Synthesis of alkyl-gem-dichlorocyclopropanes based on isoamylene fraction

Objectives. The study aims to analyze the dichlorocarbenation of the isoamylene fraction, which is a mixture of 2-methyl-butene-1 and 2-methyl-butene-2, in order to obtain the corresponding alkyl-gem-dichlorocyclopropanes in quantitative yield, and also to determine their structure.Methods. In order to determine the qualitative and quantitative composition of the reaction masses, the following analysis methods were used: gas-liquid chromatography (using the Crystal 2000 hardware complex), mass spectrometry (using a Chromatec-Crystal 5000M device with NIST 2012 database), and nuclear magnetic resonance (NMR) spectroscopy (using a Bruker AM-500 device at operating frequencies of 500 and 125 MHz).Results. Alkyl-gem-dichlorocyclopropanes were synthesized from an isoamylene fraction in the presence of catamine AB as a catalyst. Alternatively, isomeric alkenyl-gem-dichlorocyclopropanes were obtained on the basis of isoprene, and by reduction, the corresponding alkyl-gemdichlorocyclopropanes were synthesized. The synthesized substances were analyzed by gasliquid chromatography, mass spectrometry, and NMR spectroscopy, as previously mentioned above.Conclusions. The results show that the dichlorocyclopropanation of the isoamylene fraction proceeds quantitatively with the formation of a mixture of 2-methyl-2-ethyl-1,1dichlorocyclopropane and 2,3,3-trimethyl-1,1-dichlorocyclopropane. Using isoprene, countersynthesis through successive dichlorocarbenation and hydrogenation was used to synthesize 2-methyl-2-ethyl-1,1-dichlorocyclopropane, one of the products of dichlorocarbenation of the isoamylene fraction.

Characterization of the Fatty Acid Composition of Nannochloropsis salina as a Determinant of Biodiesel Properties

Nannochloropsis salina was cultured batch-wise to evaluate the potential of the alga to produce biodiesel. The cells were harvested at the end of the exponential growth phase when the concentration was 18 · 106 cells/mL culture. The growth estimated as dry weight from this cell number was (3.8 ± 0.7) mg/L. The lipid and triglyceride contents were 40% and 12% on a dry weight basis, respectively. The amount of the ratio triglycerides/total lipids was approximately 0.3.The composition of triglyceride fatty acid methyl esters (biodiesel) was analysed by gasliquid chromatography and identified as: C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, C18:3, C20:1, and C20:5. The ratio of unsaturated to saturated fatty acid contents was approximately 4.4. Additionally, the characterization of each individual fatty acid ester was discussed with regard to the fuel properties of biodiesel produced by the alga.

Gas-Liquid Chromatographic Screening Method for Six Synthetic Pyrethroid Insecticides

A method was developed for simultaneously determining 6 synthetic pyrethroid insecticides (fenpropanate, tetramethrin, permethrin, cypermethrin, fenvalerate, and deltamethrin) in apple, orange, grape, lemon, tomato, green pepper, and paprika, and sugar beet root and leaves. The pesticides were extracted with acetone and partitioned into methylene chloride. The extract was purified by column chromatography on active carbon-magnesia-diatomaceous earth and then on alumina. Analysis by gasliquid chromatography with 63Ni electron capture detection was completed in 6 min on a 3% SE-30 liquid phase, using a short column. Recoveries from fortified samples ranged from 68 to 89% in the range of 0.3-1.O ppm and from 67 to 83% in the range of 0.02-O.2ppm.

Gas-Liquid Chromatographic-Mass Spectrometric Confirmation of Endosulfan and Endosulfan Sulfate in Apples and Carrots

A gas-liquid chromatography-mass spectrometric (GLC-MS) procedure is described for the confirmation of endosulfan I, endosulfan II, and endosulfan sulfate in apples and carrots. After extraction, cleanup, and determination by electron capture gasliquid chromatography using current AOAC methodology, residues are confirmed by GLC-MS. The chemical ionization (CI) mode is used with methane as a reagent gas. Each residue is confirmed by a scan of only 4 regions of its mass spectrum rather than the full mass range. The 4 mass regions for the 2 endosulfan isomers are 274-280, 340-346, 368-374, and 404-412 atomic mass units (amu). For endosulfan sulfate, the mass regions are 286-294, 322-330, 384-392, and 420-428 amu. Four ions and their chlorine isotopic distributions are detected for each compound by this scanning technique. This method was developed by using carrots and apples to which had been added 0.1 ppm (50% of the current legal tolerance on carrots) of each of the 3 pesticides. The gas chromatographic retention times and the mass spectra of the 4 mass regions specified for the 3 pesticides were compared to those of reference standards injected under identical GLC-MS conditions and were used as the basis for confirming identity of the 3 compounds.

Volatile N-Nitrosamines in Dried Foods

An investigation was carried out to determine the levels of volatile Af-nitrosamines in several dried food commodities such as malt, instant skim milk powder, infant formula containing milk powder, instant coffee, soup and soup bases, and baby cereals. The method involves vacuum distillation of the sample from 3N KOH or 1% sulfamic acid, followed by extraction of the aqueous distillate with dichloromethane. The dichloromethane extract is then washed with an acidic buffer (to remove amines), dried over anhydrous sodium sulfate, concentrated in a Kuderna-Danish concentrator, and analyzed by gas-liquid chromatography, using a thermal energy analyzer. Detection limit is 0.1-0.5 ppb. Of the samples analyzed thus far, all malts (22 samples) and instant skim milk powders (11 samples) were positive for Af-nitrosodimethylamine (NDMA); average levels were 7.4 ppb (1.3-67.0 ppb) and 0.4 ppb (0.3-0.7 ppb), respectively. Traces of NDMA and/or JV-nitrosopyrrolidine were also detected in 3 of 20 dried soups and 5 of 10 instant coffees analyzed. Traces of NDMA and/or AT-nitrosopiperidine (NPIP) were detected in 3 of 8 powdered infant formulas. All 4 baby cereal samples were negative. The identity of NDMA in 14 samples of malt and that of NDMA and NPIP in an infant formula was confirmed by gasliquid chromatography-mass spectrometry; identity of N-nitrosamines in 3 instant coffees and 1 infant formula was independently verified by high pressure liquid chromatographic analysis.

