Sample is extracted with

The amount of Cypridina luciferin is measured with Cypridina luciferase. To measure the content of Cypridina luciferin in a tissue, the sample is extracted with methanol in the same manner as in the case of coelenterazine (Section C5.1). However, the extracted Cypridina luciferin is extremely unstable in air. Therefore, it is necessary to... 

The analytical method for difiufenican is as follows. A 50-g soil sample is extracted with 100 mL of acetonitrile for 45 min with a rotary shaker at 240 rpm. The mixture is centrifuged for 10 min at 3000 rpm, the supernatant is filtered through a glass filter funnel with anhydrous sodium sulfate and the filtrate is collected. ... 

Soxhlet extraction followed by liquid chromatography/photodiode-array detection (LC/PAD) is used for the trace determination of propanil and its major metabolite, 3,4-dichloroaniline, in soil. A 10-g soil sample is extracted with methanol in a Soxhlet system for 8 h. After the extracts have been concentrated to dryness, the residue is dissolved in 500 pL of n-hexane. °... 

Almost all anilides in water samples are directly extracted with ethyl acetate or dichloromethane, and the method of multi-residue analysis can be applied to the water samples. However, in the case of naproanilide, the water sample is extracted with an organic solvent under acidic conditions. A 5-mL volume of 1N hydrochloric acid and 50 mL of ethyl acetate-n-hexane (1 1, v/v) are added to 200 mL of water sample, and the mixed solution is shaken vigorously using a mechanical shaker for... 

An SPE method has been developed to replace the classical LLP method. Water sample is extracted with an SPE column such as Cig and styrene-divinylbenzene copolymer (PS-2) cartridges, which consist of a reversed bonded-phase silica sorbent, provided as an extraction tool. This is a simple and rapid method, and applied to the determination of residual amounts of naproanilide, propanil, mefenacet, etc. This system determines the residual amounts of most of the pesticides and has been successfully applied to determination of pesticides in water. 

A 20-g homogenized cereal or vegetable sample is extracted with an organic solvent such as acetone. Alter filtration, the solvent extract is concentrated by rotary evaporation to about 20 mL, below 40 °C. The residue is transferred with 5% sodium chloride solution and partitioned twice with n-hexane. The n-hexane extracts are dried by anhydrous sodium sulfate, which is subjected to a cleanup procedure by Horisil or silica gel column chromatography. The eluate is concentrated to dryness and the residue is dissolved in an appropriate amount of acetone for GC/ECD (Ministry of the Environment, Japan). 

Prohexadione-calcium in the samples is extracted with acidic acetone by shaking (extracted as the free acid, prohexadione). The extract is purified by a series of... 

This technique is used mainly for nonpolar compounds. Typically a small aliquot of soil (10-30 g) is dried by mixing with sodium sulfate prior to extraction. Next, the sample is extracted with a solvent for 10-20 min using a sonicator probe. The choice of solvent depends on the polarity of the parent compound. The ultrasonic power supply converts a 50/60-Hz voltage to high-frequency 20-kHz electric energy that is ultimately converted into mechanical vibrations. The vibrations are intensified by a sonic horn (probe) and thereby disrupt the soil matrix. The residues are released from soil and dissolved in the solvent. 

The sample is extracted with acetone, after addition of water, depending on the natural water content of the material, in order to ensure an acetone to water ratio of 2 1 (v/v) during the extraction. 

The extraction method for imidacloprid residues has been presented by Westwood et al. A 20-g soil sample is extracted with 20 mL of acetonitrile-water (4 1, v/v) by... 

Mepronil in plant materials is extracted with aqueous acetone. Rice straw sample is extracted with aqueous methanol. Soil samples are refluxed with alkaline methanol. After filtration, the solvent is removed by evaporation under reduced pressure and... 

Soil sample is extracted with a mixture of methanol and 0.1 M ammonium chloride. Acetamiprid, IM-1-2 and IM-1-4 residues are extracted with dichloromethane under alkaline conditions. After adding diethylene glycol, dichloromethane in the extract is removed by rotary evaporation, and the residue is subjected to a cleanup procedure using Florisil PR column chromatography and then with a packed Extrelut 20 column. 

Also, subcritical (hot/liquid) water can be used as a mobile phase for packed-column RPLC with solute detection by means of FID [942]. In the multidimensional on-line PHWE-LC-GC-FTD/MS scheme, the solid sample is extracted with hot pressurised water (without the need for sample pretreatment), and the analytes are trapped in a solid-phase trap [943]. The trap is eluted with a nitrogen flow, and the analytes are carried on to a LC column for cleanup, and separated on a GC column using the on-column interface. The closed PHWE-LC-GC system is suitable for many kinds of sample matrices and analytes. The main benefit of the system is that the concentration step is highly efficient, so that the sensitivity is about 800 times better than that obtained with traditional methods [944]. Because small sample amounts are required (10 mg), special attention has to be paid to the homogeneity of the sample. The system is... 

