The main goal of this thesis is designing and developing new smartphone-based analytical systems to provide simple, inexpensive and fast methodologies with no need for any skilled operator for the determination of the analytes of the interest outside of the laboratory environment. In the other part of this thesis, the development of new adsorbents for improving performance and analytical parameters of sorbent-based microextraction techniques is considered. In the first study, a portable smartphone-based chemiluminescence sensing was introduced for TLC imaging. The instrument detects the light generated from the chemiluminescence reaction of potassium permanganate with morphine applied on a TLC plate. In this method, a smartphone was used as a detection system and data processor. Under the optimum conditions, the limit of detection and and linearity range were obtained 5.0 × 10-1 and 1.0-2.5 × 10 mg L?1, respectively. In the second study, single-drop microextraction was combined with smartphone-based on-drop sensing. A smartphone was used for formaldehyde detection after single-drop microextraction. After simultaneous extraction and derivatization of formaldehyde, on-drop sensing of formaldehyde was performed with imaging by the smartphone. The limit of detection and linearity range were obtained 1.0 × 10-1 and 3.0 × 10-1-1.0 × 10 mg L?1, respectively. The method was used for formaldehyde assaying in textile and wastewater samples. In the third study, Smartphone-based on-cell detection in combination with emulsification microextraction was introduced for the trace level determination of phenol index in water and wastewater samples. The reaction of 4- aminoantipyrine with phenolic compounds was used to produce a colored complex. After extraction of the colored complex, a smartphone was used for on-cell detection of color intensity. The limit of detection and linearity range were obtained 2 and 5-1 × 102, respectively. In the fourth study, a combination of paper-based thin-film microextraction with smartphone-based sensing for was introduced for sulfite assay in food sample. Sulfite was converted to SO2 by acidification of the sample solution. The liberated SO2 reduced Fe(III) to Fe(II) on the paper-based film, followed by a red complex formation with 1,10-phenanthroline. The intensity of the obtained color was the basis of the measurement. The limit of detection and linearity range were obtained 4.0 × 10-2 and 1.0 × 10-1-7.0 × 102 µg L?1, respectively. In the fifth study, a portable smartphone-based colorimetric sensor was introduced for rapid determination of water content in ethanol. The method was based on the color-changing of an ethanolic solution of cobalt chloride in the presence of water. The limit of detection and linearity range were obtained 2.00 × 10-2 and 5.00 × 10-2-2.00 % v/v, respectively. The method was used for the determination of water content in real ethanol samples. In the sixth study, Chip-based liquid-liquid microextraction in combination with smartphone-based detection was introduced for the determination of copper in environmental and biological samples. After the extraction of the colored complex of copper in the chip, color sensing was performed using a smartphone. The limit of detection and linearity range were obtained 1.0 × 10-1 and 3.0 × 10-1-4.0 × 10 mg L-1, respectively. In the seventh study, a portable smartphone-based chemiluminescence sensor was introduced for rapid urine and saliva drug screening. The method used chemiluminescence reaction of potassium permanganate and tris(bipyridine)ruthenium(II) chloride for the determination of morphine and heroin. The limit of detection and linearity range were 2.0 × 10-1 and 5.0 × 10-1-3.0 × 10 mg L-1 for morphine in urine and 2.0 × 10-1 and 6.0 × 10-1-1.0 × 102 mg L-1 for heroin in saliva, respectively. In the eighth study, a covalent triazine-based framework was synthesized and used for the first time for micro solid-phase extraction of parabens followed by high-performance liquid chromatography. The magnetic nanosized sorbent was used for the extraction of parabens from several real samples. The limit of detection and linearity range were obtained 2.0 × 10-2 and 1.0 × 10-1-5.0 × 102 µg L-1, respectively for the selected parabens. In the ninth study, a covalent triazine-based framework was synthesized and used for the first time for solid-phase microextraction followed by gas chromatography. The nanosized sorbent was used for the extraction of pesticides from water and wastewater samples. The limits of detection were 3.0 × 10-2-1.1µg L-1 and linearity ranges were 1.0 × 10-1-5.0, 2.0 × 10-1-1.0 × 10 and 4.0-7.5 × 10 for profenofos, propiconazole, and difenoconazole, respectively.