VALIDATION OF LEAD (Pb) ANALYSIS METHOD IN FISH MEAL MATRIX BY ELECTROTHERMAL ATOMIC ABSORPTION SPECTROPHOTOMETRY

ABSTRACT Validation of analytical methods is the process of proving that the methods used are scientifically good and suitable for certain purposes. The aim of this study was to validate the analytical method of lead in fish meal matrix by electrothermal atomic absorption spectroscopy (ETAAS) using a phosphate modifier. The research begins with optimization of the analytical conditions that include pyrolysis (ashing) and atomizing temperature, and continues with the validation process by evaluating the analytical performance parameters using a certified reference material (CRM). Method validation was carried out by determining the level of accuracy and precision as well as lead content in a CRM Cod Muscle-422 from BCR. Each experiment was conducted at a wavelength of 283.3 nm, a lamp current of 9.0 amperes, a slit width of 1.3 nm and an argon carrier gas. The optimal pyrolysis and atomizing temperature of lead obtained by adding phosphate modifier was 650 oC and 2000 oC, respectively. The results obtained in this study indicate that the ETAAS lead analysis method using a phosphate modifier is feasible as a test method with an RSD of 3.79%, precision of 0.0043, relative error of 4.0%, accuracy of 104% and recovery of 98% ± 3%. The results of the validation method obtained that the 95% confidence interval for Pb content was 0.088 ± 0.023 µg/g, still within the range of Pb levels in the certificate, namely 0.085 ± 0.015 µg/g of Pb. Keywords: Validation, CRM, Cod Muscle, ETAAS, Lead

A Generalized Dynamic Conductance Model for High Intensity Discharge Lamps and its Prospective Application to Design Dimmable Electronic Ballast

A generalized model for high intensity discharge (HID) lamp is developed based on the Francis-Damelincourt dynamic conductance model of electric discharge by replacing the model constants A, B, C, D with four experimentally determined coefficient functions of rated lamp power and root mean square supply voltage. Experimental validation of this model is done, which shows a maximum deviation of about 5 %. Moreover, sensitivity analysis for the model coefficients is also performed, results of which conform to the physical behaviour of high pressure sodium (HPS) and metal halide (MH) lamps. This model is capable to simulate electrical characteristics of HPS and MH lamps of wide range of commercially available rated power (70–400) W fed by a wide range of supply voltage (180–250) V, 50 Hz. As a prospective application, the model is applied to design dimmable low frequency square wave electronic ballast for HID lamps. A design algorithm is proposed for this purpose. Performance analysis of the designed ballast is conducted in Matlab-Simulink environment, which shows fairly good performance of the circuit in terms of dimming accuracy (maximum deviation 2.64 %), lamp power factor (≥ 0.993), and lamp current crest factor (equal to 1.0). The model can also be utilized for designing electronic ballasts of other topologies.

A design methodology for acoustic resonance-free, high-frequency, dimmable electronic ballast for high-pressure sodium-vapour lamps

This paper presents a methodology to design acoustic resonance-free, high-frequency, dimmable electronic ballasts for high-pressure sodium vapour (HPSV) lamps having a range of rated wattage (70–400 W). After estimation of the ‘quiet window’ of an HPSV lamp, the proposed iterative algorithm is able to determine the acoustic resonance-free driving frequencies of a design ballast corresponding to 50%–100% power level. On the other hand, a developed wattage and voltage independent HPSV lamp model facilitates finding the required electrical characteristics of HPSV lamps without performing laboratory experimentation. Using the estimated driving frequencies of a design ballast and the synthesized electrical characteristics of the lamp, the design circuit parameters of an electronic ballast are determined. Performance evaluation of the designed ballasts, carried out on the Matlab–Simulink platform, indicates several important attributes, viz. higher power control accuracy (deviation ≤3.69%), near-unity lamp power factor (≥0.98), lower lamp current crest factor (<1.7) and lower lamp current total harmonic distortion (≤12.63%). Results establish the effectiveness of the proposed design methodology to design lightweight and compact electronic ballasts for HPSV lamps with less effort than conventional design practice.

Application of Mixed-Level Orthogonal Design in Determination of Heavy Metals in Soil, for Example Pb

In order to precisely determinate absorbance of all kinds of heavy metals in soil,7- important factors were optimized by mixed-level orthogonal design.For example Pb,discuss the factors influence degree on digestion and determination of Pb.Pb-absorbance trends within the area is expressed by the change of two-dimensional planar contour.Pb-absorbance distribution was drawn by 3D visualization technology.In order to optimize the orthogonal design,taking the optimal value of decentralized points in orthogonal test convert into taking the optimal value on a continuous plane. Using Minitab16 software analyzed the experimental results.The results showed that affecting Pb digestion Primary and secondary order is B(HF)> C(HNO3)> A(HClO4)> I(Acetylene flow rate)>D(HCL)>G (Assistant combustion gas)>H(Lamp current)>F(Burner height),that was adding 9 mlHNO3, 3mLHF, 3 mlHClO4 in soil samples, after microwave digestion, got the optimal Pb-absorbance value 0.304 under the the working conditions of atomic absorption spectrophotometer for Pb 217.0nm, slit width 1.3nm, burner height 4nm, assistant combustion gas 2.4 L/min, the lamp current 4.0mA, propane flow rate 4.0 L/min.

Experimental Investigation into Pulsed Nd:YAG Laser Micro-Turning of Engineering Ceramics

Laser beam machining (LBM) is the most exciting thermal energy based non-contact type advanced material machining method to process almost whole range of materials. The laser microturning of ceramics are highly demanded in the present industries because of its wide and potential uses in various engineering fields such as automobile, electronics, aerospace, biomedical applications etc. The present paper addresses the basic experimental study of Nd:YAG laser microturning of advanced engineering cylindrical shaped ceramic material to explore the desired laser output responses i.e. depth of cut and surface roughness by varying laser micro-turning process parameters such as lamp current, pulse frequency and rotational speed of workpiece etc.

Digitally Controlled Integrated Electronic Ballast with Dimming and Power Factor Correction Features

This paper presents a digitally controlled integrated electronic ballast with dimming and power factor correction features. The control circuit is based on a low-cost PIC16C71 microcontroller where the different strategies for energysaving have been implemented. The ballast is operating in closed loop achieving tight lamp current regulation through a digital Proportional-Integral algorithm. The integrated power stage is based on a frequency-controlled single-switch boost rectifier plus a half-bridge series resonant parallel loaded inverter sharing one power switch. The single-switch boost rectifier works in discontinuous inductor current mode with automatic power factor correction. Detailed analysis of the power stages and experimental results using 42-watt electronic ballast are presented.