Analysis of chemical warfare agents. II. Use of thiols and statistical experimental design for the trace level determination of vesicant compounds in air samples

Thermal desorption with gas chromatography-mass spectrometry (TD-GC-MS) remains the technique of choice for analysis of trace concentrations of analytes in air samples. This paper describes the development and application of a method for analysing the vesicant compounds sulfur mustard and Lewisites I-III. 3,4-Dimercaptotoluene and butanethiol were used to spike sorbent tubes and vesicant vapours sampled; Lewisite I and II reacted with the thiols while sulfur mustard and Lewisite III did not. Statistical experimental design was used to optimise thermal desorption parameters and the optimum method used to determine vesicant compounds in headspace samples taken from a decontamination trial. 3,4-Dimercaptotoluene reacted with Lewisites I and II to give a common derivative with a limit of detection (LOD) of 260 microg m(-3), while the butanethiol gave distinct derivatives with limits of detection around 30 microg m(-3).     

Prediction of gas chromatographic retention times of esters of long chain alcohols and fatty acids

The linear free energy of solution (DeltaG) relationship (DeltaG=DeltaGo+zdeltaG) for compounds of different carbon atoms (z) in the same homologous series is expanded and modified to cover compounds with two different hydrocarbon side chains. The expanded equation is successfully used to predict the retention times (tR) of standard esters of long chain alcohols and fatty acids of different chain lengths in both isothermal and temperature-programmed gas chromatography (TPGC). Approximately 90% of the 125 predicted tR values have a difference of less than 1.00% from the actual tR and the highest difference is 1.26%. Two different temperature gradients in TPGC are tested. The expanded equation can be used to forecast the tR of TPGC with good accuracy. The highest difference is +/-1.40% and +/-1.00% for the temperature gradients of 2 degrees C and 4 degrees C/min, respectively. However, the increments in free energy per carbon atom (zdeltaG) of the alcohol and acid are approximately equal but have slightly different temperature sensitivities. Therefore, it is very difficult to separate esters of different acid and alcohol chain length but with the same total carbon numbers. Furthermore, the difference in temperature sensitivities for the acid and alcohol side chains renders them to be inversely eluted at different temperatures.     

Determination of diclofensine, an antidepressant agent, and its major metabolites in human plasma by high-performance liquid chromatography with fluorometric detection

A sensitive and selective high-performance liquid chromatographic assay was developed for the determination of diclofensine (I) and its key metabolites in human plasma. The assay involves deproteinization of plasma, overnight Glusulase incubation to hydrolyze the major metabolite (I-B-glucuronide), extraction of the parent compound and its deconjugated metabolites (I-A, I-B and I-C) from the alkalinized aqueous phase into diethyl ether-ethanol (95:5), the residue of which (containing compounds I, I-A, I-B and I-C) is alkylated with 2-iodopropane dissolved in acetone, using solid potassium hydroxide as a catalyst. The compounds are extracted from the reaction mixture into diethyl ether, after adding ethanol-water-acetic acid (55:40:5), the residue of which is dissolved in 0.05 M sulfuric acid, and reacted with mercuric acetate at 100 degrees C, which oxidizes tertiary tetrahydroisoquinolines to their 3,4-dihydroisoquinoline derivatives, followed by a photochemical reaction in the same solution to form intensely fluorescent isoquinolinium derivatives. An aliquot of this reaction mixture is injected onto a reversed-phase high-performance liquid chromatography column (5-microns Nova-Pac C13 phase in a radial compression cartridge, 10 cm X 8 mm), using the mobile phase 0.25 M triethylammonium phosphate (pH 2.5)-0.25 M acetic acid-methanol-acetonitrile-tetrahydrofuran (150:350:125:375:25). The void volume (Vo) is approximately 1.4 min and the retention times (tR) of the respective isoquinolium derivatives of diclofensine (I) are ca. 3.5 min, internal standard (II) ca. 4.2 min, nordiclofensine (I-A) ca. 5 min, while the phenolic metabolites I-B and I-C give peaks at 6.4 min and 10.4 min, respectively. The derivatives are detected by fluorescence. The method was used to determine plasma concentrations of the parent drug (I) and its major phenolic metabolite I-B (aglycone) in plasma in two normal volunteers following a single oral 45-mg dose and following seven consecutive days of oral dosing of 45 mg three times a day as part of a multiple ascending dose tolerance study.     

