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1.
Nanometer-sized l-cysteine-capped ZnS particles have been synthesized and used as a fluorescence probe to investigate the effect of proteins on fluorescent intensity. With =190 nm, maximum and constant synchronous fluorescence enhancement was produced at 267 nm and pH 5.12 in the presence of proteins. A highly sensitive synchronous fluorescence method for the rapid determination of proteins has been developed. Under optimum conditions, calibration graphs are linear over the range 0.03–8.0 g mL–1 for bovine serum albumin (BSA), 0.01–6.0 g mL–1 for human serum albumin (HSA), 0.05–8.0 g mL–1 for -globulin (-G), and 0.04–4.0 g mL–1 for ovalbumin, respectively. The relative standard deviations of seven replicate measurements were 1.75% for 1.0 g mL–1 BSA, 1.90% for 1.0 g mL–1 HSA, 1.65% for 1.0 g mL–1 -G, and 2.32% for 1.0 g mL–1 ovalbumin.  相似文献   

2.
Summary A gas chromatographic methodology with selective detection is presented for the analysis in wines and corks of pentachlorophenol residues, which are suspected to be the most likely precursors of some off-flavours described in several wine samples. After derivatisation, pentachlorophenol acetate residues were monitored by electrolytic conductivity detection and/or mass spectrometric detection in the selective ion mode at m/z 264 and 266. Recoveries varied from 80 to 96% for wine samples fortified with 5 to 100 g l–1 and from 83 to 91% for corks (fortified at 25 to 100 g kg–1). The proposed methodology allowed for a determination limit of g l–1 for wine and 10 g kg–1 for corks.  相似文献   

3.
Arsenic in sea water was determined directly by graphite furnace atomic absorption spectrometry (GFAAS) using palladium nitrate as chemical modifier, at an optimum concentration of 15 mg l–1. Deuterium and Zeeman effect background correction were compared and gave detection limits of 0.6 and 0.8 g l–1, respectively. Precisions between 8 and 2%, for both correctors, were obtained with an injection volume of 40 l. The accuracy obtained with different reference materials: CRM-403 (1.461 g kg–1), NASS-4 (1.26 ±0.09 gl–1) and IAEA/W-4 (24–31 g l–1) was studied for large injection volumes for both background correction systems. Interferences by chloride, sodium, potassium, calcium and silicon were removed by Zeeman correction, whereas deuterium correction was much less effective and was insufficiently accurate for sea water samples.  相似文献   

4.
The interference contributions of uranium and thorium to the determination of cerium based on radionuclides141Ce and143Ce produced by irradiation in a reactor core was determined. The values of the interference contributions for141Ce were 0.28±0.01 g Ce/g U and /2.01±0.05/x10–3 g Ce/g Th, and for143Ce 1.33±0.03 g Ce/g U and /9.0±0.2/x10–3 g Ce/g Th.  相似文献   

5.
The optimum conditions for the extractive spectrophotometric determination of dioxouranium(VI) with hexamethyleneiminecarbodithioate(HMICdt) have been established. Dioxouranium(VI) reacts with this ligand at pH 4.5 to form a yellowish-orange uncharged 12 metal-ligand complex which can be extracted by chloroform. The calibration graph was linear in the range of 1–20 g ml–1 of dioxouranium(VI) at 335 nm. The molar absorptivity of the extracted species is 5.952×103 l mol–1 cm–1 with Sandell's sensitivity of 0.04 g cm–2. The average of 10 determinations of dioxouranium was 49.75 g for the samples containing 50 g of U(VI) and the variation from the mean at 95% confidence limit was 49.75±0.5955.  相似文献   

6.
Binuclear and trinuclear transition-metal -allenyl complexes—especially mixedmetal complexes—are reviewed. In recent years, a number of such compounds have been prepared by use of several synthetic methods. The most general of these methods, viz. reactions of metal propargyls and of the lower nuclearity metal allenyls with low-valent metal complexes such as metal carbonyls and platinum(0) compounds, are considered in some detail. The structures of the binuclear metal -1,2- and -3,2-allenyl complexes and of the trinuclear metal 3-1,2,2-allenyl complexes—both triangular and open—are presented and compared. Trends in the1H and13C NMR spectroscopic properties of these compounds are examined. Some aspects of reaction chemistry of the heteronuclear platinum-ruthenium -1,2-allenyl complexes are presented.  相似文献   

