Determination of residues of endosulfan and five pyrethroid insecticides in virgin olive oil using gas chromatography with electron-capture detection

A simple, fast and economical method has been developed for the determination of endosulfan and five pyrethroid insecticides, cypermethrin, deltamethrin, fenvalerate, lambda-cyhalothrin and permethrin, in virgin olive oil. The method uses a Sep-Pak alumina-N column cleanup after a liquid-liquid extraction or low-temperature precipitation step, and gas chromatography (GC) with electron-capture detection. The matrix effect was assessed for the GC systems used. Recoveries were 71-91% with RSD values of 6-17%. The method was applied to 338 virgin olive oil samples for monitoring of residues of these pesticides. Cypermethrin and lambda-cyhalothrin were detected at the limit of quantification in one sample each, while 22% of samples contained endosulfan residues, mostly at very low levels ranging from 0.02 to 0.57 mg/kg.     

A one-parameter formula for estimating the Λ well depth

A one parameter, semi-empirical formula for Λ-binding energy of heavy hypernuclei in the inverse powers of core mass number (A _c) has been developed in the framework of the folding model. Unlike similar calculations reported by other authors (Deloff 1971; Daskaloyanniset al 1985), we are able to take into account the effect arising from the difference in the number of protons and neutrons of the core nuclei having same mass number. The radius and diffuseness are parametrized using the experimentally known charge density data of a fairly large number of medium and heavy nuclei. The well depth parameter (i.e. Λ-binding energy in infinite nuclear matter) in the formula is obtained from a fit to theB _Λ data of _Λ ²⁸ Si, _Λ ⁴⁰ Ca, _Λ ⁵¹ V and _Λ ³⁹ Y. Using the original Λ-nucleus potential, theB _Λ of ground and the experimentally known excited states of these hypernuclei have also been calculated by solving numerically the two-body Schrödinger equation. The agreement with the experimental data is satisfactory.     

Reactions of Triruthenium Clusters with Quinolines: X-Ray Structures of [Ru3(μ-CO)(CO)7{μ3-η2-P(C6H5)CH2P(C6H5)2)}{μ-η2-C9H5(CH3)N}] and [Ru3(CO)10(μ-H){μ-η2-C9H6N}]

The reactions of [Ru₃(CO)₁₀(μ-dppm)] 4 with quinolines afforded [Ru₃ (μ-CO)(CO)₇{μ₃-η²-P(C₆H₅)CH₂P(C₆H₅)₂)}{μ-η²-C₉H₅(R)N}] (8, R = 4-Me; 9, R = H) as the major products along with small amounts of known compound [Ru₃(CO)₉{μ₃-η³-P(C₆H₅)CH₂P(C₆H₅)(C₆H₄)}] 5. The molecular structure of 8 has been determined by single crystal X-ray studies. The reaction of 5 with 4-methylquinoline in refluxing cyclohexane afforded 8 and two known dinuclear compounds, [Ru₂(CO)₆{μ-CH₂P(C₆H₅)(C₆H₄)P(C₆H₅}] 10 and [Ru₂(CO)₆ {μ-(C₆H₄)P(C₆H₅)(CH₂)P(C₆H₅}] 11, in 40, 12, and 10% yields, respectively. The compounds 10 and 11 are also formed from the thermolysis of 4 in addition to the major compound 5. The solid state structure of the previously reported [Ru₃(CO)₁₀(η-H){μ-η²-C₉H₆N}] 2a is also reported for comparison.     

