Residuals isolation

Amalgamated zinc residues isolated from Clemmensen reduction of an alkyl aryl ketone in glacial acetic acid were pyrophoric, and had to be immediately dumped into water after filtration to prevent ignition. 

Solvent extraction of the total lipid extracts from ceramic sherds and charred surface residues Isolation of DAGs and TAGs on silica solid phase cartridges Formation of lithiated adducts from the TAG fraction by addition of 2% lithium chloride in methanol... 

Fig. 2.1.6. On-line derivatisation and the selected characteristic mass chromatograms of butylated residues isolated from river water polluted by an industrial effluent. Reproduced with permission from Ref. [119]. 1999 by Elsevier.

Figure 13. Structures of chloroform-soluble residues isolated from peanut roots treated with [ C] PCNB. Chloroform-soluble accounted for 59.2% of the in peanut roots.

A reactor charged with 2-benzyl-l-(4-fluorophenyl)-2-dimethylamino-l-butanone (0.15 mol) and ethanolamine (1.05 mol) were dissolved in 400 ml dimethylacetamide and then treated with potassium carbonate (0.3 mol) and then heated to 140°C for 16 hours, cooled, and diluted with water. The aqueous phase was extracted several times with ethyl acetate and combined extracts washed with water and dried using magnesium sulfate. The mixture was then concentrated and the residue isolated as a yellowish-brown oil. It was purified using chromatography on silica gel with petroleum ether/ethyl acetate 2 1 to 1 1, respectively. The product was isolated as a yellow solid after recrystallization from ethyl acetate/hexane having an mp = 109-111°C. 

In the liquid chromatographic methods, separation of nitrofurans is generally carried out on nonpolar reversed-phase columns, the preferred sorbent being octadecyl bonded silica (Tabic 29.5). Polar columns containing cyanopropyl-based sorbents (164, 165) have also been used for die isocratic separation of nitrofuran residues isolated from edible animal products. A literature survey shows that there exists a clear preference for acidic mobile phases containing acetonitrile as the organic modifier (Fig. 29.5.1). 

G. Dubreucq, B. Domon, and B. Fournet, Structure determination of a novel uronic acid residue isolated from the polysaccharide produced by a bacterium originated from deep sea hydrothermal vents, CarbohydrRes., 290 (1996) 175-181. 

Cohen, E., R.J. Maxwell, and D.J. Donoghue. 1999. Automated multi-residue isolation of fluoroquinolone antimicrobials from fortified and incurred chicken liver using on-line microdialysis and high-performance liquid chromatography with programmable fluorescence detection. J. Chromatogr. B 724 137-145. 

M. J. M. Wells, Off-line multistage extraction chromatography for ultra-selective herbicide residue isolation, in Proceedings of the 3rd Annual International Symposium on Sample Preparation and Isolation Using Bonded Silicas, Analytichem International, Harbor City, CA, 1986, pp. 117-135. 

In addition to the foregoing analytical constraints, there is a fundamental consideration (often overlooked) which further restricts the range of applicability of the method. The designation of the residue isolated by the Klason procedure... 

A solution of trifluoroacetoamidine (37.8 mmol) in 20 ml methyl alcohol was treated with 4-methoxyphenylhydrazine hydrochloride (27 mmol) followed by 3.77 ml triethylamine, then stirred 6 hours at ambient temperature, and concentrated. The residue was treated with 20 ml water and 50 ml EtOAc/THF, 9 1, and the organic layer isolated. The aqueous layer was re-extracted with 50 ml EtOAc/THF, 9 1, and combined extracts were washed with water and brine. The solution was then dried using MgS04, concentrated, and 108.2% yield residue isolated and used without further purification. 

The Step 8 product mixture (22 mmol) was dissolved in 100 ml methyl alcohol, then treated with 50 ml 1M NaOH, then refluxed 2 hours, and concentrated. The concentrate was acidified with 100 ml 1M HC1 and a solid residue isolated. The solid was rinsed three times with 20 ml water, dried, and 7.9 g product isolated. RP-HPLC Method 10-95% B in 8 minutes. 

