Pesticide dispersion by spraying under tropical conditions.

Pesticide air pollution by spraying was evaluated under different temperature, humidity and wind climatic conditions in Brazil. Field experiments were performed with application towards the soil and in guava orchards, where spray dispersion was monitored by adding p-aminobenzoic acid (PABA), a fluorescent substance, as a tracer to the water contained in the spray tanks. Samples were collected with filter membranes (Whatman 180025), and the PABA was extracted from the filters by shaking with water in a Petri dish and measured in a spectrofluorometer. A spray aimed towards the soil with filters positioned on the ground and hung at different heights did not show different upward dispersion as observed when lateral pulverization was conducted. In this case, a tractor with a sprayer moved through a 3 m high and 6 m wide frame with filter membranes mounted at 60 cm intervals. Spray dispersion patterns were modified by guava leaf resistance. No influence of temperature and humidity was observed in this short-lived spraying process. Nevertheless, wind drift can occur during airborne dispersion and is an important pesticide pollution source which requires control. Droplets with PABA powered by assisted spraying upwards returned to the ground by gravity and, therefore, did not constitute a vertical source of atmospheric pollution.

An innovative nano-sorbent for selective solid-phase extraction and spectrophotometric determination of p-amino benzoic acid in cosmetic products.

OBJECTIVE: A novel nano-sorbent was developed for selective extraction and pre-concentration of p-amino benzoic acid (PABA) prior to determination by spectrophotometry. METHODS: Selective extraction of PABA from aqueous solutions was performed using a solid-phase extraction column packed with 200 mg of nickel-zinc-aluminium layered double hydroxide (Ni-Zn-Al LDH) as a nano-sorbent. Extraction procedure is based on the adsorption of p-amino benzoate ions on the Ni-Zn-Al-nitrate LDH and/or their exchanging with LDH interlayer nitrate ions. After elution of extracted analyte by 2.5 mL of 2 mol L(-1) NaCl solution, its concentration was determined spectrophotometrically at λmax = 268 nm. RESULTS: The spectrophotometry method gave a linear response for PABA within the range of 12.5-425.0 µg L(-1) with a correlation coefficient of 0.9994. In the optimum experimental conditions, the limit of detection and sorption capacity were 3.78 µg L(-1) and 21.25 mg g(-1) , respectively. CONCLUSION: The presented method uses mild separation conditions and is a sensitive, reproducible, simple, low-cost and environment-friendly technique that could be used for the extraction and determination of PABA in various cosmetic samples.

11C-Para-aminobenzoic acid PET imaging of S. aureus and MRSA infection in preclinical models and humans.

Tools for noninvasive detection of bacterial pathogens are needed but are not currently available for clinical use. We have previously shown that para-aminobenzoic acid (PABA) rapidly accumulates in a wide range of pathogenic bacteria, motivating the development of related PET radiotracers. In this study, 11C-PABA PET imaging was used to accurately detect and monitor infections due to pyogenic bacteria in multiple clinically relevant animal models. 11C-PABA PET imaging selectively detected infections in muscle, intervertebral discs, and methicillin-resistant Staphylococcus aureus-infected orthopedic implants. In what we believe to be first-in-human studies in healthy participants, 11C-PABA was safe, well-tolerated, and had a favorable biodistribution, with low background activity in the lungs, muscles, and brain. 11C-PABA has the potential for clinical translation to detect and localize a broad range of bacteria.

Bioaccumulation assessment of the sunscreen agent 2-ethylhexyl 4-(N,N-dimethylamino)benzoate in human semen by automated online SPE-LC-MS/MS.

The proven endocrine disruption nature of the sunscreen ingredient 2-ethylhexyl 4-(N,N-dimethylamino)benzoate (EDP) calls for research to understand its distribution and bioaccumulation in the human body. A sensitive analytical method to determine EDP and its metabolites in human semen based on online SPE-LC-MS/MS is described. The method has been fully validated and a standard addition calibration has been used for quantification to correct the observed matrix effects. The on-column detection limits of the analytes are between 0.2 and 0.6 ng, depending on the analyte and the sample. The repeatability of the method, expressed as relative standard deviation, was in the range 4.6-9.4%. The method was satisfactorily applied to semen samples from male volunteers who were subjected to single and repeated whole-body applications of an EDP-containing sunscreen product. EDP metabolites were found at different concentrations in semen samples from the repeated application study, thus showing evidences of bioaccumulation in humans.

