Calibration luminescence standards

Luminescent standards have been established for use in calibrating fluorescence spectrometers and have been suggested for Raman spectroscopy in the past (18). The standard is a luminescent material, usually a solid or liquid, that emits a broad reproducible luminescence spectrum when excited by a laser. Once the standard is calibrated for a particular laser wavelength, its emission spectrum is known, and it can provide the real standard output , d)i(AF) depicted in Figure 10.8. In practice, a spectrum of the standard is acquired with the same conditions as an unknown then the unknown spectrum is corrected for instrument response function using the known standard... 

An ideal luminescent standard for Raman intensity calibration would have several characteristics (17), some of which are difficult to achieve ... 

Recalibration of the instrument response function reduces or eliminates most of the instrumental factors that lead to relative intensity variations over time. For example, a luminescent standard could be used at the beginning of each session as described in Section 10.3.3. Use of the same standard and correction procedure during qualification could establish the true value of one or more peak ratios for future reference. Table 10.9 shows results for this approach applied to the example of calcium ascorbate. The ratio of the 767- and 1587 cm" peak intensities was monitored after calibration of the response function with a luminescent standard. The standard deviations listed in Table 10.9 for the 767/1582 peak height ratio provide indications of the reproducibility of the response correction and sample spectra. 

Execute procedure for response function calibration with tungsten source or luminescent standard. Acquire corrected spectrum of cyclohexane (or an alternative standard) and compare relative peak areas to established values. Store corrected spectrum. 

KJ Frost, RL McCreery. Calibration of Raman spectrometer instrument response function with luminescence standards An update. Appl Spectrosc 52 1614-1618, 1998. 

ES Etz, WS Hurst, SJ Choquette. Raman intensity calibration with glass luminescence standards. In DB Williams, R Shimizu, eds. Institute of Physics Conference Series No. 165. Philadelphia Institute of Physics, 2000, pp 121-122. 

Instrument calibration standards - physical sources such as line and tungsten lamp emissions, known instrument independent luminescence standards, and so forth... 

Requirements for standards used In macro- and microspectrofluorometry differ, depending on whether they are used for Instrument calibration, standardization, or assessment of method accuracy. Specific examples are given of standards for quantum yield, number of quanta, and decay time, and for calibration of Instrument parameters. Including wavelength, spectral responslvlty (determining correction factors for luminescence spectra), stability, and linearity. Differences In requirements for macro- and micro-standards are considered, and specific materials used for each are compared. Pure compounds and matrix-matched standards are listed for standardization and assessment of method accuracy, and existing Standard Reference Materials are discussed. 

Definition and Uses of Standards. In the context of this paper, the term "standard" denotes a well-characterized material for which a physical parameter or concentration of chemical constituent has been determined with a known precision and accuracy. These standards can be used to check or determine (a) instrumental parameters such as wavelength accuracy, detection-system spectral responsivity, and stability (b) the instrument response to specific fluorescent species and (c) the accuracy of measurements made by specific Instruments or measurement procedures (assess whether the analytical measurement process is in statistical control and whether it exhibits bias). Once the luminescence instrumentation has been calibrated, it can be used to measure the luminescence characteristics of chemical systems, including corrected excitation and emission spectra, quantum yields, decay times, emission anisotropies, energy transfer, and, with appropriate standards, the concentrations of chemical constituents in complex S2unples. 

Epstein, M. S. Velapoldl, R. A. Blackburn, D. Evaluation of Luminescent Glass Spheres as Calibration Standards for Micro-spectrofluorimetry National Bureau of Standards Gaithersburg, MD Annual Task Report to Food and Drug Administration, 1984, 1985, 1986 also, paper to be submitted. 

From the calibration curve - the plot of analytical signal (y) luminescence intensity vs. analyte concentration C in a series of standards having known analyte concentration - the sensitivity (H) is expressed as the first derivative of the calibration function at a given concentration Q ... 

Bartholomeusz DA, Andrade JD. Photodetector calibration method for reporting bioluminescence measurements in standardized units. Luminescence 2002 17 77-115. 

Sample solution is diluted 40 times by 600 mmol/L sodium hydroxide, the diluted sample solution 50 /iL is poured into the plate. After addition of a luminescence solution (40 mmol/L potassium hexacyanoferrate (II ) and 0.1 mmol/L potassium hexacyanoferrate (III) containing 5 /nmol/L luminol solution), luminescence intensity was measured. Calibration curve was obtained by measurement of the chemiluminescence intensity using GPL as a standard, and the relative amount of the glycated protein in hair was computed. 

Tbe luminescence of GGA solutions were estimated using the bacterial chip system in order to produce a calibration plot for measurement of pollution containing biodegradable substances. The luminescent intensity was correlated with concentration of BOD standard (GGA) solution. The bioluminescence increased linearly with concentration up to approximately 50 ppm. Measurement of BOD values less than 50 ppm has been achieved. The bght intensity reached saturation at concentrations of over 100 ppm. Detection limit was approximately 1(X) ppm, and the minimum measurable BOD was 1 ppm. Based on the logarithmic curve which was obtained by the measurement with a chemi-imager, two linear calibration curves and equations were estimated and approximated... 

In this assay, the minimum detectable concentration (MDC) of TSH was estimated to be less than 0.001 pIU/mL TSH. The MDC is defined as that concentration of TSH which corresponds to the relative luminescent unit that is two standard deviations from the mean relative luminescent unit of a zero calibrator. 

The dosimetry-oriented studies of AIN ceramics were performed mainly in Riso National Laboratory, Denmark. Stimulated luminescence was measured using the Riso model TL/OSL reader. The °Y/ °Sr beta source build in the Riso TL reader and a °Co standard gamma calibration facility were applied for sample irradiation. As a source of UV light in these studies, a metal halide lamp Sol-2 (K. Honley Gmbh), which simulates a solar spectrum at ground level from 300 nm upwards, was used. 

To detect ricin, we studied its inhibitory effects on luciferase expression by adding a series of concentrations of ricin into the IVT reactions in the array device. To achieve a lower detection limit, 4-hr protein expression was used, though ricin detection can be achieved in as short as 5 minutes. Ricin sample size was 2 pL. As shown in Figure 5a, the expression yield of luciferase, indicated by luminescence, decreases with the concentration of ricin (solid circles). However, the expression yield remained the same when the ricin is heat denatured and its toxicity is deactivated (open circles). The error bar of each data point indicates the standard deviation that is obtained from three repeat experiments. The calibration curve is obtained by plotting the detection... 

KG Ray, RL McCreery. Simplified calibration of instrument response function for Raman spectrometers based on luminescent intensity standards. Appl Spectrosc 51 108-116, 1997. 

BonsaU SD, Houcheime M, Straus DA, Muller G. Optical Isomers of iVJV -bisfl-phenylethyl)-2,6-pyridinedicarboxamide Coordinated to Europiiunflll) Ions as Rehable Circularly Polarized Luminescence Calibration Standards. Chem Corrmum 2007 35 3676 678. 

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