Ammoniacal Methanol Research Articles

Magnetic solid-phase extraction of triclosan using core-shell Fe3O4@MIL-100 magnetic nanoparticles, and its determination by HPLC with UV detection

The article describes the synthesis of core-shell magnetic nanoparticles (MNPs) of the type Fe3O4@MIL-100 (MIL standing for Material Institut Lavoisier), and their application as sorbent for magnetic solid-phase extraction (MSPE) of triclosan. The MNPs were prepared via circular self-assembly of ferric chloride and benzenetricarboxylic acid. The functionalized MNPs were characterized by transmission electron microscopy, FTIR and thermogravimetry. Following extraction, triclosan was eluted with ammoniacal methanol and then submitted to HPLC with UV detection. The amount of magnetic microspheres, sample pH and ionic strength, adsorption time, desorption time, desorption solvent and the volume of the eluent were optimized. Under optimum conditions, the method showed good linearity in the 0.1 to 50 mg·kg−1 triclosan concentration range in toothpaste samples. Other features include (a) intra-day and inter-day relative standard deviations (RSD, for n = 4) of <5.5 %, (b) a 30 μg·kg−1 limit of detection, and (c) extraction recoveries between 90.86 % and 101.1 %. The method was successfully applied to the determination of triclosan in children’s toothpaste.

Formation of Mutagenic/Carcinogenic Heterocyclic Amines under Moderate Conditions

More than 10 kinds of heterocyclic amines (HCAs), showing mutagenic and carcinogenic potency, have been isolated from cooked fish and meat. But many researchers say that the contribution ratio of HCAs to human cancer is very low. Our purpose in this experiment was to investigate the possibility of the formation of HCAs under moderate conditions, including in vivo. A mixture of d-glucose, creatinine, and amino acid such as glycine, methionine, threonine, and proline was dissolved in phosphate-buffered solution (pH7.4) and incubated at 37 degrees C, 50 degrees C, 128 degrees C. At an appropriate time, an aliquot of the reaction solution was treated with blue cotton. HCAs were separated from the blue cotton by elution with 2% ammoniacal methanol. The eluates were submitted to the Ames test, the micronucleus test for determination of mutagenicity, and also LC-MS analysis for the detection of HCAs. Nonadsorbates to blue cotton were treated with dichloromethane and then subjected to the mutagenicity test. In the Ames test, the mutagenic activity of the reaction mixture increased with an increase of the reaction temperature. The HCA fraction from 50 degrees C incubated solution showed high frequency in the micronucleus test using HepG2 cells. The dichloromethane fractions contained other type of mutagens different from HCAs. In HCA fractions, IQ, MeIQx, 4,8-DiMeIQx, and 7,8-DiMeIQ were identified. It is said that the heating process is an essential factor in the formation of HCAs. But our experiment shows that HCAs are produced not only in the cooking process, but also in moderate conditions such as 37 degrees C and 50 degrees C.

Analysis of wavelength-dependent photoisomerization quantum yields in bilirubins by fitting two exciton absorption bands

The absorption spectra of bilirubins were deconvoluted by two Gaussian curves of equal width representing the exciton bands of the non-degenerate molecular system. The two bands were used to study the wavelength dependence of the (4Z, 15Z) → (4Z, 15E) configurational photoisomerization quantum yield of the bichromophoric bilirubin-IXα (BR-IX), the intrinsically asymmetric bile pigment associated with jaundice and the symmetrically substituted bilirubins (bilirubin-IIIα and mesobilirubin-XIIIα), when they are irradiated in aqueous solution bound to human serum albumin (HSA). The same study was performed for BR-IX in ammoniacal methanol solution (NH4OH/MeOH). The quantum yields of the configurational photoprocesses were fitted with a combination function of the two Gaussian bands normalized to the total absorption, using the proportionality coefficients and a scaling factor as parameters. The decrease of the (4Z, 15Z) → (4Z, 15E) quantum yield with increasing wavelength, which occurs for wavelengths longer than the most probable Franck–Condon transition of the molecule, did not result in a unique function of the exciton absorptions. In particular we found two ranges corresponding to different exciton interactions with different proportionality coefficients and scaling factors. The wavelength-dependent photoisomerization of bilirubins was described as an abrupt change in quantum yield as soon as the resulting excitation was strongly localized in each chromophore. The change was correlated to a variation of the interaction between the two chromophores when the short-wavelength exciton absorption became vanishingly small. With the help of the circular dichroism (CD) spectrum of BR-IX in HSA, a small band was resolved in the bilirubin absorption spectrum, delivering part of the energy required for the (4Z, 15Z) → (4Z, 15E) photoisomerization of the molecule.

