Measurement of absolute light yield and determination of a lower limit for the light attenuation length for YAP:Ce crystal

Amperometric monoamine oxidase biosensors based on screen-printed graphite electrodes modified with nanostructured reduced graphene oxide (RGO) composites and cobalt nanoparticles (CoNPs) were developed to determine antidepressant drug substances: tianeptine, thioridazine, and fluoxetine. Combinations of carbon nanomaterials with metal nanoparticles (nanocomposites) along with retaining the properties of individual components, also provide a new quality of the developed devices due to their joint contribution. The nanomaterial-modifier was applied to the surface of screen-printed graphite electrodes using dropwise evaporation. Fixing of RGO on the surface of the screen-printed graphite electrodes occurs due to electrostatic interaction between RGO carboxyl groups and amine groups of the amine derivative on the platform of polyester polyol (H20–NH2). The CoNPs were obtained electrochemically by the method of chronoamperometry at a potentialE= – 1.0 V and different time of their accumulation (about 50 – 60 sec) on the electrode surface. According to the data of atomic force microscopy, the predominant size of CoNPs is (40 ± 2) and (78 ± 8) nm, depending on the time of electrochemical deposition of NPs. Data of electrochemical impedance spectroscopy show that nanocomposites RGO-chitosan/CoNPs and RGO-amine derivative on the polyester polyol (H20–NH2)/CoNPs platform are characterized by the lowest values of the charge transfer resistance. The use of those nanocomposites modifying the electrode surface significantly improved the analytical characteristics of the developed biosensors providing a wider range of operating concentrations from 1 × 10–4to 5 × 10–9mol/liter, greater sensitivity coefficient, better correlation coefficient, and lower limit of the detectable concentrations. A possibility of using biosensors to control the quality of antidepressants upon determination of the main active substance in medicinal drugs and biological fluids is shown. The lower limit of detectable concentrations (7 – 9) × 10–10mol/liter is attained when using tyramine as a substrate for determination of fluoxetine, thioridazine and tianeptine, respectively.

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Characterization of secondary electron blur via determination of electron attenuation length

Extreme Ultraviolet (EUV) Lithography XII ◽

10.1117/12.2586993 ◽

2021 ◽

Author(s):

Oleg Kostko ◽

Terry R. McAfee ◽

Jonathan Ma ◽

Patrick Naulleau

Keyword(s):

Secondary Electron ◽

Attenuation Length

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Determination of Halofuginone and Amprolium in Chicken Muscle and Egg by Liquid Chromatography

Journal of AOAC International ◽

10.1093/jaoac/84.1.43 ◽

2001 ◽

Vol 84 (1) ◽

pp. 43-46 ◽

Cited By ~ 9

Author(s):

Yuzo Yamamoto ◽

Fusao Kondo

Keyword(s):

Lower Limit ◽

Solid Phase ◽

Lauryl Sulfate ◽

Ultraviolet Detection ◽

Chicken Egg ◽

Chicken Muscle ◽

Limit Of Determination ◽

Cleanup Procedure ◽

Liquid Chromatographic

Abstract A liquid chromatographic (LC) method was developed for simultaneous measurement of halofuginone (HFN) and amprolium (APL) in chicken muscle and egg. HFN and APL were extracted from chicken muscle and egg with acetonitrile. In chicken egg, they were partially purified by solid-phase extraction (SPE) to separate them from impurities. The LC separation was performed on a 4.6 mm id × 250 mm TSK-gel ODS-80TM column using acetonitrile–McIlvaine buffer, pH 3.4, containing 0.01M sodium lauryl sulfate (42 + 58) as the mobile phase. Ultraviolet detection of HFN and APL was performed at wavelengths of 242 and 265 nm, respectively. Recoveries of HFN and APL from chicken muscle spiked at 0.5 μg/g were 74.8 ± 17.7 and 94.2 ± 5.0%, respectively (mean ± standard deviation [SD], n = 10). In chicken muscle, the lower limit of determination for both APL and HFN was 0.03 μg/g. Recoveries of HFN and APL from chicken egg spiked at 0.5 μg/g by a cleanup procedure using SPE were 54.6 ± 3.4 and 85.0 ± 2.4%, respectively (mean ± SD, n = 5). In chicken egg, the lower limit of determination for both APL and HFN was 0.04 μg/g.