Neonatal mice resist Plasmodium yoelii infection until exposed to para-aminobenzoic acid containing diet after weaning.

We developed a newborn (NB) mouse Plasmodium yoelii NL infection model to study malaria in early age. Surprisingly, the onset of parasitemia in P. yoelii challenged NB mice was delayed compared to adults and coincided with the weaning date when weanlings switched from maternal milk to normal chow diet. Also, compared to adult mice, parasitemia resolved much later (48 days vs 20 days post challenge) and the peak parasitemia was twice as high in weanlings. Concurrently, weanlings' germinal center reaction was delayed and diminished compared to adult mice. Maternal milk is deficient in para-aminobenzoic acid (PABA), which is required for de novo folate synthesis by Plasmodium. Suggesting a possible role for the protection afforded by PABA-deficient maternal milk, mice fed with a PABA-deficient diet after the weaning continued to control parasitemia. Despite the reduced parasitemia, these mice developed robust T follicular helper (Tfh) responses and were protected from a second P. yoelii challenge. The NB malaria model provides mechanistic insight into the human infant malaria manifestations where a diet solely based on breast-feeding reduces the incidence of severe malaria in infants. NB mice experiments also support further studies to investigate dietary PABA restriction in the management of severe malaria in infants.

Quantitative determination of TEGDMA, BHT, and DMABEE in eluates from polymerized resin-based dental restorative materials by use of GC/MS.

This study investigated the leaching of ingredients from several commercial dental composite resins cured with LED, and immersed in methanol or water for 24 h, respectively. The composites used were: Admira Dentin (VOCO), Artemis Schmelz (Enamel) (Ivoclar Vivadent), Els extra low shrinkage (Saremco Dental), Filtek Supreme XT Dentin (3 M ESPE), Gradia Direct (GC), Venus & Venus flow (Heraeus Kulzer), and XRV Herculite Prodigy Enamel (Kerr). From each dental composite four specimens with defined structure and 100-mg net weight were made. After the polymerization process, according to manufacturer's instructions, the specimens were immersed in either 1 ml water or 1 ml methanol and incubated at 37 degrees C for 24 h. Eluted ingredients triethyleneglycoldimethacrylate (TEGDMA), 2,6-di-tert-butyl-4-methylphenol (BHT), and 4-N,N-dimethylaminobenzoicacidethylester (DMABEE) were detected and quantified using gas chromatography-mass spectrometry (GC-MS). The amounts of the detected analytes from 100 mg polymerized composites ranged between the following values: TEGDMA: 0-0.5 mg (water), 0-1.6 mg (methanol); BHT: 0-0.03 µg (water), 0-0.11 mg (methanol); and DMABEE: 0-0.11 mg (water), 0-1.4 mg (methanol). We conclude from the results that the elution rates into methanol and water differ significantly. Furthermore, it is concluded that all the determined amounts eluting from the composites are far below toxic-relevant concentrations.

Determination of ink photoinitiators in packaged beverages by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry.

A new analytical method, using gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) techniques, was developed for the determination in packaged food beverages of five ink photoinitiator residues: 2-isopropylthioxanthone (ITX), benzophenone, 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB), 1-hydroxycyclohexyl-1-phenyl ketone (IRGACURE 184) and ethyl-4-dimethylaminobenzoate (EDAB). Samples were extracted from selected beverages (milk, fruit juices and wine) and relative packagings, using n-hexane and dichloromethane, respectively, purified on solid-phase extraction (SPE) silica gel cartridges, and then analyzed in GC/MS and LC/MS. The recovery percentages, obtained spiking the beverage samples at concentrations of 4 and 10 microgl(-1) with a standard mixture of photoinitiators, were in the range 42-108% (milk), 50-84% (wine), and 48-109% (fruit juices). The repeatability of the method was assessed in all cases by the % of correlation value, that was lower than 19%. The lowest limits of detection (LODs) and limits of quantification (LOQs), obtained using GC/MS, were in the range 0.2-1 and 1-5 microgl(-1), respectively. The method was applied to the analysis of forty packaged food beverages (milk, fruit juices and wine samples). The most significant contamination was that of benzophenone, found in all samples in a concentration range of 5-217mugl(-1). Its presence was confirmed by an LC/Atmospheric-Pressure PhotoIonization (APPI)/MS/MS analysis. The photoinitiator (EHDAB) was found in eleven out of forty beverages in a concentration range of 0.13-0.8 microgl(-1). Less important was the ITX contamination, found in three out of forty samples in a range 0.2-0.24 microgl(-1). The work proposes a new method to analyze ink photoinitiator residues in polycoupled carton packaging and in contained food beverages.