Distribution of Vehicular Lead in Roadside Soils of Major Roads of Brisbane, Australia

Collections were made from three sites in the urbanarea of Brisbane, Australia. At each site, soilsamples were collected from transects parallel andperpendicular to the roadway, as well as a depthprofile. Total lead was determined by refluxing thesamples with concentrated nitric acid (1 h) andorganic lead by shaking with cold ammoniacal methanol(Flameless AAS). Both chloride and bromide anionswere obtained from an aqueous extract (HPLC). Resultsshowed that vehicular emissions were the major sourceof lead in the roadside soils of this study. At siteslocated in relatively enclosed areas of higheratmospheric stability, both lead and bromide contentsdecreased markedly with increasing distance from theroadway. However, in the absence of such atmosphericstability, the distribution of both lead and bromidecontents revealed different patterns which wasattributed mainly to the effect of meteorologicalfactors such as wind direction and speed. The depthprofile of roadside soils generally showed leadaccumulation within the uppermost 5 cm, whereaselevated concentrations of bromide were observed at greater depth.

Induction of Wavelength-Dependent Photochemistry in Bilirubins by Serum Albumin

Quantum yields for Z⇄E photoisomerization of the natural bi-chromophore bilirubin IXα in ammoniacal methanol solution were found to vary with excitation wavelength, whereas no variation (within experimental error) was observed for xanthobilirubic acid and for symmetrically substituted bilirubins (bilirubin IIIα, bilirubin XIIIα, and mesobilirubin XIIIα) in the same solvent. The quantum yield for Z⇄E photoisomerization of xanthobilirubic acid bound to human serum albumin was also invariant with excitation wavelength. In contrast, quantum yields for Z⇄E photoisomerization of the symmetrically-substituted bilirubins did show marked excitation wavelength dependency when they were bound to human serum albumin. These results show that quantum yields for Z⇄E photoisomerization of bilirubins are markedly sensitive to protein binding and to the nature of pyrrole ring β-substituents. They also demonstrate that wavelength-dependent photochemistry is characteristic of bilirubins with non-identical pyrromethenone chromophores, as expected from exciton coupling theory, and that complexation with albumin induces wavelength-dependent photochemistry in symmetrically substituted bilirubins.

Screening and identification of drugs in human hair by high-performance liquid chromatography—photodiode-array UV detection and gas chromatography—mass spectrometry after solid-phase extraction a powerful tool in forensic medicine

A method is described to screen for a wide range of pharmaceuticals in human hair, 75 mg of powdered hair are incubated (12 h at + 56°C) in 2 ml of distilled water (acidic compounds) or 0.1 M hydrochloric acid (neutral and basic compounds). A twin solid-phase extraction on C 18 cartridges is used for the sample clean-up procedure. Acidic drugs are fixed at pH 2 and eluted with 1% ammoniacal methanol while neutral and basic drugs are retained on the column at pH 8.6 and eluted with methanol containing 0.5% acetic acid. The internal standard (I.S.) for the acidic extraction was bupivacaine while the I.S. for the basic extraction was prazepam. The separation of the drugs was performed using both the liquid and the gas chromatographic techniques whereas identification was achieved using photodiode array and mass spectrometric detection, respectively. The liquid chromatographic system gives an elution of the drugs following a multi step gradient from a Symmetry C 8 (Waters) 5 μm column (250×4.6 mm I.D.) at +30°C with acetonitrile-phosphate buffer (pH 3.8). Identification is achieved using the reference data (retention times and spectra) of 675 pharmaceuticals, toxicants and drugs of abuse stored in a personal library. The present method has been applied during 6 months in our laboratory. By establishing a victim's drug use history, it is a very powerful tool in forensic medicine. We illustrate the method with some real cases of police crime investigation.

