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At least 1,369 records · Page 76Linked to original sources
PubMed1998

Stability and bactericidal activity of chlorine solutions.

OBJECTIVES: To determine the stability of sodium hypochlorite (diluted household bleach) when stored for 30 days in various types of containers and to determine the efficacy of low concentrations of free available chlorine to inactivate test bacteria. DESIGN: Laboratory-based study. Solutions of standard household bleach were prepared using tap water or sterile distilled water at dilutions of 1:100, 1:50, and 1:5. Chlorine concentrations were measured, and then the solutions were placed into five polyethylene containers and left at room temperature (20 degrees C) under various conditions (translucent containers with light exposure and with or without air; brown opaque container without light or air exposure). Samples for chlorine and pH determinations were taken at time 0 and on days 7, 14, 21, 30, and 40. Bactericidal activity of chlorine solutions was assessed using the Association of Official Analytical Chemists Use-Dilution Method. Test bacteria included Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella choleraesuis. RESULTS: Chlorine concentrations at 30 days varied from the 40% to 50% range for 1:50 or 1:100 dilutions stored in containers other than closed brown containers to 83% to 85% for the 1:5 dilution stored in closed but non-opaque containers to 97% to 100% for 1:50 or 1:5 solutions stored in closed brown containers. The lowest concentration of sodium hypochlorite solution that reliably inactivated all the test organisms was 100 ppm. CONCLUSIONS: These data suggest that chlorine solutions do not need to be prepared fresh daily, as is recommended currently, and the lowest concentration of chlorine that reliably inactivates S aureus, S choleraesuis, and P aeruginosa is 100 ppm.

Chlorine↗
PubMed1999

Chromatographic separation of carotenoids.

The carotenoids are extremely reactive and consequently unstable due to their long system of conjugated double bonds. Several precautions, such as protection against light and oxygen, use of low temperature and antioxidants, analysis in the shortest possible time, should be taken during isolation and chromatography. The food samples, preferably fresh, are homogenized and immediately extracted with a suitable organic solvent. Saponification has been employed in order to hydrolyze the carotenoid esters, remove fatty material and destroy chlorophyll. This optional step facilitates subsequent carotenoid separation, identification and quantification. The separation of carotenoids is usually carried out by column chromatography, thin layer chromatography and high performance liquid chromatography, in analytical or preparative scale, on many stationary phases such as silica-gel, alumina, MgO, Ca(OH)2 and reversed-phase material (C18 and C30). The choice of the most suitable chromatographic method depends on the amount of sample, carotenoid composition, resolution, speed and purity required. Examples of carotenoid separation in different stationary phases will be shown and discussed.

Carotenoids↗
PubMed2006

Analytical methods for the determination of persistent ingredients of personal care products in environmental matrices.

Concern about the environmental fate and potential effects of synthetic organic chemicals used in soaps, lotions, toothpaste, and other personal care products continues to increase. This review describes procedures used for the analysis of five classes of these compounds-synthetic musk fragrances, antimicrobials, ultraviolet filters, insect repellents, and parabens-in water, sediment, sewage sludge, air, and aquatic biota. The primary focus is on sample extraction and preparation methods for these compounds. Instrumental methods commonly used for these compounds are also discussed.

Animals↗
PubMed2002

Improved method for gas chromatographic-mass spectrometric analysis of 1-(13)C-labeled long-chain fatty acids in plasma samples.