7.
Summary A simple multi-residue procedure has been developed and applied to the analysis of pesticides in groundwater samples from the Comunidad Valenciana, a predominantly agricultural area on the Mediterranean coast of Spain. The procedure includes a liquid-liquid extraction, after addition of NaCl on the samples, and a subsequent analysis by capillary gas chromatography using a dual detection system with electron capture and nitrogen-phosphorous detectors. This allows the determination of more than 30 compounds (organophosphorous, organochlorine and pyrethroid pesticides) at the low ppb (g l–1) levels. Detection limits obtained varied between 0.01 g l–1 (lindane, fonofos) and 0.5 g l–1 (cypermethrin). An additional injection of the sample extracts into a gas chromatograph equipped with a column of different polarity and electron capture detector is used for the confirmation of chromatographic peaks. The recommended procedure has been applied to 66 ground water samples. Pesticides, including organophosphorus and organochlorine compounds were detected in 31 of them, in levels ranging from 0.02 to 0.7 g l–1.  相似文献   

8.
Summary Two packing materials, C18 and PLRP-S, are studied for on-line trace enrichment of phenolic compounds in water. Various precolumns of different internal diameter are also tested and the addition of an ion-pair reagent to increase retention and thus, breakthrough volumes of phenolic compounds, is studied. Best results are obtained when a PLRP-S precolumn is coupled on-line with a C18 analytical column and DAD detector. Addition of TBA considerably increases breakthrough volumes. In contrast, when a C18 precolumn is used, breakthrough volumes are lower and it is impossible to determine TCP and PCP, under the experimental conditions used, because of interference of other nonpolar compounds in the samples. The performance of the system is evaluated with river and tap water and the preconcentration of 10 ml of sample in a PLRP-S precolumn involves a linear range between 1 g 1–1 and 20 l–1 and limits of determination between 0.5 g l–1 and 1 g l–1 are obtained.  相似文献   

9.
Zusammenfassung Eine neue Methode zur Durchführung gravimetrischer Bestimmungen im Mikrogrammbereich wurde beschrieben; diese beruht im wesentlichen darauf, daß der Niederschlag nicht mehr zusammen mit dem Filter, sondern nach Überführen mit einem geeigneten Lösungsmittel in einem separaten Wägegefäß gewogen wird.Die dazu nötigen Geräte und deren Herstellung wurden beschrieben. Nach dieser Methode wurden folgende Bestimmungen mit zufriedenstellender Richtigkeit durchgeführt: 2,5–25g Al, 5–50g Cu und 5–50g Zn mit Oxin, 2,5–25g Fe(III) und 2,5–25g Ti(IV) mit N-Benzoyl-phenylhydroxylamin, 5–50g Ni und 5–50g Cu mit Salicylaldoxim, 2,5–50g Co(II) und 2,5–50g Fe(III) mit -Nitroso--naphthol sowie 5–50g Chlorid als Silberchlorid.
Precipitation analysis in the microgram-scale: A new method
Summary A new method for gravimetric determinations in the microgram-scale is described. This method is based on the fact that the precipitate is not weighed together with the filter but is transferred to a separate weighingvessel using a suitable solvent. The necessary simple devices and their use are described. The following determinations were carried out with satisfying accuracy: 2,5–25g Al, 5–50g Cu and 5–50g Zn with Oxine, 2,5–25g Fe and 2,5–25g Ti withN-benzoylphenylhydroxylamine, 5–50g Ni and 5–50g Cu with salicylaldoxime, 2,52–50g Co and 2,5–50g Fe with -nitroso--naphthol and 5–50g chloride as silver chloride.
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10.
A sub-micrometer thin-layer DNA modified carbon fiber microcylinder electrode was prepared by electrodeposition of ct-DNA at 1.5V (vs. Ag/AgCl). The voltammetric behavior of dopamine (3-hydroxytyramine) was investigated at the modified electrode. It was found that the modified electrode exhibits a highly electrocatalytic activity toward dopamine oxidation. Differential pulse voltammetry was used for determination of dopamine in pH 7.4 phosphate buffer solution. A linear response of the peak current versus the concentration was found in the range of 4×10–6 to 10–4molL–1 at 10–4molL–1 AA (ascorbic acid) coexistence (R=0.9959) and the range of 6×10–5 to 10–3molL–1 at 10–3molL–1 AA (R=0.9960). The presence of a high concentration of ascorbic acid did not interfere with the determination. The proposed method exhibited good recovery and reproducibility. This method can be applied to the detection of DA in real samples.  相似文献   

