First derivative spectrophotometric determination of strychnine and brucine in nux vomica liquid extract

A simple, rapid, and accurate method is presented for determining strychnine and brucine in nux vomica liquid extract. The 2 alkaloids are directly extracted from the alkaline liquid extract with 0.1N H2SO4, and the liberated alkaloids are determined separately using first derivative spectrophotometry. The minimum strychnine and brucine concentrations detectable by means of this method are 3.0 micrograms/mL. The method has been successfully applied to the analysis of 3 batches of nux vomica liquid extract.     

Colorimetric assay of strychnine and brucine in nux vomica.

Two colorimetric methods are described for the estimation of strychnine and brucine in nux vomica. The first is a modification of the Karawya and Ghourab method for the determination of strychnine, in which the sensitivity of the color is increased by changing certain conditions of the method. The second was developed for the determination of brucine and is based on measuring the intensity of the violet color produced by treating brucine with nitric acid and methanolic stannous chloride. In the presence of large amounts of strychnine, brucine is isolated prior to colorimetric analysis by a quantitative thin layer chromatographic technique.     

Gas-liquid chromatographic determination of strychnine in grain baits.

A simple and rapid gas-liquid chromatographic procedure, using a 6' times 1/4' glass column packed with 5% SE-30 on Chromosorb W (DMCS) and a flame ionization detector, is described. Grain baits containing strychnine alkaloid are ground, mixed, and extracted by shaking with chloroform containing an internal standard, 1,3,5-triphenylbenzene. Without further cleanup, extract filtrates are injected directly into a gas chromatograph. Peak height ratios are used for quantitation of strychnine. The analysis of commercial samples shows that the method compares well with a commonly employed ultraviolet spectrophotometric method; good precision, with recoveries ranging from 89.9 to 91.7%, is obtained in the analysis of prepared samples. The method is sensitive to 2 mug strychnine.     

High-performance liquid chromatographic determination of strychnine in grain baits.l.

A simple and rapid high-performance liquid chromatographic procedure is described for the determination of strychnine. Grain baits containing strychnine alkaloid are ground, mixed, and extracted by shaking with chloroform. Without further cleanup, extract filtrates are injected directly into a liquid chromatograph. Chromatography is complete within 7 min and peak heights are used for quantitation. Separations were made on a 30 cm times 4 mm id stainless steel column packed with mu Porasil (8-12 mum silica). The eluting solvent was methanol-chloroform (10+90) at a flow rate of 2.0 ml/min. Recovery of spiked samples ranged from 91.5 to 95.2%. Confirmation of strychnine from a commercial sample was made by high resolution mass spectrometry with mass agreement to 1.2 ppm.     

Simultaneous assay for six alkaloids in opium, using high-performance liquid chromatography.

A method is described for the quantitative determination of morphine, codeine, cryptopine, thebaine, papaverine, and narcotine in opium by high-performance liquid chromatography. The alkaloids are isolated from a dilute acid extract by adsorption on an Amberlite XAD-2 resin column and eluted first with methanol and then with chloroform-methanol (3+1). After solvent removal by reduced pressure evaporation, the alkaloids are redissolved in chloroform-methanol (3+1). The sample solution, plus brucine as an internal standard, is injected onto a Corasil II column and eluted with hexane that is gradient programmed with a solution of chloroform-methanol-diethylamine (100+300+1). The absorbances of the separated alkaloids are continuously monitored at 254 nm, using a flow-through ultraviolet double-beam photometer.     

New PVC nitrate-selective electrode: application to vegetables and mineral waters

The paper refers the analytical potentialities of the oxa-azamacrocycles as potentiometric ionophores for the construction of electrodes selective to nitrate. Afterward, the membrane selective to nitrate is designed and optimized using a [3.3.3.3]oxazane as an ionophore. The membrane was prepared using dibutylphthalate as a solvent mediator, tetraoctylammonium as a lipophilic membrane additive, and poly(vinyl chloride (PVC) as a polymeric matrix, applied directly onto a conductive graphite/epoxy resin support. The electrodes presented a slope of 60 +/- 0.1 mV log(-1), a low limit of linear response of 4.2 x 10(-6) mol L(-1), a useful lifetime of 1 year, and improved selectivity characteristics when compared with other nitrate electrodes. The good working characteristics of this electrode, constructed without inner-reference solution, made possible its application to the determination of nitrate in different types of vegetables and bottled mineral waters without the use of a conditioning solution. The application of a significant F test proved that the results obtained were similar to those attained by application of the brucine spectrophotometric method adopted as a reference technique. Linear regression analysis also showed good agreement between the results obtained by the proposed method and the reference one.     

