Extraction of 2-nitroaniline and 2-nitro-4-methylaniline from aqueous solutions

Results of extraction of 2-nitroaniline and 2-nitro-4-methylaniline from aqueous solutions with organic solvents are shown to depend on the nature of extractants, pH of the aqueous phase, its saturation with water and electrolytes. The optimal conditions for the extraction of the compounds of interest are created by using water-saturated ethylacetate as the extractant at a pH value in the range from 1.0 to 12.0. The rate of extraction was calculated necessary to remove the desired amounts of 2-nitroaniline and 2-nitro-4-methylaniline from aqueous solutions using the above solvents.     

Extraction of lambda-cyhalothrin from aqueous dioxan solutions

The results of extraction of lambda-cigalotrin from dioxan aqueous solutions by hydrophobic organic solvents are presented. It is shown that the degree of extraction depends on the nature of the extractant, the water to dioxan ratio, and saturation of the water-dioxan layer with the electrolyte. The highest efficiency of lambda-cigalotrin extraction was achieved using chlorophorm as a solvent under desalination conditions. The extraction factor was calculated necessary to obtain the desired amount of lambda-cigalotrin from the water-dioxan solution (4:1) with the help of the extractants being used.     

Isolation, extractive concentration, and determination of caffeine in the studies of blood plasma

The optimal conditions for the isolation of caffeine from human blood by means of acetone extraction are described with special reference to the peculiarities of extraction from aqueous solutions. The possibility of concentration and purification of caffeine from blood plasma using acetone and aceton-chlorophorm mixture (2:8) as the solvents is illustrated. In addition, purification by silica-gel thin layer chromatography is discussed. Thin layer chromatography, UV-spectrophotometry, and high performance liquid chromatography are considered as potential methods for the identification and quantitative determination of caffeine.     

Extraction of trifluralin from acetonitrile solutions

Results of extraction of trifluralin from an aqueous acetonitrile solution using various organic solvents are presented. The degree of extraction was shown to depend on the nature of extractant and the water/acetonitrile ratio. An optimal electrolyte and the degree of saturation of the water-acetonitrile layer with this electrolyte were selected. The highest efficiency of extraction was achieved by using water-saturated ethylacetate as an extractant. The indices of extraction were calculated as necessary for the isolation of a given amount of trifluralin from aqueous acetonitrile (4:1) solutions with the solvents considered in the present study.     

Extraction of 2-amino-4-nitrophenol and 4-phenylphenol from aqueous solutions

The authors provide the results of extraction of 2-amino-4-nitrophenol and 4-phenilphenol from aqueous solutions by five organic soluvants. The dependence of the extraction degree on some factors (nature of extragent, pH of aqueous phase medium, extragents saturation with water) was established. Necessary extraction rate for isolation of preset quality of the test substances was calculated.     

Features of extracting phenol and 4-methylphenol from aqueous solutions

Phenol and 4-methylphenol were extracted from aqueous solutions by 5 organic solvents. The degree of extraction depended on such factors as type of extracting agent, pH of aqueous phase, and water saturation of extracting agent. The necessary number of extractions for obtaining the preset volumes of studied compounds is calculated.     

Extraction of basic metabolites of monomethyloxybenzene isomers from aqueous solutions

The results are presented of extraction of 1-methyl-3,4-dioxybenzene, 1-methyl-2,5-dioxybenzene and 4-oxybenzene acid from aqueous solutions with hydrophobic and hydrophilic organic soluvants. It is shown that the degree of extraction depends on the nature of the extragents and pH of the aqueous phase medium. Extraction multiplicity for obtaining necessary quantities of the compounds is calculated.     

Extraction of nitrobenzene and its metabolite 3-aminohydroxybenzene from water solutions

The article presents the results of nitrobenzene and 3-aminohydroxibensene extraction from aqueous solutions by means of five organic solvents. The following factors influence on the extraction degree is shown: the nature of the extracting agent, aqueous phase pH, saturation of some extracting agents with water. The number of extractions for isolation of the necessary quantities of the compounds studied is calculated.     

Methods for detecting diazoline in chemicotoxicological studies]

New specific methods of diazolin detection by microcrystalline and chromogenic reactions as well as by thin-layer sorbent chromatography were developed. These methods were used to detect diazolin, isolated from biological object by water acidified with oxalic acid. It was stated that diazolin is detectable in chlorophorm extraction obtained both from acidic and from alkaline aqueous solutions.     

Cloud point extraction coupled with back extraction: a green methodology in analytical chemistry

Recently, cloud point extraction (CPE) coupled with back extraction (BE) has been suggested as a promising alternative to liquid-liquid extraction. In CPE, non-ionic surfactants in aqueous solutions form micelles and the solution becomes turbid when heated to the cloud point temperature. Microwave- or ultrasonic-assisted BE can be performed after CPE and before injection of the sample for instrumental analysis by ultraviolet-visible spectroscopy, high-performance liquid chromatography, gas chromatography, gas chromatography-mass spectrometry, or liquid chromatography-mass spectrometry. This article reviews selected published scientific research on the application of CPE-BE to the determination of alkaloids, drugs and organophosphorus compounds from several complex matrices. This method could be scaled-up for use in forensic science.     

