Showing papers on "Detection limit published in 1970"
53 citations
TL;DR: In this article, a new method for continuous recording of the hydrogen content of atmospheric air is described, based on reduction of mercuric oxide and determination of the resulting mercury vapor by absorption in the 2537-A line.
Abstract: A new method for continuous recording of the hydrogen content of atmospheric air is described. The method is based on reduction of mercuric oxide and the determination of the resulting mercury vapor by absorption in the 2537-A line. The standard error of the calibration for 0.5 ppm H2 is 3%. The limit of detection is 0.01 ppm. Preliminary results are discussed.
47 citations
TL;DR: The absorptiometric assay was used in the determination of blood level fall-off curves and urinary excretion of each compound in a dog following the administration of single 10-mg./kg dose, while the GLC assay was use to extend the limits of detection of the absorpt iometric assay and to determine the blood level falls-off curve in man following a single oral 50-mg.
43 citations
TL;DR: In this article, a chemical exchange reaction between ferric iron and bismuth-EDTA at pH 4.0 was used to determine iron by anodic stripping voltammetry.
40 citations
TL;DR: The PFBO derivative showed excellent detection enhancement, and consequently it was chosen for further study with the drugs amphetamine and various ephedrines Linear electron capture detector responses were shown by these N-acyl derivatives in the sub-nanogram region and the limits of detection, depending upon the specific compound, were between 10 and 60 pg.
Abstract: β-Phenylethylamine was converted to its trifluoroacetamide (TFA), pentafluoropropionamide (PFP), heptafluorobutyramide (HFB), pentadecafluorooctanamide (PDFO) and pentafluorobenzamide (PFBO) derivatives The gas chromatographic characteristics and flame ionization versus electron capture detection properties were investigated The PFBO derivative showed excellent detection enhancement, and consequently it was chosen for further study with the drugs amphetamine and various ephedrines Linear electron capture detector responses were shown by these N-acyl derivatives in the sub-nanogram region and the limits of detection, depending upon the specific compound, were between 10 and 60 pg It is proposed that the PFBO derivative, subsequent to the development of an isolation procedure, will prove admirably suitable to the determination of these and similar drugs in plasma after administration of therapeutic dosages
27 citations
TL;DR: The reproducibility of the method was demonstrated by the consistent estimates obtained for the concentrations of noradrenaline, dopamine and 3‐methoxytyramine in whole rat brain, and the recoveries of exogenous amines taken through the procedure were low and very variable.
Abstract: 1. A method is described whereby the catecholamines, their precursors and metabolites may be estimated in the same brain sample. The method, outlined below, was rigorously tested in pure solution before being applied to the estimation of the catechol and methoxyamines in extracts of rat brain. (i) The brain tissue was homogenized in perchloric acid and the perchloric acid removed as its insoluble potassium salt. (ii) The acid metabolites of the amines were extracted from the acidified extract into ethyl acetate. (iii) After extraction with ethyl acetate, the aqueous extract was treated with acetic anhydride and sodium hydrogen carbonate and the acetylated derivatives of the amines extracted into dichloromethane. (iv) The aqueous solution remaining after extraction with dichloromethane contains the acetylated amino-acids. Acetyl-dopa could be extracted into dichloromethane only after acidification of this aqueous solution. The acetyl-dopa in this dichloromethane extract could be estimated fluorimetrically. (v) The dichloromethane extract containing the acetylated amines was chromatographed on paper in the organic phase of a mixture of toluene:ethyl acetate:methanol:water, 10:1:5:5. (vi) The acetylated amines were eluted and estimated fluorimetrically. A new method was developed for the estimation of 3-methoxytyramine and its acetylated derivative.
2. The reproducibility of the method was demonstrated by the consistent estimates obtained for the concentrations of noradrenaline, dopamine and 3-methoxytyramine in whole rat brain. Adrenaline and metanephrine were not detected. The concentration of normetanephrine in rat brain was at the limit of detection of the method.
3. Although the estimation for the levels of endogenous amines in whole rat brain were consistent, the recoveries of exogenous amines taken through the procedure were low and very variable. Control experiments demonstrated that the exogenous amines were lost at the perchloric acid extraction stage of the procedure.
25 citations
TL;DR: In the procedure described, beryllium is isolated by solvent extraction in the form of a volatile, thermally stable chelate with trifluoroacetylacetone, and is then determined by gas chromatography with an electron-capture detector.
