Calibration curve

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

A Convection Calibration Method for Local Heat Flux Gages

Abstract: An apparatus for calibrating local heat flux gages in convective air flows is described. Heat transfer from a ''hot'' gage to a ''cold'' fluid was measured using a guarded hot-plate technique. The system was used to calibrate Gardon-type circular foil heat flux gates of 1/8 in. and 1/16 in. outer diameters. The reslts indicate that the calibration curves are nonlinear, which is different from the linear calibration obtained using the standard radiation technique. The degree of nonlinearity matches the analysis which accounts for the effect of the temperature distribution in the gage foil. The effect of this temperature distribution can be neglected in the standard radiation calibration but is often significant in convection applications. These results emphasize the importance of calibrating heat flux gates in thermal environments similar to those in which they will be used.

Potentiality of chemometric approaches for the determination of (+)-catechin in green tea leaves at the surface of multiwalled carbon nanotube paste electrode

Abstract: Differential pulse voltammetry technique assisted by chemometric methods such as multivariate curve resolution-alternating least squares (MCR-ALS) has been proposed as a valuable approach for (+)-catechin determination in the presence of gallic acid at the surface of multiwalled carbon nanotube paste electrode. Central composite design and response surface methodology were used to optimize the influencing parameters. To determine (+)-catechin in the presence of unexpected electroactive interference with a very high degree of overlapping, second-order electrochemical data were generated by changing the pulse height as an instrumental parameter. After potential shift correction, MCR-ALS results show that second-order calibration could be applied with great success for electroanalytical determination of highly overlapped electroactive species. The linear least-squares calibration curve based on the area under concentration profile was provided over the range of 0.10–2.69 μM for (+)-catechin, whereas detection limit was found to be 0.017 μM. Also in this study, the effect of rotational ambiguity associated with a particular MCR solution under a set of constraints was investigated.

A sampling mechanism employing the phase transition of a gel and its application to a micro analysis system imitating a mosquito

Abstract: Poly(N-isopropylacrylamide) gel swells and shrinks in response to a variation in temperature. This phenomenon was utilized to construct a micro sampling mechanism. A 2 mm ×10 mm ×19 mm gel used in the mechanism changed its volume immediately in response to a step change in temperature and stabilized within 1 min. Also, the gel could change its volume reproducibly in response to repeated thermal cycles. The sampling mechanism was incorporated in a micro system with a micro glucose sensor based on the detection of hydrogen peroxide. After the gel was shrunk at 40°C making contact with a buffer solution, the inlet of the sampling mechanism was placed in contact with a sample solution at 30°C. It was observed that the sample solution was introduced and moved into the interior of the system following the swelling of the gel. The micro glucose sensor showed a distinct response accompanying a peak with a 90% response time between 2 and 10 s. A linear calibration curve was obtained for glucose concentrations less than 2.5 mM. A microneedle of an inner diameter of 50 μm was connected to the inlet of the flow channel. Sampling and sensing could also be conducted successfully with a 90% response time between 1 and 4 min. The linear range of the calibration curve was expanded to 5 mM by sucking through the microneedle.

Determination of Ca and Mg in aqueous solution by laser-induced breakdown spectroscopy using absorbent paper substrates.

Abstract: Laser-induced breakdown spectroscopy has been performed to detect trace metal elements (Ca and Mg) in aqueous solution. In order to overcome the sensitivity drawbacks in liquid sample analysis, an absorbent paper was used as the sample support in this experiment. Calibration curves were constructed by using the standard solution with variable concentration and the limit of detection was estimated for each element. Finally this system was used to analyze three types of water samples collected from different locations in Nanjing, China and the results were compared with inductively coupled plasma atomic emission spectroscopy and showed good correlation.