HPLC-UV method for nicotine, strychnine, and aconitine in dairy products

The toxic nitrogen alkaloids nicotine, strychnine, and aconitine were quantitated in whole milk, skim milk, and cream using solid-phase extraction cleanup and HPLC-UV with dual wavelength detection. Samples were extracted in McIlvaine's buffer with EDTA and then partitioned with aqueous acetonitrile and hexane. The aqueous phase was concentrated and passed through an OASIS HLB column. The column was eluted with methylene chloride/ammonium hydroxide, 1 mL/1 microL, v/v. The eluent was acidified with hydrochloric acid and evaporated. The sample was diluted for HPLC with acetonitrile/phosphate buffer pH 7.4. Chromatography was performed on an Xterra RP-18 column using a gradient of acetonitrile and ammonium bicarbonate buffer at pH 9.8. Nicotine and strychnine were monitored at 260 nm; aconitine was monitored at 232 nm. Calibration curves were generated from external standards in the range 0.2-10 microg/mL using 1/x weighting. Mean recoveries in whole milk spiked between 0.1 and 10 ppm were the following: nicotine 89.2%, strychnine 75.7%, and aconitine 85.1%. Mean recoveries in skim milk spiked between 0.1 and 10 ppm were the following: nicotine 72.1%, strychnine 78.2%, and aconitine 82.9%. Mean recoveries in cream spiked between 0.2 and 20 ppm were the following: nicotine 87.9%, strychnine 76.9%, and aconitine 82.0%. Relative standard deviations of recovery were less than 20% in each case.     

Wildlife deaths in Scotland resulting from misuse of agricultural chemicals

Deaths of wild and domestic animals have been investigated over a seven-year period. A large number of animals have been poisoned by deliberate misuse of pesticides. These have included many protected species as well as domestic animals. Three pesticides, alphachloralose, mevinphos and strychnine, were found to be used in 94% of these cases. Misuse of pesticides was mainly seasonal and much of it was associated with the protection of young game birds and some arable crops. The difficulties of countering this illegal practice are discussed.     

Spectrophotometric analysis of alkaloids with picrolonic acid.

The spectroscopic characteristics of the interaction of alkaloids with picrolonic acid were studied. In solvents of low and intermediate polarity, the presence of alkaloids caused a red shift of the 322 nm band of nonionized picrolonic acid to 355 nm, corresponding to the anionic resonance band. There was also a considerable increase in absorptivity, which was dependent on both the basicity (pKa) and molar concentration of the alkaloid present. Arylamines, aromatic N-heterocycles, and alkaloids lacking an aliphatic amine moiety did not show observable shifts. The interaction was developed into a spectrophotometric assay for the following alkaloids in pharmaceutical preparations: atropine, ephedrine, codeine, emetine, quinine, and strychnine. The method is sensitive to 2 mug alkaloid/ml, with an accuracy of not equal to 1.5% and a standard deviation of not equal to 1.05 - 1.31%.     

A multiresidue method for the determination of insecticides and triazine herbicides in fresh and processed olives

A simple, rapid, and low-cost gas chromatographic multiresidue method has been developed for the analysis of pesticide residues in raw and processed olives. This has been validated for 19 insecticides and triazine herbicides, covering a wide range of polarities. The method uses low-temperature precipitation to remove lipids and gives good cleanup for gas chromatography analysis with nitrogen phosphorus and electron capture detection. Recoveries are between 71 and 99%, with relative standard deviation values of 5-15%.     

Broad tuning of the human bitter taste receptor hTAS2R46 to various sesquiterpene lactones, clerodane and labdane diterpenoids, strychnine, and denatonium

Sesquiterpene lactones are a major class of natural bitter compounds occurring in vegetables and culinary herbs as well as in aromatic and medicinal plants, where they often represent the main gustatory and pharmacologically active component. Investigations on sesquiterpene lactones have mainly focused on their bioactive potential rather than on their sensory properties. In the present study, we report about the stimulation of heterologously expressed human bitter taste receptors, hTAS2Rs, by the bitter sesquiterpene lactone herbolide D. A specific response to herbolide D was observed i.a. for hTAS2R46, a so far orphan bitter taste receptor without any known ligand. By further investigation of its agonist pattern, we characterized hTAS2R46 as a bitter receptor broadly tuned to sesquiterpene lactones and to clerodane and labdane diterpenoids as well as to the unrelated bitter substances strychnine and denatonium.     

振动能量流的计算方法研究

振动能量流法是研究柔性结构振动的重要方法,能量流的计算是其中的关键步骤,传统的基于模态叠加的导纳能量流计算法计算精度不高,处理复杂结构时计算过程复杂,该文提出了基于波动理论的导纳能量流计算方法和基于有限元分析的能量流计算方法。通过对一具体模型计算对比,表明波动计算法精度最高,模态叠加法存在模态截断误差,而有限元法在划分网格细时也能保证计算精度。有限元法是一种适合于各种复杂结构的分析方法,值得在工程上推广。     

A new, rapid, high-sensitivity analysis of amino acids in food type samples

A new approach to the analysis of free amino acids and amino acids from hydrolyzed foods is described. The method is based on reaction of the free amino acids with phenylisothiocyanate to form stable derivatives which are subsequently separated by liquid chromatography. Sample preparation procedures are described and results are compared with conventional ion exchange results. Reproducibility of the new method has been determined on a typical food type sample.     

