Calibration curve

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

Analyzing unburned carbon in fly ash using laser-induced breakdown spectroscopy with multivariate calibration method

Abstract: This paper presents an alternate calibration method for measurement of the unburned carbon (UC) in fly ash using laser-induced breakdown spectroscopy (LIBS). Fly ashes studied in this research were produced from pulverized coal in a muffle furnace and the UC was determined by a loss-on-ignition (LOI) test. We apply both univariate calibration and multivariate calibration methods to LIBS data to establish the calibration curve of the UC in measured samples, and the performance of these two approaches was compared. Our analysis shows that traditionally used univariate calibration in LIBS does not qualify quantitative analysis of fly ashes from different kinds of coal due to the presence of matrix effects. Instead, multivariate calibration has a better performance as the matrix effects can be taken into account with the influence of the spectroscopic signals of other components in fly ash. The correlation coefficients R2 of multivariate calibration reach 0.994 (fly ashes from one kind of coal) and 0.981 (fly ashes from different kinds of coal), which is significantly improved compared with univariate calibration.

Determination of trace amounts of palladium by flame atomic absorption spectrometry after ligandless-dispersive liquid–liquid microextraction

Abstract: Ligandless dispersive liquid–liquid microextraction (LL-DLLME) was successfully used as a sample preparation method prior flame atomic absorption determination of trace amount of palladium in water and standard samples. In the LL-DLLME method, carbon tetrachloride and ethanol were used as extraction and dispersive solvents, respectively. Several factors that may be affected on the extraction process, such as extraction and disperser solvent, the volume of extraction and disperser solvent, pH of the aqueous solution and extraction time were optimized. Under the optimum conditions, the calibration curve was linear in the range of 15.0 ng mL−1 to 7.0 µg mL−1 of palladium with R2=0.9993 (n = 9) and detection limit was 1.4 ng mL−1 based on 3Sb. The relative standard deviation of eight replicate determination of 2.0 μg mL−1 palladium was ±1.5%. The LL-DLLME method was applied to the separation and preconcentration of trace quantities of palladium prior to its determination in water and standard samples.

Determining the Amount of Copper(II) Ions in a Solution Using a Smartphone

Abstract: When dissolving copper in nitric acid, copper(II) ions produce a blue-colored solution. It is possible to determine the concentration of copper(II) ions, focusing on the hue of the color, using a smartphone camera. A free app can be used to measure the hue of the solution, and with the help of standard copper(II) solutions, one can graph a calibration curve to determine the concentration of copper in solution and calculate the mass of copper that has been dissolved or, for example, the percentage of copper in an alloy.

On Calibration of pH Meters

Abstract: The calibration of pH meters including the pH glass electrode, ISE electrodes, buffers, and the general background for calibration are reviewed. Understanding of basic concepts of pH, pOH, and electrode mechanism is emphasized. New concepts of pH, pOH, as well as critical examination of activity, and activity coefficients are given. The emergence of new solid state pH electrodes and replacement of the salt bridge with a conducting wire have opened up a new horizon for pH measurements. A pH buffer solution with a conducting wire may be used as a stable reference electrode. The misleading unlimited linear Nernstian slope should be discarded. Calibration curves with 3 nonlinear portions for the entire 0—14 pH range due to the isoelectric point change effect are explained. The potential measurement with stirring or unstirring and effects by double layer (DL) and triple layer (TL) will be discussed.