Spectrophotometric Determination of Thiocyanate in Human Saliva Employing Micropumping Multicommutation Flow System

ABSTRACT

A procedure based on a multicommutated approach for the determination of thiocyanate (SCN⁻) in human saliva is described. The method was based on the reaction of Fe(III) with SCN⁻, producing a red complex that was monitored at 480 nm. Under optimum experimental conditions, a linear response ranging from 0.5 to 10.0 m mol L⁻¹ SCN⁻ (R = 0.9991), a relative standard deviation of 1.0% (n = 10) for a sample 5 m mol L⁻¹ SCN⁻, a detection limit (3σ criterion) of 50 µ mol L⁻¹, a sampling rate of 60 determinations per hour, reagent consumption of 0.02 mg Fe(III) per determination, and a waste generation of 1.6 mL per determination were achieved.

KEYWORDS:

• human saliva
• multicommutation flow analysis
• multipumping
• spectrophotometry
• thiocyanate

ACKNOWLEDGMENTS

The authors are grateful to CAPES (Brazil)/GRICES (Portugal), FACEPE, and CNPq for financial support and to those individuals who provided the saliva samples to make this investigation feasible.

Notes

^a On/off indicates a 0.1 s/0.1 s pulse of the solenoid micropump.

^a Data are interferent/analyte concentration ratios, in m mol L⁻¹.

^b Maximum tested ratio.

^a Results expressed in m mol L⁻¹.

^b n = 3.

^c Samples 1–6: nonsmokers; 7–11: smokers.

^d After spiking 1.0 m mol L⁻¹.

The labels ^∗ and ^∗∗ indicate that the values are related to consumption and waste generation per determination, respectively.