BACKGROUND: Gas chromatographic-mass spectrometric (GC/MS) tracking of stable-isotope-labeled substrates is useful in metabolic studies. However, GC/MS analysis of long-chain fatty acid methyl esters yields results that mostly depend on their concentration in the system. We describe a protocol aimed to obviate this and other drawbacks in plasma [1-(13)C]palmitic and [1-(13)C]oleic acid measurements. METHODS: Lipoproteins were separated by sequential ultracentrifugation. Free or esterified heptadecanoic acid was used as internal standard. Fatty acids were derivatized to trimethylsilyl (TMS) esters. GC separation was in isothermal mode at 210 degrees C for 27 min. For both TMS-palmitate and TMS-oleate, M and [M + 1] signals were simultaneously acquired with a dual acquisition program in single-ion monitoring mode. Calibration mixtures containing increasing amounts of labeled fatty acids were prepared gravimetrically to construct calibration curves for isotopic enrichment. Likewise, five calibration curves (for increasing concentrations) were constructed for each fatty acid; this allowed selection of the most appropriate curve for the concentration in a plasma sample. RESULTS: Oleic acid-TMS ester was clearly separated from that of its stereoisomer, elaidic acid. Within a 10-fold concentration range, the isotopic ratio was independent on the amount of the analyte in the sample, with a maximum uncertainty of 0.34% in terms of molar percent excess. In addition, the within- and between-day imprecision (CV) of the method was <1%. CONCLUSION: Results obtained with this method are independent of concentration and sufficiently precise for tracking 1-(13)C-labeled palmitic and oleic acids in biological samples

Calibration↗
PubMed2002

Optimal DNA isolation method for detection of bacteria in clinical specimens by broad-range PCR.

Broad-range amplification of bacterial DNA from clinical specimens has proved useful for the diagnosis of various bacterial infections, especially during antimicrobial treatment of the patient. Optimal sample processing protocols for diagnostic broad-range bacterial PCR should release DNA from an array of target organisms with equal efficiencies and wash out inhibitory factors from various sample types without introducing bacterial DNA contamination to the amplification reaction. In the present study, two physical cell wall disintegration methods, bead beating and sonication, for enhanced detection of organisms with difficult-to-lyse cell walls were studied. The analytical sensitivities of several commercially available DNA purification kits, which were used with and without additional cell disintegration steps, were compared by using dilution series of model bacteria. Selected purification methods were used to process routine clinical specimens in parallel with the standard phenol-ether DNA extraction, and the results obtained by bacterial PCR and sequencing with the two template preparations were compared. The method with the DNA isolation kit with the lowest detection limits from the bacterial suspensions (Masterpure) did not prove to be superior to the standard method when the two methods were applied to 69 clinical specimens. For another set of 68 clinical specimens, DNA purified with a glass fiber filter column (High Pure) with an additional sonication step yielded results well in accord with those obtained by the standard method. Furthermore, bacterial DNA was detected in four samples that remained PCR negative by the standard method, and three of these contained DNA from gram-positive pathogens. Three samples were positive by the standard method only, indicating the limitations of applying any single method to all samples.

Bacteria↗
PubMed2006

High-performance liquid chromatographic method for the determination of moclobemide and its two major metabolites in human plasma.

A selective, sensitive, and simple high-performance liquid chromatographic (HPLC) method was developed for the determination of moclobemide and its two major metabolites, Ro 12-5637 and Ro 12-8095, in human plasma. Sample preparation (0.5 ml of plasma) involved solid-phase extraction (SPE) using Speedisk H(2)O-Philic DVB columns. Separations were performed on a Waters XTerra RP18 column (5 microm, 150 mm x 4.6 mm). The mobile phase consisted of 10 mM KH(2)PO(4) with 1% triethylamine (pH 3.9) and acetonitrile (83:17, v/v), and a flow-rate was 1.2 ml/min. The total run time was 13 min. UV detection was performed at 240 nm. Mean absolute recoveries were > or =90% and the limit of quantification (LOQ) for all analytes was 0.02 mg/l. Calibration curves were linear (r>0.995) over a wide range of the analyte concentrations in plasma; thus, the method is suitable for different clinical studies when large variations in the drug/metabolites concentrations are observed. During a 5-day assay validation procedure the accuracy and precision were tested and proven (relative errors (RE)< or =13%; intra-day coefficient of variation (CV)< or =7%; inter-day CV< or =13%). Many drugs frequently used in the target patient population were evaluated for potential interference in order method selectivity to be ensured. The assay has been used in a clinical pharmacokinetic study to assess steady-state pharmacokinetics of moclobemide and two metabolites in depressive patients on mono- and combined therapy.

Benzamides↗
PubMed2002

Development of a sample preparation method for the analysis of oxidized flavonols in onions and leek.

