Levels Of Benzoic Acid Research Articles

Simultaneous quantification of major phytohormones and related compounds in crude plant extracts by liquid chromatography–electrospray tandem mass spectrometry

A rapid and sensitive method was developed for simultaneous quantification of multiple classes of phytohormones and some related metabolites in crude plant extracts without purification or derivatization. High-performance liquid chromatography and electrospray ionization–tandem mass spectrometry with multiple reaction monitoring were used to quantify auxins, cytokinins, abscisic acid, gibberellins, jasmonates, salicylates, and a number of related metabolites in crude plant extracts. The technology was applied to analyze biotic and abiotic stress-induced changes of phytohormones in Arabidopsis tissues, starting with 50–100 mg fresh tissue. Biotic and/or abiotic stresses were shown to differentially affect levels of salicylic acid, jasmonic acid, indole-3-acetic acid, and benzoic acid, in comparison to their methyl esters. Compared with previous methods, sample preparation time and amount of sample required for analysis of phytohormones are reduced, and more classes of hormones are quantitatively profiled. Structurally diverse compounds from complicated biological matrices are determined with high selectivity and sensitivity.

Performance of a Growth–No Growth Model for Listeria monocytogenes Developed for Mayonnaise-Based Salads: Influence of Strain Variability, Food Matrix, Inoculation Level, and Presence of Sorbic and Benzoic Acid

A previously developed growth–no growth model for Listeria monocytogenes, based on nutrient broth data and describing the influence of water activity (aw), pH, and acetic acid concentrations, was validated (i) for a variety of L. monocytogenes strains and (ii) in a laboratory-made, mayonnaise-based surimi salad (as an example of a mayonnaise-based salad). In these challenge tests, the influence of the inoculation level was tested as well. Also, the influence of chemical preservatives on the growth probability of L. monocytogenes in mayonnaise-based salads was determined. To evaluate the growth–no growth model performance on the validation data, four quantitative criteria are determined: concordance index, % correct predictions, % fail-dangerous, and % fail-safe. First, the growth probability of 11 L. monocytogenes strains, not used for model development, was assessed in nutrient broth under conditions within the interpolation region. Experimental results were compared with model predictions. Second, the growth–no growth model was assessed in a laboratory-made, sterile, mayonnaise-based surimi salad to identify a possible model completeness error related to the food matrix, making use of the above-mentioned validation criteria. Finally, the effect on L. monocytogenes of common chemical preservatives (sorbic and benzoic acid) at different concentrations under conditions typical of mayonnaise-based salads was determined. The study showed that the growth–no growth zone was properly predicted and consistent for all L. monocytogenes strains. A larger prediction error was observed under conditions within the transition zone between growth–no growth. However, in all cases, the classification between no growth (P = 0) and any growth (P > 0) occurred properly, which is most important for the food industry, where outgrowth needs to be prevented in all instances. The results in the sterile mayonnaise-based salad showed again that the growth–no growth zone was well predicted but that also, in real food systems, a transition zone between growth and no growth exists. This became even more obvious for lower inoculation levels. The maximum-allowed concentration of benzoic and sorbic acid in mayonnaise-based salads, according to the European Union legislation, eliminated the growth of L. monocytogenes. Concentrations of 600 and 300 ppm were already sufficient to inhibit growth at 7 and 4°C, respectively, under conditions associated with mayonnaise-based salads (pH 5.6; aw, 0.985).