The extraction of deoxypeganin from aqueous solutions with organic solvents]

Studies of deoxypeganin extraction with various organic solvents have shown that up to 88% of the agent can be easily extracted by chloroform if the medium pH values are 11-12. The presence of electrolytes in deoxypeganin aqueous solutions does not influence the degree of the agent extraction with organic solvents.     

Detection of drugs using XAD-2 resin. I:Choice of resin, chromatographic conditions, and recovery studies

Amberlite XAD-2, a nonionic polystyrene divinylbenzene resin, was first used for the analysis of drugs in urine and a number of reports have described the development at optimal conditions for extraction, including type of resin columns, pH conditions, and eluting solvents. XAD-4 and XAD-7 resins were compared to the similarly structured XAD-2 resin and no significant advantage over the XAD-2 resin for drug screening was observed. A quantity of 5 to 6 g of resin was found to have sufficient capacity for the extraction of 200 ml of pentobarbital solution (1 mg/100ml). A column flow rate of approximately 15 ml/min (gravitational flow) was sufficient for analysis and slower rates were not more efficient. A mixture of ethyl acetate and 1,2-dichloroethane (3:2) was found to give best overall recovery (66 to 94%) of drugs, the resulting extracts being reasonably free of interfering substances. A pH value of 8.5 is recommended as optimum for comprehensive analysis of acidic and basic drugs. Recovery studies were conducted on spiked samples to determine drug losses occuring during various steps in the XAD-2 extraction procedure for four acidic (amobarbital, secobarbital, pentobarbital, and phenobarbital) and four basic (morphine, codeine, meperidine, and methadone) drugs. A relatively small amount (0 to 5%) of the drugs was not adsorbed by the resin and amounts varying from 6 to 40% failed to be desorbed by the eluting solvent. Additional losses occurred during the removal and analysis of TLC spots. Recovery of drugs from aqueous solutions analyzed with the XAD-2 resin were compared to recoveries reported in the literature with other XAD-2 resin methods for the extraction of drugs from urine. Recovery of phenobarbital, morphine, and codeine improved by 4 to 23% while recoveries of amobarbital, pentobarbital, secobarbital, methadone, and meperidine were 4 to 28% less efficient when compared to literature data.     

The comparative characteristics of the extractive capacity of solvents in removing aminazine from liver tissue

Comparative assessment of extractive ability of some solvents with different physical and chemical properties is presented. Use of amphiphilic solvent acetone to isolate aminazine gave higher results. Experimental works (on dogs) showed that use of aqueous acid solutions for aminazine extraction in chemical toxicological investigation is unsuitable.     

Optimal conditions for extraction of "caffetin" and "saridon" tablet components from aqueous solutions

Using a mathematical method of experiment planning (Latin square), the authors suggest the optimal conditions for extraction of propifenasone and paracetamol, the basic components of caffeine and saridon tablets, from water solutions: extraction with ethylacetate (pH 2) for 5 min in the presence of an electrolyte (sodium chloride or ammonium sulfate) quantum satis. The possibility of extraction of caffeine and codeine under these conditions was tested. When extracting the components of caffeine and saridon tablets, paracetamol, propifenasone, and caffeine should be extracted with ethylacetate at pH 2 and codeine by chloroform at pH 10.     

The extraction and infrared identification of gamma-hydroxybutyric acid (GHB) from aqueous solutions

The chemical analysis of gamma-hydroxybutyric acid (GHB) in most forensic laboratories is complicated by the highly polar nature of the GHB molecule, which makes it unsuitable for direct analysis by gas chromatography (GC). Consequently, a popular analytical approach is to convert GHB into the corresponding lactone or a derivative compound that is then identified by mass spectrometry employed in conjunction with GC (GC/MS). An alternative approach is presented here where GHB may be isolated as a free acid specie from complex aqueous solutions employing a liquid-liquid extraction technique. This approach can yield a relatively pure residue of GHB that presents an infrared transmission spectrum that is sufficiently distinct for identification purposes. Infrared spectroscopy (IR) is a very popular technique that is available to most crime laboratories. The liquid-liquid extraction behavior of GHB is examined in detail and the uniqueness of the infrared spectrum is discussed.     

