore, public distress is reduced. This study tests the application of domestic bleach (4% NaCIO) to temporarily "crash" immature Aedes populations in water-filled containers. Spray application NaClO (215 ppm) resulted in a mean 48-h mortality of 100, 100, 97, and 88% of eggs, second-instar larvae, fourth-instar larvae, and pupae, respectively. In the field, NaClO delayed ovipositing by 9 d in cooler months, and 11 d in hotter months, after which oviposition resumed in treated receptacles. We found bleach treatment of pot-plant bases did not cause wilting, yellowing, or dropping of leaves in two ornamental plants species. Domestically available NaClO could be adopted for a "crash and release" strategy to temporarily suppress wild populations of Ae. aegypti in containers before release of Wolbachia-infected mosquitoes. The "crash and release" strategy is also applicable to other mosquito species, e.g., Aedes albopictus (Skuse), in strategies using released mosquitoes.

Influence of Ethylenediaminetetraacetic Acid on the Active Chlorine Content of Sodium Hypochlorite Solutions When Mixed in Various Proportions

Introduction This study documented the time-related effect on active chlorine content of NaOCl solutions of different concentrations after dilution with ethylenediaminetetraacetic acid (EDTA) in various proportions. Methods Five NaOCl solutions (Milton, Black and Gold domestic bleach, and the surfactant containing products, White King and Hypochlor 1% and 4% forte) were mixed with EDTA in the following proportions: 90:10, 75:25, and 50:50. Changes in active chlorine content were determined at intervals between 5 and 18 minutes. Results Results were analyzed statistically by using general linear statistical models in SPSS. With the exception of White King solutions, EDTA substantially and rapidly reduced available chlorine even in small proportions, with loss being extreme at first and then more gradual. The reaction was exothermic. Results showed that White King mixed 90:10 lost on average only 8% of its active chlorine at its first measurement (approximately 5 minutes) but lost 36% of its active chlorine when mixed 75:25. The Hypochlor products at 90:10 dilution lost on average 27%–31% active chlorine during this time period. Mixing EDTA with NaOCl caused a dramatic loss of active chlorine for all solutions mixed 50:50. NaOCl solutions containing surfactant had less active chlorine loss for the 75:25 and 90:10 admixtures. Conclusions NaOCl and EDTA should not be present in the root canal at the same time if the therapeutic benefits of NaOCl are to be realized, but the order in which they should be used for endodontic irrigation remains a matter of debate.

Use of a Mixture of Surrogates for Infectious Bioagents in a Standard Approach to Assessing Disinfection of Environmental Surfaces

We used a mixture of surrogates (Acinetobacter baumannii, Mycobacterium terrae, hepatitis A virus, and spores of Geobacillus stearothermophilus) for bioagents in a standardized approach to test environmental surface disinfectants. Each carrier containing 10 microl of mixture received 50 microl of a test chemical or saline at 22 +/- 2 degrees C. Disinfectant efficacy criteria were > or = 6 log(10) reduction for the bacteria and the spores and > or = 3 log(10) reduction for the virus. Peracetic acid (1,000 ppm) was effective in 5 min against the two bacteria and the spores but not against the virus. Chlorine dioxide (CD; 500 and 1,000 ppm) and domestic bleach (DB; 2,500, 3,500, and 5,000 ppm) were effective in 5 min, except for sporicidal activity, which needed 20 min of contact with either 1,000 ppm of CD or the two higher concentrations of DB.

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Dissolution of porcine incisor pulps in sodium hypochlorite solutions of varying compositions and concentrations