Inhibitive detection of benzoic acid using a novel phenols biosensor based on polyaniline–polyacrylonitrile composite matrix

A novel sensitive and stable phenols amperometric biosensor, based on polyaniline–polyacrylonitrile composite matrix, was applied for determination of benzoic acid. The electrochemical biosensor functioning was based on the inhibition effect of benzoic acid on the biocatalytic activity of the polyphenol oxidase (PPO) to its substrate (catechol) in 0.1 M phosphate buffer solution (pH 6.5). A potential value of −50 mV versus SCE, and a constant catechol concentration of 20 μM were selective to carry out the amperometric inhibition measurement. The kinetic parameters Michaelis-Menten constant ( K M app ) and maximum current ( I max) in the absence and in the presence of benzoic acid were also evaluated and the possible inhibition mechanism was deduced. The inhibiting action of benzoic acid on the polyphenol oxidase electrode was reversible and of the typical competitive type, with an apparent inhibition constant of 38 μM. This proposed biosensor detected levels of benzoic acid as low as 2 × 10 −7 M in solution. In addition, the effects of temperature, pH value of solution on the inhibition and the interferences were investigated and discussed herein. Inhibition studies revealed that the proposed electrochemical biosensor was applicable for monitoring benzoic acid in real sample such as milk, yoghurt, sprite and cola.

Influence of benzoic acid and dietary protein level on performance, nitrogen metabolism and urinary pH in growing-finishing pigs

An experiment was conducted to examine the effect of benzoic acid and two dietary protein levels on pig performance, nitrogen balance and urinary pH. A total of 24 crossbred barrows (26 kg to 106 kg BW) received one of four diets: low protein level with and without 1% benzoic acid (LP− and LP+, respectively) and high protein level with and without 1% benzoic acid (HP− and HP+, respectively). The animals were fed restrictively grower and finisher diets and were kept in metabolic cages in weeks 3, 6, 9, and 12 of the experiment. The addition of benzoic acid did not improve weight gain and feed conversion ratio. N-intake and digested N were only influenced by dietary protein level (p<0.01), while N-balance was similar in all four diets. Dietary benzoic acid improved N-digestibility in the grower period (p<0.01) but not in the finisher period. The addition of benzoic acid reduced urinary pH by about one pH-unit in both feeding periods independent of the protein level of the diet (p<0.01) and increased the concentration of urinary hippuric acid markedly (p<0.01). The results of this study indicate a positive influence of dietary benzoic acid on pigs especially in case of feeding a low protein diet in the grower period.

(169) Antioxidant Levels in Frozen and Processed Lingonberries and Bog Blueberries

Frozen lingonberries (Vaccinium vitis-idaea subsp. minus) and bog blueberries (V. uliginosum) were processed using recipes of the Alaska Cooperative Extension Service. Overall antioxidant activity (H-ORAC) was 71 μmol·g-1 of TE for frozen bog blueberries and for lingonberries, 160–165 μmol·g-1 of TE. Processing into fruit leather and drying increased levels in bog blueberries to 260–430 μmol·g-1 of TE and lingonberries to 457–939 μmol·g-1 of TE. Leathers and dried fruit had significantly higher levels of total anthocyanins (frozen bog blueberries: 2.1 μg·g-1, leather: 8.0 μg·g-1, dried: 9.8 μg·g-1; frozen lingonberries 1.4 μg·g-1, leather: 4 μg·g-1, dried: 5.2 μg·g-1); total phenolics (frozen bog blueberries: 4.8 μg·g-1, leather: 19 μg·g-1, dried: 26 μg·g-1; frozen lingonberries 7.7 μg·g-1, leather 24 μg·g-1, dried: 38 μg·g-1); and quercetin (frozen bog blueberries: 6.7 μg·g-1, leather: 86 μg·g-1, dried: 150 μg·g-1; frozen lingonberries 7.7 μg·g-1, leather 110 μg·g-1, dried: 430 μg·g-1). Bog blueberries did not have detectible levels of p-coumeric acid or benzoic acid, but lingonberries showed a significant increase in dried fruit and leather (frozen fruit p-coumeric: 0.18 μg·g-1g, leather: 0.45 μg·g-1, dried: 1.4 μg·g-1; frozen fruit benzoic: 0.41 μg·g-1, leather: 0.84 μg·g-1, dried: 0.71 μg·g-1). Frozen and processed lingonberries had little or no vitamin C. Bog blueberries had detectible levels in all treatments [highest in leather (440 μg·g-1), frozen berries (220 μg·g-1)]. ORAC, total anthocyanins, total phenolics, and quercetin were detected in all other processing methods (canned fruit, syrup, canned juice, jam, sauce, frozen j uice, and freezer jam). Levels were similar to or lower than frozen fruit.