Lipid-rhodopsin hydrophobic mismatch alters rhodopsin helical content

The ability of photoactivated rhodopsin to achieve the enzymatically active metarhodopsin II conformation is exquisitely sensitive to bilayer hydrophobic thickness. The sensitivity of rhodopsin to the lipid matrix has been explained by the hydrophobic matching theory, which predicts that lipid bilayers adjust elastically to the hydrophobic length of transmembrane helices. Here, we examined if bilayer thickness adjusts to the length of the protein or if the protein alters its conformation to adapt to the bilayer. Purified bovine rhodopsin was reconstituted into a series of mono-unsaturated phosphatidylcholines with 14-20 carbons per hydrocarbon chain. Changes of hydrocarbon chain length were measured by (2)H NMR, and protein helical content was quantified by synchrotron radiation circular dichroism and conventional circular dichroism. Experiments were conducted on dark-adapted rhodopsin, the photo-intermediates metarhodopsin I/II/III, and opsin. Changes of bilayer thickness upon rhodopsin incorporation and photoactivation were mostly absent. In contrast, the helical content of rhodopsin increased with membrane hydrophobic thickness. Helical content did not change measurably upon photoactivation. The increases of bilayer thickness and helicity of rhodopsin are accompanied by higher metarhodopsin II/metarhodopsin I ratios, faster rates of metarhodopsin II formation, an increase of tryptophan fluorescence, and higher temperatures of rhodopsin denaturation. The data suggest a surprising adaptability of this G protein-coupled membrane receptor to properties of the lipid matrix.     

New Histamine-Related Five-Membered N-Heterocycle Derivatives as Carbonic Anhydrase I Activators

A series of histamine (HST)-related compounds were synthesized and tested for their activating properties on five physiologically relevant human Carbonic Anhydrase (hCA) isoforms (I, II, Va, VII and XIII). The imidazole ring of HST was replaced with different 5-membered heterocycles and the length of the aliphatic chain was varied. For the most interesting compounds some modifications on the terminal amino group were also performed. The most sensitive isoform to activation was hCA I (K_A values in the low micromolar range), but surprisingly none of the new compounds displayed activity on hCA II. Some derivatives (1, 3a and 22) displayed an interesting selectivity for activating hCA I over hCA II, Va, VII and XIII.     

Some derivatives of 4-fluorobenzenethiol

Various metallic and organometallic derivatives of 4-fluorobenzenethiol have been prepared directly from the thiol. Its Ag(I), Ni(II) and Pb(II) salts were used to synthesize thioethers thioesters. New compounds have been characterized by elemental analysis, NMR (H-1, F-19 and C-13) and mass spectroscopy.     

Functional monomers and polymers. XCVII. Synthesis of oligomer models of polyethyleneimine derivatives containing pendant thymine bases

A series of oligomer models of polyethyleneimine derivatives having pendant thymine bases were prepared by the reaction of carboxyethyl derivatives of thymine with oligomer amines using an activated-ester method. It was found that the hypochromicity values obtained from UV spectra and pKa values obtained from spectrophotometric titrations depend on the chain length of the oligomers and the thymine content of the polymers.     

Influence of the structure of the mesogenic core on the thermotropic properties of ω-unsaturated fluorinated liquid crystals

Three series of calamitic liquid crystals have been prepared, consisting of a mesogenic core attached to which is a perfluorinated chain via a thioester linkage, and a hydrocarbon chain containing a terminal double bond. The rigid core is either a monophenyl, biphenyl or phenyl benzoate group. The mesomorphic properties were characterized by polarizing optical microscopy and differential scanning calorimetry. The influence of the structure of the mesogenic core and of the hydrocarbon chain length on mesomorphic behaviour was studied. Increasing the length of the alkyl chain strongly reduces the mesomorphic behaviour while increasing the number of aromatic rings in the core increases the transition temperatures, with the widest LC range observed for derivatives with the phenyl benzoate core. The introduction of a single ring as the mesogenic core is considered of great interest in the development of low cost liquid crystal materials.     