A method is presented for the determination of oxidized flavonols (i.e., hydroxybenzoylbenzofuranones) in plant material. Onions and leek are investigated using a newly developed solid-phase extraction procedure for sample preparation prior to high-performance liquid chromatography (HPLC). It is shown that the addition of ascorbic acid as antioxidant is necessary to prevent the generation of the researched analytes during this procedure. Nevertheless, the plant extracts do under certain conditions catalyze the oxidation of flavonoles resulting in benzofuranones.

Antioxidants↗
PubMed2005

Online concentration by field-amplified sample injection in acidic buffer for analysis of fangchinoline and tetrandrine in herbal medicine by flow injection-micellar electrokinetic capillary chromatography.

A novel, rapid, and continuous online concentration approach based on field-amplified sample injection for the analysis of fangchinoline and tetrandrine was developed in this paper by combination of flow injection-MEKC. The BGE used was a solution composed of 75 mM H3PO4-triethylamine-2.5% v/v polyoxyethylene sorbitan monolaurate-20% v/v methanol buffer (pH* 5.0). The analytes prepared in 50% v/v aqueous ethanol were used as the test analytes. Sample was injected electrokinetically between plugs of water. When the cations reached the boundary between the water plug and BGE, they slowed down and became concentrated. Thereafter, MEKC was initiated for the separation. This results in 6.8-8.9-fold improvement in concentration sensitivity relative to conventional CE methods. The separation could be achieved within 10 min and sample throughput rate can reach up to 50/h. The repeatability (defined as RSD) was 4.8, 4.4% with peak height evaluation and 3.6, 0.94% with peak area evaluation for TET and FAN, respectively.

Alkaloids↗
PubMed1993

Application of solid-phase extraction in the determination of U-82217 in rat serum, urine and brain.

The techniques of solid-phase extraction (SPE) were applied in the analytical method development for the determination of U-82217, 3-(5-cyclopropyl-1,2,4-oxadiazol-3-yl)-5-[(4-methoxyphenyl)methyl] -imidazo[1,5-a]quinoxalin-4(5H)-one, in rat serum, urine and brain. Samples of serum, urine or brain homogenate containing U-82217 were loaded on C18 SPE columns and eluted with acetonitrile (300 microliters). The prepared samples were analyzed by reversed-phase HPLC using an ODS column with a mobile phase of acetonitrile-water (45:55, v/v) containing 0.12% of acetic acid (pH 6.0 +/- 0.1). The UV absorbance of the column effluent was monitored at a wavelength of 318 nm. The absolute extraction recovery from serum, urine and brain samples was ca. 90%. Linear calibration graphs were obtained over the ranges 5 ng/ml-20 micrograms/ml (serum), 20 ng/ml-20 micrograms/ml (urine) and 50 ng/g-200 micrograms/g (brain). The intra- and inter-assay precision and accuracy were all found to be < 13% at the concentrations evaluated. The strategy in SPE development and the application of this method to the determination of U-82217 in rat serum and brain for a pharmacokinetic study are also discussed.

Animals↗
PubMed1983

A new direct solid-phase radioimmunoassay for carcinoembryonic antigen without pretreatment of serum samples.

We examined some fundamental conditions for establishing a new simplified radioimmunoassay system for CEA. The system consists of antibody-coated plastic beads and radiolabeled tracer antibody. The reactivity of this system with several purified CEA preparations can vary due to differences in the nature of antibody preparations used either for coating beads or for tracer antibody. Among purified CEA preparations, we also found some differences in reactivity with a given immobilized antibody preparation. The assay system that resulted, referred to as bead-direct-RIA, needs neither pretreatment of serum samples nor centrifugation in any of its steps, and has a wide assay range, measuring CEA concentrations of 1-300 ng/ml using only 50 microliters of a serum sample. Its accuracy, reproducibility, dilution effect, and analytical recovery proved the reliability of this method. The mean value +/- S.D. for 48 normal adults was 2.5 +/- 1.0 ng/ml. It was found by comparative studies that the Z-gel method of Hoffmann-La Roche generally gave the highest values, the antibody-disc method of Dainabot gave the lowest, and the values by bead-direct-RIA fell between those of the 2 other methods and correlated well with either value. Follow-up studies on patients with malignancy indicated that the values by bead-direct-RIA fluctuated in parallel with those by Roche and Dainabot kits.