Simultaneous trace determination of nine organic UV-absorbing compounds (UV filters) in environmental samples.

A new sensitive method has been successfully developed and validated for the simultaneous determination and quantification of nine estrogenic UV filters (benzophenone-1, benzophenone-2, benzophenone-3, benzophenone-4, 4,4-dihydroxybenzophenone, ethyl-4-aminobenzoate, 2-ethyl-hexyl-4-trimethoxycinnamate, 3-(4-methylbenzylidene)-camphor, 3-benzylidene-camphor) in different environmental matrices. After optimisation of extraction conditions for the best recovery of polar to lipophilic compounds from fish tissue and a subsequent lipid clean-up in HPLC, fish extraction recoveries exceeded 72% for all nine UV filters. Identification and quantification of compounds was performed for lipophilic UV filters with gas chromatography-electroionisation-mass spectrometry and for polar and mid-polar compounds with liquid chromatography coupled to electrospray ionisation mass spectrometry. Instrumental detection limits (IDL) varied between 5 and 260 pg injected and method detection limits (MDL) were in the low ng/g lipids range for all test compounds. The described analytical methods are shown to be useful to screen for estrogenic UV filters in environmental samples such as fish and polar organic chemical integrative samplers.

Rapid and sensitive HPLC assay for simultaneous determination of procaine and para-aminobenzoic acid from human and rat liver tissue extracts.

A sensitive and rapid high-performance liquid chromatography method has been developed for simultaneous determination of procaine and its metabolite p-aminobenzoic acid (PABA) from human and rat liver tissue extracts. The method has been validated according to ICH guidelines in terms of selectivity, linearity, lower limit of detection, lower limit of quantitation, accuracy, precision and recovery from human and rat liver tissue extracts. Chromatography was carried out on a Discovery C(18) column using 10mM ammonium acetate at pH 4.0 and acetonitrile as mobile phase. Retention times for procaine and PABA were 6.6 and 5.3 min, respectively. Linearity for each calibration curve in both tissue extracts was observed across a range from 10 microM to 750 microM for procaine and PABA. The lower limit of detection for both procaine and PABA was 5 microM and the lower limit of quantitation was 10 microM in both tissue extracts. The intra- and inter-day relative standard deviations (R.S.D.) for both procaine and PABA were <6%. Recoveries of procaine and PABA from human and rat liver tissue extracts were determined by two different methods with a single-step protein precipitation technique being employed in both methods. Recoveries for both procaine and PABA were greater than 80% from both human and rat liver tissue extracts.

Use of liquid chromatography with electrochemical detection for the determination of antioxidants in less common fruits.

Neurodegenerative disorders (NDD) have become the common global health burden over the last several decades. According to World Health Organization (WHO), a staggering 30 million people will be affected by Alzheimer's disease in Europe and the USA by 2050. Effective therapies in this complex field considering the multitude of symptoms associated with NDD indications, have not been found yet. Based on the results of NDD related studies, prevention appears to be the promise alternative. Antioxidative and anti-inflammatory properties are hypothesized for natural phenolics, a group of plant secondary products that may positively impact neurodegenerative diseases. In these studies, phenolic-rich extracts from less common fruit species: Blue honeysuckle (Lonicera edulis, Turcz. ex. Freyn), Saskatoon berry (Amelanchier alnifolia Nutt.), and Chinese hawthorn (Crateagus pinnatifida Bunge) were obtained and analyzed to detect neuroprotective substances content and establish a potential therapeutic value. High performance liquid chromatography with electrochemical detection was optimized and further applied on analysis of the extracts of less common fruit species. It was observed that Chinese hawthorn and Blue honeysuckle extracts are potent source of neuroprotective phenolic antioxidants. In accordance the results, it appears that the fruit or formulated products may have the potential for the prevention of neurodegenerative diseases.

