Extraction hydrocarbons analyses

The data obtained by the analysis have become key remediation criteria and it is essential that the environmental analyst (and others who may use the data) be knowledgeable about the various analytical methods. It is also important to know that minor method deviations may be found from region to region. For example, in terms of nomenclature, itself a complex and often ill-defined area of petroleum science (Chapter 1) (Speight, 1999), the analytical methods may refer to total petroleum hydrocarbons as mineral oil, hydrocarbon oil, extractable hydrocarbon, and oil and grease. 

The quality of the analysis of polynuclear aromatic hydrocarbons is often dependent on the extraction efficiency. Clay and other cohesive soils lower the ability to extract polynuclear aromatic hydrocarbons. Another potential problem with polynuclear aromatic hydrocarbon analysis is that the test kits may have different responses for different compounds. 

Lee, F., and D. Schuetzle, Sampling, Extraction, and Analysis of Polycyclic Aromatic Hydrocarbons from Internal Combustion Engines, in Handbook of Polycyclic Aromatic Hydrocarbons (A. Bjprseth, Ed.), pp. 27-94, Dekker, New York, 1983. 

Chemical Analysis. Preliminary attempts to extract hydrocarbon components from the anthraxolite by means of toluene were unsuccessful, even though several percent of nitrogen, oxygen, and hydrogen are known to be present. Table III lists the elemental analysis of anthraxolite blended from five different nodules. Results were reproducible, and the deviation from 100% is thus thought to represent some systematic error. 

Volatile hydrocarbons Analysis of petroleum ether extract of water Electron capture [196]... 

It is interesting that a bituminous coal (Sample 4) gave organic acids qualitatively similar to those of lignite coal see Figure Id). Major identified compounds were p-hydroxybenzoic acid and two isomers of hydroxybenzenedicarboxylic acid, benzene di- and tricarboxylic acids. No ortho or meta isomer of hydroxybenzoic acid was detected. We have found that solvent-extractable hydrocarbons obtained from this raw coal consist mainly of n-alkanes (Cjj to 3 ). This is quite different from other results which showed that aromatic hydrocarbons were the major solvent-extractable material of several bituminous and anthracite coals (21). Indeed, petrographic analysis shows that this coal has a high content of sporinite (14.3 wt %) and a low content of vitrinite (30.2 wt %) (33). 

Hydrocarbon Analysis. Sediment samples were thawed and mixed to provide a homogeneous sample. Approximately 150 g wet weight was placed in a Soxhlet extraction apparatus and saponified-extracted with benzene /0.5 N KOH-methanol (50/50) (ca. 250 ml total) for 24 hours, or until the extraction solution was clear (6,11,12). An internal standard consisting of ca. 50 ug each of 5,a-androstane and o-terphenyl was added prior to extraction to provide assurance of extraction efficiency, separation of saturated and unsaturated fractions and to provide a standard reference for the gas chromatographic data system. Methylstearate (the methyl ester of stearic acid) was added to select samples to verify saponification efficiency. 

Barkenbus, B. D., C. S. Mac Dougall, W. H. Griest, and J. E. Caton (1983). Methology for the extraction and analysis of hydrocarbons and carboxylic acids in atmospheric particulate matter. Atmos. Environ. 17, 1537-1543. 

The hydrocarbons were extracted by passing 100 mL diethyl ether through the columns over a period of about 15 min. The ether extracts were dried with anhydrous sodium sulfate overnight, and then they were evaporated in a conical tube under a stream of dry nitrogen to 2 mL without external heating. One mL hexane was added, and the sample evaporated to 1 mL. The extracted hydrocarbons were separated into saturate and aromatic types using a modification of a procedure described by Warner (19) and employed in these laboratories for sediment analysis (20). Fifteen grams of Davison silica gel (100-200 mesh) in a Chroma-flex column were washed with 30 mL methylene chloride, then 40 mL hexane. The 1-mL sample was first eluted with 40 mL hexane to obtain the saturate fraction, and then with 86 mL 20% methylene chloride in hexane to obtain the aromatic fraction. Each fraction was evaporated to 1 mL then 1 mL of internal standard was added and the sample reevaporated to 1 mL and analyzed by GC. A 20-/i,g/mL solution of 2,6,10-trimethyldodecane in hexane was used for the saturate internal standard and a solution of 20/ig/mL hexamethyl-benzene was used for the aromatics analysis. 