Tacrine-Coumarin Derivatives as Topoisomerase Inhibitors with Antitumor Effects on A549 Human Lung Carcinoma Cancer Cell Lines

A549 human lung carcinoma cell lines were treated with a series of new drugs with both tacrine and coumarin pharmacophores (derivatives 1a–2c) in order to test the compounds’ ability to inhibit both cancer cell growth and topoisomerase I and II activity. The ability of human topoisomerase I (hTOPI) and II to relax supercoiled plasmid DNA in the presence of various concentrations of the tacrine-coumarin hybrid molecules was studied with agarose gel electrophoresis. The biological activities of the derivatives were studied using MTT assays, clonogenic assays, cell cycle analysis and quantification of cell number and viability. The content and localization of the derivatives in the cells were analysed using flow cytometry and confocal microscopy. All of the studied compounds were found to have inhibited topoisomerase I activity completely. The effect of the tacrine-coumarin hybrid compounds on cancer cells is likely to be dependent on the length of the chain between the tacrine and coumarin moieties (1c, 1d = tacrine-(CH₂)_8–9-coumarin). The most active of the tested compounds, derivatives 1c and 1d, both display longer chains.     

γ-Radiolysis of ketone polymers. I. Studies of symmetrical aliphatic ketones as model compounds

γ-Radiolysis of model ketones of the general structure R(C?O)R, neat and in hydrocarbon solution, show that the radio-chemical degradation of these aliphatic ketones can be explained by mechanisms analogous to those generally accepted for the photochemical decompositions of the same compounds. The G (type I) and G (type II) yields are found to decrease with increasing total chain length of the ketone as monitored by the products (R? H) and (CH₃CO? R), respectively. Differences in the relative yields of type I and II products are attributed to the higher incident energies involved in γ-radiolysis as compared to ultraviolet photolysis. Evidence is presented for energy transfer from paraffinic solvents to aliphatic ketonic solutes. Solid- and condensed-phase studies show the importance of rotational and diffusional mobility to the yields of the type II and I processes, respectively.     

高效液相色谱法分离测定3-取代-(R,S)-β-丙氨酸对映异构体

以1-氟-2,4-二硝基-5-L-缬氨酰胺(Marfey试剂)为衍生试剂,采用反相高效液相色谱法分离了3-取代-(R,S)-β- 丙氨酸对映异构体。采用梯度洗脱(流动相 A:体积分数为0.1%的三氟乙酸乙腈溶液;流动相B:体积分数为0.1%的三氟乙 酸水溶液)成功分离了 32种3-取代-(R,S)-β-丙氨酸衍生物,所有化合物都是R型异构体衍生物(R-L)较S型异构体衍生物 (S-L)先洗脱。除3-羟基苯和4-羟基苯的疏水参数较小,但其取代的β-丙氨酸衍生物的保留时间较长、分离因子较小外, 其他疏水参数大的取代基的β-丙氨酸衍生物保留时间都长于疏水参数小的取代基的β-丙氨酸衍生物。该文同时测定了R -和S-β-丙氨酸的对映体过剩值。     

气相色谱中测定死时间的Grobler－Balizs法和Ambrus法的比较

经理论推导和实验数据验证，证明测定死时间的Ｇｒｏｂｌｅｒ－Ｂａｌｉｚｓ法和Ａｍｂｒｕｓ法是同一的。     

Polymeric sulfated surfactants with varied hydrocarbon tail: I. Synthesis, characterization, and application in micellar electrokinetic chromatography

