Analysis of fumigants and fumigant residues.

The terms fumigant and fumigant residue are defined. Interrelationships between physically and chemically bound residues, storage environments, nature of the substrate and other influencing factors are outlined. Analytical methods include polarography by DME and RPE, titrimetry, spectrophotometry, and GC with microthermal conductivity, hydrogen flame ionization, electron capture, microcoulometric, thermionic, and flame photometric detector systems, with backup by enzymatic, radiometric, NAA and X-ray flourescence methods. Various aspects are illustrated with different fumigants used commercially. Supplementary methods to extend the power and usefulness of analytical methods in fumigant research are indicated.     

Dietary intake and residues of organochlorine pesticides in foods from Hsinchu, Taiwan.

The levels of contamination with various organochlorine pesticides (such as total HCH, heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, endosulfan, and total DDT) of different foods from 3 traditional markets were determined to estimate Taiwanese daily intake of organochlorine pesticides. Of the 18 organochlorine pesticides investigated, alpha-HCH, beta-HCH, lindane, delta-HCH, heptachlor, heptachlor epoxide, dieldrin, endrin, alpha-endosulfan, p,p'-DDE, and p,p'-DDT were detected at concentrations ranging from 0.26 to 10.2 ng/g wet weight. Contamination with organochlorine pesticides followed the order heptachlor > dieldrin > alpha-endosulfan > HCH isomers > heptachlor epoxide > DDT. Frequencies of detection of organochlorine pesticide residues ranged from 2.0 to 52.3%. alpha-Endosulfan was the most frequently detected organochlorine pesticide in the foods analyzed, followed by heptachlor epoxide (47.6%) and alpha-HCH (38.9%). Estimated daily intakes (EDIs) of organochlorine pesticides from foods were 1.137 micrograms for total HCH, 2.147 micrograms for heptachlor, 0.702 microgram for heptachlor epoxide, 0.624 microgram for endosulfan, 0.098 microgram for cyclodiene, and 0.541 microgram for total DDT. These EDIs were only 0.075% of the acceptable daily intake (ADI) for lindane, 47.5% of ADI for heptachlor and heptachlor epoxide, 0.045% of ADI for total DDT, and 1.01% of ADI for aldrin and dieldrin. Therefore, consumption of the foods analyzed does not pose a risk to consumer health.     

The conformational states of cyclopeptide systems. VIII. Synthesis of cyclohexapeptides containing residues of L-valine, L-norvaline, L-leucine, and glycine

Summary The synthesis of seven cyclic hexapeptides containing the residues of L-valine, L-norvaline, L-leucine, and glycine has been effected.Chemical Faculty of the Polytechnic Institute (Gdansk, Poland).M. M. Shemyakin Institute of Bioorganic Chemistry, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 57–63, January–February, 1975.     

Analysis of pesticide residues in fruits, vegetables, and milk by gas chromatography/tandem mass spectrometry.

A method for detection, quantitation, and confirmation of more than 100 pesticides by gas chromatography (GC) with ion trap mass spectrometry (MS/MS) has been developed. The sensitivity of this method for many analytes is equal to or lower than those of selective GC detectors such as flame photometric detectors and electrolytic conductivity detectors. Using MS/MS, very low detection limits and good confirmation (1 precursor ion and 2 or more product ions) are achieved simultaneously. The entire list of pesticides is screened with 2 injections per sample. Samples are introduced onto the column by a temperature-programmed cold injection to maximize response. Each pesticide is run with its own unique set of parameters, which fragment the compound, retaining only the precursor ion. This ion is then refragmented to create a product spectrum. The selectivity of MS/MS gives a very clean spectrum, making compound identification and confirmation clear, even with a relatively dirty food matrix. If care is taken to maintain the injection port and guard column, this method can reliably identify and confirm more than 100 pesticides at the low parts-per-billion range.     

Synthesis of regular polypeptides including lysine,proline, and alanine residues

Summary From the epigeal part ofThermopsis alterniflora, in addition to the alkaloids found previously, argentine, argentamine, and a new alkaloid, dimethamine, which is a representative of the bimolecular series, have been isolated. The structure of 3-(3,4-dihydro-N-methylcytisin-5-yl)-N-methylcytisine has been proposed for dimethamine on the basis of IR, UV, mass, and NMR spectra and also from its conversion products.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 218–222, March–April, 1972.     

Synthesis of regular polypeptides including lysine, proline, and alanine residues

Conclusions Polypeptides of the following sequences have been obtained: -Lys-Pro-,-Lys₂-Pro-, -Lys₃-Pro-,-Lys-Pro₂-, and -Lys-Ala-, with molecular weights of from 1000 to 14,000. It has been established that the use of pentachlorophenyl esters for polymerization in place of 2,4,5-trichlorophenyl esters leads to a considerable increase in the molecular weights of the polypeptides.Institute of Chemistry, Academy of Sciences of Tadzhik SSR. Institute of Molecular Biology, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 210–213, March–April, 1974.     

Determination of organochlorine pesticide residues in medicinal plants sold in Coimbra, Portugal.

Levels of 14 organochlorine pesticide residues--1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) group (p,p'-DDT, o,p'-DDT, p,p'-DDD, and p,p'-DDE), HCH isomers (alpha-, beta-, and gamma-HCH), hexachlorobenzene (HCB), aldrin, dieldrin, endrin, heptachlor, alpha-endosulfan, and endosulfan sulfate--were evaluated in 127 samples of medicinal plants collected in pharmacies (78 samples) and herb stores (49 samples) in 1996. Samples were divided between 15 national brands and 7 foreign brands. Most samples sold in pharmacies contained residues of gamma-HCH (51.3%). All residues were detected in analyzed samples, with exception of endrin in herb store samples. Detection frequency varied between 51.3% for gamma-HCH and 1.3% for endrin in pharmacy samples, and between 34.7% for HCB and 4.1% for endosulfan sulfate in herb store samples. Maximum residue levels were exceeded in 38 (48.7%) pharmacy samples and in 26 (53.1%) medicinal herb store samples.     

Analysis of herbicide residues in cereals, fruits and vegetables

The determination of herbicide residues in cereals, fruits and vegetables by chromatographic methods is reviewed. The principal chemical groups of herbicides, like phenoxyacids, benzonitriles, ureas, triazines, dinitroanilines, chloroacetamides, carbamates, uracils, glyphosate and bipyridylium compounds, are considered. This review briefly provides some basic information on food sample extraction, clean-up, derivatization and determination of herbicide residues.     

Synthesis of regular polypeptides,containing arginine residues

Conclusions Using the method of activated ethers, we synthesized the regular polypeptides: H-(Ala-Arg)_n-OH, H-(Ala-Ala-Arg)_n-OH, H-(Ala-Arg-Arg)_n-OH, and H-(Gly-Arg-Arg)_nlOH with a M_av of 1200–7000.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2596–2597, November, 1972.