Selective colorimetric determination of TNT partitioned between an alkaline solution and a strongly basic Dowex 1-X8 anion exchanger

The Meisenheimer anions formed from TNT in KOH solutions in alcohol or acetone were used in screening tests for TNT among possible nitro-explosives. The same reaction was used for the spectrophotometric assay of TNT in soil by CRREL (Cold Regions Research & Engineering Laboratory of the U.S. Army) method, also known as Jenkins' method, but the color stability was too dependent on the solution composition and the water tolerance was low, necessitating complete drying of soil samples (which may cause partial analyte decomposition) prior to analysis. This study reports the development of a colorimetric method based on the solid phase extraction (SPE) of the Meisenheimer anion formed from TNT and aqueous NaOH into a strongly basic anion exchange resin Dowex 1-X8 (OH(-) form). The orange-red color that developed both in the solid resin and solution phases was persistent for at least 1h. The resin was let to swell in alcohol, washed first with 1M aqueous NaOH, and then with H(2)O before use. To 5 mL of 4-400 ppm TNT solutions in 1:1 (v/v) acetone-water, 0.5 mL of 5% NaOH was added, diluted to 50 mL with 1:1 acetone-water, and the resulting solutions (containing the orange-red Meisenheimer anion of TNT) were agitated at room temperature with 0.9 g resin for < or =50 min. TNT exhibited a reasonably constant distribution coefficient between the resin and aqueous phases. The absorbance of the filtered solutions was measured against a reagent blank at 500nm. The TNT-loaded resins were regenerated with 1M HCl containing sodium sulfite. The calibration line of filtrate absorbance versus analytical concentration was linear over two orders of magnitude between 0.4 and 40 ppm TNT in final solution. Unlike Jenkins' method, the method was tolerant to 100-fold (by mass) of common soil anions like sulfate, nitrate, and chloride. The basic advantages of the developed colorimetric method over the similar CRREL/Jenkins' method may be summarized as color stability, water and common ion tolerance, lowering of the LOD, and widening of the linear range. As opposed to Jenkins' method, the charge-transfer bands characteristic to colorimetric detection were not obscured by the presence of water. The method is suitable for on-site applications, because the color developed in heterogenous solution was stabilized, and the method can be easily practiced with a portable colorimeter to large numbers of samples.     

SPME与GC/MS相结合检验尿液中的氯胺酮

目的应用固相微萃取与气相色谱-质谱联用技术分析尿液中的氯胺酮。方法对影响SPME萃取效果的萃取头类型、萃取时间、解析时间、离子强度等因素条件进行优化,分析尿中氯胺酮。结果在0.5~2.5μg/m l范围内线性关系良好,线性相关系数为0.995 6;最小检出限为2.5μg/L。结论该方法具有预处理简单、分析速度快、灵敏度高等优点,适合实际案件尿样的检验。     

The chemical interconversion of GHB and GBL: forensic issues and implications.

In this work, the interconversion of GHB and GBL in a variety of aqueous media was studied. The effects of solution pH and time were determined by spiking GHB or GBL into pure water and buffered aqueous solutions, and determining the GHB and GBL contents at various time intervals. The degree of GBL hydrolysis to GHB was determined for several commercial aqueous-based GBL products, and further studied as a function of time. The effects of temperature and time were also determined for five commercial beverages spiked with GHB or GBL. GHB and GBL contents were determined using high performance liquid chromatography (HPLC). GHB and/or GBL confirmations were made using gas chromatography-mass spectrometry (GC-MS) and/or infrared spectroscopy (IR). Solution pH, time, and storage temperature were determined to be important factors affecting the rate and extent of GBL hydrolysis to GHB. Under strongly alkaline conditions (pH 12.0), GBL was completely converted to GHB within minutes. In pure water, GBL reacted to form an equilibrium mixture comprising ca. 2:1 GBL:GHB over a period of months. This same equilibrium mixture was established from either GHB or GBL in strongly acidic solution (pH 2.0) within days. A substantial portion of GBL (ca. 1/3) was hydrolyzed to GHB in aqueous-based GBL products, and in spiked commercial beverages, after ambient storage for a period ranging from several weeks to several months. Heat increased and refrigeration decreased the rate of GBL hydrolysis relative to ambient conditions. These studies show that hydrolysis of GBL to GHB does occur in aqueous-based solutions, with samples and time frames that are relevant to forensic testing. Implications for forensic testing and recommendations are discussed.     

Solid-phase cation exchange extraction of basic drugs from the urine of racing greyhounds

The extraction of basic drugs from the urine of racing greyhounds has been carried out for many years using solvent extraction. This paper describes an extraction method that utilises a cation exchange column. Fourteen basic drugs were introduced onto the column in their ionised form, washed with organic and aqueous solvents and eluted with basic methanol. Three drugs, cyclizine, procaine and quinine were determined in authentic samples from racing greyhounds. A comparison of the solid-phase method with liquid-liquid extraction showed an increase in the efficiency of extraction and a reduction in both the time and cost incurred. The method requires a minimal volume of sample and solvent, little glassware and is easily automated.     

Thin layer chromatography for the analysis of certain anti-inflammatory medicines

This work was devoted to the elucidation of conditions for isolation of ketorolac and diclofenac from biological fluids. A method is proposed for the extraction of these compounds from solutions with organic solvents at different pH values. Other methods permit to optimize identification of analytes by thin layer chromatography while the densitometric technique may be used for qualitative and quantitative analysis of their composition in biological fluids.