ChemInform Abstract: Electrolytic Oxidation of Ketones in Ammoniacal Methanol in the Presence of Catalytic Amounts of KI.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Electrolytic Oxidation of Ketones in Ammoniacal Methanol in the Presence of Catalytic Amounts of KI

Electrolytic Oxidation of Ketones in Ammoniacal Methanol in the Presence of Catalytic Amounts of KI

Determination of metanephrines in plasma by liquid chromatography with electrochemical detection

Metanephrines are O-methylated metabolites of catecholamines. We report the use of liquid chromatography with electrochemical detection to determine plasma concentrations of normetanephrine (NMN) and metanephrine (MN). Plasma NMN and MN in 32 normal volunteers and inpatients were compared with concentrations in 23 patients with pheochromocytoma. Metanephrines were adsorbed from plasma onto a cation-exchange column and eluted with ammoniacal methanol. The dried residue was dissolved in mobile phase and injected onto a reversed-phase column. Recoveries of NMN and MN from 1 mL of plasma averaged 50-70%, and results varied linearly with quantity injected over a range of 0.13-55 pmol. The detection limit was 25 fmol for NMN and 50 fmol for MN. Intra-assay CVs were < 5%. In normal volunteers and inpatients, plasma concentrations of NMN ranged between 0.12 and 0.73 nmol/L (mean 0.38 nmol/L), and MN between 0.06 and 0.63 nmol/L (mean 0.19 nmol/L). Plasma NMN concentrations were increased in all 23 patients with pheochromocytoma (range 1-172 nmol/L), whereas MN concentrations (range 0.10-382 nmol/L) were increased in only 9 patients. The assay method is reliable and sensitive and offers an approach to examine the extraneuronal metabolism of catecholamines. The method may also be useful in the diagnosis of pheochromocytoma.

Mutagenicity of commercial hair dyes and detection of 2,7-diaminophenazine

Four commercial oxidative-type hair dye formulations, A, B, C, and D, were treated with hydrogen peroxide (H 2O 2) to simulate normal conditions of use, and the oxidized hair dyes were tested for their mutagenicity in Salmonella typhimurium TA98 in the presence of a mammalian metabolic activation system (S9 mix). Most of them did not show obvious mutagenicity in the range of 1–25 μl/plate and all exhibited bactericidal activity at 10 μl/plate. In order to evaluate the mutagenicity of hair dyes both before and after H 2O 2 oxidation, rayon linked to a copper-phthalocyanine derivative (blue rayon) was used as an adsorbent for the elimination of interfering bactericidal compounds. Adsorbed compounds on blue rayon were eluted with ammoniacal methanol and eluents were subjected to the Ames test. The mutagenicity of the blue-rayon extracts in TA98 with S9 mix was increased by H 2O 2 oxidation. The blue-rayon extracts obtained from oxidized A and B were potent mutagens and reverted 334 and 999 colonies/10 μl of original substance, respectively. In addition, 88 and 249 ng of 2,7-diaminophenazine, which was extremely mutagenic in TA98 with S9 mix, were detected in the extracts of 40 ml of the hair dye formulations A, and B, respectively. The mutagenicity in oxidized hair dye formulations was successfully detected by use of blue-rayon extraction. 2,7-Diaminophenazine was only formed in the hair dye formulations containing m-phenylenediamine by H 2O 2 oxidation. Therefore, attention needs to be paid to the use of m-phenylenediamine as a hair dye component, not only for its own toxicity but also for that of its oxidation products.

Binding of benzo[a]pyrene metabolites in the rat intestinal lumen by magnetic polyethyleneimine microcapsules following an intragastric dose of [14C]benzo[a]pyrene.