Determination of nitrite in soil extracts and water samples by a nitrogen oxide electrode

Abstract

Work to evaluate the Orion nitrogen oxide electrode indicated that this electrode can be used satisfactorily for determination of nitrite in soil extracts and water samples. The electrode method of analysis described is simple, rapid, and precise, and its results agree closely with those obtained by the colorimetric method of Griess‐Ilosvay. The electrode method has the advantage that its results are not affected by color or turbidity or by Cu²⁺ and Hg²⁺ present in samples under analysis     

Method for the estimation of nutrient uptake kinetic parameters using nonparametric statistics

The uptake of many plant nutrients has been shown to follow Michaelis‐Menten enzyme kinetics, and as a result several methods of collecting and analyzing uptake data have been developed. The method proposed here consists of a continuously flowing hydroponic system and a method of data analysis that estimates a value of K_mand V_max for each plant. The method is nondestructive; it does not require large amounts of space; and the plants are near steady‐state uptake. In simulated experiments with various assumptions about variability in the data, the nonparametric statistical analysis of the results provided estimates as good as or better than regression analysis estimates of the two parameters of the Michaelis‐Menten equation.     

Gas chromatographic methods for determination of gamma-BHC in technical emulsifiable concentrates and water-dispersible powder formulations and in lindane shampoo and lotion: collaborative study

Although the gas chromatographic separation of the isomers of BHC was demonstrated two decades ago, the present AOAC method of analysis of BHC for gamma-isomer (lindane) content is based on a separation carried out on a liquid chromatographic partition column. A method of analysis has been developed that uses an OV-210 column for separation of the gamma-isomer from the other isomers and impurities in technical BHC. Di-n-propyl phthalate was chosen as an internal standard. The same system allows quantitation of lindane in lotion and shampoo after these products are extracted with ethyl acetate-isooctane (1 + 4). The analytical methods were subjected to a collaborative trial with 10 laboratories. The coefficient of variation for technical BHC was 2.83%. For the water-dispersible powder and emulsifiable concentrate, the coefficients of variation were 2.89% and 4.62%, respectively. Coefficients of variation for 1% lindane lotion and shampoo were 4.36% and 11.92%, respectively. The method has been adopted official first action.     

Gas chromatographic determination of cholesterol in egg products

A method has been developed for quantification of cholesterol in fresh egg yolks, spray-dried egg yolks, fresh whole eggs, and spray-dried whole eggs. The method uses saponification followed by petroleum ether extraction of cholesterol. Separation of organic and aqueous layers is enhanced by sodium chloride. Petroleum ether extracts are dried under nitrogen and redissolved in chloroform-methanol (2 + 1) for injection into a gas chromatograph. Cholesterol is separated and quantitated on a high temperature capillary column coated with 5% diphenyl and 95% dimethyl polysilicone crosslinked gum. The method was compared with the current AOAC method 17.017-17.022, and results indicated no significant difference (alpha = 0.05). However, the proposed method allowed separation and analysis of 16 samples in 7 h while the current AOAC method allowed separation and analysis of only 4 samples in 9 h.     

Determination of haloanisols in white wine by immunosorbent solid-phase extraction followed by enzyme-linked immunosorbent assay

A high through-put screening immunochemical method to control the presence of 2,4,6-trichloroanisol (TCA) and 2,4,6-tribromoanisol (TBA), the main agents responsible for the musty odor in wine samples, has been developed. The method involves a selective (antibody-antigen) solid-phase extraction (SPE), followed by enzyme-linked immunosorbent assay (ELISA) analysis. The sample preparation method established uses for immunosorbents (ISs) prepared by covalently coupling antibodies developed for TCA on a sepharose support. At present, about 200-400 ng L-1 of TBA and TCA can be detected in white wine samples by the IS-SPE-ELISA method described here without any preconcentration step. Simultaneous analyses of many samples are possible with this method. Related chloroanisoles (2,3- and 2,6-dichloroanisols and 2,3,4,5-tetrachloroanisol) and chlorophenols (2,3,4,6-tetrachlorophenol and pentachlorophenol) usually present in contaminated wine samples are also effectively retained by the IS, although only 2,4,6-TCA and 2,4,6-TBA are detected by the ELISA used. The immunopurification procedure developed could also be useful as a selective cleanup method prior to chromatographic analysis.     

Analytical methods for determining ascorbic acid in biological samples, food products, and pharmaceuticals

Over the last decade, numerous publications have appeared describing analyses for ascorbic acid in food products, pharmaceuticals, and biological samples. This review focuses on the chemistry associated with many of these procedures. The papers discussed have historical importance, are important to understanding the method, or have significantly advanced ascorbic acid analysis. The review has 4 major sections: spectroscopic, electrochemical, enzymatic, and chromatographic methods of analysis.     

应用寡核苷酸微阵列检测基因突变

寡核苷酸阵列技术是一种高度集成化、快速的基因分析手段，已广泛用于基因突变检测、序列测定、基因表达分析、疾病诊断等。本文主要介绍应用该技术进行基因突变检测的三种方法：杂交信号增益法、杂交信号消减法与微测序分析。三种方法各有优势，通过选择适当的方法，将为基因突变检测提供更佳的分析途径。