11.
ET-AAS is investigated for the analysis of high purity mercury. Two possibilities are proposed: ET-AAS determination of trace analytes in the presence of high mercury concentrations or after matrix separation by reduction. The ET-AAS analysis of high-purity mercury under optimal instrumental parameters permits fast and reproducible determination of 0.03 gg–1 Al, Cd and Mn; 0.05 gg–1 Cu, Co, Cr, Fe, Ni and Pb and 0.2 gg–1 V. Preliminary mercury matrix reductive separation with ascorbic acid allows determination of 0.005 gg–1 Cd, 0.02 gg–1 Cu, Cr and Mn, 0.03 g g–1 Co, Ni and Pb, 0.05 g g–1 Al and Fe and 0.1 gg–1 V, but the reproducibility is lower. The main advantage of the second procedure is that it avoids laboratory and instrument pollution with toxic mercury.  相似文献   

12.
The aim of the present study was to develop a sensitive method to measure dextromethorphan and dextrorphan in urine by HPLC to support pharmacogenetic studies in ethnic groups. Linearity was assessed in the range: 0.015–10 g mL–1 for dextromethorphan and 1-10 g mL–1 for dextrorphan. Inter and intra-day coefficients of variation were < 10%. Limits of detection and quantitation were 0.003 g mL–1 and 0.015 g mL–1 for dextromethorphan and 0.24 g mL–1 and 1.0 g mL–1 for dextrorphan, respectively. The method is reliable in helping determine the phenotype of Mexican ethnic groups using model drugs such as dextromethorphan.  相似文献   

13.
Preconcentration of trace transition and heavy metal ions by precipitation with APDC has been combined with energy-dispersive X-ray fluorescence for environmental sea water analysis. The preconcentration procedure implies adding of 500 g Mo ion and 10 ml of 1% water solution of APDC to a 500 ml water sample at pH 4, filtering off on a Millipore filter and analyzing after drying. Realistic detection limits are at 1 g·l–1 level and precision varies between 10–25% at about 5 g·l–1 level, depending on the element. Eleven sea water samples, covering Albanian Adriatic and Ionian coast, are analyzed for trace metal ions.  相似文献   

14.
Inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine the concentration of platinum (Pt) in silicone breast implant gel (range, 0.26–48.90 g g–1 Pt; n=15), elastomer (range, 3.05–28.78 g g–1 Pt; n=7), double lumen (range, 5.79–125.27 g g–1 Pt; n=7), foam (range, 5.79–8.36 g g–1 Pt; n=2), and capsular tissue (range, 0.003–0.272 g g–1 Pt; n=15). The results show that very high levels of Pt are present in the encasing elastomer, double lumen, and foam envelope materials. Silicone breast implants can be a source of significant Pt exposure for individuals with these implants.  相似文献   

15.
Summary The hydrocarbon composition of the particle and gas phases in the urban atmosphere has been studied by filtration and parallel adsorption on active charcoal and polyurethane foam (PUF). Gas chromatography (GC) and GC coupled to mass spectrometry (GC-MS) have been used for the analysis of the organic matter extracts obtained with each system. In the case of the particle and PUF samples these extracts were fractionated into aliphatic and aromatic compounds. This approach has allowed to identify up to 247 hydrocarbon molecules showing that C0–C5 alkylbenzenes are the major compounds in the charcoal extracts whereas C14–C23 n-alkanes, C0–C4 alkylnaphthalenes, C0–C4 alkylbiphenyls and C3–C5 alkylbenzenes are those predominantly found in the PUF materials. The particles essentially contain C17–C38 n-alkanes and parent polycyclic aromatic hydrocarbons (PAH). These qualitative differences are paralleled by a progressive concentration decrease from the more to the less volatile hydrocarbons. Thus, the total charcoal extracts average 80 g/m3, the PUF compounds represent 4 /m3 and the particle hydrocarbons 0.7 g/m3. These latter airborne materials are essentially composed of petrogenic residues 0.6 g/m3 (aliphatic fraction) whereas the pyrolytic PAH only involve 0.08 g/m3.  相似文献   