Simple and Robust N-Glycan Analysis Based on Improved 2-Aminobenzoic Acid Labeling for Recombinant Therapeutic Glycoproteins.

N-glycans of therapeutic glycoproteins are critical quality attributes that should be monitored throughout all stages of biopharmaceutical development. To reduce both the time for sample preparation and the variations in analytical results, we have developed an N-glycan analysis method that includes improved 2-aminobenzoic acid (2-AA) labeling to easily remove deglycosylated proteins. Using this analytical method, 15 major 2-AA-labeled N-glycans of Enbrel® were separated into single peaks in hydrophilic interaction chromatography mode and therefore could be quantitated. 2-AA-labeled N-glycans were also highly compatible with in-line quadrupole time-of-flight mass spectrometry (MS) for structural identification. The structures of 15 major and 18 minor N-glycans were identified from their mass values determined by quadrupole time-of-flight MS. Furthermore, the structures of 14 major N-glycans were confirmed by interpreting the MS/MS data of each N-glycan. This analytical method was also successfully applied to neutral N-glycans of Humira® and highly sialylated N-glycans of NESP®. Furthermore, the analysis data of Enbrel® that were accumulated for 2.5 years demonstrated the high-level consistency of this analytical method. Taken together, the results show that a wide repertoire of N-glycans of therapeutic glycoproteins can be analyzed with high efficiency and consistency using the improved 2-AA labeling-based N-glycan analysis method.

Simultaneous determination of procaine and para-aminobenzoic acid by LC-MS/MS method.

A sensitive high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for simultaneous determination of procaine and its metabolite p-aminobenzoic acid (PABA). N-Acetylprocainamide (NAPA) was used as an internal standard for procaine and PABA analysis. This assay method has also been validated in terms of linearity, lower limit of detection, lower limit of quantitation, accuracy and precision as per ICH guidelines. Chromatography was carried out on an XTerra MS C(18) column and mass spectrometric analysis was performed using a Quattro Micro mass spectrometer working with electro-spray ionization (ESI) source in the positive ion mode. Enhanced selectivity was achieved using multiple reaction monitoring (MRM) functions, m/z 237-->100, m/z 138-->120, and m/z 278-->205 for procaine, PABA and NAPA, respectively. Retention times for PABA, procaine and NAPA were 4.0, 4.7 and 5.8min, respectively. Linearity for each calibration curve was observed across a range from 100nM to 5000nM for PABA, and from 10nM to 5000nM for procaine. The intra- and inter-day relative standard deviations (RSD) were <5%.

Effects of ionic liquid as additive and the pH of the mobile phase on the retention factors of amino benzoic acids in RP-HPLC.

As an organic salt, ionic liquids are widely used as new solvent media. In this paper, three positional isomers, such as o-amino benzoic acid, m-amino benzoic acid, and p-amino benzoic acid are separated with four different ionic liquids as additives to the mobile phase using reversed-phase (RP) high-performance liquid chromatography (HPLC). Amino benzoic acids are biologically active substances; the p-isomer is present in a group of water-soluble vitamins and is widely known as a sunscreen agent. The ionic liquids used are 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium methylsulfate, and 1-octyl-3-methylimidazolium methylsulfate. The effects of the length of the alkyl group on the imidazolium ring and its counterion, the concentrations of the ionic liquid, and the effect of the pH of the mobile phase on the retention factor of the amino benzoic acid isomers are studied. Separation with the ionic liquid in the eluent was better than the separation without the ionic liquid. The pH mainly affected the retention and elution order of the solutes in RP-HPLC.

Determination of amino acids in tobacco samples by capillary electrophoresis/indirect absorbance detection with isolation of the electrolysis compartment and p-Aminobenzoic acid as a background electrolyte.

