Fast and interference free determination of calcium and magnesium in honeys by solid phase extraction followed by flame atomic absorption spectrometry

Abstract

Um procedimento para preparo de amostras, baseado na extração em fase sólida e eluição em duas etapas foi desenvolvido para a determinação da concentração total de Ca e Mg em méis de abelha. As amostras de mel foram tratadas como segue: soluções de amostra (50 mL) a 5,0% (m/v) foram passados a uma vazão de 20 mL min -1 , através de resina Dowex 50W×8-400, para reter íons Ca(II) e Mg(II) e separá-los da matriz contendo glicose e frutose, e dos minerais aniônicos. Depois, 20 mL de uma solução de HNO 3 0,5 mol L -1 foram usados para remover os íons K e Na. Finalmente, Ca e Mg foram eluídos com 5 mL de solução de HCl 2,0 mol L -1 antes da medida de suas concentrações por espectrometria de absorção atômica em chama (FAAS). O procedimento proposto para o preparo da amostra foi rápido (30 min) e permitiu medir as concentrações de Ca e Mg em mel, com precisão de 1-5% e exatidão de 1-3%. Os limites de detecção de 24 ng g -1 de Ca e 4,4 ng g -1 de Mg foram obtidos para FAAS com este procedimento.A sample preparation procedure based on the solid phase extraction and the two-step elution was developed for the determination of the total concentrations of Ca and Mg in bee honeys. The honey samples were treated as follows: the 5.0% (m/v) sample solutions (50 mL) were passed at the flow rate of 20 mL min -1 through the resin beds of Dowex 50W×8-400 to retain the Ca(II) and Mg(II) ions and separate them from the matrix of glucose and fructose in addition to the anionic minerals. Afterwards, 20 mL of a 0.5 mol L -1 HNO 3 solution was used to remove the K and Na ions. Finally, Ca and Mg were eluted prior to the measurements of their concentrations by flame atomic absorption spectrometry (FAAS) using 5 mL of a 2.0 mol L -1 HCl solution. The proposed sample preparation procedure was fast (30 min) and enabled to measure the concentrations of Ca and Mg in honey with the precision of 1-5% and the accuracy of 1-3%. The limits of detection of 24 ng g -1 of Ca and 4.4 ng g -1 of Mg were obtained for FAAS with this procedure.

Interference-Free Determination of Trace Copper in Freshly Ripened Honeys by Flame Atomic Absorption Spectrometry Following a Preconcentration by Solid-Phase Extraction and a Two-Step Elution Process

“…It is worth noticing that Dowex 50 W × 8-400 is an unspecific resin, and therefore other metal ions, e.g. , Ca(II), Fe(III), Mg(II), Mn(II), and Zn(II), are quantitatively retained and can be eluted along with Cu(II) ions (Pohl, Stecka and Jamroz 2012a , 2012b ). Under these conditions, it is possible to preconcentrate all of these metals from the honey matrix in a corresponding SPE procedure and determine them by FAAS without any interference resulting from the presence of high amounts of fructose, glucose, K, and Na.…”

“…Flame atomic absorption spectrometry (FAAS) with an air-acetylene flame is a well-established element specific detection technique commonly used for the analysis of honey as to the content of Cu and other trace elements (Pohl 2009 ; Pohl et al 2009 ). Unfortunately, organic (glucose and fructose mostly) and inorganic (cationic and anionic minerals, such as chlorine, potassium [K], sodium [Na], and phosphorous) constituents of the honey matrix are often responsible for different kind of spectral and nonspectral interferences that accompany FAAS measurements (Hernandez et al 2005 ; dos Santos et al 2008 ; Pohl et al 2012a , b ). For that reason, analyzed samples of honey are mineralized before determinations by FAAS to simplify the sample matrix and eliminate related matrix effects.…”

In vitro effect of cocoa leachates on growth and development of Moniliophthora roreri ([Cif.] H.C. Evans et al.) isolated from Theobroma cacao (L.)

“…To determine the compounds that are present in the three leachate samples and their concentration, the physicochemical analysis of cocoa leachates was carried out at the Water and Soils Laboratory of the Faculty of Agricultural Sciences at Universidad Nacional de Colombia. The following variables were evaluated: pH, using the potentiometric method (Tello and Fernández, 2012); OH, CaCO 3, and HCO 3 by titration with H 2 SO 4 (Roldán and Ramírez, 2008); chlorides by titration with AgNO 3 (Carrasquero and Castillo, 2002); sulfates using barium chloride by turbidimetric titration (Aguilera et al, 2010); phosphates and ammonium by colorimetric titration (D'Angelo et al, 2001); Ca, Mg, K and Na using atomic absorption spectrometry (Pohl et al, 2012), and B by potentiometric titration (Peña et al, 2012). The electrical conductivity (EC) was measured by reading with a conductivity meter (Schott, Lab960 and electrode of the same brand) at 25°C and the sodium adsorption ratio (SAR) that consists of the ratio between Na and Ca plus Mg (Peña et al, 2012).…”

The difference between calcium ion levels in saliva before and after consuming red dragon fruit (Hylocereus polyrhizus)

“…The AAS was used in analytical methods to determine the metal and metalloid elements, which measurements are based on light absorption with specific wavelengths by metal atoms in a state free; the results were then recorded. 22 Saliva samples were prepared in advance for quantitative analysis of the salivary calcium ion with AAS. Preparation of saliva samples was carried out by using 1 ml of saliva sample into a 50 ml volumetric flask, 1 ml of nitric acid (HNO 3 HNO 3 65% b/v), and the solution was diluted with distilled water to the limit mark.…”