Boron tribromide (1.56 mmol) was slowly added to a solution of the Step 4 product (1.2 mmol) dissolved in 8 ml CH2C12 at -10°C and the mixture stirred 90 minutes. It was quenched with 30 ml methyl alcohol, then warmed to ambient temperature, and stirred an additional 2 hours. The mixture was diluted with CH2C12 and washed with water, 1M HC1, saturated NaHC03 solution, and saturated brine. The solution was dried, then concentrated, and a solid orange residue isolated. The residue was... 

A solution of the Step 3 product (7.0 g) was treated with 10% palladium on carbon (800 mg) and 100 ml methyl alcohol, then hydrogenated 2 hours under 1 atm hydrogen, then filtered through diatomaceous earth. The solution was concentrated and the residue partitioned between CH2C12 and dilute HC1. The aqueous phase was further extracted twice with CH2C12 and these extracts were discarded. The aqueous layer was basified with 1 M NaOH, then re-extracted twice with CH2C12, dried with Na2S04, concentrated, and the residue isolated. The residue was used directly in the next step without additional purification. 

The Step 6 product (13.84 mmol) in 70.0 ml CHC13 cooled to approximately 0°C was treated dropwise with 6.00 ml oxalyl chloride, then stirred 5 minutes at 0°C, and an additional 2 hours at ambient temperature. The mixture was concentrated and an yellow residue isolated. The residue was dissolved in 70.0 ml CHC13, then treated with 1.70 ml pyridine and 2-methyl-2-propanol (36.60 mmol). The solution... 

Palladium on carbon (10%, 0.10g) was added to a solution of the Step 4 product (2.0 mmol) in methyl alcohol and stirred 18 hours at room temperature under a hydrogen atmosphere. The mixture was filtered through a filter aid, concentrated, and the residue isolated in 96% yield. The residue was converted into the fumaric acid salt and crystallized from methyl alcohol/diethyl ether and the product isolated as a colorless solid, mp = 150-152°C. 

Methyl 3,3-diphenyl-2,3-epoxypropionate (27.5 mmol) and 2-(3,4-dimethoxy-phenyl) ethanol (30.2 mmol) were dissolved in 20 ml CH2CI2 at ambient temperature and 5 drops boron trifluoride etherate added. The mixture was stirred for 2 hours, concentrated, and the residue isolated in 89% yield and used without further purification. 

Bromine (9.62 g) dissolved in 30 ml chloroform was added to acetovanillone (10.0 g) dissolved in 150 ml chloroform at 0 to — 5 °C, the mixture stirred 4 hours, and the residue isolated. The residue was washed with water, the organic layer dried, concentrated, tritrated with diethyl ether, and the product isolated, mp = 148-152°C. 

Hydrolyze the amide by refluxing 250 mg with 2.5 mL of 20% sodium hydroxide for 20 min. Isolate the primary or secondary amine produced, by extraction into ether, and identify as described under Group 1(d). Liberate the acid by acidification of the residue, isolate by filtration or extraction, and characterize by bp or mp and the mp of an appropriate derivative. 

This report presents a discussion of recent applications of combined gas chromatography-mass spectrometry to analysis of pesticide residues isolated from human, animal, and environmental media. Emphasis will be placed on analytical techniques, related gas chromatographic column technology, and analysis of fragmentation pathways pertinent to the identification of pesticide residues. 

Figure 8. Total ion current chromatograms of extracts containing organo-clMrine pesticide residues isolated from adipose tissue (A) fraction 1 and...

Table I. Gas Chromatographic Peak Identities and Characteristic Mass Spectral Fragments and Intensities of Some Organochlorine Pesticide Residues Isolated From Human Adipose Tissue...

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