Freon 113 extraction

Day 4 for cadmium, copper, iron, lead, and zinc by Freon extraction and flameless atomic absorptiometry. 

Mercury was determined after suitable digestion by the cold vapour atomic absorption method [40]. Lead was determined after digestion by a stable isotope dilution technique [41-43]. Copper, lead, cadmium, nickel, and cobalt were determined by differential pulse polarography following concentration by Chelex 100 ion-exchange resin [44,45], and also by the Freon TF extraction technique [46]. Manganese was determined by flameless atomic absorption spectrometry (FAA). 

The following analytical techniques seem to be adequate for the concentrations under consideration copper and nickel by Freon extraction and FAA cold vapour atomic absorption spectrometry, cobalt by Chelex extraction and differential pulse polarography, mercury by cold vapour atomic absorption absorptiometry, lead by isotope dilution plus clean room manipulation and mass spectrometry. These techniques may be used to detect changes in the above elements for storage tests Cu at 8 nmol/kg, Ni at 5 nmol/kg, Co at 0.5 nmol/kg, Hg at 0.1 nmol/kg, and Pb at 0.7 nmol/kg. 

Statham [448] has optimised a procedure based on chelation with ammonium dithiocarbamate and diethylammonium diethyldithiocarbamate for the preconcentration and separation of dissolved manganese from seawater prior to determination by graphite furnace atomic absorption spectrometry. Freon TF was chosen as solvent because it appears to be much less toxic than other commonly used chlorinated solvents, it is virtually odourless, has a very low solubility in seawater, gives a rapid and complete phase separation, and is readily purified. The concentrations of analyte in the back-extracts are determined by graphite furnace atomic absorption spectrometry. This procedure concentrates the trace metals in the seawater by a factor of 67.3. 

Commonly used methods for the determination of petroleum hydrocarbon contamination in soil are modifications of Environmental Protection Agency method 418.1, which use sonication or a Soxhlet apparatus for analyte extraction and either infrared spectrometry [5] or gas chromatography with flame ionization detection [6-7] for extract analysis. Regardless of the analytical method following the extraction, both modifications use Freon-113, which has been implicated as a cause of ozone depletion. Therefore, alternative methods are being sought for the determination of hydrocarbon contamination in environmental samples that reduce the need for this halogenated solvent. 

This method (EPA 1664) is a liquid-liquid extraction gravimetric procedure that employs n-hexane as the extraction solvent, in place of 1,1,2-trichloroethane (CFC-113) and/or 1,2,2-trifluoroethane (Freon-113), for determination of the conventional pollutant oil and grease. Because the nature and amount of material determined are defined by the solvent and by the details of the method used for extraction, oil and grease method-defined analytes are used. The method may be modified to reduce interferences and take advantage of advances in instrumentation provided that all method equivalency and performance criteria are met. However, n-hexane is a poor solvent for high-molecular-weight petroleum constituents (Speight, 1999, 2001). Thus, the method will produce erroneous data for samples contaminated with heavy oils. 

Freon-extractable material is reported as total organic material from which polar components may be removed by treatment with silica gel, and the material remaining, as determined by infrared (IR) spectrometry, is defined as total recoverable petroleum hydrocarbons (TRPHs, or total petroleum hydrocarbons-IR). A number of modifications of these methods exist, but one particular method (EPA 418.1 see also EPA 8000 and 8100) has been one of the most widely used for the determination of total petroleum hydrocarbons in soils. Many states use or permit the use of this method (EPA 418.1) for identification of petroleum products and during remediation of sites. This method is subject to limitations, such as interlaboratory variations and inherent inaccuracies. In addition, methods that use Preon-113 as the extraction solvent are being phased out and the method is being replaced by a more recent method (EPA 1664) in which n-hexane is used as the solvent and the n-hexane extractable material (HEM) is treated with silica gel to yield the total petroleum hydrocarbons. 

In interpreting the data for the total petroleum hydrocarbons in a sample, the amount of moisture cannot be ignored because moistme blocks the extraction of petroleum hydrocarbons by another hydrocarbon (Freon). Potentially, sulfm or phthalate compounds also interfere with total petroleum hydrocarbons analyses. This is similar to the problem of strong interferences from phthalate esters or chlorinated solvents when one is using electron capture methods to look for chlorinated compounds such as polycholorbiphenyls or pesticides. 

The ASTM method for total petroleum hydrocarbons (ASTM book) is similar to the standard EPA method (EPA 418.1) and calls for extraction with Freon. The estimated variability of the test method is quesUonable and may leave room for serious errors in the calculation of total petroleum hydrocarbons. 