The solubility of dental pulp tissue in sodium hypochlorite has been extensively investigated but results have been inconsistent; due most likely to variations in experimental design, the volume and/or rate of replenishment of the solutions used and the nature of the tissues assessed. Traditionally, the sodium hypochlorite solutions used for endodontic irrigation in Australia have been either Milton or commercial bleach, with Milton being the most common. Recently, a range of Therapeutic Goods Administration (TGA) approved proprietary sodium hypochlorite solutions, which contain surfactant, has become available. Some domestic chlorine bleaches now also contain surfactants. The purpose of this study was to perform new solubility assessments, comparing Milton with new TGA approved products, Hypochlor 1% and Hypochlor 4% forte, and with a domestic bleach containing surfactant (White King). Ten randomly assigned pulp samples of porcine dental pulp of approximately equal dimensions were immersed in the above solutions, as well as representative concentrations of sodium hydroxide. Time to complete dissolution was measured and assessed statistically. White King 4% showed the shortest dissolution time, closely followed by Hypochlor 4% forte. White King 1% and Hypochlor 1% each took around three times as long to completely dissolve the samples of pulp as their respective 4% concentrations, while Milton took nearly 10 times as long. The sodium hydroxide solutions showed no noticeable dissolution of the pulp samples. The composition and content of sodium hypochlorite solutions had a profound effect on the ability of these solutions to dissolve pulp tissue in vitro. Greater concentrations provided more rapid dissolution of tissue. One per cent solutions with added surfactant and which contained higher concentrations of sodium hydroxide were significantly more effective in dissolution of pulp tissue than Milton.

Activity of selected oxidizing microbicides against the spores of Clostridium difficile: Relevance to environmental control

Clostridium difficile is an increasingly common nosocomial pathogen, and its spores are resistant to common environmental surface disinfectants. Many high-level disinfectants (eg, aldehydes) are unsuitable for environmental decontamination because they need several hours of contact to be sporicidal. This study tested the potential of selected oxidative microbicides to inactivate C. difficile spores on hard surfaces in relatively short contact times at room temperature. The spores of a clinical isolate of C. difficile were tested using disks (1 cm diameter) of brushed stainless steel in a quantitative carrier test. The spores of C. sporogenes and Bacillus subtilis, common surrogates for evaluating sporicides, were included for comparison. The clostridia were grown separately in Columbia broth (CB), and B. subtilis was grown in a 1:10 dilution of CB. Each disk received 10 microL test spores with an added soil load, and the inoculum was dried. One disk each was placed in a glass vial and overlaid with 50 microL test formulation; controls received an equivalent volume of normal saline with 0.1% Tween 80. At the end of the contact time the microbicide was neutralized, the inoculum recovered from the disks by vortexing, the eluates were membrane filtered, and the filters placed on plates of recovery medium. The colony-forming units (CFU) on the plates were recorded after 5 days of incubation. The performance criterion was > or = 6 log(10) (> or = 99.9999%) reduction in the viability titer of the spores. The microbicides tested were domestic bleach with free-chlorine (FC) levels of 1000, 3000, and 5000 mg/L; an accelerated hydrogen peroxide (AHP)-based product with 70,000 mg/L H2O2 (Virox STF); chlorine dioxide (600 mg/L FC); and acidified domestic bleach (5000 mg/L FC). Acidified bleach and the highest concentration of regular bleach tested could inactivate all the spores in < or = 10 minutes; Virox STF could do the same in < or = 13 minutes. Regular bleach with 3000 mg/L FC required up to 20 minutes to reduce the viability of the all the spores tested to undetectable levels; chlorine dioxide and the lowest concentration of regular bleach tested needed approximately 30 minutes for the same level of activity. Acidified bleach, Virox STF, and regular bleach (3000-5000 mg/L FC) could inactivate C. difficile spores on hard environmental surfaces in approximately 10 to 15 minutes under ambient conditions. All of these products are strong oxidizers and should be handled with care for protection of staff, but acidified and regular bleach with high levels of FC also release chlorine gas, which can be hazardous if inhaled by staff or patients.

The shelf-life of sodium hypochlorite irrigating solutions.

Sodium hypochlorite (bleach) solutions are widely used as irrigants in endodontics. Their tendency to deteriorate is worsened by environmental influences which could cause loss of available chlorine content. This study measured the loss of available chlorine concentration in a range of sodium hypochlorite solutions under conditions which mimic clinical usage and storage. Domestic bleach, both undiluted and diluted with demineralised water or hard water, was tested, along with Milton, for initial concentration of available chlorine, and then retested after varying periods and modes of storage to measure loss of chlorine concentration. The types of storage were: (1) in closed plastic bottles which were opened daily and agitated; (2) in open plastic bottles; (3) in syringes exposed to sunlight; (4) in syringes kept in the dark; (5) in open stainless steel bowls; (6) in closed stainless steel bowls; and (7) when heated to 50 degrees C. Not all solutions were tested under all storage conditions. Of the solutions opened daily, undiluted domestic bleach was the most stable and Milton was the least stable. Initially, diluted bleach left open deteriorated rapidly but deterioration slowed with time. Solutions in syringes exposed to sunlight showed the most rapid loss of chlorine content. Heated bleach lost nearly 5 per cent of its strength in six hours. Diluted bleach surprisingly, increased its chlorine concentration in open bowls probably due to evaporation of water. Dilution of bleach with hard tap water did not significantly affect shelf-life. Preloading of diluted bleach into syringes appears to be a sound technique if the syringes are stored away from light. This study reinforces the need for sodium hypochlorite to be stored in closed opaque containers. Constant opening of containers appears to cause greater loss in chlorine concentration of diluted bleach solutions, perhaps because a lower concentration of sodium hydroxide allows the pH to drop more rapidly.

