A Novel Method Using Solid-Phase Extraction with Slotted Quartz Tube Atomic Absorption Spectrometry for the Determination of Manganese in Walnut Samples

Abstract

Mn²⁺ was separated and preconcentrated using both solid-phase extraction (SPE) and a slotted quartz tube (SQT), and detected by a flame atomic absorption spectrometry (FAAS) system. Firstly, Mn²⁺ was retained on a column filled with Amberlite CG-120 resin, and then retained Mn²⁺ ions on the Amberlite CG-120 resin eluted with 5 mL of 4 mol/L HNO₃. This part was called the “first preconcentration step”. Furthermore, to determine the Mn²⁺ in a walnut sample, the SQT device was also used after the separation and preconcentration of Mn²⁺ from the Amberlite CG-120 resin so as to further improve the sensitivity of system. This part was called the “second preconcentration step” in this study. The enrichment factor and limit of detection values were found to be 360 fold and 0.22 μg/L, in turn, after a two-step preconcentration method. The good accuracy of method was confirmed with the use of standard reference material (spinach leaves, NIST-1570a).