The methods for hydrocarbon extraction and analysis are similar to those previously described (16,17,18). Sediment samples were soxhlet-extracted in methanol benzene (1 1) for 48 hr. Copper wool was placed beneath the thimble to facilitate drainage and removal of elemental sulfur. Lipids were partitioned into a pentane-benzene layer (3 combined washes) followed by a wash of saturated NaCl solution, dried overnight with Na2S04, and vacuum-evaporated to dryness. The extract was redissolved in pentane and fractionated by column chromatography on alumina over silica gel (both 5% deactivated with H20). Aliphatics were eluted with three column volumes of pentane, followed by three column volumes of benzene to elute aromatics. Only analyses of the pentane fractions are reported here. 

EXTRACTION AND ANALYSIS OF HYDROCARBONS FROM SEA WATER AND SEDIMENTS... 

Sampling, filtration, extraction and analysis techniques used Location Hydrocarbons studied Range of concentrations and general comments Reference... 

Saim N, Dean JR, Abdullah MP, Zakaria Z (1998) An experimental design reproach Iot the determination of polycyclic aromatic hydrocarbons from highly contaminated soil using accelerated solvent extraction. Anal Chem 70 420-424 Shen J, Shao X (2005) A comparison of accelerated solvent extraction, Soxhiet extraction, and ultrasonic-assisted extraction for analysis of terpenoids and sterols in tobacco. Anal Bioanal Chem 383 1003-1008... 

The solvents used for the extraction and analysis of carotenoids should be carefully purified before use to remove impurities. In most cases this means redistillation of the solvent. In the case of diethyl ether, the removal of peroxides is also important. Petroleum ether used for the extraction and chromatography of carotenoids should be passed through silica gel to remove sulfur compounds and unsaturated hydrocarbons. The methodology used in the isolation and identification of carotenoids has been covered in a recent review (Davies, (1976). A brief introduction to these techniques is presented below. 

Hazard, S.A. Brown, J.L. and Betz, W.R. Extraction and analysis of hydrocarbons associated with leaking underground storage tanks. LC-GC 1991, 9, 40-42. 

Analytical Procedures. Standard methods for analysis of food-grade adipic acid are described ia the Food Chemicals Codex (see Refs, ia Table 8). Classical methods are used for assay (titration), trace metals (As, heavy metals as Pb), and total ash. Water is determined by Kad-Fisher titration of a methanol solution of the acid. Determination of color ia methanol solution (APHA, Hazen equivalent, max. 10), as well as iron and other metals, are also described elsewhere (175). Other analyses frequendy are required for resia-grade acid. For example, hydrolyzable nitrogen (NH, amides, nitriles, etc) is determined by distillation of ammonia from an alkaline solution. Reducible nitrogen (nitrates and nitroorganics) may then be determined by adding DeVarda s alloy and continuing the distillation. Hydrocarbon oil contaminants may be determined by ir analysis of halocarbon extracts of alkaline solutions of the acid. 

Pesticides. Chlorinated hydrocarbon pesticides (qv) are often found in feed or water consumed by cows (19,20) subsequently, they may appear in the milk, where they are not permitted. Tests for pesticides are seldom carried out in the dairy plant, but are most often done in regulatory or private specialized laboratories. Examining milk for insecticide residues involves extraction of fat, because the insecticide is contained in the fat, partitioning with acetonitrile, cleanup (FlorisH [26686-77-1] column) and concentration, saponification if necessary, and determination by means of paper, thin-layer, microcoulometric gas, or electron capture gas chromatography (see Trace and residue analysis). 

Oakmoss. Extracts of oakmoss are extensively used in perfumery to furnisli parts of the notes of the fougnre or chypre type. The first step in the preparation of an oakmoss extract is treatment of the Hchen Evemiaprunastri (L.) Ach., collected from oak trees mainly in southern and central Europe, with a hydrocarbon solvent to obtain a concrete. The concrete is then further processed by solvent extraction or distillation to more usable products, of which absolutes are the most versatile for perfumery use. A definitive analysis of oakmoss volatiles was performed in 1975 (52). The principal constituents of a Yugoslav oakmoss are shown in Table 15 (53). A number of phenoHc compounds are responsible for the total odor impression. Of these, methyl P-orcinol carboxylate is the most characteristic of oakmoss. 

The heavy metal salts, ia contrast to the alkah metal salts, have lower melting points and are more soluble ia organic solvents, eg, methylene chloride, chloroform, tetrahydrofiiran, and benzene. They are slightly soluble ia water, alcohol, ahphatic hydrocarbons, and ethyl ether (18). Their thermal decompositions have been extensively studied by dta and tga (thermal gravimetric analysis) methods. They decompose to the metal sulfides and gaseous products, which are primarily carbonyl sulfide and carbon disulfide ia varying ratios. In some cases, the dialkyl xanthate forms. Solvent extraction studies of a large number of elements as their xanthate salts have been reported (19). 

---