[Simultaneous determination of nitrapyrin and its metabolite residues in food crops by derivatization with gas chromatography-triple quadrupole mass spectrometry].

A method based on precolumn derivatization along with gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) was developed for the determination of nitrapyrin and its metabolite, 6-chloropicolinic acid, in crops. The samples were extracted by acid acetonitrile, and subjected to precolumn derivatization using a sulfoacid. The quantification of the analytes was performed by the internal standard method. Good linear relationships between the peak areas and mass concentrations of the analytes were obtained in the range of 0.025-0.2 mg/L with correlation coefficients greater than 0.995 (n=6). The limits of quantification (LOQs) were 0.05 mg/kg. The recoveries of the analytes in crops at three spiked levels (0.05, 0.1, and 0.2 mg/kg) were in the range of 80.4%-98.4%, with relative standard deviations between 1.0% and 10.1% (n=6). This new method satisfies the related regulations for the determination of nitrapyrin and its metabolite in crops.

Retort beef aroma that gives preferable properties to canned beef products and its aroma components.

The objective of this study is to identify the properties and responsible compounds for the aromatic roast odor (retort beef aroma) that commonly occurs in canned beef products and could contribute to their palatability. The optimal temperature for generating retort beef aroma was 121°C. An untrained panel evaluated both uncured corned beef and canned yamato-ni beef and found that they had an aroma that was significantly (P < 0.01) similar to the odor of 121°C-heated beef than 100°C-heated beef. The panel also noted that the aroma of 121°C-heated beef tended to be (P < 0.1) preferable than that of 100°C-heated beef. These results suggest that retort beef aroma is one constituent of palatability in canned beef. GC-MS (gas chromatography-mass spectrometry) analysis of the volatile fraction obtained from 100°C- and 121°C-heated beef showed that the amounts of pyrazine, 2-methylpyrazine and diacetyl were higher in the 121°C-heated beef than in the 100°C-heated beef. GC-sniffing revealed that the odor quality of pyrazines was similar to that of retort beef aroma. Therefore, pyrazines were suggested to be a candidate responsible for the retort beef aroma. Analysis of commercial uncured corned beef and cured corned beef confirmed the presence of pyrazine, 2-methylpyrazine and 2,6-dimethylpyrazine.

Estimation of sulfolax and antimicrobial preservatives in laxative drops.

A simple, fast, precise, economic, selective and accurate HPLC method for simultaneous estimation of sorbicacid, sodium picosulphate and methyl parabensodium in laxative drops has been developed and subsequently validated. Chromatographic separation was achieved using gradient elution with mix phosphate buffer pH 7.0 and acetonitrile. The column used was purospherstar C18, 5 µm, 25 cm × 4.6mm kept at 25°C with 1 ml/min flow rate using detection (PDA) at 263 nm. The retention times of sorbicacid, sodium picosulphate and methyl paraben sodium were found to be 4.6, 7.4 and 11.4 minutes respectively. The proposed method was found to be linear over a concentration range of 8-12 µg/ml for sorbic acid, 60-90 µg/ml for sodium picosulphate and 16-24 µg/ml formethyl paraben sodium respectively. The recovery was found to be 99.13-101.68% for sorbic acid, 99.81-100.21% for sodium picosulphate and 99.84-100.09% for methyl paraben sodium respectively. The limit of detection (LOD) for sorbicacid, sodium picosulphate and methyl parabensodium were found to be 0.032 µg/ml, 0.337 µg/ml and 0.131 µg/ml respectively and limit of quantitation (LOQ) for sorbicacid, sodium picosulphate and methyl parabensodium were found to be 0.097 µg/ml, 1.023 µg/ml and 0.399 µg/ml respectively. The method was validated with respect to specificity, precision, accuracy, linearity and robustness according to guidelines of ICH.

Design, characterization and applications of new ionic liquid matrices for multifunctional analysis of biomolecules: a novel strategy for pathogenic bacteria biosensing.