Antibodies, Neoplasm↗
PubMed1993

HPLC method for rapid determination of acetylator phenotype by measuring urinary caffeine metabolites.

A validated reversed-phase high-performance liquid chromatographic (RP-HPLC) method is developed for the selective and rapid determination of two major metabolites of caffeine, namely 5-acetylamino-6-formylamino-3-methyluracil (AFMU) and 1-methylxanthine (MX) from human urine. HPLC separation is achieved by means of a Supersphere-60 RP-Select B (4 microns) analytical column using a non-linear gradient elution programme of 70-95% solvent B (2.5% acetic acid-methanol, 60:40, v/v) in solvent A (water-acetonitrile, 80:20, v/v). A selective UV detection method is used for determination of AFMU, MX and internal standard with readings at 284, 268 and 248 nm, respectively. Urine samples are prepared for measurement by a simple chloroform-diethyl ether (80:20, v/v) extraction. The assay is validated with respect to linearity, sensitivity, accuracy, precision and system suitability. All validation parameters are found to be within the required limits. The limit of detection of AFMU and MX is found to be 50 ng/200 microliters urine. Calibration curves show good linearity between 0.1 and 5 micrograms/200 microliters urine concentration range for both metabolites. The assay is sufficiently sensitive and rapid (4.5 min chromatographic run) to be applied for routine monitoring of change in AFMU/MX molar ratio, indicating acetylation phenotype and change of caffeine metabolism in clinical cocktail studies.

Caffeine↗
PubMed2006

Global methods for protein glycosylation analysis by mass spectrometry.

Mass spectrometry has been an analytical tool of choice for glycosylation analysis of individual proteins. Over the last 5 years several previously and newly developed mass spectrometry methods have been extended to global glycoprotein studies. In this review we discuss the importance of these global studies and the advances that have been made in enrichment analyses and fragmentation methods. We also briefly describe relevant sample preparation methods that have been used for the analysis of a single glycoprotein that could be extrapolated to global studies. Finally this review covers aspects of improvements and advances on the instrument front which are important to future global glycoproteomic studies.

Acetylglucosamine↗
PubMed2004

Solid-phase microextraction-gas chromatography-mass spectrometry for the analysis of selective serotonin reuptake inhibitors in environmental water.

The continuous contamination of surface waters by pharmaceuticals is of most environmental concern. Selective serotonin reuptake inhibitors (SSRIs) are drugs currently prescribed for the treatment of depressions and other psychiatric disorders and then, they are among the pharmaceuticals that can occur in environmental waters. Solid-phase microextraction (SPME) coupled to gas chromatography-mass spectrometry has been applied to the extraction of five SSRIs--venlafaxine, fluvoxamine, fluoxetine, citalopram and sertraline--from water samples. Some of the analytes were not efficiently extracted as underivatized compounds and so, an in situ acetylation step was introduced in the sample preparation procedure. Different parameters affecting extraction efficiency such as extraction mode, fiber coating and temperature were studied. A mixed-level fractional factorial design was also performed to simultaneously study the influence of other five experimental factors. Finally, a method based on direct SPME at 100 degrees C using polydimethylsiloxane-divinylbenzene fibers is proposed. The performance of the method was evaluated, showing good linearity and precision. The detection limits were in the sub-ng/mL level. Practical applicability was demonstrated through the analysis of real samples. Recoveries obtained for river water and wastewater samples were satisfactory in all cases. An important aspect of the proposed method is that no matrix effects were observed. Two of the target compounds, venlafaxine and citalopram, were detected and quantified in a sewage water sample.

Gas Chromatography-Mass Spectrometry↗
PubMed2004

The determination of trace metal pollutants in environmental matrices using ion chromatography.

