Determination of volatile phenols in red wines by dispersive liquid-liquid microextraction and gas chromatography-mass spectrometry detection.

A new method was developed for analysing 4-ethylguaiacol and 4-ethylphenol in the aroma of red wines using dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry detection (GC-MS).
Parameters such as extraction solvent, sample volume and disperser solvent were studied and optimised to obtain the best extraction results with the minimum interference from other substances, thus giving clean chromatograms. The response linearity was studied in the usual concentration ranges of analytes in wines (50-1500 microg/L). Repeatability and reproducibility of this method were lower than 5% for both volatile phenols.
Limits of detection and limits of quantification were also determined, and the values found were 28 and 95 microg/L for 4-ethylguaiacol and 44 and 147 microg/L for 4-ethylphenol, respectively.
This new method has been used for the determination of the volatile phenols concentration in different samples of Tannat wine affected by Brettanomyces contamination.

High-performance liquid chromatography method development and validation for simultaneous determination of five model compounds, antipyrine, metoprolol, ketoprofen, furosemide and phenol red, as a tool for the standardization of rat in situ intestinal permeability studies using timed wavelength detection.

A simple, precise, accurate and rugged reversed-phase high-performance liquid chromatography (HPLC) method has been developed and validated for the simultaneous determination of five permeability model compounds, viz. antipyrine, metoprolol, ketoprofen, furosemide and phenol red.
The method was intended to standardize rat in situ single-pass intestinal perfusion studies to assess the intestinal permeability of drugs in the market as well as new chemical entities. Optimum resolution was achieved by gradient elution on a Symmetry Shield C-18 analytical column with the mobile phase consisting of a mixture of aqueous potassium dihydrogen orthophosphate (pH 5.5; 0.01 m) and methanol at a flow rate of 1.5 mL/min.
The retention times of antipyrine, metoprolol, ketoprofen, phenol red and furosemide were about 9, 12, 13, 16 and 17 min, respectively. Data acquisition was carried out using a photo diode array detector in the wavelength range 210-600 nm. Extraction of chromatograms was carried out by timed wavelength.
Data obtained in all studies indicated that the method was suitable for the intended purpose. The validated method was found to be linear and precise in the working range. Suitability of storage under various conditions and freeze/thaw impact at cold temperature were established to ensure complete sample recovery without any stability issues. Recovery very close to the spiked amounts indicated that the method was highly accurate and suitable for use on routine basis.

A simple and rapid high-performance liquid chromatography method for determining furosemide, hydrochlorothiazide, and phenol red: applicability to intestinal permeability studies.

A simple reversed-phase high-performance liquid chromatography (HPLC) method with ultraviolet detection at 280 nm was developed for simultaneous quantitation of furosemide and hydrochlorothiazide along with phenol red as a nonabsorbable marker for in situ permeability studies in anaesthetized rats.
A jejunal segment of approximately 10 cm was isolated and cannulated in both ends for inlet and outlet solution. The perfusate was collected every 10 min, and samples were analyzed using the developed method.
The mobile phase was acetonitrile-water-triethylamine-glacial acetic acid (41.5 + 57.4 + 0.1 + 0.9, adjusted to pH 5.6) at a flow rate of 1 mL/min; the run time was 9 min. The calibration graphs were linear for all 3 compounds (r>> 0.999) across the concentration range of 7.93-125 microg/mL for phenol red and 6.25-100 microg/mL for hydrochlorothiazide and furosemide.
The limits of quantitation were 7.2, 8.9, and 6.8 microg/mL for furosemide, hydrochlorothiazide, and phenol red, respectively. The coefficients of variation for intraassay and interassay precision were less than or equal to 7.6%, and the accuracy was between 93.2-103.4%. Using the single pass intestinal perfusion technique and the suggested HPLC method for sample analysis, mean values of 0.25 x 10(-4) (+/-0.16) cm/s and 0.22 x 10(-4) (+/-0.13) cm/s were obtained for furosemide and hydrochlorothiazide, respectively.

Construction of a colorimetric sensor array based on the coupling reaction to identify phenols

Phenols are harmful to the human body and the environment. Since there are a variety of phenols in actual samples, this requires a sensor which possesses the ability to simultaneously distinguish them. Herein, we report a colorimetric sensor array, which uses two nanozymes (Fe-N-C nanozymes and Cu-N-C nanozymes) as electronic tongues for fingerprint identification of six phenols (2,4,6-trichlorophenol (2,4,6-Tri), 4-nitrophenol (P-np), phenol (Phe), 3-chlorophenol (3-CP), 4-chlorophenol (4-CP), and o-nitrophenol (O-np)) in the environment.
Nanozymes catalyzed the reaction of hydrogen peroxide, different phenols and 4-aminoantipyrine (4-AAP) to produce different color variations. These signal changes as fingerprints encouraged us to develop a pattern recognition method for the identification of phenols by linear discriminant analysis (LDA). The six phenols at 50 nM have their own response patterns, respectively. Surprisingly, this sensor array had distinguished the six phenols in actual samples successfully.

