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PubMedDate not supplied

High-performance capillary electrophoretic separation of carbohydrates with indirect UV detection using diethylamine and borate as electrolyte additives.

The separation of underivatized carbohydrates was investigated using capillary zone electrophoresis with indirect UV detection based on sorbic acid or riboflavin. In comparison with sodium hydroxide, the separation of carbohydrates was greatly improved using diethylamine (DEA) as an electrolyte additive. Since the conductivity of DEA is much lower than that of sodium hydroxide, a stable baseline and a 3-5 times improvement in separation efficiency was observed at a pH as high as 12.6. It was found that DEA reduced the electrophoretic mobility of carbohydrates by formation of ion-pairs, and also reduced the electroosmotic flow by masking the silanol groups at the capillary surface. Many monosaccharides, including glucose, rhamnose, mannose, and fructose, which have very similar pKa values, were completely separated using 5% DEA at pH 12.6. The separation of di- and trisaccharides using indirect detection with a borate buffer at pH 9.5 was also investigated. The separation of disaccharides was greatly improved with borate complexation using riboflavin as a background electrolyte (BGE) over the sodium hydroxide and DEA electrolyte system with sorbic acid as BGE. The resolution of carbohydrates increased as pH increased, and sucrose, trehalose, raffinose, and maltotriose were successfully separated at pH 11.8.

Boric Acids↗
PubMed1998

The thiobarbituric acid (TBA) reaction in foods: a review.

The wide diffusion of 2-thiobarbituric acid (TBA) in the scientific literature is due to the TBA assay, or TBA test, which has been employed in the determination of autoxidative alterations of fats and oils. Two processes occur in autoxidation, generally: the free radical and the photo-oxidation mechanisms. The better studied is the free radical mechanism. The hydroperoxiepidioxides and bicycloendoperoxides are malonaldehyde (MDA) precursors. The absorption spectrum obtained with oxidized fatty foods is like the spectrum obtained when TBA and MDA react. However, during the secondary phase of the autoxidation process other aldehydes (alkanals, 2-alkenals, dienals) are formed which react with TBA, and they are responsible for off-flavors. Three kinds of pigments (yellow, orange, red adducts) are involved. Also, aromatic aldehydes, which constitute the flavor profile of diverse fruits and essential oils, form with TBA the characteristic arylidene-2-TBA acids. Other substances, such as ketones, ketosteroids, acids, esters, sugars, imides and amides, amino acids, oxidized proteins, pyridines, pyrimidines, and vitamins can react with TBA; they are named TBARS (substances that react with TBA), and form principally in meats and meat derivatives. Several organic or bio-organic acids, as shikimic and sorbic acids, react photometrically with TBA if a Malaprade reaction takes place before. A structural study of the red adduct TBA-MDA has been carried out.

Aldehydes↗
PubMed2002

Assessment of the correlation between exposure to benzene and urinary excretion of t, t-muconic acid in workers from a petrochemical plant.

OBJECTIVES: The investigation covered 148 workers from three plants with different levels of benzene exposure. The aim of the study was to assess the correlation between workers' personal exposure and urinary excretion of t, t-muconic acid (TTMA). METHODS: The personal exposure to benzene was measured by the sampling of the workplace air on sorbent tubes with active charcoal followed by elution with carbon disulphide and gas chromatographic determination. The individual internal exposure was assessed by determination of TTMA in urine by a liquid chromatographic method. The urine samples were collected at the beginning (t(0)) and end (t(1)) of the work shift. RESULTS: The individual whole-shift concentrations of benzene in workplace air in the three studied facilities varied from 0.1 to 67.53 mg/m(3). The concentration of TTMA at the beginning of the shift (t(0)) was from 0.02 to 2.53 mg/l and at the end of the shift (t(1)) was from 0.02 to 9.96 mg/l. Significant correlation was found between benzene level in workplace air and TTMA concentration in urine at the end of the work shift, with a correlation coefficient r=0.425 ( P=0.01). CONCLUSIONS: The analysis of the obtained results shows that TTMA can be used as a biological indicator for benzene exposure. The registered single cases of workers with unexpectedly high results for t, t-muconic acid are explained by their consumption of canned foods containing sorbic acid as a preservative. The subjects involved in similar studies should be advised not to consume canned foods 12 h before the examination.

Benzene↗
PubMed1996

Determination of carbohydrates by high-performance capillary electrophoresis with indirect absorbance detection.