Semi-permeable magnetic polyethyleneimine (PEI) microcapsules have been developed to trap carcinogens and their metabolites in vivo and their time-dependent binding of a model carcinogen, [14C]benzo[a]pyrene [( 14C]BaP), is studied within the intestinal lumen. Overall, approximately 0.5% of an intragastric BaP dose was bound by these microcapsules recovered from faeces with specific binding of metabolites (nmol/10(6) recovered microcapsules) being similar in the 0-24-h and 24-48-h periods, but approximately 10-fold lower in the 48-72-h period. Successive extractions of microcapsules with ammoniacal methanol, 2.5 N HCl, methanol and dimethylsulfoxide released approximately 60% of bound radiolabeled and the unextracted radiolabel was presumed to have been bound covalently. By contrast, greater than 90% of bound radiolabel was extractable from the faeces of the treated animals and from microcapsules treated in vitro with [14C]7,8-dihydroxy-9,10-epoxytetrahydrobenzo[a]pyrene (BaPDE), indicating that the in vivo microcapsule-bound metabolites were not derived either from adsorbed faecal material or from [14C]BaPDE formed in situ. A time-dependent appearance of BaP 3,6-dione was found. Also the qualitative and quantitative patterns of metabolites trapped by microcapsules, as assayed by h.p.l.c., were consistent only with a unique set of BaP metabolites being bound within the intestinal lumen. Hence these carcinogen-binding microcapsules can be used to investigate the in situ formation of carcinogen metabolites within the intestinal tract.

Photobilirubin II.

An improved preparation of photobilirubin II in ammoniacal methanol is described. Evidence is presented which distinguishes between the two structures proposed earlier for photobilirubin II in favour of the cycloheptadienyl structure. Nuclear-Overhauser-enhancement measurements with bilirubin IX alpha and photobilirubin II in dimethyl sulphoxide are complicated by the occurrence of negative and zero effects. The partition coefficient of photobilirubin II between chloroform and phosphate buffer (pH 7.4) is 0.67.

Adsorption of mutagens to cotton bearing covalently bound trisulfo-copper-phthalocyanine

A method for separating nonpolar mutagens from their dilute aqueous solutions is described. It utilizes the affinity of the mutagens to a phthalocyanine derivative attached to cotton through a covalent bond. For mutagens having 3 or more fused aromatic rings in their structures, efficient adsorption took place on soaking the cotton in their solutions. The mutagens adsorbed can be recovered by elution with ammoniacal methanol. Mutagenicity in smoker's urine, cooked beef, and river water was detected by use of this method.

Urinary metanephrines as measured by liquid chromatography with an on-line post-column reaction detector.

In this method for measuring metanephrine and normetanephrine in urine, they are freed from their conjugates by hydrolysis in acid, neutralized, and isolated on a cation-exchange resin. Both metanephrines are co-eluted with ammoniacal methanol and the eluate is concentrated 10-fold with respect to the original urine volume by evaporation and reconstitution. The recovered metanephrines ae separated by reversed-phase (C18) "high-pressure" liquid chromatography with use of a mobile phase consisting of 10 mmol/L trichloroacetate, pH 2.7, containing 30 mL of acetonitrile per liter. The metanephrines are detected at 365 nm after being converted to vanillin in a post-column reaction with alkaline periodate. Total metanephrine values for most patients were appreciably lower than values obtained by the comparison procedure, that of Pisano (Clin. Chim. Acta 5: 406, 1970); however, results obtained by the two methods for two patients with pheochromocytomas agreed well.

Luminescence of bilirubin

The 525 nm luminescence from bilirubin in ammoniacal methanol at 77 K, which had previously been thought to be phosphorescence, is reinterpreted as fluorescence on the grounds of the short lifetime (< 5 ns) of its major component. Band-shape analysis of the corresponding absorption band reveals it to consist of at least two components with different solvent shifts.

