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This study presents a novel, cost‐effective approach involving spectrophotometric and smartphone paper‐based (SPB) methods and a distinctive salting‐out air‐assisted dispersive microextraction procedure to quantify thiocyanate in saliva samples. The method relies on the inhibitory effect of thiocyanate on quinoneimine dye formation during the Emerson reaction with sodium hypochlorite. Spectrophotometry quantifies the extracted dye by monitoring quinoneimine color intensity reduction at 525 nm. In the SPB method, extracted dye is applied to a paper strip, a smartphone captures the colored paper, and an application analyzes red, green, and blue components. All analyte determination and extraction variables were explored. Both methods exhibit good linearity (10–100 μg/L) with a coefficient of determination of 0.9991 and a limit of detection of 7.5 μg/L for the spectrophotometric method, and a coefficient of determination of 0.9988 and a limit of detection of 8.8 μg/L for the SPB method. The calculated values for the enrichment factor and extraction recovery of the developed extraction methodology were 46% and 93%, respectively. The methods detect thiocyanate in saliva samples, producing results comparable to a validated method. [ABSTRACT FROM AUTHOR]

• Synthetization of newly boronic acid-CDs in one step. • Effect of variables such as pH, incubation time and several organic and inorganic as interferences were studied. • A highly luminescence CDs was obtained with less than 10 nm in size and highly quantum yield 22.65%. • Glucose in saliva sample was detected via the static quenching mechanism of fluorescent light. The drawbacks of using an enzymatic assay as a traditional protocol for glucose include cost, time consumption, instability, and denaturation of glucose oxidase. Recently, glucose sensing with the aid of boronic acid-based molecules and their derivatives has been developed as an alternative tool to commonly used methods. In this work, a simple single-step hydrothermal method was effectively applied to synthetized boronic acid-functionalized sulfur-doped carbon nanodots (BS-CDs) using 3-thiophenylboronic acid as the starting material. In comparison with the common two-step synthetization of nanoparticle-based sensors, this synthesis procedure is less demanding and equally as effective in terms of nanofabrication and quantum yield 22.63%. The present sensing method arises from the assembly and fluorescence quenching of fluorescence nanoparticles (BS-CDs) when the glucose solution was added. The fluorescence intensity was recorded and applied to selectively estimate glucose in the concentration range of 1–250 μM with a detection limit of 0.57 μM. Fluorescence nanoparticles with boronic acid had excellent selectivity and strongly resisted interference from several biomolecules. The developed chemosensor was successfully applied in the measurement of glucose in human saliva. [ABSTRACT FROM AUTHOR]