A change of phenolic acids content in poplar leaves induced by methyl salicylate and methyl jasmonate

The contents of seven different phenolic acids such as gallic acid, catechinic acid, pyrocatechol, caffeic acid, coumaric acid, ferulic acid and benzoic acid in the poplar leaves (Populus Simonii × Populus Pyramibalis c. v and Populus deltoids) suffocated by Methyl jasmonate (MeJA) and Methyl salicylate (MeSA) were monitored for analyzing their functions in interplant communications by using high-pressure liquid chromatography (HPLC). The results showed that the contents of phenolic acids had obviously difference in leaves exposed to either MeSA or MeJA. When P.deltoides leaves exposed to MeJA or MeSA, the level of gallic acid, coumaric acid, caffeic acid, ferulic acid and benzoic acid was increased, gallic acid in leaves treated with MeJA comes to a peak at 24 h while to a peak at 12-d having leaves treated with MeSA. When P. Simonii × P. Pyramibalis c. v leaves were exposed to MeJA or MeSA, the level of gallic acid, pyrocatechol and ferulic acid was increased; The catechinic acid and benzoic acid had a little drop; The caffeic acid and coumaric acid were undetected in both suffocated and control leaves. This changed pattern indicated that MeJA and MeSA can act as airborne signals to induce defense response of plants.

Biochemistry of ginseng root tissues affected by rusty root symptoms

Ginseng rusty root, a disorder of unknown cause (s), in which reddish-brown to orange-brown areas develop on the surface of field-grown roots, was studied at the cellular and biochemical levels. Using light microscopy, the affected areas were shown to comprise of the epidermis and underlying 6–8 cell layers of the cortical tissues. Rusty root areas ranged from small clusters of 3–4 cells to larger expanding areas of > 80 cells. These cells appeared golden-brown and stained a bluish-green with Toluidine Blue indicating the presence of phenolic compounds. Energy-dispersive X-ray spectroscopy and atomic emission spectrometry of affected epidermal cells revealed a significant accumulation of Fe, Al, Si, Mg and other cations when compared to adjoining healthy cells. The concentrations of the six most common ginsenosides found in ginseng roots (Rg 1, Re, Rb 1, Rc, Rb 2, and Rd) were reduced by 40–50% in rusty root-affected epidermal and cortical tissues when compared to adjacent healthy tissues. Total phenolic compounds were increased by up to threefold in affected tissues and HPLC analysis revealed significantly higher levels of quercetin, cinnamic acid, vanillic acid, p-coumaric acid, benzoic acid, chlorogenic acid and catechin. In vitro phenolic–metal binding assays confirmed that phenolic compounds were able to sequester positively-charged metal ions, in particular Fe, to form a phenolic–metal ion complex. In ginseng callus cultures, accumulation of phenolic compounds was increased threefold within 12 h of treatment with chitosan (1%), and to a lesser extent by wounding. Specific defense enzymes, namely phenylalanine ammonia-lyase (PAL, E.C. 4. 3. 1. 5.), polyphenoloxidase (PPO, E.C. 1. 10. 3. 1.) and peroxidase (POD, E.C. 1. 11. 1. 7.), were also significantly enhanced in treated callus tissues and in rusty root tissues. On field-grown ginseng roots, application of chitosan induced symptoms similar to rusty root, whereas wounding and ethylene treatments did not. Based on these results, rusty root symptoms on ginseng are proposed to result from an induction of host defense responses, especially phenolic production, in epidermal and underlying cortical cells. This induction is likely due to attempted invasion by as-yet uncharacterized chitin-containing soil fungi, which were observed in many of the affected cells. Subsequent oxidation of phenolic compounds and sequestration of metal ions, in particular Fe, appear to be largely responsible for the symptoms observed.