The influence of surfactant hydrocarbon tail on the solute/pseudostationary phase interactions was examined. Four anionic sulfated surfactants with 8-, 9-, 10-, and 11-carbon chains having a polymerizable double bond at the end of the hydrocarbon chain were synthesized and characterized before and after polymerization. The critical micelle concentration (CMC), polarity, and aggregation number of the four sodium alkenyl sulfate (SAIS) surfactants were determined using fluorescence spectroscopy. The partial specific volume of the polymeric SAIS (poly-SAIS) surfactants was estimated by density measurements and capillary electrophoresis (CE) was employed for determination of methylene selectivity as well as for elution window. The CMC of the monomers of SAIS surfactants decrease with increase in chain length and correlated well when fluorescence method was compared to CE. The physicochemical properties (partial specific volume, methylene selectivity, electrophoretic mobility, and elution window) increased with an increase in chain length. However, no direct relationship was found between the aggregation number and the length of hydrophobic tail of poly-SAIS surfactants. These polymeric surfactants were then used as pseudostationary phases in micellar electrokinetic chromatography (MEKC) to study the retention behavior and selectivity factor of 36 benzene derivatives with different chemical characteristics. Although variation in chain length of the polymeric surfactants significantly affects the retention of nonhydrogen bonding (NHB) benzene derivatives, these effects were less pronounced for hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD) benzene derivatives. Therefore, hydrophobicity of poly-SAIS surfactants was found to be a major driving force for retention of NHB derivatives. However, for several benzene derivatives (NHB, HBA, and HBD) significantly higher selectivity factor was observed with longest chain polymeric surfactant (e.g., poly(sodium 10-undecenyl sulfate), poly-SUS) compared to shorter chain polymeric surfactant (e.g., poly(sodium 7-octenyl sulfate), poly-SOcS). In addition, the effect of the surfactant hydrophobic chain was also found to have some impact on migration order of NHB, HBA, and HBD benzene derivatives.     

Indole derivatives.

The nature of the products of reduction of nitro compounds of the indole series containing a polysulfide chain depends on the length of the latter. In mono- and disulfides only the nitro groups are reduced, and diamino monosulfides and diamino disulfides are formed. In the reduction of the dinitro trisulfide the chain is cleaved and an amino thiol is formed. The reduction of acetylthionitro compounds is accompanied by migration of the S-N bond, as a result of which an acetamido thiol is formed.     

Some derivatives of 2,3,5,6-tetrafluorobenzenethiol

Various metallic and organometallic derivatives of 2,3,5,6-tetrafluorobenzenethiol have been prepared directly from the thiol. Its Cu(I) and Pb(II) salts were converted into thioethers and thioesters. All new compounds have been characterized by elemental analysis, NMR (H-1 and F-19) and mass spectroscopy.     

Thermotropic phase behavior of long-chain alkylammonium-alkylcarbamates

A series of alkylammonium-alkylcarbamates with different chain length including transdermal permeation enhancer Transkarbam 12 have been prepared and characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), temperature-dependent Fourier transform infrared spectroscopy (FTIR) and temperature-dependent X-ray powder diffraction. Four transitions have been observed including solid-solid transition (I), melting (II), decomposition of the carbamate salt (III) and boiling of the released amine (IV). The first transition was connected with rearrangement of the hydrocarbon chain packing and unusual shift of symmetric CH₂ stretching vibration in the IR spectra to lower wavenumbers indicated increase of conformational order. The second transition represented melting of the molecule and the third one was attributed to the decomposition of the carbamate salt into two amine molecules and carbon dioxide as evidenced by combination of DSC and TGA curves.     

Photophysical properties and antibacterial activity of meso-substituted cationic porphyrins

A series of derivatives of 5,10,15,20-tetrakis-(4-N-methylpyridyl)-porphine, where one N-methyl group was replaced by a hydrocarbon chain ranging from C6 to C22, were characterized for their photophysical and photosensitizing properties. The absorption and fluorescence features of the various compounds in neutral aqueous solutions were typical of largely monomeric porphyrins, with the exception of the C22 derivative, which appeared to be extensively aggregated. This was confirmed by the very low triplet quantum yield and lifetime of the C22 derivative as compared with 0.2-0.7 quantum yields and 88-167 micros lifetimes for the other porphyrins. The photophysical properties and photosensitizing activity toward N-acetyl-L-tryptophanamide of the C22 porphyrin became comparable to those typical of the other derivatives in 2% aqueous sodium dodecyl sulfate, where the C22 compound is fully monomerized. All the porphyrin derivatives exhibited at micromolar concentrations photoinactivation activity against both Staphylococcus aureus and Escherichia coli, even though the gram-negative bacteria were markedly less photosensitive. The photosensitizing efficiency was influenced by (1) the amount of cell-bound porphyrin, which increased with increasing length of the hydrocarbon chain; and (2) the tendency to undergo partial aggregation in the cell, which seems to be especially important for the C22 derivative.     