A review is presented detailing the development of ion chromatography (IC) as a selective analytical tool for the determination of toxic metals and their organic species in many environmental sample matrices. A brief outline of ion chromatographic principles, together with an overview of the stationary phases used to separate metals, namely ion exchangers, modified ion pair sorbents and chelating ion exchangers, and the methods for detecting metal ions including hyphenation with spectroscopy and sample preparation schemes are also given, prior to a critical examination of developed methods for various metals including arsenic, chromium, cadmium, lead, mercury, beryllium, aluminium and uranium since 1990.

Chromatography, Ion Exchange↗
PubMed1999

Automated gas chromatographic method for the determination of ethanol in canned salmon.

A method has been developed for the determination of ethanol in canned salmon using automated headspace sampling in conjunction with analysis by gas chromatography. The thermal process for the commercial sterilization of canned salmon is shown to provide an effective extraction of the ethanol so that the fluid removed from the can may be used as the analytical sample with minimal preparation prior to analysis. Ethanol content is measured directly, without the need for an internal standard, by either GC/MS or GC/FID. The headspace autoanalyzer allows for a rapid determination of ethanol with greater reproducibility than could be obtained with manual injection systems. The GC/MS technique can also provide an advantage in that simultaneous single ion monitoring of the two major ethanol ions provides additional protection from interferences. To assess the applicability of this technique to other substrates, Atlantic sea scallop meats were also successfully analyzed by this technique.

Animals↗
PubMed2002

Estimation and correction of matrix effects in gas chromatographic pesticide multiresidue analytical methods with a nitrogen-phosphorus detector.

The assessment of matrix effects in the quantification of organophosphorus pesticides in fruit and vegetables by GC-NPD, were studied applying ANCOVA. Calibration curves prepared in solvent were compared with calibration curves prepared in a blank matrix extract for eight different commodities, establishing whether the matrix induces systematic or proportional errors in the quantification of the pesticides. In such cases correction functions were obtained and validated by quantifying spiked samples using solvent calibrations and applying the correction functions to the data obtained. The results were compared with those obtained by quantification using matrix-matching calibrations and with those from 100% recovery experiments. It was found that the matrix effects can be avoided using the correction functions. Finally the contribution of the correction functions to the uncertainty of the results was estimated as well as their stability during a four month period.

Calibration↗
PubMed2001

[Identification of proteome molecules by proteomics using two-dimensional gel electrophoresis and MALDI-TOF MS].

Genomic technologies have enabled rapid accumulation of information from complex biological systems over the last two decades. The complete DNA sequence is now known for many organisms and the informational database obtained from genome sequencing projects has provided the base for the specification of proteome - the protein complement of genome. Genomic functions can be inferred from the analysis of gene structure and gene expression profiles because proteins are the functional molecules of an organism. Integrated technologies including protein separation, identification, characterization and information manage system are essential to analyze the proteins in complex cellular matrix. This study is focusing on the strategies of proteome analysis using sample preparation, 2-dimensional gel electrophoresis, processing of protein spots and identification of proteins, protein-protein interaction and posttranslational modification using MALDI-TOF-MS. 2-D gel electrophoresis is currently the most powerful protein separation technique and MALDI-TOF MS is powerful identification technique for protein and peptides as a sensitive, rapid, and high resolution analytical method. The developed integrated proteome technologies are very useful to understand the biological phenomena at molecular level by identifying the new molecules and their modifications in various cellular processes, and can be applied for biotechnology including medical science.

Databases, Protein↗
PubMed1978

Surface and in-depth analysis of biological and organic materials by ion scattering spectroscopy (ISS).

In recent years, new surface analytical techniques such as auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS), and ionscattering spectroscopy (ISS) have been developed. Some of these techniques have been used for the analysis of biological and organic materials with moderate success due to the problems inherent in the nature of these samples. The preparative techniques also complicate the application of many instrumental methods. Detailed studies to characterize fish scales taken from different environments, structural investigations on organo-metallic complexes, and analysis of human hair are presented to demonstrate the usefulness of ion scattering spectroscopy.

Animals↗