The design, preparation and performance for novel UV-light absorbing (room-temperature) ionic liquid matrices (UV-RTILMs) for matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) were reported. A series of UV-RTILMs was prepared by ultrasonication of equimolar of acid (mefenamic acid) and bases (aniline (ANI), pyridine (Pyr), dimethyl aniline (DMANI) and 2-methyl picoline (2-P)). The UV-RTILMs have not only significant absorbance at the desired wavelength (337 nm of the N2 Laser), but also have available protons that can easily undergo proton transfer reactions to ionize the target molecules. The novel UV-RTILMs have the ability to ionize different and wide classes of compounds such as drugs, carbohydrate, and amino acids. The new UV-RTILMs series have been successfully and selectively applied for biosensing the lysates of pathogenic bacteria in the presence of the cell macromolecules. A new strategy for biosensing pathogens was presented via sensing the pathogens lysate in the cell suspension. The new materials can effectively detect the bacterial toxins without separation or any pretreatment. They offered excellent ionization of labile oligosaccharides with protonated peaks. They could significantly enhance the analyte signals, produce homogeneous spotting, reducing spot-to-spot variation, excellent vacuum stability, higher ion peak intensity, and wide application possibility. The physical parameters such as molar refractivity, molar volume, parachor, surface tension, density and polarizability were calculated and tabulated. The new UV-RTILMs could offer excellent reproducibility and great repeatability and they are promising matrices for wide applications on MALDI-MS.

Determination of pyridine, 2-picoline, 4-picoline and quinoline from mainstream cigarette smoke by solid-phase extraction liquid chromatography/electrospray ionization tandem mass spectrometry.

The present paper describes the development and validation of a new reversed-phase liquid chromatography-electrospray ionization tandem mass spectrometric method (RP-HPLC-ESI-MS/MS) for simultaneous determination of pyridine, 2-picoline, 4-picoline and quinoline from mainstream cigarette smoke. Liquid-liquid extraction followed by solid-phase extraction was applied to extract the target analytes from cigarette smoke. Baseline chromatographic separation was achieved by utilizing a Zorbax SB-Aq (4.6x150 mm, 5 microm) column in gradient chromatographic conditions with acetonitrile and ammonium acetate buffer as mobile phases. Popular commercially available Indian brand filtered and non-filtered cigarettes were analyzed using the same method. The identification of each chemical was established by chromatographic retention times, analyte specific fragmentation patterns and relative peak area ratios of two product/precursor ion pairs. The limit of detection of this method ranged from 1.74 to 14.32 ng/cig using an injection volume of 20 microl. The reproducibility of this method is excellent and better standard deviations were obtained compared to literature reported values for these chemicals. RSD value is less than 9% for all analytes.

Smoke from traditional commercial, harm reduction and research brand cigarettes impairs oviductal functioning in hamsters (Mesocricetus auratus) in vitro.

BACKGROUND: Cigarette smoke from 2R1 research brand cigarettes and specific toxicants in smoke inhibit oviductal functioning. Our purpose was to test the hypothesis that smoke from commercial cigarettes, including harm reduction cigarettes, inhibits oviductal functioning and to measure the concentration of previously identified toxicants in smoke from research and commercial cigarettes. METHODS: Mainstream (MS) and sidestream (SS) smoke solutions from two research, six traditional commercial and three harm reduction brands were tested in vitro using an oviductal assay that measures ciliary beat frequency, oocyte retrieval rate and smooth muscle contraction. RESULTS: Generally, smoke from each brand of cigarette was inhibitory in the three oviductal bioassays. SS, the major component of environmental tobacco smoke, was usually more inhibitory than MS, the smoke inhaled by active smokers. Nine cigarette toxicants, previously shown to be highly inhibitory in the oviductal bioassays, were quantified in MS and SS. 4-Methylpyridine, which was inhibitory by itself in picomolar doses, was present in the highest concentration in MS and SS solutions from all brands tested. In general, toxicant concentrations were higher in SS than in MS solutions. CONCLUSIONS: These data show that commercial brands of cigarettes, including harm reduction cigarettes, contain toxicants that inhibit biological processes in the oviduct and could affect reproductive outcomes.

Pyridines in cigarette smoke inhibit hamster oviductal functioning in picomolar doses.

Past studies showed that chemicals in cigarette smoke inhibit oviductal functioning in vivo and in vitro. The purposes of this study were to identify individual toxicants in cigarette smoke solutions that inhibit various aspects of oviductal functioning and to determine their effective doses using in vitro bioassays. Solid phase extraction and gas chromatography-mass spectrometry (GC-MS) were used to identify individual chemicals in mainstream (MS) and sidestream (SS) cigarette smoke solutions. Pyridines, which were the most abundant class of compounds identified, were purchased, assayed for purity, and tested in dose-response studies on hamster oviducts. The lowest observable adverse effect level was determined for each pyridine derivative using the oocyte pick-up rate, ciliary beat frequency, and infundibular muscle contraction assays. 2-Methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, and 4-vinylpyridine were inhibitory at picomolar concentrations in all assays. This work shows picomolar doses of pyridines with single methyl or ethyl substitutions significantly inhibit oviductal functioning raising questions regarding the safety of these compounds.

Analytical control of a pharmaceutical formulation of sodium picosulfate by capillary zone electrophoresis.

