Development of an optical redox chemical sensor for nitrite determination

Abstract

Recebido em 18/7/11; aceito em 14/10/11; publicado na web em 20/1/12An optical chemical sensor for the determination of nitrite based on incorporating methyltrioctylammonium chloride as an anionic exchanger on the triacetylcellulose polymer has been reported. The response of the sensor is based on the redox reaction between nitrite in aqueous solution and iodide adsorbed on sensing membrane using anion exchange phenomena. The sensing membrane reversibly responses to nitrite ion over the range of 6.52×10 -6 -8.70×10 -5 mol L -1 with a detection limit of 6.05×10 -7 mol L -1 (0.03 mg mL -1) and response time of 6 min. The relative standard deviation for eight replicate measurements of 8.70×10-6 and 4.34×10-5mol L -1 of nitrite was 4.4 and 2.5 %, respectively. The sensor was successfully applied for determination of nitrite in food, saliva and water samples.

Ion pair-based dispersive liquid–liquid microextraction combined with UV-Vis spectrophotometry as a circuitous assay for nitrite

“…The technique is based on the reaction of nitrite with iodide excess in acidic medium to form triiodide, 9,10,31 which is then colorimetrically monitored via its color after extraction into the small volume of extraction solvent. The technique is based on the reaction of nitrite with iodide excess in acidic medium to form triiodide, 9,10,31 which is then colorimetrically monitored via its color after extraction into the small volume of extraction solvent.…”

“…The proposed method has some advantages in comparison with the other extraction and determination methods for nitrite, 3,9,10,16,[32][33][34] including low consumption of organic solvents and reagents, easy access, simplicity and low cost of the extraction device. Also, this DLLME 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 procedure did not need the conventional disperser solvent to be applied, because the Aliquat 336 was used as anion carrier and disperser agent simultaneously.…”

“…Various methods have been proposed for the determination of nitrite ion, such as spectrophotometry, [9][10][11][12] electrochemistry, [13][14][15] chromatography, [16][17][18] electrophoresis 19,20 and so on. Excluding the spectrophotometry, most of these methods are not suitable for routine determination of nitrite because they require expensive equipment and materials and include time-consuming steps.…”

“…Subsequently,10.0 g of each sample were weighed and placed in a beaker, and 5 mL of borax solution (5%) and 150 mL of hot water was added and placed in a hot water path(80-90 °C) for 30 min. Subsequently,10.0 g of each sample were weighed and placed in a beaker, and 5 mL of borax solution (5%) and 150 mL of hot water was added and placed in a hot water path(80-90 °C) for 30 min.…”

Utilizing of Ag@AgCl@graphene oxide@Fe3O4 nanocomposite as a magnetic plasmonic nanophotocatalyst in light-initiated H2O2 generation and chemiluminescence detection of nitrite

“…The sample treatment was performed according to the AOAC recommended method[29]. 2.0 g of each adequately crushed sample was mixed and homogenized in a mortar.…”