Ultrafast Proton-Transfer Reaction in Phenol-(Ammonia) n Clusters: An Ab Initio Molecular Dynamics Investigation

The ability of phenol to transfer a proton to surrounding ammonia molecules in a phenol-(ammonia)n cluster depends on the relative orientation of ammonia molecules, and a critical field of about 285 MV cm-1 is essential along the O-H bond for the proton-transfer process. Ab initio MD simulations reveal that the proton-transfer process from phenol to ammonia cluster is spontaneous when the cluster has at least eight ammonia molecules, and the proton-transfer event is almost instantaneous (about 20-120 fs).
These simulations also reveal that the rate-determining step for the proton-transfer process is the reorganization of the solvent around the OH group.
During the solvent reorganization process, the fluctuations in the solvent occur until a particular set of configurations projects the field in excess of the critical electric field along the O-H bond which drives the proton-transfer process. Further, the proton-transfer process follows a curvilinear path which includes the O-H bond elongation and out-of-plane movement of the proton and can be referred to as a “bend-to-break” process.

Inhibition studies of bacterial α-carbonic anhydrases with phenols

The α-class carbonic anhydrases (CAs, EC 4.2.1.1) from the bacterial pathogens Neisseria gonorrhoeae (NgCAα) and Vibrio cholerae (VchCAα) were investigated for their inhibition by a panel of phenols and phenolic acids. Mono-, di- and tri-substituted phenols incorporating additional hydroxyl/hydroxymethyl, amino, acetamido, carboxyl, halogeno and carboxyethenyl moieties were included in the study.

Phenol red

from Bio Basic
PB0420 | 25g: 70.88 EUR

Phenol Red

from Glentham Life Sciences
GT9844-100G | 100 g: 110.00 EUR

Phenol Red

from Glentham Life Sciences
GT9844-250G | 250 g: 181.00 EUR

Phenol Red

from Glentham Life Sciences
GT9844-25G | 25 g: 62.00 EUR

Phenol Red

from Glentham Life Sciences
GT9844-5G | 5 g: 46.00 EUR

Phenol Red Solution

from GenDepot
CA013-010 | 100ml: 69.00 EUR

Phenol-liquid, saturated with water

from Bio Basic
PC5523 | 100ml: 91.76 EUR

Phenol red, sodium salt

from Bio Basic
PD0424 | 25g: 63.92 EUR

Phenol Red (sodium salt)

from MedChemExpress
HY-D0169A | 500mg: 108.00 EUR

Phenol Red sodium salt

from Glentham Life Sciences
GT6682-100G | 100 g: 142.00 EUR

Phenol Red sodium salt

from Glentham Life Sciences
GT6682-25G | 25 g: 70.00 EUR

Phenol Red sodium salt

from Glentham Life Sciences
GT6682-5G | 5 g: 44.00 EUR

Ceraplex , No Phenol red

from GenDepot
C3320-050 | 500ml: Ask for price

PHENOL RED BROTH BASE

from Alphabiosciences
P16-104-10kg | 10 kg: 899.00 EUR

PHENOL RED BROTH BASE

from Alphabiosciences
P16-104-2kg | 2kg: 234.00 EUR

PHENOL RED BROTH BASE

from Alphabiosciences
P16-104-500g | 500 g: 100.00 EUR

PHENOL RED DEXTROSE BROTH

from Alphabiosciences
P16-105-10kg | 10 kg: 743.00 EUR

PHENOL RED DEXTROSE BROTH

from Alphabiosciences
P16-105-2Kg | 2 Kg: 200.00 EUR

PHENOL RED DEXTROSE BROTH

from Alphabiosciences
P16-105-500g | 500 g: 90.00 EUR

PHENOL RED LACTOSE BROTH

from Alphabiosciences
P16-121-10kg | 10 kg: 1254.00 EUR

PHENOL RED LACTOSE BROTH

from Alphabiosciences
P16-121-2Kg | 2 Kg: 312.00 EUR

PHENOL RED LACTOSE BROTH

from Alphabiosciences
P16-121-500g | 500 g: 121.00 EUR
The best NgCAα inhibitrs were phenol, 3-aminophenol, 4-hydroxy-benzylalcohol, 3-amino-4-chlorophenol and paracetamol, with KI values of 0.6-1.7 µM. The most effective VchCAα inhibitrs were phenol, 3-amino-4-chlorophenol and 4-hydroxy-benzyl-alcohol, with KI values of 0.7-1.2 µM. Small changes in the phenol scaffold led to drastic effects on the bacterial CA inhibitory activity. This class of underinvestigated bacterial CA inhibitors may thus lead to effective compounds for fighting drug resistant bacteria.