Concentration Profiling in Rat Tissue by High-Resolution Magic-Angle Spinning NMR Spectroscopy: Investigation of a Model Drug

The utility of high-resolution magic-angle spinning (HR-MAS) NMR for studying drug delivery in whole tissues was explored by dosing female Sprague-Dawley rats with topical or injectable benzoic acid (BA). In principle, HR-MAS NMR permits the detection of both intra- and extracellular compounds. This is an advantage over the previous detection of topically applied BA using microdialysis coupled to HPLC/UV as microdialysis samples only the extracellular space. Skin and muscle samples were analyzed by (1)H HR-MAS NMR, and BA levels were determined using an external standard solution added to the sample rotor. One to two percent of the BA topical dose was detected in the muscle, showing that BA penetrated through the dermal and subcutaneous layers. Since BA was not detected in the muscle in the microdialysis studies, the NMR spectra revealed the intracellular localization of BA. The amount of BA detected in muscle after subcutaneous injection correlated with the distance from the dosing site. Overall, the results suggest that HR-MAS NMR can distinguish differences in the local concentration of BA varying with tissue type, dosage method, and tissue proximity to the dosing site. The results illustrate the potential of this technique for quantitative analysis of drug delivery and distribution and the challenges to be addressed as the method is refined.

Regulation of circadian methyl benzoate emission in diurnally and nocturnally emitting plants.

Emission of methyl benzoate, one of the most abundant scent compounds of bee-pollinated snapdragon flowers, occurs in a rhythmic manner, with maximum emission during the day, and coincides with the foraging activity of bumblebees. Rhythmic emission of methyl benzoate displays a "free-running" cycle in the absence of environmental cues (in continuous dark or continuous light), indicating the circadian nature of diurnal rhythmicity. Methyl benzoate is produced in upper and lower snapdragon petal lobes by enzymatic methylation of benzoic acid in the reaction catalyzed by S-adenosyl-L-methionine:benzoic acid carboxyl methyltransferase (BAMT). When a detailed time-course analysis of BAMT activity in upper and lower petal lobes during a 48-hr period was performed, high BAMT activity was found at night as well as in continuous darkness, indicating that the BAMT activity is not an oscillation-determining factor. Analysis of the level of benzoic acid during a 24-hr period revealed oscillations in the amount of benzoic acid during the daily light/dark cycle that were retained in continuous darkness. These data clearly show that the total amount of substrate (benzoic acid) in the cell is involved in the regulation of the rhythmic emission of methyl benzoate. Our results also suggest that similar molecular mechanisms are involved in the regulation of methyl benzoate production in diurnally (snapdragon) and nocturnally (tobacco and petunia) emitting plants.

Free and conjugated benzoic acid in tobacco plants and cell cultures. Induced accumulation upon elicitation of defense responses and role as salicylic acid precursors.

Salicylic acid (SA) is a key endogenous component of local and systemic disease resistance in plants. In this study, we investigated the role of benzoic acid (BA) as precursor of SA biosynthesis in tobacco (Nicotiana tabacum cv Samsun NN) plants undergoing a hypersensitive response following infection with tobacco mosaic virus or in tobacco cell suspensions elicited with beta-megaspermin, an elicitor from Phytophthora megasperma. We found a small pool of conjugated BA in healthy leaves and untreated cell suspensions of tobacco, whereas free BA levels were barely detectable. Infection of plants with tobacco mosaic virus or elicitation of cells led to a rapid de novo synthesis and accumulation of conjugated BA, whereas free BA was weakly induced. In presence of diphenylene iodonium, an inhibitor of superoxide anion formation, SA accumulation was abolished in elicited cells and much higher BA levels were concomitantly induced, mainly as a conjugated form. Furthermore, piperonylic acid, an inhibitor of cinnamate-4-hydroxylase was used as a powerful tool to redirect the metabolic flow from the main phenylpropanoid pathway into the SA biosynthetic branch. Under these conditions, in vivo labeling and radioisotope dilution experiments with [(14)C]trans-cinnamic acid as precursor clearly indicated that the free form of BA produced in elicited tobacco cells is not the major precursor of SA biosynthesis. The main conjugated form of BA accumulating after elicitation of tobacco cells was identified for the first time as benzoyl-glucose. Our data point to the likely role of conjugated forms of BA in SA biosynthesis.