FIGURE 3 2 Solvent extraction efficiencies (EF) as functions of dielectric constants (D), solubility parameters (6), and polarity parameters (P and E -). Solvents studied silicon tetrachloride, carbon disulfide, n pentane. Freon 113, cyclopentane, n-hexane, carbon tetradiloride, diethylether, cyclohexane, isooctane, benzene (reference, EF 100), toluene, trichloroethylene, diethylamine, chloroform, triethylamine, methylene, chloride, tetra-hydrofuran, l,4 dioxane, pyridine, 2 propanol, acetone, ethanol, methanol, dimethyl sulfoxide, and water. Reprinted with permission from Grosjean. ... 

Freon 11) using a liquid-liquid extractor at 28-30 °C. Next, the extract was concen-... 

The extraction technique can play an important role in the recovery of volatiles, resulting in different profiles of volatiles for the same variety [67]. The direct extraction of Cucumis melo L. var. cantaloupensis with Freon 11 under low temperature was capable of recovering compounds never found before in melons [26]. The authors attributed this to the non-destructive extraction at low temperatures and the very efficient capillary chromatographic system used for the analysis. 

Extraction using a supercritical fluid (CO2, N20 or CHC1F2 Freon-22) is a well-known process in the food industry (cf. 6.1). Extractors used for analytical purposes operate on the same principle. They incorporate a highly resistant tubular container into which the sample is placed (in solid or semi-solid form) with the supercritical fluid. Two modes of operation are employed ... 

Seventy-gram aliquots of the milled sample were added to a glass extraction thimble for Soxhlet extraction. The milled sample was extracted sequentially for 2 h with 300-mL portions of four different solvents Freon 113, methylene chloride, acetone, and methanol. Following extraction, each solvent extract was dried and then concentrated as described earlier by using a 30 °C evaporation temperature for concentrating the Freon 113 and methylene chloride extracts and a 50 °C evaporation temperature for concentrating the other solvents. 

Figure 5.11. Variation of the composition of the catalytic phase as a function of the SbF5 concentration in the n-pentane isomerization in HF—SbF5.90 T — 15°C, pm = 5 bars, volume of the catalytic phase = 57 ml. , Mass of C5+, o, mass of C5H (Freon-113 extract) a, % weight of Cs+ + C5H (methylcyclopentane extract).

Regardless of the analytical method used following the extraction, both modifications use Freon-113, which has been implicated as a cause of ozone depletion. Therefore, alternative methods are being sought for the determination of hydrocarbon contamination in environmental samples that reduce the need for this halogenated solvent. 

It has been shown [73] that carbon dioxide is less efficient as an extractant for the heavier polycyclic aromatic hydrocarbons than nitrous oxide and Freon-22. This deficiency can be remedied by using a mixture of water, methanol and methylene dichloride [73]. 

Freon or dichloromethane extraction gives precise and accurate estimates of oil and grease contents of soil [104]. Thermal desorption mass spectrometry has been used as a rapid method for the determination of oil in soil. The analysis takes only 20 minutes [33]. 

A soil sample was soxhlet extracted with freon and the extract was analyzed for petroleum hydrocarbons (PHC) by IR spectrometry. The concentration of PHC in the sample was found to be 285 mg/kg. A 40 g portion of this sample was spiked with 2 mL of 1000 mg/L PHC standard. The concentration of the spiked sample was measured as 326 mg/kg. Determine the accuracy of the analysis as the percent recovery of the amount spiked. 

Total petroleum hydrocarbons — Freon extraction followed by IR spectroscopy or extraction with methanol or methylene chloride and determination by GC-F1D. 

The term oil and grease refers to a broad class of organic substances recovered from the sample matrices by extraction with an appropriate solvent. Such recovery, therefore, is characteristic of certain physical properties of the compounds, primarily the volatility of the compounds and their solubility in the extraction solvent. The solvent must be immiscible in water and volatile, as well as readily distilled on a water bath. Many solvents or mixed-solvent systems should be suitable for the extraction of oil and grease in aqueous and nonaqueous samples. These include petroleum ether, w-hexanc, methylene chloride, methyl ter/-butyl ether, and trichlorotrifhroroethan (freon). These solvents are listed in Table 1. 

Among these solvents, freon has been extensively used in the oil and grease extraction. However, because of its ozone depletion action, the manufacture and use of Freon is currently being curtailed, and other solvents are now being used. 

In recent years, many of the technologically outdated methods of 40 CFR Part 136 have been upgraded to incorporate the latest advances in instrumental analysis. For example, capillary chromatographic columns with superior compound resolution replaced obsolete packed columns in gas chromatography (GC) and GC/MS analytical methods Freon 113, a chlorofluorocarbon harmful to the environment, was phased out as the extraction solvent in oil and grease analysis and replaced with hexane in Method 1664 (EPA, 1999b). 

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