A fast, convenient and sensitive method of capillary zone electrophoresis (CZE) and indirect UV detection was proposed for the determination of 16 amino acids. p-Aminobenzoic acid (PAB) was selected as a background electrolyte (BGE). An isolated cell included a BGE buffer part and an electrode buffer one, which were jointed with a glass frit. The isolated cell can prevent PAB from the electrode reaction and improve the stability of the detection baseline. The separation conditions of amino acids were investigated, such as different BGEs, BGE concentration, buffer pH and electroosmotic flow (EOF) modifiers. Under the selected separation conditions, 14 amino acid peaks could be separated in 12 min. The detection limits of the amino acids were in the range of 1.7 - 4.5 micromol/L. The isolated cell is suitable for reagents reacting on the electrodes in capillary electrophoresis. The proposed method has been successfully applied to the determination of the amino acids in tobacco samples.

Adsorption of aromatic organic acids onto high area activated carbon cloth in relation to wastewater purification.

Adsorption of aromatic organic acids: benzoic acid (BA), salicylic acid (SA), p-aminobenzoic acid (pABA) and nicotinic acid (NA), onto high area activated carbon cloth from solutions in 0.4 M H(2)SO(4), in water at natural pH, in 0.1 M NaOH and also from solutions having pH 7.0 were studied by in situ UV-spectroscopic technique. The first-order rate law was found to be applicable for the kinetic data of adsorption. The rates and extents of adsorption of the organic acids were the highest from water or 0.4 M H(2)SO(4) solutions and the lowest from 0.1 M NaOH solution. The order of rates and extents of adsorption of the four organic acids in each of the four solutions (0.4 M H(2)SO(4), water, solution of pH 7.0 and 0.1 M NaOH) was determined as SA>BA>NA approximately pABA. These observed orders were explained in terms of electrostatic, dispersion and hydrogen bonding interactions between the surface and the adsorbate species, taking the charge of the carbon surface and the adsorbate in each solution into account. Adsorption of BA in molecular form or in benzoate form was analyzed by treating the solution as a mixture of two components and applying Lambert-Beer law to two-component system. The adsorption isotherm data of the systems studied were derived at 30 degrees C and fitted to Langmuir and Freundlich equations.

Novel magnetic and fluorescent nanocomposite as a sensitive probe for the determination of proteins.

The Fe(3)O(4)/(sodium oleic acid/ethyltrimethyl ammonium bromide)(n)/4-aminobenzoic acid (Fe(3)O(4)/(NaOL/CTAB)(n)/PABA) nanocomposites have been prepared by a layer-by-layer self-assembly approach. This kind of nanocomposites have fluorescent, magnetic and water-soluble properties. Taking advantage of the magnetic property of nanocomposites, we can separated them from solution easily by using a permanent magnet. By using their strong fluorescence, we can detect proteins. At pH 6.98, the fluorescence of Fe(3)O(4)/(NaOL/CTAB)(n)/PABA nanocomposites can be enhanced by the proteins. Under optimal conditions, the linear ranges of calibration curves were 0.2-20, 0.2-13, 0.2-10 microg mL(-1) for gamma-globulin (gamma-IgG), human serum albumin (HSA), and bovine serum albumin (BSA), respectively. The detection limits were 0.02, 0.01, 0.02 for gamma-IgG, HSA and BSA, respectively. The method has been applied to analyze the total proteins in human samples and the results were in good agreement with those reported by the hospital. This method is sensitive, simple and potential in many areas.

Determination of impurities in pharmaceutical preparations containing folic acid.

In the presented study, the HPLC method was used for the determination of impurities (p-aminobenzoic acid and p-aminobenzoyl-L-glutamic acid) in single-component pharmaceutical products containing folic acid. The determination was performed using a spectrophotometric detector at lambda = 269 nm wavelength.

Aminobenzoic acid compounds as HOCl traps for activated neutrophils.