A new procedure for the analytical control of a pharmaceutical formulation by capillary zone electrophoresis (CZE) is proposed. It allows the simultaneous determination of the major compounds in the formulation: active compound (sodium picosulfate) and preservative (methylparaben), and the degradation products of the preservative, which slowly degrades by hydrolysis or by transesterification with sorbitol (sweetener in excess in the formulation) yielding p-hydroxybenzoic acid and sorbitolparaben, respectively. UV-Vis detection in the absorption maxima of the analytes and 20 mM borate solution at pH 10 as background electrolyte are used. Results are compared with those provided by the HPLC procedure. The method has also been validated using the HPLC procedure as the reference method, evaluating selectivity, accuracy, linearity and precision. The CZE procedure developed is sufficiently accurate and the precision achieved is about 1% for major and 3% for minor compounds.

Compositional heterogeneity in parenteral lipid emulsions after sedimentation field flow fractionation.

This study examines the size and compositional heterogeneity of particles in a commercial lipid emulsion (Intralipid) before and after equilibration with penclomedine, a highly lipophilic cytotoxic agent. Emulsions were fractionated by sedimentation field-flow fractionation (sedFFF), and particle sizes of the monodisperse fractions were determined by photon correlation spectroscopy. The triglyceride (TG), phosphatidylcholine (PC), and penclomedine (in drug loaded emulsions) contents in each fraction were determined by HPLC. The aqueous-entrapped volume within Intralipid was determined to be approximately 10% by size-exclusion chromatography using [3H]mannitol. Thirteen sedFFF fractions collected from the drug free emulsions yielded particles ranging in size from 154 to 423 nm. Total channel recoveries were 89% and 95% for TG and PC, respectively. Apparent particle densities varied significantly with size, suggesting heterogeneity in composition as confirmed by PC/TG mass ratios which varied dramatically. Computer fits of the distribution profiles suggested populations of phospholipid vesicles and oil droplets containing excess phospholipid in addition to classical emulsion droplets. Drug loading induced a significant shift of the predominant triglyceride containing population to a larger particle size. The penclomedine distribution profile closely mimicked that of the TG rather than the PC fraction. These studies suggest the need to consider not only size distribution but also compositional distribution in characterizing parenteral emulsions.

Comutagenesis-II. Some factors influencing the in vitro metabolism of 2-amino-3-methylpyridine.

Factors affecting the metabolism of 2-amino-3-methylpyridine (2A3MP) in vitro have been studied and the conditions which allow maximal metabolism established. Ring nuclear and methyl hydroxylation, and 1-N-oxidation of 2A3MP were linear with respect to arochlor 1254 induced rat S9 supernatant (10,000 g fraction) up to 4.86 mg per ml. The results showed that 20 min incubation time was adequate to observe metabolites formed from 2A3MP. The rate of metabolite production increased with increase in substrate concentration up to 2 µmol per incubate. Using the data obtained the apparent K(m) and V(max) values were calculated using Hanes-Wolf and Lineweaver-Burk plot. No N-hydroxylation of the exo-amino group was observed.

Aprikalim: radioimmunoassay and pharmacokinetic studies in mouse, monkey, and dog.

A stereoselective and specific radioimmunoassay (RIA) was developed for aprikalim (RP 52891), a novel potassium channel opener. Antibodies were produced in rabbits immunized with the pure levorotatory enantiomer (1R,2R) of the hapten derivative bearing an acid function at the end of the lateral chain and conjugated to bovine serum albumin. In displacement studies with the enantiomerically pure radioligand (radioiodinated tyrosine methyl ester conjugate of the hapten derivative), the opposite enantiomer showed only 0.1% cross-reaction. Negligible binding occurred when analogues or metabolites of aprikalim were tested for cross-reactivity. The detection limit was 0.25 ng/mL (9.31 x 10(-10) M) in a 20-microL plasma sample. The assay was used successfully to determine aprikalim pharmacokinetics in mice, monkeys, and dogs. Beagle dogs were given a 10 micrograms/kg intravenous (iv) bolus dose or 10 micrograms/kg iv bolus followed by 0.1 microgram/kg/min infused over 30 min (nonhypotensive doses which reduce myocardial infarct size significantly). The plasma concentrations declined monoexponentially with a mean overall elimination half-life of 1.53 h and a mean plasma clearance of 52 mL/min (5.1 mL/min/kg). A slow-release oral formulation produced a significant delay in the rate of absorption, a 4-fold decrease in the peak plasma level, and a 2-fold decrease in apparent oral bioavailability relative to that observed for an oral solution. A comparison of aprikalim pharmacokinetic parameters in mouse, monkey, and dog revealed great similarity in disposition characteristics in these species.