Further studies on mating disruption of the red bollworm, Diparopsis castanea Hampson (Lepidoptera: Noctuidae), with a microencapsulated mating inhibitor

Water-based ultra-low volume (WULV) applications to cotton at fourday intervals of a 1% a.i. polyurea-based microencapsulated formulation of the pheromone inhibitor 9-dodecenyl acetate (E/Z 80:20) in a 0·2-ha field cage in Malawi resulted in an average reduction of 60·2% in nightly mating of females of Diparopsis castanea Hmps. A relatively constant level of inhibitor was maintained by spraying with 30 g/ha initially and decreasing by 10% with each successive spray. Examination of the mated status of 1712 female moths sampled on 88 occasions revealed that, in the presence of inhibitor, mating increased linearly with increasing population density from 22 to 2844 moths/ha (equal numbers of males and females). In an openfield trial, WULV applications of 30 and 60 g of 1 % a.i. microencapsulated inhibitor/ha to isolated cotton plots (0·4–1·2 ha) at seven- and 14-day intervals had no measurable disruptive effect on released populations of moths as measured by oviposition and larval infestation of the crop, although there was some reduction in egg fertility and catches of males in pheromone traps in the treated plots. Timeseries analyses by gasliquid chromatography (GLC) of the residual inhibitor on filterpaper discs and cotton leaves in the field gave similar results, and GLC measurement of inhibitor on filter papers removed at intervals from the test plots showed that inhibitor loss was very rapid, typically 60% within two days and almost 100% after six days. Loss of inhibitor was less rapid in the field cage and under laboratory conditions. Physical and chemical evaluation of microcapsule deposition on cotton plants revealed that spray droplets penetrated to all parts of the plant but that deposition was greatest on the upper laminae of the top leaves of the plant. Methodology for assessing the success of mating-disruption experiments is described and discussed, and the failure of the open-field experiments is attributed mainly to the rapid loss of inhibitor from the formulation in the field.

Gas-Liquid Chromatographic Determination of Disulfoton in Formulations: Collaborative Study

A rapid method is described for the determination of disulfoton (0,0-diethyl S-[2-(ethylthio)-ethyl] phosphorodithioate) in formulations by gasliquid chromatography (GLC). Samples are dissolved in acetone, and, after an internal standard is added, the samples are diluted to volume with solvent. They are then injected into a gas chromatograph equipped with a flame ionization detector and quantitated by peak height or area measurements. Fourteen collaborators made duplicate determinations on 4 samples including the technical product, a liquid, and 2 granular formulations. The average coefficient of variation was 0.847% for the liquid samples and 1.90% for the granules. The method has been adopted as official first action.

Gas-Liquid Chromatographic Determination of Organophosphorus Insecticide Residues in Fruits and Vegetables

A method intended for regulatory purposes is described for the determination of organophosphorus insecticide residues in fruits and vegetables. Eighteen organophosphorus insecticides, azinphos-ethyl, chlorpyrifos, diazinon, dichlorvos, dimethoate, ethion, ethoate-methyl, fenitrothion, fenthion, formothion, malathion, methidathion, mevinphos, parathion, phosalone, phosphamidon, thiometon, and trichlorphon, and 7 metabolites, fenitrooxon, fenthion sulfoxide, fenthion sulfone, malaoxon, desethylphosphamidon, thiometon sulfoxide, and thiometon sulfone, were extracted from different crops with acetone and partitioned into hexane or ethyl acetate, according to their polarities. The hexane extract was cleaned up by eluting from a Florisil column with acetone-hexane (4+96). The ethyl acetate extract needs no cleanup. The concentrated extracts were analyzed by gasliquid chromatography using thermionic detectors. Recoveries conducted at fortification levels ranging from 0.1 to 2 mg/kg were in most cases above 80%. The limit of sensitivity is less than 0.1 mg/kg.

Gas-Liquid Chromatographic Determination of Dioxathion and Quintiofos in Organophosphorus Dip Washes

A rapid method for the analysis of dip washes is described which eliminates the usual solvent extraction procedure. The dip wash is initially diluted with acetone and then with petroleum ether. The diluted dip wash is analyzed by gasliquid chromatography, using an alkali ionization detector sensitive to phosphorus compounds. The method was applied to the determination of dioxathion (2,3-ρ-dioxanedithiol S,S-bis(O,O-diethyl phosphorodithioate)), and quintiofos (O-ethyl O-8-quinolyl phenylphosphonothioate) dip washes. Average recoveries from fouled dip washes were 100 and 104%. GLC of these compounds with an internal standard is described, which improves the precision of the method to ±2%.

Determination of Residues from the Herbicide 2,4-Dichloro-l-(4-nitrophenoxy)-benzene in Rice and Wheat by Electron Capture Gas-Liquid Chromatography

A residue method has been developed which is capable of determining not only 2,4-dichloro-1-(4-nitrophenoxy)-benzene but a majority of the known metabolites of this compound. The residues are reduced to a common amine intermediate which is further derivatized and quantitatively measured by electron capture gasliquid chromatography. The method is sensitive to 0.01 ppm and is readily suited to routine use. The method has been used on rice and wheat samples.