This study was designed to develop traps for hypochlorous acid (HOCl) which could be used to detect HOCl in the microenvironment of activated neutrophils. Reagent HOCl was found to react with para-aminobenzoic acid (PABA) in aqueous solution to produce a predominant metabolite detectable by high performance liquid chromatography (HPLC). Mass spectroscopy and nuclear magnetic resonance identified this metabolite as the ring addition product 3-chloro PABA. The related compound para-aminosalicylic acid (PAS) was also metabolized by HOCl to 3-chloro PAS. The formation of the 3-chloro metabolite was specific for reactions involving HOCl, since several other oxidants in chloride buffer failed to produce the metabolite. Human blood neutrophils activated by phorbol myristate acetate or zymosan in the presence of PABA (or PAS) used their HOCl to produce large amounts of the 3-chloro metabolite. The formation of 3-chloro PABA was inhibited by azide, catalase, and taurine, which is consistent with the production of the metabolite by the neutrophil myeloperoxidase (MPO) pathway. The reaction of HOCl with PABA and PAS was relatively slow as shown by competitive reactions with endogenous antioxidants like taurine, methionine, and glutathione. This was confirmed in reactions involving PABA/PAS and reagent HOCl or HOCl generated by the MPO enzyme system. In these in vitro systems, glutathione and serum completely inhibited the formation of the 3-chloro metabolite. In contrast, activated neutrophils metabolized PABA/PAS to the 3-chloro metabolite even in the presence of 1% serum. These findings demonstrate that PABA and PAS are specific trapping agents for HOCl produced by neutrophils in complex biological conditions.

A prospective, comparative study of the para-aminobenzoic acid test and faecal elastase 1 in the assessment of exocrine pancreatic function.

BACKGROUND: The assessment of exocrine pancreatic insufficiency is part of the routine work-up of patients with persistent diarrhoea or suspected steatorrhoea. Direct and indirect tests for the diagnosis of exocrine pancreatic insufficiency have their drawbacks. Measurement of faecal elastase 1 by enzyme-linked immunoabsorbent assay is a simple, non-invasive, robust test for exocrine pancreatic insufficiency. METHODS: We performed a prospective comparison of the para-aminobenzoic acid test and faecal elastase 1 test in 45 patients being investigated for diarrhoea or suspected steatorrhoea. Details of clinical suspicion, imaging and response to treatment were recorded. RESULTS: Exocrine pancreatic function was normal in 20 patients with normal para-aminobenzoic acid and faecal elastase 1 levels. Eight patients had exocrine pancreatic insufficiency with low para-aminobenzoic acid and faecal elastase 1 levels, which improved with enzyme supplementation. In 14 of the 15 patients with low or borderline low para-aminobenzoic acid and normal faecal elastase 1 levels, a non-pancreatic cause was found; one patient had a false positive para-aminobenzoic acid test. Two had normal para-aminobenzoic acid but low faecal elastase 1 levels. One improved with pancreatic supplementation, and imaging revealed chronic pancreatitis. The other had a false positive faecal elastase 1 test related to profuse diarrhoea. CONCLUSIONS: Faecal elastase 1 estimation is a simple, non-invasive, robust test of exocrine pancreatic insufficiency, performed on an out-patient stool sample. Its diagnostic performance is superior to that of the para-aminobenzoic acid test in investigating patients with diarrhoea or suspected steatorrhoea.

Evaluation of the mutagenicity of an N-nitroso contaminant of the sunscreen Padimate O: N-nitroso-N-methyl-p-aminobenzoic acid, 2-ethylhexyl ester (NPABAO).

The nitrosamine contaminant, N-nitroso-N-methyl-p-aminobenzoic acid, 2-ethylhexyl ester (NPABAO), of the major sunscreen ingredient Padimate O (4-N,N'-dimethylamino-benzoic acid, 2-ethylhexyl ester) was synthesized and tested for mutagenicity in the Salmonella typhimurium and mouse lymphoma L5178Y TK +/- assays. In contrast to the previously reported positive responses in S. typhimurium tester strains TA100 and TA1535 [Loeppky et al., 1991], there were no increases in the number of revertants with strains TA98, TA100, TA1535, and TA1538 in either the Salmonella plate incorporation [Ames et al., 1975] or preincubation [Yahagi et al., 1977] assays. Additional testing with Salmonella, following the modified preincubation procedure [Rogan, 1990] that gave the initial positive response, was also negative. Data from the mouse lymphoma assays were also uniformly negative. During synthesis of NPABAO, small amounts of 4-N,N'-dimethylamino-3-nitrobenzoic acid, 2-ethylhexyl ester (DMANBAO) can be formed. To determine whether the reported positive mutagenicity response of NPABAO could be the result of trace amounts of DMANBAO in the NPABAO, that compound was also synthesized and tested for mutagenicity with Salmonella. Positive responses were obtained with tester strains TA98 and TA 1538 but not with TA100 and TA1535, indicating that DMANBAO was not responsible for the increase in revertants originally reported.