Determination of benzoyl peroxide and benzoic acid levels by HPLC during wheat flour bleaching process.

Freshly milled wheat flour has a pale yellow color due to its carotenoids content. Benzoyl peroxide is a bleaching agent typically used to give such flour a better appearance. This free-radical initiator promotes carotenoids oxidation, thereby producing less colored compounds, and benzoic acid is a main final product. Samples of wheat flour were treated with 150 ppm of benzoyl peroxide to begin a bleaching process, and then subjected to ethyl ether extraction at different intervals of time. Benzoyl peroxide and benzoic acid levels in these extracts were monitored by means of HPLC in individual experiences. The resulting concentration of benzoyl peroxide after 9 days of contact with the bleaching agent was 11 ppm, dropping afterward to nondetectable levels. A maximum value for benzoic acid of 16 ppm was found after 12 h of bleaching. Subsequently this level decreased continuously until reaching a residual value of 6 ppm after 3 months.

Benzoic acid in some milk products from the market in the Czech Republic

Benzoic acid is a natural component of fermented milk products. The level of benzoic acid depends on the level of hippuric acid in used milk and on the process of dairy product manufacture, especially on the technologically used microorganisms. A hygienic limit 30 mg/kg of benzoic acid in milk products was laid down in the Czech Republic in 1997. In our study we determined the levels of benzoic acid in model yoghurts and in some milk products from Czech market. The benzoic acid content was determined by HPLC, by the use of our modification of the provisional IDF standard 139(1987). All samples of model yoghurts and all samples of milk products from the market showed levels of benzoic acid below the newly set hygienic limit. Highest level of benzoic acid was determined in the sample of white cheese (22.85 mg/kg), all other products based on white cheese showed average levels. Cottage cheese products (sample P), which belongs to the family of milk products for children, showed a very low level of benzoic acid, which is considered as a very positive result.

Influence of yogurt cultures on benzoic acid content in yoghurt

Benzoic acid is not the natural metabolite in ruminants, therefore it is blocked in their gastrointestinal system in the form of benzoylglycine (hippuric acid). Change of hippuric acid into benzoic acid is realized by yoghurt cultures during yoghurt preparation. The influence of yoghurt cultures most frequented species J22, WV2, JK, T767 + T, J2, RX, JOB, WV3 and two strains MILCOM a. s. Laktoflora (used for preparation of yoghurt cultures) on benzoic acid level was tested on model yoghurts, produced from cow milk. One model of yoghurt was produced from goat milk, inoculated with yoghurt culture WV2. The levels of benzoic acid were determined by HPLC with SOP (standard operation procedure) used by the Czech Agricultural and Food Inspection. All experimental samples were prepared by the same technology and the same starting raw material and inoculated by the above 8 most frequently used yoghurt cultures. Differences between the used yoghurt cultures were found and statistically confirmed.