Abstract: The toxic nature of beryllium necessitates the use of a sensitive method for its detection. Present methods are not entirely satisfactory and the use of gas chromatography for the detection and determination of beryllium has been advocated. In the procedure described, beryllium is isolated by solvent extraction in the form of a volatile, thermally stable chelate with trifluoroacetylacetone, and is then determined by gas chromatography with an electron-capture detector. Results are presented for the determination of aqueous beryllium solutions and for beryllium contained in urine. Satisfactory results were obtained with both direct solvent extraction and solvent extraction after wet oxidation of the sample. The rate of excretion of beryllium by rats was measured by this method. The procedure is rapid, reliable and sensitive; the limit of detection is l ng ml–1.
22 citations
TL;DR: A detecting system incorporating an interference filter is described for use in atomic-fluorescence spectroscopy analysis in the 200.0-300.0 nm spectral region, and results are compared with those from either a monochromator or a solar-blind photomultiplier.
21 citations
TL;DR: An automated method for the determination of boron in sewage, sewage effluents and river waters on the Technicon AutoAnalyzer is described in this paper, where the reaction of carminic acid with borons in concentrated sulphuric acid is used.
Abstract: An automated method for the determination of boron in sewage, sewage effluents and river waters on the Technicon AutoAnalyzer is described The reaction of carminic acid with boron in concentrated sulphuric acid is used The limit of detection is about 0·02 mg l–1 of boron and the standard deviation is ±0·03 mg l–1 at concentrations of 3·0 mg l–1 of boron The interference of nitrate and its suppression by the use of phenol are examined
19 citations
TL;DR: In this article, the authors described the evaluation of polycyclic aromatic compounds, separated by thin-layer chromatography on acetylated cellulose, by means of a spectrofluorometer.
18 citations
TL;DR: In this paper, the authors used instrumental neutron activation analysis and Ge(Li) gamma-ray spectroscopy in biological and environmental samples to determine the presence of mercury in the 279 keV gamma ray.
Abstract: Mercury is determined by instrumental neutron activation analysis and Ge(Li) gamma-ray spectroscopy in biological and environmental samples. Samples are sealed in polyethylene vials and irradiated with standards for 8–10 hours in a water cooled assembly at a thermal neutron flux of 8.1012 neutrons/cm2/second. High resolution gamma-ray spectroscopy allows the measurement of the 279 keV gamma ray of203Hg. Corrections are made for203Hg decay and for75Se interference on the 279 keV gamma-ray. No interferences are important in biological or environmental samples and the problem of mercury volatilization and loss is eliminated by cooling during irradiation and the use of a sealed irradiation/counting container. The precision (counting statistics) of a single determination range from 0.4 to 15% (relative standard deviation). The detection limit for mercury varies with sample composition. For human blood the detection limit is 0.0035 ppm Hg.
TL;DR: In this article, a device for the automatic determination of iodine with a continuously operating ashing oven was built for PBI determinations, which requires simple servicing and is suitable to make 30 analyses per hour.
TL;DR: The specific determination of traces of nicotinamide and nicotinic acid by a combination of thin-layer chromatography and direct fluorescence spectroscopy is described and compares favourably with reflectance spectroscopic and fluorescence quenching techniques.
TL;DR: Specifications and blank evaluations for the spectrophotofluorometric detection of serotonin and serotonin after reaction with ortho-phthaldialdhyde (O.P.T.) are presented and it is indicated that the characteristic serotonin-O.T. wavelength was a composite of peaks at 459 and 490 nm.
Abstract: Specifications and blank evaluations for the spectrophotofluorometric detection of serotonin and serotonin after reaction with ortho-phthaldialdhyde (O.P.T.) are presented. Sensitivity (detection limit) and precision for the serotonin-direct method were 55.9 ng./ml. and 2.7 ng./fluorescence intensity unit, respectively. There was a linear relationship between serotonin concentration and fluorescence produced in the range 2,797 ng./ml. to the detection limit. Blank fluorescence was composed of scattering, reagent, reagent and glassware contaminants and tissue components. The largest and most variable of these exhibited a peak of maximal fluorescence at ca. 400 nm. wavelength. It arose primarily from glassware and reagent contaminants and was not easily controllable. The blank altered the height and configuration of the serotonin spectrum producing atypicallity and resulting in inability to obtain an accurate reading for the serotonin component. No single common blank could be produced or described for correction of all specimens. The tissue blank for mid-jejunum was less than 0.2% of gross serotonin fluorescence at 545 nm. wavelength. Computer analyses indicated that the serotonin-O.P.T. blank was composed of peaks at the following wavelengths: 389, 407, 426, 448, 474 and 507 nm. A single chloroform wash was found to remove blanks peaking at 389, 426 and 474 nm. wavelengths eliminating atypicallity and permitting a more accurate reading of serotonin-O.P.T. at 473 nm. wavelength. A common reagent blank was also achieved. The chloroform wash produced a 17% loss of serotonin-O.P.T. Computer analyses further indicated that the characteristic serotonin-O.P.T. peak at 473 nm. wavelength was a composite of peaks at 459 and 490 nm. The use of O.P.T. permitted the fluorometric detection of serotonin down to a concentration of 12.3 ng./ml. with a precision of 0.1 ng./fluorescence intensity unit, and with standard linearity from 313 ng./ml. to the detection limit. These specifications represented 4.5- and 27.3-fold increases in sensitivity and precision, respectively, over the serotonin-direct method. The use of O.P.T. with a chloroform wash increased detection sensitivity to 75 ng./ml.; precision remained unaffected.