Chemical disinfection to interrupt transfer of rhinovirus type 14 from environmental surfaces to hands

Rhinoviruses can survive on environmental surfaces for several hours under ambient conditions. Hands can readily become contaminated after contact with such surfaces, and self-inoculation may lead to infection. Whereas hand washing is crucial in preventing the spread of rhinovirus colds, proper disinfection of environmental surfaces may further reduce rhinovirus transmission. In this study, the capacities of Lysol Disinfectant Spray (0.1% o-phenylphenol and 79% ethanol), a domestic bleach (6% sodium hypochlorite diluted to give 800 ppm of free chlorine), a quaternary ammonium-based product (7.05% quaternary ammonium diluted 1:128 in tap water), and a phenol-based product (14.7% phenol diluted 1:256 in tap water) were compared in interrupting the transfer of rhinovirus type 14 from stainless steel disks to fingerpads of human volunteers upon a 10-s contact at a pressure of 1 kg/cm2. Ten microliters of the virus, suspended in bovine mucin (5 mg/ml), was placed on each disk, and the inoculum was dried under ambient conditions; the input number on each disk ranged from 0.5 x 10(5) to 2.1 x 10(6) PFU. The dried virus was exposed to 20 microliters of the test disinfectant. The Lysol spray was able to reduce virus infectivity by > 99.99% after a contact of either 1 or 10 min, and no detectable virus was transferred to fingerpads from Lysol-treated disks. The bleach (800 ppm of free chlorine) reduced the virus titer by 99.7% after a contact time of 10 min, and again no virus was transferred from the disks treated with it.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical disinfection of duck hepatitis B virus: a model for inactivation of infectivity of hepatitis B virus.

The susceptibility of duck hepatitis B virus (DHBV) to the virucidal effects of sodium hypochlorite (NaOCl) and sodium dichloroisocyanurate (NaDCC) was compared to hepatitis B virus (HBV) with the aim of using the duck as a model for studying HBV disinfection. Using viral DNA polymerase (DNAP) as a target, inhibition of DNAP activity by chlorine disinfectants was found to be concentration-dependent but independent of contact time. Two minute exposure of minimal effective concentrations of sodium hypochlorite (domestic bleach: 3600 ppm and industrial bleach: 3180 ppm) and sodium dichloroisocyanurate (3000 ppm available chlorine) to DHBV- and HBV-rich plasma totally inhibited DNA polymerase activity. DHBV particles in DHBV-carrier duck plasma (10(4.5) ID50/mL) were treated with these concentrations and inoculated intravenously into 18 one-day old ducklings (six animals/disinfectant). Analysis of plasma (0, 7 and 14 days post-infection) and post-mortem liver (14 days post-infection) by DNA hybridization techniques showed that DHBV DNA was undetectable in samples from all animals inoculated with disinfected virus particles. However, post-inoculation plasma and liver of 18 of 18 control ducklings inoculated with untreated virions were positive for DHBV DNA. These results show for the first time that total inhibition in vitro of hepadnavirus DNA polymerase activity by chemical disinfectants is predictive of inactivation of infectivity in vivo.

