A highly sensitive and selective spectrofluorimetric method for the determination of manganese at nanotrace levels in some real, environmental, biological, soil, food and pharmaceutical samples using 2-(α-pyridyl)-thioquinaldinamide.

M Jamaluddin Ahmed,Faisal Hossain,M Tazul Islam

doi:10.1039/c7ra12762f

Abstract

A very simple, ultra-sensitive and highly selective non-extractive spectrofluorimetric method is presented for the determination of manganese at nano-trace levels using 2-(α-pyridyl)-thioquinaldinamide (PTQA). PTQA has been proposed as a new analytical reagent for the direct non-extractive spectrofluorimetric determination of manganese(vii). This novel fluorimetric reagent, PTQA becomes oxidized in a slightly acidic (0.0125–0.05 M H2SO4) solution with manganese(vii) in absolute ethanol to produce a highly fluorescent oxidized product (λex = 319 nm; λem = 373 nm). Constant and maximum fluorescence intensities were observed over a wide range of acidity (0.0125–0.05 M H2SO4) for the period between 5 min and 24 h. Linear calibration graphs were obtained for 0.01–800 μg L−1 of Mn, having a detection limit of 1 ng L−1; the quantification limit of the reaction system was found to be 10 ng L−1 and the RSD was 0–2%. A large excess of over 60 cations, anions and complexing agents do not interfere in the determination. The developed method was successfully used in the determination of manganese in several standard reference materials (alloys, steels, hair and sediments) as well as in some environmental waters (potable and polluted), biological samples (human blood, urine and hair), soil samples, food samples (vegetables, fruits, tea, rice, and wheat), fertilizer samples and pharmaceutical samples (multivitamin-mineral tablets and syrup), solutions containing both manganese(ii) and manganese(vii) speciation and complex synthetic mixtures. The results of the proposed method for assessing biological, food and vegetables samples were comparable with AAS and ICP-MS and were found to be in excellent agreement.

Highlights

Manganese is an essential trace element in the metabolism of all living organisms, including plants and bacteria, and is found in all tissues of man
To 0.1–1.0 mL of a neutral aqueous solution containing 0.1– 8000 ng of manganese(VII) in a 10 mL calibrated ask was mixed with a 1 : 70–1 : 300 fold molar excess of the 2-(a-pyridyl) thioquinaldinamide (PTQA) reagent solution followed by the addition of 0.5–2 mL of 0.025 M of sulfuric acid
A new simple, ultra sensitive, highly selective and inexpensive spectro uorimetric method with the manganese(VII)–PTQA system was developed for the determination of manganese in some real, environmental, biological, soil, food, vegetable, fruit and pharmaceutical samples, for continuous monitoring to establish the nano-trace levels of manganese in different samples matrices

Summary

Introduction

Manganese is an essential trace element in the metabolism of all living organisms, including plants and bacteria, and is found in all tissues of man. Manganese is a potential carcinogen.[1] Among the inorganic chemicals, manganese, chromium, and selenium and certain organometallic derivatives of these metals have been found to be carcinogenic under special conditions and are considered potential inorganic genotoxic agents.[2] The hazards of manganese have been known for a long time. The accurate determination of manganese in environmental and biological materials is of considerable importance for both metabolic and toxicological studies in humans and animals because of its dose-dependent harmful and bene cial roles. Analytical techniques of satisfactory sensitivity and accuracy have not been widely available and attempts by many researchers to use

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