Phenols detection

Interaction of formaldehyde with 2,4-dinitrophenylhydrazine in acid media causes 2,4-dinitrophenylhydrazone (DNPhydrazone) formaldehyde formation. Gas-chromatographic analysis of 2,4-DNP-hydrazone formaldehyde toluene extract with an electron holding detector makes it possible to detect it at the level of 0,001 mg/dm. Phenol is detected in the form of tribromphenol yield, the hexane extract of which undergoes chromatography with an electron holding detector which provides the level of phenol detection of 0.001 mg/dm (the limit of quantitative detection). 

PHENOLIC COMPOUND CONCENTRATIONS AND PHENOL DETECTED IN SEVERAL COMMERCIAL RED WINES... 

Phenol is not expected to bioconcentrate significantly in aquatic organisms. Reported log bioconcentration factors (BCF) in fish for phenol include 0.28 for goldfish, (Kobayashi et al. 1979) and 1.3 for golden orfe (Freitag et al. 1984). The highest mean level of phenol detected in bottom fish from Commencement Bay in Tacoma, WA, was 0.14 ppm (Nicola et al. 1987). The levels of phenol in the water or sediments were not stated. 

The level of phenol detected in blood or urine may not accurately reflect actual phenol exposure because phenol may also appear as a metabolite of benzene or other drugs. It has been shown that under certain acidic conditions used for the hydrolysis of conjugated phenols, acetyl salicylic acid (aspirin) may produce phenol (Baldwin et al. 1981) and yield spuriously higher values for phenol in blood and urine. 

It should be noted here that in specifying the rules for the first probe (phenols), it became clear that rules for choosing the column and mobile phase interact significantly with detector rules. 0.1% acetic acid works well as a competing acid additive in terms of chromatography of the phenols. However, carboxylate ions are known to quench the fluorescence of phenols. Thus, if one were to use a fluorescence detector for trace phenol detection, an alternative competing acid, such as 0.1% phosphoric acid should be substituted. It was decided that mobile phase/detector interaction rules would be the first detector rules to be added to the knowledge base. 

Fig. 6.1.1. Monomeric phenols detected m lignin acidolysis reaction mixtures...

ZnO nanoparticles dispersed CH composite films deposited onto glassy carbon electrode (GCE) have been used for immobilization of tyrosinase enzyme for phenol detection. This biosensor shows 95% of steady-state current within 10s, sensitivity as 182 pA mmol"1 L with a detection limit of 5.0 x 10"8 mol/L, exhibits maximum response at 50°C and retains 91% current after about 20 days [39], A sol-gel derived ZnO matrix has been used to immobilize tyrosinase for determination of phenol concentration from 1.5 x 10"7 to 4.0 x 10"5 mol L"1 with detection limit of 8.0 x 10 s mol L"1 and sensitivity of 168 pA mmol L"1. This biosensor shows 95% of steady-state current within 15s after 2 weeks [40], Chen et al. have immobilized mushroom tyrosinase oxidase onto ZnO nanorods for the phenol and catechol detection. The linear concentration ranges have been obtained from 0.02 to 0.1 mM and 0.01 to 0.4 mM, for phenol and catechol, respectively. The apparent Km has been estimated as 0.24 mM for phenol and 1.75 mM for catechol [59],... 

When oxidising benzaldehydes with peroxygen compounds one must be aware of the possible Dakin reaction which can occur as a side reaction. As one would expect alkaline conditions to promote the Dakin reaction we first studied peracid systems (Fig. 10). Surprisingly, significant levels of phenol were discovered in this reaction. However, when alkaline H2Oz was used excellent yields of acid were obtained with no phenol detected and no hydroxylation of the isopropyl group. 

The variation in peak height for the phenol signal as a function of the potential applied to the electrochemical cell is shown by the hydrodynamic voltammogram in Fig. 4. Maximum sensitivity for phenol detection is achieved at a potential of +850 mV versus Ag/AgCl, or greater. Our experiments were conducted at a potential of +870 mV. 

Giuliani, E., Fernandes, R., Brazaca, L. C., Rodriguez-Mendez, M. L., Antonio de Saja, J. Zucolotto, V. (2011). Immobilization of lutetium bisphthalocyanine in nanostmc-tured biomimetic sensors using the LBL technique for phenol detection Biosensors and Bioelectronics 26, 4715—471. 

The Ag-Ab was collected in the effluent, the enzyme substrate PP added, and the product phenol detected at a bienzymatic biosensor identical to the one described earher. By packing the column with a large excess of cocaine, more than 200 assays were performed before the column required regeneration. 

Melting and Solidifying-Points—Boiling-Point and Distillation— Determination of Esters—Determination of Alcohols— Tables for the Calculation of Esters and Alcohols—Separate DMermination of Citronellol in Presence of Gwaniol—Determination of Aldehydes and Ketones— Miscellaneous Processes—Determination of Phenols—Detection of Chlorine—Determination of Hydrocarbons—Detection of some Common Adulterants. 

Phenolformal-dehyde resins Phenol Silica gel G (F254) CHCI3-CCI4 (7 1) MejCaBuNHz (1 1) spray Adsorption 155 Reaction with 2,4 dinitrobenzenesul-fonylchloride, then TLC (3% phenol detectable)... 

T.A. Sergeyeva, L.A. Gorbach, O.A. Slinchenko, L.A. Goncharova, O.V. Piletska, 0.0. Brovko, L.M. Sergeeva and G.V. Elska, Towards development of colorimetric test-systems for phenols detection based on computationally-designed molecularly imprinted polymer membranes. Mater. Sci. Eng. C, 30 (3) 431-436,2010. 

Color Reactions of Phenols (Detection) Reaction with Ferric Chloride General Considerations... 

Merkoci A, Anik U, Cevik S, Cubukcu M, Guix M (2010) Bismuth film combined with screen-printed electrode as biosensing platform for phenol detection. Electroanalysis 22 1429-1436... 

Odaci D, Timur S, Telefoncu A (2004) Immobilized Jerusalem artichoke (Helianthus tuberosus) tissue electrode for phenol detection. Artif Cells Blood Substit Biotechnol 32 (2) 315-323. doi 10.1081/bio-120037836... 

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