Catalysis of aryl-halogen exchange by nickel(II) complexes using sodium hypochlorite

As a result of this and previous research in this area, we view macrocyclic Ni II complexes as versatile catalysts for a wide variety of synthetically useful transformations. In addition to catalyzing the epoxidation of olefins with high turnover numbers, the synthesis of haloarenes can now be conducted under conditions that employ readily available Ni II catalysts and an inexpensive oxidant such as domestic bleach

Comparison of Two Methods of Fecal Analysis of Herbivore Diet

Two techniques for determining the proportions of different plant species eaten by the brushtailed opossum (Trichosurus vulpecula) were compared. Both techniques-bacterial degradation and chemical maceration of feces-produced similar results, and confirmed that a correction factor is needed to allow for the differential loss of cuticle of some plant foods during digestion or preparation of feces for microscopic examination. J. WILDL. MANAGE. 43(2):468-473 A reliable method for measuring the species composition and proportions of foods in the diet of herbivores is required; this is especially important where the management of animals or vegetation is contemplated. All the techniques used have drawbacks. Directly observing the feeding animals or the resulting browsed or grazed vegetation to assess species and amounts eaten does not always give accurate results (Wallmo et al. 1973). Examining the macroor microscopic contents of stomachs or rumens is not practicable on live animals, and the results may be unreliable (Westoby et al. 1976). Examining the microscopic fragments in feces is potentially 1 of the best ways, but this can be difficult, and some workers doubt the accuracy of the results obtained (Slater and Jones 1971). However, an advantage of this method is the ease of collecting and storing material. Fresh fecal samples can be kept refrigerated in air-tight containers, or stored in a simple preservative such as 70% ethanol. One of the problems associated with fecal analysis is that of identifying the plant fragments seen on the microscope slide. For predominantly leaf-eating animals, including most ungulates and the brush-tailed opossum, this is simplified by the characteristic shape and arrangement of the epidermal cells of the leaves of each plant species. These features are molded on the overlying cutin, which is indigestible and passes through the gut of herbivores. Some cuticles, however, may break down physically to such an extent that they cannot be recognized. A number of herbs, grasses, and more fragile-leaved tree species have long cells of the epidermis that are too poorly defined to produce a diagnostic cuticle, but they almost always have characteristic stomata, cell inclusions, glands, or hairs, particularly on the abaxial surface of the leaf. Thus, in most cases identification is possible with the aid of a reference collection of representative leaf cuticles. Identifying fragments of food items other than leaves may not be so straightforward. Seeds may be identified either macroor microscopically, and fragments of flowers, petioles, stems, fruit, and other plant parts may sometimes be identified to species. However, even when the available or likely food plants are known, the preparation of reference material to include all these plant parts is very time consuming and often impracticable. 468 J. Wildl. Manage. 43(2):1979 This content downloaded from 157.55.39.181 on Thu, 29 Sep 2016 06:16:05 UTC All use subject to http://about.jstor.org/terms FECAL ANALYSIS OF HERBIVORE DIET Fitzgerald and Waddington 469 A more intractable problem with food studies using fecal analysis is determining whether the proportions in which various species are represented on the microscope slides are similar to the proportions in which they were eaten, or whether the digestive processes of the animal and the methods of preparing material have altered the proportions. Various techniques have been used to prepare fecal material for microscopic examination. For example, Dusi (1949) and Voth and Black (1973) used chloral hydrate solution to clear the cuticle fragments. Martin (1955) and Stewart (1967) used nitric acid to macerate the fecal samples, removing mesophyll while leaving cuticles identifiable, while Dunnet et al. (1973) used a mixture of nitric acid and chromic acid. Williams (1969), after initial mechanical preparation of fecal samples, added boiling water and finally sodium hypochlorite (domestic bleach). Cuticles can also be separated by macerating the plant material with bacteria. This method has been used by Skoss (1955) to study the structure and composition of cuticles, by Luow et al. (1949) on rumen samples, and by Rogerson et al. (1976) on feces from sheep. Rogerson et al. claimed that this is a simpler and more effective technique than chemical preparation, and that it gave repeatable results in terms of botanical composition. To test this claim, we attempted to compare the bacterial technique with the chemical one used by Dunnet et al. (1973) and Fitzgerald (1976) in studies of the diet of the brush-tailed opossum. We also took the opportunity to validate, for each plant species eaten, the use of predetermined correction factors which take into account both the destructive effect of nitric-chromic acid and the digestive processes of the animals. We are grateful to R. E. Brockie, D. G. Dawson, M. R. Rudge, and B. M. Fitzgerald for help with this paper.