Multivariate optimization of an aqueous two-phase extraction for determination of cadmium and manganese in food sample

Analytical application of flower-shaped nickel nanomaterial for the preconcentration of manganese in domestic wastewater samples

In this study, detection sensitivity of the conventional flame atomic absorption spectrophotometer (FAAS) for the determination of manganese (Mn2+) was enhanced by employing a preconcentration method from wastewater samples. Flower-shaped Ni(OH)2 nanomaterials were synthesized and used as sorbent material in preconcentration procedure. With the aim of attaining optimum experimental conditions, effective parameters of extraction method were optimized and these included pH of buffer solution, desorption solvent concentration and volume, mixing type and period, nanoflower amount, and sample volume. The detection limit of the optimized method was determined to be 2.2 μg L-1, and this correlated to about 41-fold enhancement in detection power relative to direct FAAS measurement. Domestic wastewater was used to test the feasibility of the proposed method to real samples by performing spike recovery experiments. The wastewater sample was spiked at four different concentrations of manganese, and the percent recoveries determined were in the range of 95-120%.

Doehlert design in the optimization of procedures aiming food analysis - A review

In the present paper is presented a review on the application of Doehlert design in the optimization of some of the steps of analytical procedures aimed the analysis of food samples. The theoretical principles and the main characteristics of this type of design are described. In addition, the main advantages and limitations of Doehlert design over other designs (Central Composite Design and Box-Behnken) and its application in the area of food analysis are discussed. Finally, to illustrate its potential, some examples of Doehlert design application in other areas of food chemistry without the purpose of analytical determination will be briefly presented.

Determination of Mn(II) and Mn(VII) in beverage samples using magnetic dispersive micro-solid phase extraction coupled with solidified floating organic drop microextraction followed by graphite furnace atomic absorption spectrometry

Magnetic dispersive micro-solid phase extraction (MDMSPE) was coupled with solidified floating organic drop microextraction (SFODME) for direct separation and preconcentration of Mn(II) and Mn(VII) before graphite furnace atomic absorption spectrometry determination. MDMSPE involved use of magnetic ZnFe₂O₄ nanotubes for adsorbing Mn(VII). Sorbent was isolated from aqueous phase by an external magnet. Mn(II) in upper solution from MDMSPE was further enriched by SFODME. This method avoids tedious pre-oxidation/pre-reduction operation and time-consuming centrifugation/filtration step. An enrichment factor of 200-fold was obtained. Detection limits of this method were 0.005 and 0.007 ng mL^-1 for Mn(II) and Mn(VII) with relative standard deviations of 4.0% and 4.8% (n = 9), respectively. This method was successfully used for detection of Mn(II) and Mn(VII) in tap water, ice tea, energy drink, mineral water, sprite drink and carbonated drink. A certified reference material of water sample was analyzed with satisfactory results. Recoveries of spike experiments ranged from 92.5 to 106%.