Determination of Benzoic and Sorbic Acids in Labaneh by High-Performance Liquid Chromatography

Benzoic and sorbic acid contents of 14 packaged commercial labaneh (concentrated set yogurt) samples were determined by HPLC method using a reverse phase C-18 column and a mobile phase of 90:10, phosphate buffer:methanol. There was a linear relationship between peak area versus benzoic and sorbic acids concentrations between 32 and 300 mg/l. Recoveries of benzoic acid added at 31·8 and 63·6 mg/100 g to commercial packaged labaneh, averaged 90·3 and 90·6% with coefficient of variability (cv.) of 0·5 and 0·2, respectively. Recoveries of sorbic acid added at 28·0 and 56·0 mg/100 g labaneh, averaged 101·1 and 97·4% with cv. of 0·5 and 0·8, respectively.Benzoic acid was detected in eight labaneh samples in the range of 33–2000 mg/kg while sorbic acid was detected in seven samples, and it ranged between 87 and 900 mg/kg. Three samples were found to contain both benzoic and sorbic acids. Six labaneh samples contained low levels of benzoic acid (<32 mg/kg). These are probably the indigenous benzoic acid normally encountered with in some fermented dairy products.

Concentration levels of sorbic and benzoic acids in soft drinks

The quantity of sorbic and benzoic acids in soft drinks is determined by reverse‐phase high performance liquid chromatography (HPLC) method. A good separation of the two preservatives was obtained by using a mobile phase composed of ammonic acetate 5 mM at pH 4.4 and aceto‐nitrile (80/20), and with UV detection. The average levels of benzoic acid varied between 73.4 ±2.51 (brand F) and 429 ±2.21 (brand K), and those of sorbic acid between 72.3 ±1.04 (brand M) and 199 ± 7.72 (brand A). Likewise, the estimated daily intake (EDI) for each additive was calculated, resulting in a higher intake of benzoic acid (38.3 mg) than sorbic acid (5.98 mg). In both cases, the values were lower than the acceptable daily intake (ADI).

Metabolic fate of S-(-)-pulegone in rat

1. S-(-)-pulegone was administered orally to rat (250 mg/kg) and the nature of the urinary metabolites was investigated. Eleven metabolites, namely S-(-)-menthofuran, piperitone, piperitenone, p-cresol, 5-hydroxypulegone, 4-methylcyclohexenone, 3- methylcyclohexanone, isopulegone, pulegol, 7-hydroxypiperitone and benzoic acid, have been isolated from rat urine. It is assumed that menthofuran, isopulegone and 4- methylcyclohexenone retain the stereochemistry of the parent compound, whereas in other metabolites the stereochemistry at the asymmetric centres is not known. 2. The relative amounts of various major metabolites present in the total urine extracts from the R-(+) and S-(-)-pulegone-treated rat were established by glc analyses. Urine samples of rats treated with R-(+)-pulegone contained higher levels of p-cresol and piperitenone than in similar experiment carried out with S-(-)-pulegone, whereas the levels of unmetabolized pulegone, piperitone and benzoic acid were considerably higher in the urine of rat treated with S-(-)-pulegone than in a corresponding experiment with R-(+)-pulegone. 3. Phenobarbital-induced rat liver microsomes converted S-(-)-pulegone to S-(-)-menthofuran (VII) and piperitenone (III) in the presence of NADPH and O2. The levels of VII and III were significantly higher in similar experiments carried out with R-(+)-pulegone. 4. Based on these studies, metabolic pathways for the biotransformation of S-(-)pulegone in rat have been proposed and possible reasons for the observed difference in the toxicity mediated by these two enantiomers are discussed.

Use ofin VitroSkin Penetration Data and a Physiologically Based Model to Predictin VivoBlood Levels of Benzoic Acid

A physiologically based pharmacokinetic (PB PK) model was developed to predict plasma levels of benzoic acid (BA) in the hairless guinea pig after topical exposure at three finite dose levels. The PB PK model consisted of four compartments: (1) rapidly perfused tissues; (2) slowly perfused tissues; (3) liver, representing the route of elimination of BA from the plasma after biotransformation to hippuric acid; and (4) plasma. The predictive capacity of the PB PK model was assessed by comparing plasma BA levels measured experimentally with those predicted by the model. The percutaneous absorption of finite doses of BA in the model was described by a transdermal input function, which was derived fromin vitropercutaneous absorption studies in which viable hairless guinea pig skin in flow-through diffusion cells was exposed to BA. Physiological parameters used in the model were calculated from previously published values. Biochemical parameters, including partition coefficients and metabolic constants, were measured experimentallyin vitro.The PB PK model predictions were generally in good agreement with measured plasma levels for each of the dose levels studied. The predicted plasma BA levels and the measured values were closer for the highest dose (120 μg/cm2) than for either of the other two doses used (12 and 40 μg/cm2). The effects of optimizing the metabolic constants and the transdermal input function parameters on the predicted curve shape and fit to that of the measured plasma BA levels were assessed. Varying the transdermal input parameters produced closer agreement between predicted and measured values.