High-performance capillary electrophoresis (HPCE) methods with indirect absorbance detection (IAD) have been developed for the determination of carbohydrates, e.g. glucose, fructose, rhamnose, ribose, maltose, lactose, sucrose and gluconic acid. The suitability and performance of six background electrolytes (BGEs), i.e., 1-naphthylacetic acid (NAA), 2-naphthalenesulfonic acid, 1,3-dihydroxynaphthalene, phenylacetic acid, p-cresol and sorbic acid, for the IAD method were investigated. The effects of the concentration of the BGE, pH and temperature on the CE separation of these analytes were evaluated. NAA was found to be best suited as the carrier buffer and background absorbance provider for the detection at 222 nm. The optimal CE performance was found when employing 2 mM NAA, pH 12.2, at 25 degrees C. In comparison with the previous method that used sorbate as the BGE, the present method utilizing NAA shows a 3-6 fold increase in the separation efficiency and a 2-5 fold improvement in the detection limit. The calculated number of theoretical plates is in the range of 1.0-3.0 x 10(5). The precision of the present method for most sugar analytes, measured by the coefficient of variation (C.V.), typically, is less than 1% for the migration time and better than 3% for the peak height and peak area (n = 6). The detection limit is about 0.1 mM for all analytes, except for ribose for which it is about 0.2 mM. This new method is fast, accurate and can be readily applied to real biological samples for quantitative determination of selected carbohydrates.

Calibration↗
PubMed1999

Incidence of contamination of preserved saline solutions during normal use.

PURPOSE: To ascertain the incidence of microbial contamination of preserved contact lens saline solutions with normal patient use. METHODS: Eight different brands of preserved saline were dispensed to 40 patients attending optometric practices in the Sydney area. After specific periods of time (7 to 28 days), the samples were collected and the solution bottle nozzles and contents underwent microbial analysis. RESULTS: The overall contamination rate was approximately 26% for contents only and 55% for nozzles of preserved saline solutions. This rate remained constant for all periods of use. Coagulase-negative Staphylococci were most frequently isolated. No Acanthamoebae were isolated. Saline preserved with ethylene-diamine-tetraacetic acid (EDTA) in conjunction with sorbic acid showed the highest percentage of sterility. CONCLUSIONS: The results of this study show that preserved saline became contaminated with gram-positive bacteria. This is in contrast to our previously published paper using unpreserved saline, where contamination was predominantly with gram-negative bacteria. The overall contamination rates with preserved saline were lower than for unpreserved saline.

Contact Lens Solutions↗
PubMed1995

The effects of potassium sorbate and lactic acid on the shelf-life of vacuum-packed chicken meats.

In this research, the effects of 5% potassium sorbate (PS) and 3% lactic acid (LA) applications on total mesophylic aerobic bacteria, total psychrotrophic aerobic bacteria, lactic acid bacteria, staphylococci and coliform bacteria, pH values, thiobarbituric acid (TBA) numbers, and sensorial properties of vacuum-packed chicken leg and breast meats were investigated during storage at 4 +/- 1 C. In addition, residual sorbate was examined. A decrease in bacterial counts of chicken leg and breast meats was observed in the periods following the treatments of PS and LA; however, towards the end of the storage period, the effectiveness of PS was greater than that of LA. Although no effect was observed on pH values of samples treated with PS, LA caused a decrease in pH values in chicken meats. Both PS and LA treatments resulted in high TBA numbers. Although the shelf-life periods of samples treated with PS and LA were about 30 d, vacuum-packed controls and unsealed controls (both of which were untreated) lost their edibility on the 18th and the 6th d, respectively. Sensory analysis panel members could not distinguish between PS samples and control samples. However, samples containing LA had lower scores than others. Both PS and LA treatments were considered to be acceptable. Quantities of sorbic acid found in the samples treated with PS were below the Acceptable Daily Intake established by the Food and Agriculture Organization/World Health Organization.

Animals↗
PubMed1999

Trans,trans-muconic acid, a biological indicator to low levels of environmental benzene: some aspects of its specificity.

BACKGROUND: The specificity of trans,trans-muconic acid (MA) as a biomarker of exposure to low benzene levels and the role of sorbic acid (SA) as a confounding factor were evaluated. MA, a urinary ring-opened metabolite of benzene, has been recently proposed for the biological monitoring of populations exposed to low levels of this chemical. The usual presence of MA in urine of non-occupationally exposed people is generally attributed to benzene world-wide contamination (mainly by smoking habits, urban pollution, and maybe by food contamination). However, the scientific literature reveals that the common food preservative and fungistatic agent SA is converted into MA though in trace amounts. METHODS: Urinary benzene and MA before and after administration of SA were measured in smokers and non-smokers. Benzene dissolved in urine was analyzed injecting a headspace sample in a gas-chromatografic system. Urinary MA was measured by means of a HPLC apparatus. RESULTS: The mean background values of MA were about 60 mg/L (or 50 mg/g creat.); after experimental administration of SA (447 mg), the mean urinary MA concentration became more than 20 times higher. The biotransformation rates of SA into MA after ingestion of 447 mg of SA ranged from 0.05 to 0.51%. The ratio between unmetabolized benzene in the two groups of smokers and non-smokers was significantly different from the ratio between MA in the same two groups. DISCUSSION: Other sources of MA excretion, different from benzene, influence the urinary concentration of the metabolite: only 25% of MA background values can be attributed to benzene. The urinary MA induced by 100 mg of ingested MA is 77% of that expected after an 8-hour benzene exposure to 0.5 ppm (current threshold limit value according to ACGIH). In conclusion, MA is not a sufficiently specific biomarker of low benzene exposure; a significant effect of SA ingestion is predictable.