Solvent extraction, sometimes called liquid-liquid extraction, involves the selective transfer of a substance from one liquid phase to another. Usually, an aqueous solution of the sample is extracted with an immiscible organic solvent. For example, if an aqueous solution of iodine and sodium chloride is shaken with carbon tetrachloride, and the liquids allowed to separate, most of the iodine will be transferred to the carbon tetrachloride layer, whilst the sodium chloride will remain in the aqueous layer. The extraction of a solute in this manner is governed by the Nernstpartition or distribution law which states that at equilibrium, a given solute will always be distributed between two essentially immiscible liquids in the same proportions. Thus, for solute A distributing between an aqueous and an organic solvent,... 

If a 1-g soil sample is extracted with 10 mL of extractant, then the component extracted is evenly distributed throughout the lOmL. This means the final result will need to be multiplied by 10 because the component was diluted 1 10 (this assumes an extractant density of lg/mL). This then is related back to the volume or mass of soil in the original sample, or it may be directly related back to the field. It may also be necessary to apply other conversion or correction factors, such as the percent water present in the original soil sample, depending on the procedure used. 

The sample is extracted with a mixture of hexane, acetone and water. After separation, the hexane phase is reduced in volume and divided into two aliquots, one of which is first shaken with 7% fuming sulphuric acid to remove lipids, and then with cyanide to eliminate interference by elemental sulphur. The other aliquot is evaporated to dryness and heated with ethanolic potassium hydroxide. The two aliquots are injected into a gas chromatograph fitted with a glass capillary column and an electron capture detector. Hexabromobenzene is used as an internal standard. Polychlorinated biphenyls are determined quantitatively by comparing the peaks of the sample with those of Clophen A... 

Spengler and Jumar [90] used a spectrophotometric method and thin layer chromatography to determine carbamate and urea herbicide residues in sediments. The sample is extracted with acetone, the extract is evaporated in vacuo at 40°C and the residue is hydrolysed with sulphuric acid. The solution is made alkaline with 15% aqueous sodium hydroxide and the liberated aniline (or substituted aniline) is steam distilled and collected in hydrochloric acid. The amine is diazotized and coupled with thymol, the solution is cleaned up on a column of MN 2100 cellulose power and the azo-dye is determined spectrophotometrically at 440nm (465nm for the dye derived from 3-chloro- or 3.4-dichloroaniline) with correction for the extinction of a reagent blank. 

Solvent extraction is a very widely used and simple preconcentration technique. After the sample is extracted with a suitable solvent (such as methylene chloride), the extract is concentrated by evaporation and subjected to analysis. One important requirement is extremely clean solvents fortunately these are now commercially available. Because of the evaporation step, solvent extraction cannot be used for the analysis of very volatile compounds. Depending on sample size, sensitivities of 0.1 ppb can easily be achieved. 

This method published by MAFF (1993a) is not applicable to oilseeds or compound feeds containing milk powder. The sample is extracted with light petroleum and the residue then heated with 3 M HCl. This is filtered, washed, dried and re-extracted with light petroleum. 

System (3) is a specific method for simultaneously measuring cortisone, hydrocortisone, prednisone, and prednisolone as endogenous glucocorticoids in plasma [151]. A 1 mL sample is extracted with 9 mL of 2 1 dichloromethane-ethyl ether. The extract is washed once with 2 mL of O.IM HCl, twice with 2 mL of O.IM NaOH, and dexamethasone is added as the internal standard. The column is 5 pm silica gel (25 cm x 3.2 mm), and the mobile phase is 1937 20 42 1 dichloromethane-tetrahydrofuran-methanol-anhydrous acetic acid eluted at a flow rate of 1.3 mL/min. Detection is by UV absorbance UV at 254 nm, and a limit of detection of 10 pg/L has been repotted. 

Filter/Sorbent Methods. The methods developed using filter/ sorbent sampling trains are listed in Table III. The sampling train consists of a 37-mm diameter filter contained in a cassette filter holder followed by a sorbent tube as described above. Samples are collected at 1 liter/min to obtain the prescribed sample volume. After sampling is completed, the filter is removed from the filter holder and placed in a glass vial with the front sorbent section and capped. The combined sample is extracted with toluene and the resulting solution is analyzed by gas chromatography. 

Three standardized methods were found in the Official Methods ofAnalysis of the Association of Official Analytical Chemists (AOAC 1990). The first of these methods is based on the extraction of crops (kale, endive, carrots, lettuce, apples, potatoes, and strawberries) with ethyl acetate and isolation of the residue followed by a sweep codistillation cleanup prior to GC/thermionic detection (Method 968.24). The second of these methods utilizes Florisil column chromatography clean-up followed by GC/FPD (Method 970.53). In the third method (Method 970.52), the sample is extracted with acetonitrile, and the residue is partitioned into petroleum ether followed by Florisil clean-up and GC/KC1 thermionic detection. Identifications are based on combinations of gas, thin-layer, and paper chromatography. The recovery for diazinon in this method is stated to be greater than 80% no data on limits of detection were given. 

A specific cleanup procedure based on immunoaffinity chromatography with polyclonal antibodies has been described by Gude et al. (50) for the gas chromatographic determination of chloramphenicol in swine tissues. In this method, tissue sample is extracted with acetonitrile/4% sodium chloride (1 1) Following centrifugation, the supernatant is purified with n-hexane, and chloram-... 