Comparison of extraction methods to monitor pesticide residues in surface water

A regular monitoring program to study the pesticide concentration in surface waters has been carried out since 1976 in Hungary by the National Plant Protection Organization of the Ministry of Agriculture and Regional Development jointly with the Regional Water Authorities. At the beginning of this program a liquid-liquid partition method is used to extract the pesticides from water samples. After checking the pH value, one sample aliquot is extracted to analyze the basic and neutral compounds. Another aliquot is acidified to pH 2 and extracted to analyze acidic compounds. Disadvantages of this method are high solvent consumption and the need to apply solvents (methylene chloride and diethyl ether) that are harmful to human health. Therefore, the solid-phase extraction method has been introduced. This method has another advantage in that by using the vacuum manifold a number of samples can be extracted simultaneously depending on the capacity (number of ports) of the manifold. Three types of cartridges (LiChrolut EN, ISOLUTE ENV+, and Carbograph) are tested. The suitability and reproducibility of the extraction on various cartridges is studied and compared through recovery experiments. Recoveries are done for 22 active ingredients at spiking levels of 1-5 times the limit of determination (in the range of 0.05-2.5 microg/L) with each extraction method. Individual recovery values as well as average recoveries for all methods are between 70% and 100%, with the relative standard deviation generally below 20%. Carbograph is the only cartridge among those studied that can be used to extract both neutral and acidic compounds in one sample loading step using two different consecutive elution steps.     

Synthesis and structure of a new heptaborate oxoanion isomer: B7O9(OH)5(2-)

The nonmetal borate [H3N(CH2)7NH3][B7O9(OH)5].H2O (1) was prepared via a neat reaction of 1,7-diaminoheptane with excess boric acid under mild nonhydrothermal conditions. Single-crystal X-ray characterization of 1 revealed a new isomer of the heptaborate anion, B7O9(OH)5(2-). The heptaborate anion in 1 is comprised of four fused (BO)3 rings sharing three four-coordinate boron atoms and a single three-coordinate oxygen atom. This anion is a structural isomer of another recently described heptaborate anion, consisting of a chain of three (BO)3 rings. Compound 1 crystallized in the triclinic space group P1 with a=9.3266(17) A, b=10.1222(19) A, c=10.847(2) A, alpha=89.422(2) degrees, beta=82.349(2) degrees, gamma=75.158(2) degrees, V=980.7(3) A3, and Z=2.     

Crystalline alcoholamine borates and the triborate monoanion

The triborate and pentaborate compounds 3-hydroxy-2,2-dimethylpropylammonium triborate(1+), [HOCH2C(CH3)2NH3][B3O3(OH)4] (1), and 2-hydroxyethylammonium pentaborate(1-), [HOCH2CH2NH3][B5O6(OH)4].H2O (2), were prepared by crystallization from concentrated aqueous boric acid solutions containing the respective alcoholamines at a boric acid-alcoholamine mole ratio of 3.33:1.00. Compound 1 crystallized in the triclinic space group P1 with a = 5.9595(9) A, b = 6.3024(9) A, c = 15.594(2) A, alpha = 91.218(2) degrees , beta = 91.138(2) degrees , gamma = 118.034(2) degrees , V = 516.56(13) A (3), and Z = 2; 2 crystallized in the monoclinic space group P2 1/ n with a = 11.2469(8) A, b = 9.5091(6) A, c = 11.5422(8) A, beta = 90.175(1) degrees , V = 1234.41(15) A (3), and Z = 4. Compound 1 contains a rare example of a structurally characterized hydroxyl-hydrated triborate monoanion. Comparisons are made with other known examples of this anion.     

Synthesis and Inclusion Properties of Macrocyclic Polyethers Containing Phosphonic Groups

Abstract

Three novel polyether macrocycles II-IV bearing phosphonic groups have been synthesised in satisfactory yields. Macrocycle II was found to form a 1:1 inclusion compound with cyclohexane and thus was easily isolated from the reaction mixture as a clathrate. The crystal and molecular structure of the cyclohexane solvate has been determined by single crystal X-ray analyses and refined to an R of 0.028 for 3199 reflection. The compound is monoclinic, space group P2₁n with a = 15.886(6) Å, b = 11.657(5) Å, c = 18.621 (6) Å, β = 90.12(3)°, Z = 2. The whole molecule exhibits a great deal of disorder and the different conformations were modelled as consisting of two different primary conformers with population approximately 60:40.