Determination of Lead in Bee Products by Solid Surface Fluorescence Using Complexation and Coacervation at Room Temperature Processes. An Environmental Friendly Methodology.

An accurate, economic and green methodology for Pb(II) monitoring in bee products is proposed. Complexed metal traces were preconcentrated on Nylon membranes using the coacervation phenomenon based on room temperature reaction between the cationic surfactant hexadecyltrimethylammonium bromide and the bile salt sodium cholate. The increase in solid surface fluorescence signal of dyes 8-hydroxyquinoleine and o-phenanthroline due to Pb(II) presence was used for the metal quantification. Experimental variables that influence on preconcentration step and fluorimetric sensitivity were optimized using uni-varied assays. Pb(II) concentration was determined on membranes by solid surface fluorescence at λem = 470 nm (λexc = 445 nm), using a solid sample holder. The calibration at optimal experimental conditions showed a LOD of 4.2 × 10-4 mg Kg-1 with a linear range of 1.28 × 10-3 mg Kg-1 to 8.73 mg Kg-1 and was successfully applied to Pb(II) quantification in different bee products produced in central west region of Argentina. The proposed methodology was applied to all samples after appropriate dilution. Accuracy methodology was evaluated by comparison of the obtained results with those found by ICP-MS, with percentage relative error under 8%. The precision was better than 0.0344 CV for Pb(II) determination.

Copper Traces Quantification in Bee's Products by Solid Surface Fluorescence. A Green Analytical Proposal.

A new methodology based on the fluorescence of Cu(II) ternary system with o-phenanthroline (o-Phen) and eosin (Eo) dyes is proposed. The metal was selectively retained on Nylon membranes and the solid surface fluorescence (SSF) was used for anayte quantification. Experimental variables that influence the formation of Cu(II)-o-Phen-eo system and retention step were studied and optimized. At optimal experimental conditions, an adequate tolerance to foreign species was shown with a LOD of 1.18 ng L-1 and a LOQ of 3.57 ng L-1. The methodology was evaluated for their greenness profile and successfully applied to analyte determination in bee's products of West-Center Argentina. Recovery studies showed values near to 100% being satisfactorily validated by ICP-MS.

Determination of lead traces in honey using a fluorimetric method.

Heavy traces metals may be present in honey being their detection very important for the quality control and it also serves as an indicator of environmental pollution. A new methodology for lead traces determination has been developed based on the quenching effect of the metal on fluorescent emission of 8-hydroxyquinoline and o-phenanthroline at λem = 360 nm (λexc = 250 nm). Experimental variables that influence on fluorimetric sensitivity were optimized by uni-variation assays. The calibration graph using zeroth order regression was linear from 0.105 µg L-1 to 51.8 µg L-1, with correlation coefficient better than 0.998. Under the optimal conditions, the limits of detection and quantification were of 0.035 µg L-1 and 0.105 µg L-1, respectively. The trueness of the methodology was assessed trough parallel samples analysis by ICP-MS. The proposed method showed good sensitivity, adequate selectivity with good tolerance to foreign ions, and was applied to the determination of lead trace amounts in honey from San Luis city (Argentina) with satisfactory results.

Novel method for determination of zinc traces in beverages and water samples by solid surface fluorescence using a conventional quartz cuvette.

A new method for zinc pre-concentration/separation and determination by molecular fluorescence is proposed. The metal was complexed with o-phenanthroline and eosin at pH 7.5 in Tris; a piece of filter paper was used as a solid support and solid fluorescent emission measured using a conventional quartz cuvette. Under optimal conditions, the limits of detection and quantification were 0.36 × 10(-3) and 1.29 × 10(-3) µg L(-1), respectively, and the linear range from 1.29 × 10(-3) to 4.50 µg L(-1). This method showed good sensitivity and selectivity, and it was applied to the determination of zinc in foods and tap water. The absence of filtration reduced the consumption of water and electricity. Additionally, the use of common filter papers makes it a simpler and more rapid alternative to conventional methods, with sensitivity and accuracy similar to atomic spectroscopies using a typical laboratory instrument.