For tissue analysis, the sample is extracted with ethyl acetate in the presence of sodium chloride and piperonyl butoxide. After centrifugation, the supernatant is evaporated to dryness, and the residue is dissolved with dichloromethane/ hexane (1 1) to be applied onto a Bond-Elut silica cartridge. Following successive cartridge washing with petroleum ether and ethyl acetate/hexane (4 6), chloramphenicol is eluted with ethyl acetate/hexane (7 3) and the eluate is evaporated to dryness. The residue is dissolved in 0.05 M Tris/hydrochloric acid buffer pH 10.4, extracted with diethyl ether, and the extract is evaporated to dryness. Tlie... 

Simeonidou et al. (238) reported an ion-pair liquid chromatographic method for the determination of sulfadiazine, sulfamethazine, sulfadimethoxine, and sulfaquinoxaline residues in chicken muscle. According to this method, a 3 g ground tissue sample is extracted with 30 ml chloroform. Following centrifugation the supernatant is filtered and a 10 ml aliquot is extracted with 1 ml 3N hydrochloric acid and submitted to precolumn derivatization with fluorescamine. Liquid chro-... 

According to the modified procedure (602), milk is thoroughly mixed in its storage container immediately before transfer of the 1 ml aliquot in the extraction tube. This is necessary because approximately 50% of phenylbutazone in milk is associated with the cream. The sample is extracted with 2.4 ml diethyl ether and 2.4 ml petroleum ether in presence of 1 ml ethanol and 100 1 25% ammonia solution. The organic layer that contains the milk lipids is discarded. Five ml hexane-tetrahydro furan (4 1) is added to the aqueous layer, which is tiien acidified with hydrochloric acid and the layers are mixed. Under the acidic conditions, phenylbutazone partitions quantitatively into tlie organic layer, which is collected, evaporated, and dissolved in the mobile phase to be analyzed by liquid chromatography. Separation is performed on a reversed-phase column using an isocratic 0.02 M phosphate buffer/methanol mobile phase, and determination is by ultraviolet detection at 264 nm (Fig. 29.18.2). The limit of detection and limit of quantification were 3.0 and 5.4 ppb, respectively (Table 29.17). 

The sample is extracted with dichloromethane by using one of three techniques Soxhlet extraction (10 g of sample with 300 mL of solvent for 16 h), blender extraction (25 g of sample with sodium sulfate and 3 X 150 mL of solvent), or sonication (25 g of sample with sodium sulfate and 3 X 150 mL of solvent) (21). Once the sample has been extracted, the solvent volume is reduced by using either rotary evaporation or a Kudema-Danish apparatus. 

Silica columns can tolerate relatively heavy loads of triglyceride and other nonpolar material. Such material is not strongly adsorbed and can easily be washed from the column with 25% diethyl ether in hexane after a series of analyses (83). Procedures for determining vitamins A and E have been devised in which the total lipid fraction of the food sample is extracted with a non-aqueous solvent, and any polar material that might be present is removed. An aliquot of the nonpolar lipid extract containing these vitamins is then injected into the liquid chromatograph without further purification. Direct injection of the lipid extract is possible because the lipoidal material is dissolved in a nonpolar solvent that is compatible with the predominantly nonpolar mobile phase. Procedures based on this technique are rapid and simple, because there is no need to saponify the sample. 

Caverly and Unwin [536] have described a rapid and sensitive technique for the determination of the residues of the fungicides furalaxyl and metalaxyl in soils. The soil sample is extracted with acetone in a Soxhlet apparatus and then the extract is analysed by gas chromatography using NP-selective detection. Recoveries are generally in excess of 80% with detection limits of 0.1 mg/kg. 

A 1-L aliquot, or any appropriate volume of accurately measured aqueous sample, is extracted with methylene chloride by liquid-liquid extraction. The extract is concentrated to 1 mL or any small volume on a Kudema-Danish setup. A florisil column cleanup may be necessary if the sample is dirty, or the presence of interferences is known or suspected or if A-nitrosodiphenylaminc is to be determined. 

Chlorinated dioxins and dibenzofurans are best analyzed by GC/MS techniques, using both low- and high-resolution mass spectrometry. A measured amount of sample is extracted with a suitable solvent. The solvent extract containing the analytes is concentrated down to a small volume and then subjected to cleanup for the removal of interferences. The extract is injected onto the GC... 

Ultraviolet Spectrophotometry Pentazocine can be determined in pentazocine hydrochloride tablets by a UV spectral method. The sample is extracted with sulfuric acid, basified, extracted with ether and back-extracted into 1 in 70 dilute sulfuric acid. The absorbance of the solution in 0.5 N H2SO1L is determined at 278 nm and compared to that of the standard preparation. A cation exchange column isolation method can be utilized to determine pentazocine in pentazocine lactate injection. Pentazocine is eluted from the column with methanol 6 N HC1 (1 1). Sample absorbance is read at 278 nm and compared to a pentazocine standard at approximately 120-w.g/ mL (3). 

---