Adult↗
PubMed1983

Review: putative mutagens and carcinogens in foods. II: sorbate and sorbate-nitrite interactions.

Sorbic acid and potassium sorbate are widely used Generally Recognized as Safe (GRAS) food additives with an extremely high (25 mg/kg) acceptable daily intake level. Some children between the ages of 6-24 months may actually ingest this amount. While presently not permitted to be added directly to meat and poultry products in the US, potassium sorbate has been proposed as a preservative for bacon, as an additive in conjunction with nitrite and ascorbate or erythorbate. Sorbate and nitrite form several species of direct-acting mutagens and genotoxic agents when present together at pH's mimicking gastric conditions. Two of the mutagens have been identified as ethylnitrolic acid and 1,4-dinitro-2-methylpyrrole. Mutagen formation is blocked by ascorbate at low pH. Ascorbate at eightfold molar excess leads to inactivation of 1,4-dinitro-2-methylpyrrole near neutral pH but does not destroy the mutagenic nitro compound at low pHs. The combination of sorbate with nitrite represents a potential health risk in the absence of adequate inactivating levels of ascorbate (vitamin C).

Carcinogens↗
PubMed1984

Microbial contamination of a vitamin A formulation, prepared in local pharmacies, and its preservation against yeasts and moulds.

The microbial contamination of 44 samples of a vitamin A preparation in sucrose syrup was investigated. The contaminants were almost exclusively yeasts and moulds. Microbiological and physicochemical studies showed that sorbic acid was the preservative of choice for this formulation. The results are discussed with respect to the preservation of non-sterile pharmaceuticals.

Drug Contamination↗
PubMed1978

System for evaluating clostridial inhibition in cured meat products.

A method for evaluating inhibition of Clostridium botulinum, C. sporogenes, and C. perfringens in cured meat products was developed. This system can easily be used in the microbiology laboratory using aluminum ointment tubes as the product container. Swells caused by gas production by the organism are easily observed by using the aluminum tubes. Results obtained confirmed earlier work on the inhibitory effect of sodium nitrite and sorbic acid against the clostridia in cured meat products.

Animals↗
PubMed2006

Simultaneous determination of sorbic and benzoic acids in food dressing by headspace solid-phase microextraction and gas chromatography.

A facile headspace solid-phase microextraction (HS-SPME) procedure using 85 microm polyacrylate (PA) fiber is presented for the simultaneous determination of preservatives (sorbic and benzoic acids) in food dressing, including Thousand Island Dressing, HellMANN'S Salad Dressing and Tomato Ketchup, by gas chromatography (GC) with flame ionization detector (FID). The method presented preserves the advantages typical of HS-SPME such as simplicity, low intensity of labor, low cost and solvent free. The main factors affecting the HS-SPME process, such as extraction temperature and time, desorption temperature and time, the acidity and salt concentration of the solution, were optimized. Limits of detection (LODs) of the method were 2.00 microg/L for sorbic acid and 1.22 microg/L for benzoic acid. Relative standard deviations (RSDs) for quintuplicate analyses at three concentration levels of 0.10, 2.0 and 20 mg/L ranged between 3.86 and 14.8%. The method also showed good linearity n a range from 0.02 to 40 mg/L with correlation coefficients (R2) of 0.9986 for sorbic acid and 0.9994 for benzoic acid. Recoveries for the two analytes in all the samples tested ranged from 83.44 to 113.2%. Practical applicability was demonstrated through the simultaneous determination of sorbic and benzoic acids in the three complex samples.

Benzoates↗
PubMed1983

Determination of antimicrobial preservatives in pharmaceutical formulations using reverse-phase liquid chromatography.

A specific stability-indicating reverse-phase high-performance liquid chromatographic analytical method has been developed to quantitate the antimicrobial preservatives methylparaben, propylparaben, butylparaben, sorbic acid, and benzoic acid in a series of typical pharmaceutical formulations. The mobile phase of this system is a water-acetonitrile mixture, modified by various acids and buffers. The proportions of water and acetonitrile as well as the type and amounts of modifiers are varied in order to achieve optimum chromatography. This method has been used successfully to quantitate preservatives in solutions, suspensions, creams, lotions, and ointments, and can be readily adapted to routine automated assays, either for routine product evaluation or stability programs.