[Metabolism of an antioxidant of the 3-hydroxypyridine class]. / Metabolizm antioksidanta iz klassa 3-oksipiridina.

Study of biotransformation of 2-ethyl-6-methyl-3-hydroxypyridine (2E6M3O) in rats by using high performance liquid chromatography and mass spectrometry resulted in isolation and identification of its 5 metabolites represented by dealkylated and conjugated products of transformation. In terms of manifestation of the pharmacological effect of 2E3M3O, of interest may be the identified metabolite 2E6M3O-phosphate which was found in considerable amounts in the livers of the animals. All the rest metabolites were detected only in the rat urine.

Identification of meibomian gland lipids by gas chromatography-mass spectrometry: application to the meibomian lipids of the mouse.

Methods are described for the structural determination of the constituent alcohols, steroids and fatty acids from meibomian gland esters. The compounds, obtained from hydrolysed extracts, were separated and quantified as trimethylsilyl and methyl ester-trimethylsilyl derivatives by fused-silica capillary column gas chromatography. Structural information relating to the position of chain branching and the position of double bonds in the aliphatic chains of the acids and alcohols was obtained from the mass spectra of a number of other derivatives. Thus pyrrolidide-trimethylsilyl and picolinyl ester-trimethylsilyl derivatives provided information on both branching and unsaturation. The double-bond position in unsaturated fatty acids was also examined by use of trimethylsilyl derivatives of the derived glycols. The positions of chain branching of the alcohols were determined by the spectra of their acetate and nicotinate derivatives and by their gas-liquid chromatographic retention times. In meibomian gland lipids from the mouse, cholesterol was the major constituent; alcohols from the n-, iso-, anteiso- and unsaturated series were present with iso-C26 and anteiso-C27 being the most abundant. Mono-unsaturated fatty acids belonged mainly to the omega 9 series and saturated acids belonged to the iso-, anteiso- and n-series. Several 1,2-diols were also identified. The most abundant of these had iso-C16 and iso-C20 chains. GC-MS studies on the intact wax esters showed them to be composed of the branched-chain alcohols and both branched-chain and unsaturated acids.

Quantitative differences in volatiles from healthy mouths and mouths with periodontitis.

It has been suggested that orally derived volatile aromatic amines may be of possible diagnostic use and may contribute to the etiology or pathogenesis of periodontal disease. Using gas chromatography and gas chromatography/mass spectrometry, we identified and quantitated pyridine and picolines in the headspace of incubated whole saliva from healthy and diseased subjects. The oral health of subjects was evaluated by four standard oral-health indices. Volatile aromatic amines were virtually absent from subjects with healthy oral cavities, but were present in the oral cavities of subjects with periodontitis to the extent of 636.4 (SEM 154.7) ng/5 mL of saliva. Pyridine and picolines in saliva of diseased subjects may be related to the disease process.

Characterization of pharmacologically important prototropic species derived from a pyridinemethanol antimalarial by electronic absorption and fluorescence spectroscopy.

Variations of the absorption and fluorescence spectra of the experimental antimalarial drug, alpha-dibutylaminomethyl-2,6-bis(p-trifluoromethylphenyl)-4-pyridinemethanol, were investigated throughout the pH region in concentrated sulfuric acid media and in n-hexane. The predominant prototropic species at physiological pH is the singly charged cation. In the pH 6--12 region, the structured fluorescence of the monocation is quenched with the concomitant appearance of a diffuse, long wavelength emission while the corresponding absorption spectra shift only slightly to longer wavelengths. Furthermore, the dibutylamino group exhibits an unusually low basicity. This behavior is explained as due to the formation of an intramolecular hydrogen bond in the neutral molecule in the ground and lowest excited singlet states. A similar intramolecular hydrogen bond in the monocation is not spectroscopically visible.

Bis-(p-hydroxyphenyl)-pyridyl-2-methane: The common laxative principle of Bisacodyl and sodium picosulfate.

After both oral and rectal administration in humans (4,4'-diacetoxy-diphenyl)-(pyridyl-2)-methane (bisacodyl, Dulcolax) and 4,4'-(2-pyridyl-methylene)-diphenol-disulfuric acid semiester disodium (sodium picosulfate, Laxoberal) are hydrolyzed to bis-(p-hydroxyphenyl)-pyridyl-2-methane (BHPM). In both cases BHPM is responsible for the laxative action. Experiments in rats and guinea pigs have shown that the hydrolysis of picosulfate, in contrast to that of bisacodyl, is attributable to the microorganisms of the intestinal flora.