Calibration curve

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

A Calibration Method for Infra-Red Prism Spectrometers1

Abstract: A method of high accuracy applicable to various prisms in infra-red spectrometry has been used to calibrate NaCl and KBr prisms. The method requires only a small number of experimental bands, is practically independent of resolving power, provides an extensive wave-length range, and permits a tabulated calibration without the necessity of drawing calibration curves. The procedure is described in detail with an example.

Error Analysis of an Evaporation Method for Determining Hydrodynamic Properties in Unsaturated Soil

Abstract: Solving soil unsaturated flow problems requires knowledge of the water retention θ(h) and unsaturated hydraulic conductivity K(θ) relationships. The purpose of this study was to investigate more thoroughly the properties and accuracy of an evaporation method described by Wind (1969) for determining θ(h) and K(θ) from laboratory cores. Evaporation from a vertical column of soil was first simulated using numerical solution of Richards equation for a given set of soil hydraulic properties. The simulated data were then used to evaluate the ability of Wind's method to provide estimations of the retention and unsaturated conductivity curves when measurement errors were taken into account. The main sources of error were (i) errors due to the position of the tensiometers in the sample, (ii) errors due to the calibration of the transducers used for the pressure head measurements, and (iii) errors due to layering in the soil column. The estimated water retention curves were sensitive only to soil layering. On the other hand, small uncertainties in the position of the tensiometers (1 or 2 mm) and in the calibration curve of the transducers for the pressure head measurements (1-5%) had a great influence on the estimated hydraulic conductivity curves. A correction procedure was proposed and was satisfactory when errors of position in the tensiometers were taken into account. Results also showed that temperature corrections related to viscosity of liquid water were large. Finally, this method gives poor estimates of hydraulic conductivities when raw tensiometric data are corrupted with small errors in their position or calibration.

Cold Vapor Atomic Absorption determination of mercury by Flow Injection Analysis using a Teflon membrane phase separator coupled to the absorption cell

Abstract: A Flow Injection Analysis (FIA) procedure for the determination of trace amounts of mercury by the Cold Vapor Atomic Absorption (CVAA) method is presented. In order to make efficient use of the FIA technique, a new flow cell was developed to permit a rapid separation of elemental mercury from the carrier solution. The design of this device is based on the permeability of Hg 0 in commercially available Teflon (PTFE) tape, which acts as a membrane phase separator. The calibration curve is linear up to 70 ng.ml −1 ( A = 0.005 + 0.008 Hg(ng.ml −1 ); r = 0.9996) using a 15-cm open cell approach, with a detection limit of 1.4 ng. ml −1 (0.66 ng of mercury), considering a signal to noise ratio of three. The standard deviation is s = ±0.004 absorbance units, calculated at a level of 50 ng.ml −1 of Hg 2+ . The sampling rate was 110 samples per h.