Benzoates↗
PubMed1997

Evaluation of preservative effectiveness in pharmaceutical products: the use of a wild strain of Pseudomonas cepacia.

A sodium benzoate-sorbic acid preservative system of a pharmaceutical product was proved effective against a wild strain of Pseudomonas cepacia, following the official method of the Italian and British Pharmacopoeias. However, this preservative system was ineffective against a challenge of Ps. cepacia wild strain cells grown in the unpreserved pharmaceutical product and on culture media different from those described by the Pharmacopoeias. The adaptive resistance of the wild strain of Ps. cepacia was not demonstrated with a laboratory strain (ATCC 25609). In contrast, p-hydroxybenzoate-based preservative systems proved to be efficient in protecting the pharmaceutical product against a challenge of wild and laboratory strains of Ps. cepacia grown in the different conditions described above. The results obtained suggest the usefulness, in the official methods for testing pharmaceutical preservatives, of using wild microbial strains isolated from the pharmaceutical environment. Metabolic adaptive responses, capable of affecting the antimicrobial sensitivity of wild micro-organisms used to challenge the preserved product, can be detected by using cells grown in the unpreserved pharmaceutical product.

Benzoates↗
PubMed1984

The effect of food preservatives on pH homeostasis in Escherichia coli.

The effects of cinnamic, propionic, benzoic and sorbic acids on the growth and intracellular pH of Escherichia coli were investigated. The data suggest that the potency of weak acids as food preservatives is related to their capacity to reduce specifically the intracellular pH. The data also suggest that although both the undissociated forms of the acid cause the intracellular pH to fall, growth inhibition is due predominantly to the undissociated acid.

Benzoates↗
PubMed1991

Effect of chemical treatments on the micro-organisms associated with malting of sorghum grains and sorghum malt.

The effect of five chemical preservatives on the micro-organisms associated with sorghum grain and malts was investigated. Sorbic acid, sodium benzoate, nisin, formaldehyde and lime at concentrations up to 500, 100, 1000, 1500 and 2000 ppm, respectively did not adversely affect the malting properties of sorghum grain. Only HCHO and Ca(OH)2, each of which prevented bacteria and mould growth at 500 and 2000 ppm, respectively, were sufficiently effective at maximum practicable concentrations to control microbial contamination during malting.

Bacteria↗
PubMed1977

Spectrophotometric determination of some preservatives in milk.

Benzoic acid, propyl p-hydroxybenzoate, and sorbic acid in milk have been determined by using the corresponding first derivative curves of absorption spectra of clarified milk samples. The delta A/delta lambda curves were computed and the concentration of each preservative was calculated using 1 point, 2 points, and/or 3 points. In all cases, the percentage error was within 2.4%.

Animals↗
PubMedDate not supplied

[Preservation of margarine in fungicidal paper].

The authors studied the effect of a new type of package material, fungicide paper with one side coated with sorbic acid (fungicide) at a rate of 0.08 g per square decimeter of the surface and other side coated with water- and gas-proof polymer film 60 to 80 microns thick, on the quality of margarine of storage. It was established that by the end of storage the surface of margarine samples packed in parchment and fungicide paper did not exhibit any mold. At the same time, however, the processes of oxidation and formation of the stuff layer were most pronounced in margarine packed in parchment. The amount of the stuff layer in margarine increased toward the end of storage, amounting to 6.63% in margarine packed in parchment and to 5.16% in that packed in fungicide paper.

Chemical Phenomena↗
PubMed1990

[Preservatives and dental caries. Can preservatives in food and beverages influence oral health?].

There has been a pronounced decline in dental caries in industrialized countries during the last decades. The most obvious explanation is exposure to fluorides. However, the decline started before fluorides were extensively used. Theoretically, a contributory factor may have been increased consumption of foods containing preservatives. The aims of the present study were to find out whether increased intake of preservatives has occurred, and to assess the effect of two commonly used preservatives, sorbic acid and benzoic acid, on bacterial growth and on plaque acidogenity in vivo. Results from five consumption reports from the Central Bureau of Statistics of Norway were used to estimate changes in consumption of basic foods containing the preservatives mentioned. A modified broth dilution method was used to determine the growth inhibitory effects on selected oral streptococci. Plaque-pH measurements were performed with a microelectrode to assess possible effects on acid production. Data pointed towards increased consumption of preservatives. Legal concentrations of preservatives inhibited bacterial growth. Similar concentrations of the preservatives had a negligible effect on acid production in dental plaque (0.4% W/V), whereas higher concentrations (2% W/V) had an inhibitory effect.

Benzoates↗