On the autoxidation of bilirubin

The instability of oxygenated aqueous solutions of bilirubin in the dark is due to several distinguishable processes: autoxidation, surface phenomena and precipitation-aggregation. Autoxidation occurs in aqueous solutions over a pH range 7.4–13.2 in the presence of even traces of oxygen. Several autoxidation products have been isolated and identified. At pH 7.4–8.8 bilirubin precipitates from 2.5 × 10 −5 M solutions and adsorbs to the walls of the glass container. In ammoniacal methanol, chloroform and dimethyl sulfoxide aggregation phenomena do not occur and autoxidation is very slow.

The determination of thebaine in Papaver bracteatum Lindl by gas-liquid chromatography

Several solvents have been examined in the process of developing a convenient method for extracting powdered material and removing interfering pigments to produce an extract of Papaver bracteatum suitable for g.l.c. assay. The most suitable extracting solvent was aqueous acetic acid (5%); the assay method gave satisfactory reproducibility with a wide range of plant materials (coefficient of variation 0.63 to 3.33%). The accuracy was checked by recovery experiments with pure thebaine and by examination of exhausted marcs. The presence of other alkaloids did not interfer with the assay. There were substantial differences in the amounts of thebaine extracted from capsule and root samples by ammoniacal methanol and by aqueous acetic acid, indicating the presence of thebaine in a "bound" form. The minimum amount of thebaine that could readily be determined by the g.l.c. method was 0.3 mg in the sample of powder used for the assay.

Analytical method for residues of bromoxynil octanoate and bromoxynil in soil

AbstractA method is described for the analysis of bromoxynil and its octanoate in soil. The sample is extracted with ammoniacal methanol which, on standing, converts any octanoate present to bromoxynil. Diazomethane converts this to bromoxynil methyl ether which is estimated by g.l.c. Additional clean‐up may be effected by t.l.c. With a 40 g sample the method can detect 0.05 mg/kg. Recoveries are better than 80 % down to 0.1 mg/kg and about 55 % at the limit of detection (0.05 mg/kg).

Synthesis of the sequence of oxytocin on a hydroxymethylstyrene‐divinylbenzene polymer

AbstractThe preparation of a hydroxymethylstyrene‐2%‐divinylbenzene polymer is described.The optimal method for the esterification of this polymer with N‐t‐butoxy‐carbonyl amino acids was found by using N,N′‐carbonyldiimidazole, the remaining hydroxyl groups being protected by formation of their acetates.On this polymer the nonapeptide sequence of the hormone oxytocin was synthesized and then split off in two ways. Tertiary base‐catalysed methanolysis (found in this Laboratory) gave the nonapeptide methyl ester: Z‐Cys(BZL)‐Tyr‐Ile‐Gln‐Asn‐Cys(BZL)‐Pro‐Leu‐Gly‐OMe a. L‐Amino acids are meant. b. Abbreviations used here and later: IUPAC, Information Bulletin 25, February 1966, 32‐40; 26, August 1966, 11‐19; 27, December 1966, 16‐18; 30, October 1967, 27‐32. , and ammoniacal methanol gave the carboxy‐terminal amide: Cys(BZL)‐Tyr‐Ile‐Gln‐Asn‐Cys(BZL)‐Pro‐Leu‐Gly‐NH2(H2O · HBr).The usual debenzylation and cyclization of the amide gave biologically active material.

Extraction and purification of steroid conjugates with ion exchange resins: measurement of androsterone sulfate and dehydroepiandrosterone sulfate in plasma.

A method is presented for the extraction and purification of steroid conjugates from aqueous media using ion exchange resins. Diluted serum or plasma is adjusted to pH 3 and passed through an IR-4B column in acetate form. The extracted conjugates are eluted from the column with ammoniacal methanol. Excess ammonia is removed under vacuum and the extract is then passed through an IR-120 column in H+ form. The eluate from this column will contain purified steroid conjugates, methanol, traces of volatile acids and water. The acids, methanol and water are removed under vacuum in less than 10 min, leaving a clean, dry extract readily handled by paper chromatography. Recovery of steroid monosulfates through both columns is about 87%. This method has been applied to the determination of dehydroepiandrosterone sulfate and androsterone sulfate in human peripheral plasma.