16.
A method for the determination of aldrin, dieldrin, DDT, DDE, and DDD contamination in animal fats (beef tallow, lard, and chicken fat) without using toxic reagents is developed, that uses high-performance liquid chromatography after the sample has been prepared by matrix solid-phase dispersion (MSPD) with acidic alumina oxide. A reversed-phase C1-silica column with a mobile phase of 50% (v/v) ethanol solution (in water) and a photo-diode array detector were used for the determination. Average recoveries of the target compounds (0.2–5.0 g g–1) ranged from 84–98%, with coefficients of variation of <5%. The limits of quantitation were 0.16 g g–1 for AD, 0.10 g g–1 for DD, 0.06 g g–1 for DDT, 0.07 g g–1 for DDE, and 0.05 g g–1 for DDD. No toxic reagents were used at all.  相似文献   

17.
Summary In natural waters, heavy metals such as Cd may be present in bound form. It is, therefore, important to consider chemical speciation, especially at low concentrations of the metal where a significant part can be bound by other trace constituents so tightly that it escapes several forms of its determination. It has been demonstrated that even the very strong complexant APDC is unable to leach out all of the heavy metal present in several coastal water samples from the German Bight.This paper describes a new micro method for the determination of total Cd in natural waters. First a small sample is dried in a polypropylene vial. Then the salt residue is heated to 90° C with a mixture of sulphuric and nitric acid for digestion of organic trace constituents (and oxidation of sulphides if present). After dilution subsamples are neutralized using an excess of NaHCO3 buffer solution. Extraction results are then independent from the possible slight variations of pH. The extractant, a solution of APDC in CCl4 is stable for weeks, and even the extract is stable for at least 16h. Precision is in the range of 7% at a concentration of 0.066 g Cd l–1; the detection limit is below 0.002 g l–1 and can be lowered, if necessary, by enlargement of the original sample. According to the sensitivity of the method the typical blank of 0.022 g Cd l–1 is high, but it is rather constant (mean variation from the mean: 0.0024 g l–1).Teil XI: Fresenius Z. Anal. Chem. 299, 206–207 (1979)  相似文献   

18.
The formation of nucleic acids/8-hydroxyquinoline/yttrium(III) ternary complexes and their fluorescent properties have been studied. The nucleic acids studied include native and thermally denatured calf thymus DNA, fish sperm DNA and yeast RNA. In the range of pH 7.6–8.5, controlled by NH3-NH4C1 buffer, ternary complexes are formed that fluoresce at different wavelengths with different nucleic acids. Based on the fluorescence reactions, sensitive spectrofluorimetric methods for nucleic acids are proposed. In optimal conditions, the calibration curves were linear in the range 0.5–4.0 gml–1 for calf thymus DNA, 0.5–2.5 g ml–1 for fish sperm DNA and 0.5–4.0 g ml–1 for yeast RNA. The limits of determination (3 ) were 0.030 g ml–1 for calf thymus DNA, 0.020 g ml–1 for fish sperm DNA and 0.090 g ml–1 for yeast RNA. Corresponding to the interferences of coexisting substances, six synthetic samples were constructed and the results of determination were satisfactory.  相似文献   

19.
The determination of trace metals, e.g. Bi, Cd, Pb, in high-purity aluminium, zinc and commercial steel by flame or graphite furnace atomic absorption spectrometry following their preconcentrations as iodo complexes on XAD-1180 resin by means of a short column system is described. The recoveries are quantitative (95%). The relative standard deviations varies between 6% and 10%. The relative errors are less than 8% in a concentration range of 1 × 10–3 –4 × 10–5%. Detection limits for flame AAS and GFAAS were in the ranges of 0.002–0.110 g/ml and 0.0003–0.004 g/ml or in the ranges of 0.08–4.40 g/g and 0.012–0.16 g/g with respect to the solid samples, respectively.  相似文献   

20.
This paper presents a new method for the determination of Hg(II) in waters, using indirect spectrophotometric measurements of the Hg(II) dithizone complex. The reagent is a mixture of dithizone, CDTA (1,2-cyclohexylene-dinitrilo-tetraacetic acid), thiourea, ethylic alcohol and glycine. Sensitivity and working range are 0.4 g · l–1 and 2–100 g · l–1, respectively. A comparison of the results with those of the cold-vapor atomic absorption spectrometry shows a good correlation for different samples revealing only small interferences. The new method is well suited for on-line measurements, easy to run and has low cost equipment.  相似文献   

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