Calibration curve

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

Electrospun composite of polypyrrole-polyamide as a micro-solid phase extraction sorbent

Abstract: A micro-solid phase extraction technique was developed using a novel polypyrrole-polyamide nanofiber sheet, fabricated by electrospinning method. The applicability of the new nanofiber sheet was examined as an extracting medium to isolate malathion as a model pesticide from aqueous samples. Solvent desorption was subsequently performed in a microvial, and an aliquot of extractant was injected into gas chromatography–mass spectrometry. Various parameters affecting the electrospinning process including monomer concentration, polyamide content, applied voltage, and electrospinning time were examined. After fabricating the most suitable preparation conditions, influential parameters on the extraction and desorption processes were optimized. The developed method proved to be rather convenient and offers sufficient sensitivity and good reproducibility. The limit of detection (S/N = 3) and limit of quantification (S/N = 10) of the method under optimized conditions were 50 and 100 ng L−1, respectively. The relative standard deviation at concentration level of 1 ng mL−1 was 2% (n = 3). The calibration curve of analyte showed linearity in the range of 0.1–1 ng mL−1 (R 2 = 0.9975). The developed method was successfully applied to tap and Zayanderood river water samples, while the relative recovery percentages of 98% and 96% were obtained, respectively. The whole procedure showed to be conveniently applicable and quite easy to be manipulated.

Application of laser-induced breakdown spectrometry for direct determination of trace elements in starch-based flours

Abstract: Spatially resolved laser-induced breakdown spectrometry (LIBS) was investigated to evaluate the feasibility as a quick and simple method to analyze trace elemental concentrations in starch-based flour samples. A Nd∶YAG laser beam (λ = 1064 nm, 30 mJ pulse−1) has been used for generation of laser-induced plasma on sample surface under reduced pressure of argon atmosphere. A series of starch powder samples containing different concentrations of Sr, Mg, Al, Cu, Cr, K, Mn, Rb, Cd, and Pb were used to construct the calibration curves and estimate detection limits of measurements. The calibration graphs for all elements show good linearity (correlation coefficient, r > 0.99) in the range 0–160 µg g−1 or within three orders of magnitude. Detection limits achieved were below 18 µg g−1 for all elements studied in this work. The lowest detection limit (0.3 µg g−1) was obtained from Sr measurement. Precision (%RSD) for the selected analysis was in the range 2–10%. The standard addition method was applied to assess the accuracy of LIBS using a NIES standard rice sample. The concentrations of Mg and Mn in NIES standard rice sample determined by spatially resolved LIBS technique have good agreements with those of certified value within an error range. The results indicate that spatially resolved LIBS has been shown to be an accurate technique for determining trace elements of ppm (µg g−1) level in starch-based food samples directly with an acceptable precision without any tedious digestion and dilution procedure.