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Determination of Tianeptine in Tablets by High-Performance Liquid Chromatography with Fluorescence Detection

Journal of AOAC International ◽

10.1093/jaoac/90.3.720 ◽

2007 ◽

Vol 90 (3) ◽

pp. 720-724

Author(s):

Sevgi Tatar Ulu

Keyword(s):

Lower Limit ◽

High Performance ◽

Limit Of Detection ◽

Internal Standard ◽

Linear Calibration ◽

Fluorescence Detector ◽

Relative Standard ◽

Validation Parameters ◽

Limit Of Quantitation

Abstract A sensitive and selective high-performance liquid chromatographic method has been developed for the determination of tianeptine (Tia) in tablets. The method is based on derivatization of Tia with 4-chloro-7-nitrobenzofurazan (NBD-Cl). A mobile phase consisting of acetonitrile10 mM orthophosphoric acid (pH 2.5; 77 + 23) was used at a flow rate of 1 mL/min on a C18 column. The Tia-NBD derivative was monitored using a fluorescence detector, with emission set at 520 nm and excitation at 458 nm. Gabapentin was selected as an internal standard. Linear calibration graphs were obtained in the concentration range of 45300 ng/mL. The lower limit of detection (LOD) was 10 ng/mL at a signal-to-noise ratio of 4. The lower limit of quantitation (LOQ) was 45 ng/mL. The relative standard values for intra- and interday precision were <0.46 and <0.57%, respectively. The recovery of the drug samples ranged between 98.89 and 99.85%. No chromatographic interference from the tablet excipients was found. The proposed method was validated in terms of precision, robustness, recovery, LOD, and LOQ. All the validation parameters were within the acceptance range. The proposed method was applied for the determination of Tia in commercially available tablets. The results were compared with those obtained by an ultraviolet spectrophotometric method using t- and F-tests.

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Cosmic X-ray observations

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1969.0193 ◽

1969 ◽

Vol 313 (1514) ◽

pp. 301-315 ◽

Cited By ~ 6

Keyword(s):

Lower Limit ◽

Short Duration ◽

Spectral Information ◽

X Ray ◽

Proportional Counters ◽

Position Data ◽

Intense Source

In the first few years following the discovery of discrete cosmic X-ray sources, about three dozen objects were detected (Friedman, Byram & Chubb 1967; Fisher, Johnson, Jordan, Meyerott & Acton 1966; Clark et al . 1965; Gursky, Gorenstein & Giacconi 1967; Bradt, Naranan, Rappaport & Spada 1968; Cooke, Pounds, Stewardson & Adams 1967; Giacconi, Gorenstein, Gursky & Waters 1967; Chodil et al . 1967 b ). They represent a brightness range of about a thousandfold from the most intense source, Sco XR–1, ca . 5 x 10 -10 J m -2 s -1 , to the weakest sources at a few times 10 -13 J m -2 s -1 . The lower limit of detectability is inherent in the short duration of rocket flights and the limiting size of instrumentation that can be carried in vehicles like Aerobee, Skylark and Nike Apache. As a result of this instrumentation barrier, the pace of discovery has now slowed down considerably, and the next great surge in detection of new sources will have to await the use of satellites. Spectral information is still based on the relatively crude resolution of proportional counters and scintillation counters, so that no conclusive determination of thermal or non-thermal mechanisms is yet possible. Because position data are obtained with the use of mechanical collimators, accuracies of a few minutes of arc are the best that have been achieved, and only for a few sources. As a consequence, only a few X-ray objects are reliably identified with optical and radio counterparts.

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Determination of Total Chlorine in Chrysotile by X-ray Fluorescence Spectrometry

Applied Spectroscopy ◽

10.1366/0003702944028489 ◽

1994 ◽

Vol 48 (2) ◽

pp. 236-240 ◽

Cited By ~ 1

Author(s):

Régina Zamojska ◽

Jeff Sharman ◽

Yvon Cote ◽

Carmel Jolicoeur

Keyword(s):

Lower Limit ◽

Limit Of Detection ◽

Colorimetric Method ◽

Standard Addition ◽

Exchange Chromatography ◽

Water Soluble ◽

X Ray ◽

Limit Of Determination ◽

A Minor

Energy-dispersive x-ray spectrometric methods have been developed for the determination of chlorine in asbestos (chrysotile) fibers. Chlorine, which is a minor constituent, is determined by a standard addition method from the ground fiber and by a standardless method in six different fibers. The lower limit of detection for a qualitative analysis and the lower limit of determination for a quantitative analysis of chlorine in the asbestos matrix are 40 ppm and 120 ppm, respectively. The water-soluble and acid-soluble chlorine have also been determined by ion-exchange chromatography and by a colorimetric method. The agreement of the three different methods is very good in all cases.

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