Calibration curve

About: Calibration curve is a research topic. Over the lifetime, 6552 publications have been published within this topic receiving 95128 citations.

Algal density assessed by spectrophotometry: A calibration curve for the unicellular algae Pseudokirchneriella subcapitata.

Abstract: The unicellular algae Pseudokirchneriella subcapitata (Korschikov) Hindak has been frequently used for ecotoxicological tests. In this paper, a calibration curve is proposed correlating absorbance values (684 nm) and cell density for routine ecotoxicological experiments. Density (cells/mL) could be estimated as follow: Cell Density = e {[ln (absorbance_684) +16.439]/1.0219} (n=130; r2=0.9998). Residual distribution revealed that the equation could be applied for algal densities under 5,000,000 cells/mL and/or absorbance values as high as 0.5. Key words: Pseudokirchneriella subcapitata, spectrophotometry, ecotoxicological tests.

Calibration of single-particle inductively coupled plasma-mass spectrometry (SP-ICP-MS)

Abstract: We have identified incomplete particle vaporization and non-linear detector response as the major factors that cause the non-linearity of SP-ICP-MS measurements at high particle mass. The contribution of incomplete vaporization to the deviation from the linearity of the ICP-MS intensity is estimated using a mathematical model of particle vaporization. The non-linear detector response in the pulse-counting mode is due to the overlapping of the analyte ions at the detector within the 40 ns dead time of the electron multiplier. The overlap can be severe because of the relatively short pulse duration of 300 μs of the ion plumes of the discrete sample particles. The non-linear detector response has been modeled using Poisson statistics. We have also examined the applicability of calibration methods based on the standard particles, discrete standard solution droplets, and continuous nebulization of standard solution. The standard-solution calibration method requires linear calibration curves. The method may also suffer from errors due to the difference in the sensitivity of the standard solution and sample particles. Calibration using standard particles and discrete standard solution droplets do not have these limitations.

The Dynamic Calibration of Tipping-Bucket Raingauges

Abstract: The dynamic calibration of three types of tipping-bucket raingauges extensively used in the Nordic countries was performed. The tested and calibrated gauges were: “LTH gauge”, PLUMATIC gauge and RIMCO gauge. It was found that with regard to all tested gauges, the volume of water which tips the bucket is not a constant characteristic for the gauge; it depends on rainfall intensity. Thus, in order to avoid errors, a calculation of the rainfall intensity or of rainfall volume from tipping-bucket registrations must go through empirical, usually non-linear calibration function. The procedure involved in the dynamic calibration of the tipping-bucket raingauges is described in the paper. Examples of typical calibration curves are provided. The magnitude of errors, in respect of measured rainfall intensity, which occur when linear gauge calibration is used is stated too.

The use of infrared spectroscopy for determination of polypropylene stereoregularity

Abstract: This study examines the application of infrared (IR) spectrometry to the determination of polypropylene (PP) stereoregularity. The use of the absorption bands at 998 cm−1 and 841 cm−1 as indices of isotacticity and bands at 1167 cm−1 and 973 cm−1 as internal references have been explored. Calibration curves relating various absorption ratios to isotacticity as measured by 13C nuclear magnetic resonance are reported. The ratios A998/A973 and A841/A973 are the most useful and provide linear correlations with isotacticity. The effect of instrument type on the calibration has been investigated for both dispersive and Fourier transform type IR spectrometers. For samples annealed at room temperature the average of measurements on the same set of PP films by five instruments provide the calibrations: A998/A973 = 1.08 ± 0.02 (mm)−0.15 ± 0.03; and A841/A973 = 0.84 ± 0.06 (mm)−0.04 ± 0.02. High temperature annealing increases the crystallinity of the samples and the corresponding value of the absorption ratio but is not necessary for obtaining reproducible calibration curves.