TL;DR: In this article, the use of a Ge(Li-drifted) semiconductor detector and gamma-ray sources with radio-isotopic sources provides an X-ray analytical method that is advantageous for the determination of high-Z elements in ores.
TL;DR: In this article, a procedure was described which incorporated acetone solutions to increase the platinum sensitivity to 3 μg ml−1 for 1% absorption and the detection limit to 1 p.p.m.
TL;DR: In this paper, a 10-mg Ag bead containing the precious metals, as extracted by fire assaying, is arced at 8 A dc in graphite electrodes in the presence of 10 mg of either Rh or Pt metal powder.
Abstract: A method has been developed for the determination of microgram levels of Pt, Pd, Rh, and Au. A 10-mg Ag bead containing the precious metals, as extracted by fire assaying, is arced at 8 A dc in graphite electrodes in the presence of 10 mg of either Rh or Pt metal powder. The matrix elements, Ag and Pt, or Rh, serve as internal standards, and intensity ratios Pt/Rh or Rh/Pt, Pd/Rh, and Au/Ag are determined. Precision of the method is about ±5% coefficient of variation for Pt and Rh, ±15% for Pd, and ±19% for Au. Limits of detection are below 1 μg, giving analysis limits (for a 1-assay-ton sample) of about 1–30 ppb for these precious metals.
TL;DR: In this article, a spark source mass spectrograph was used to analyze aqueous solutions by sparking to frozen drops of the sample solution, and the minimum detection limit obtained from a 10−8 coulomb exposure was about 5 × 10−7 M solution concentration.
Abstract: Aqueous solutions can be analyzed directly in a spark source mass spectrograph by sparking to frozen drops of the sample solution. The minimum detection limit obtained from a 10−8 coulomb exposure is about 5 × 10−7 M solution concentration. Analytical precision of 8 to 30% relative is achieved through use of an internal standard added to the sample solution.
01 Jan 1970
TL;DR: In this article, the determination of residual pesticides beta sifiutrin in potato (Solanum tuberosum L) was conducted by Gas Chromatography (GC), the separation was conducted on a 08-1 (30mxO.25pm) coloum, using a nitrogen gas as mobile phase at flow rate of 25 mUmin.
Abstract: The determination of residual pesticides beta sifiutrin in potato (Solanum tuberosum L) was conducted by Gas Chromatography (GC) . The separation was conducted on a 08-1 (30mxO.25mmxO.25pm) coloum, using a nitrogen gas as mobile phase at flow rate of 25 mUmin. The determination of beta sifiutrin in potato with GC was based on the verification method. The detection was ECO detector. Verification parameters tested were linearity, accuracy, precision, limit of detection (LOO), and limit of quantitation (LOO). Linearity had a correlation coelficient (r) of 0.9992. Accuracy had a recovery value of 99.49%. Precision had a value of relative standard deviation (% RSO) of 2.48%. The limit of detection (LOO) and limit of quantitation (LOO) obtained was 0.001305 and 0.00435 mg/kg. The result of this research showed that the method of determination of residual pesticides beta siflutrin in potato with GC can be used as a routine analysis.
TL;DR: In this paper, the potential of solid state detectors in the quantitative determination of medium weight elements by γ-excited X-ray fluorescence was evaluated and the results demonstrate that a non-destructive and fast determination is possible with a precision of a few per cent, a sensitivity of at least 104 cpm/per cent concentration and a detection limit below 100 ppm.
Abstract: The potential of solid state detectors in the quantitative determination of medium weight elements by γ-excited X-ray fluorescence was evaluated. As criteria, sensitivity, precision and detection limits have been determined for the quantitative analysis of tin and molybdenum in a series of realistic and well characterized samples within a concentration range of 0.04–9%. The results demonstrate that a non-destructive and fast determination is possible with a precision of a few per cent, a sensitivity of at least 104 cpm/per cent concentration and a detection limit below 100 ppm.
TL;DR: In this article, a non-destructive determination of chlorine traces in Selenium by means of a large volume Ge (Li) detector for high-resolution γ-spectrometry is described.