Hydrogen Peroxide Stimulates Salicylic Acid Biosynthesis in Tobacco.

Hydrogen peroxide induced the accumulation of free benzoic acid (BA) and salicylic acid (SA) in tobacco (Nicotiana tabacum L. cv Xanthi-nc) leaves. Six hours after infiltration with 300 mM H2O2, the levels of BA and SA in leaves increased 5-fold over the levels detected in control leaves. The accumulation of BA and SA was preceded by the rapid activation of benzoic acid 2-hydroxylase (BA2H) in the H2O2-infiltrated tissues. This enzyme catalyzes the formation of SA from BA. Enzyme activation could be reproduced in vitro by addition of H2O2 or cumene hydroperoxide to the assay mixture. H2O2 was most effective in vitro when applied at 6 mM. In vitro activation of BA2H by peroxides was inhibited by the catalase inhibitor 3-amino-1,2,4-triazole. We suggest that H2O2 activates SA biosynthesis via two mechanisms. First, H2O2 stimulates BA2H activity directly or via the formation of its substrate, molecular oxygen, in a catalase-mediated reaction. Second, higher BA levels induce the accumulation of BA2H protein in the cells and provide more substrate for this enzyme.

Effects of Sublethal Exposure on Lethal Body Burdens of Narcotic Organic Chemicals in Daphnia magna

This work examines the hypothesis that exposure of Daphnia magna to sublethal levels of narcotic contaminants may affect subsequent sensitivity of the animals. Prior exposure (24 h) of Daphnia to sublethal levels of acetone, acetophenone, benzene, benzoic acid, butanol, 1,2-dichlorobenzene, 2-methylnaphthalene, 1,2,4-trichlorobenzene, 1,1,2,2-tetrachloroethane, and toluene had no effect on their sensitivity to effective levels of these chemicals in eight of 10 cases. Effective burdens (24-h acute exposure) were independent of the sublethal body burdens (24-h sublethal exposure) and of the sublethal water concentrations (P < 0.025) in eight of 10 cases. Butanol and benzoic acid were the exceptions. The null hypothesis was then accepted in 80% of the cases. These results imply that animals from polluted sites should be no more resistantto high body residues of pollutants than those from clean sites and that the toxicity of narcotic organic contaminants may be independent of the time course of uptake.

Simultaneous determination of sorbic acid, benzoic acid and parabens in foods: a new gas chromatography-mass spectrometry technique adopted in a survey on Italian foods and beverages.

A gas chromatographic-mass spectrometric technique is described for the simultaneous determination of sorbates, benzoates and other lipophilic preservatives in foods and beverages. The selected ions monitoring (SIM) technique allowed unambiguous identification of the compounds under study. This methodology eliminated all kinds of interferences from the complex food matrices which affect most routinely-used techniques, HPLC included. A very simple and time-saving extraction procedure was therefore employed, since subsequent purification steps were unnecessary, even for detection of trace levels of preservatives. The detection limits fell within the range of 100-200 pg. With this analytical technique, we have conducted a survey on sorbic acid, benzoic acid, methyl, ethyl, and propyl 4-hydroxybenzoate levels in 249 samples of foods and beverages on sale in markets in the Rome area. Samples were chosen from among those currently preserved by these additives. All compounds were also determined by a routinely-used HPLC technique for method comparison.