Statistical mechanical model for diffusion of simple penetrants in polymers. III. Applications—vinyl and related polymers

The theory developed in Part I of this series is modified to accommodate polymers that possess closely spaced, bulky side groups on the chains. The side groups give rise to free space between the chain “cores,” which reduces the chain separation required for penetrant motion transverse to the local chain axis. The theory is then identical to that of Part I, except that penetrant diameters minus a constant factor are employed in place of the normal diameters. In most of the cases studied the reduction factor for a given polymer may be estimated with reasonable precision from chain geometry data. This diameter-reduction effect is the likely explanation of the apparent proportionality between the activation energy of diffusion and the square of the penetrant diameter reported earlier for vinyl polymers. The data quoted here and in Part II are analyzed to give a semitheoretical correlation between the effective jump length L? and ΔE, the activation energy of diffusion. This correlation appears to be equally valid for glassy and rubbery noncrystalline polymers.     

Water-hydrocarbon interfaces: effect of hydrocarbon branching on interfacial structure

Molecular dynamics simulation are performed for the water/hydrocarbon system to study the effect of hydrocarbon branching on interfacial properties. The following two series of hydrocarbons are considered: (1) n-pentane, 2-methyl pentane, and 2,2,4-trimethyl pentane (constant chain length) and (2) n-octane, 2-methyl heptane, and 2,2,4-trimethyl pentane (constant molecular mass). With a simple algorithm for identification of surface sites and mapping nonsurface sites to these surface sites, intrinsic profiles were constructed with respect to the surface layer. Intrinsic density profiles for water and hydrocarbons with respect to the hydrocarbon and water surface, respectively, resemble density profiles of liquids in the presence of a wall. Order parameters were used to study orientation of molecules with respect to the surface normal and the hydrogen bond network was characterized in terms of the number of hydrogen bonds per water molecule and percentage of hydrogen bonded molecules in the first coordination shell. The corresponding intrinsic profiles were obtained. The O-H bond for surface water was found to have two preferential orientations, pointing toward the hydrocarbon phase and parallel to the interface. Hydrocarbon molecules in series 1 orient along the interface with the more branched molecule better aligned. For molecules in series 2, the larger molecular length reduces the alignment of molecules along the interface.     

Spectrofluorimetric determination of guanethidine sulphate, guanoxan sulphate and amiloride hydrochloride in tablets and in biological fluids using 9,10-phenanthraquinone

A highly sensitive spectrofluorimetric method for the determination of some drugs of the monosubstituted guanidine derivatives in laboratory made tablets, in spiked human serum and in urine samples is presented. The method is based on the reaction of guanethidine sulphate (I), guanoxan sulphate (II) and amiloride hydrochloride (III) with 9,10-phenanthraquinone (IV) to give highly fluorescent derivatives. The linearity ranges were found to be 0.06-0.96 mug/ml for (I) and (II) and 0.04-0.28 mug/ml for (III), with relative standard deviation less than 2%. Mean percentage recoveries for tablets were found to be 99.9 +/- 1.3, 100.5 +/- 1.1 and 100.0 +/- 1.6 for I, II and III, respectively. For I and III the results are highly correlated with the B.P. methods. Using the synchronous fluorimetry, differentiation between I and II was possible. Chloroform, dichloromethane and ethyl acetate have been used to extract I, II and III, respectively from serum and urine at basic pH, followed by applying the proposed fluorimetric method. Percentage recoveries were found to be 95.7-102.2%. The limit of detection is 0.04 mug/ml for I and II and 0.02 mug/ml for III.