Soxhlet extraction sludges

Stevens et al. [21] NMs and PCMs Digested sewage sludge United Kingdom - Soxhlet extraction with dichloromethane - Silica gel and gel-permeation chromatography - GC-MS... 

Maskarinec and Harvey [61] have described a method for the screening of solid wastes and sludges for organic compounds. The technique involves sequential extraction with acidic, basic and neutral media and the extracts are all analysed directly by gas chromatography with fused silica columns. Results achieved using the technique are discussed. The method is compared with traditional Soxhlet extraction. 

The infrared method that has been used most frequently (EPA 418.1) is appropriate only for water samples. A separatory funnel liquid-liquid extraction technique is used to extiact hydrocarbons from the water. A method (EPA 5520D) using a Soxhlet extraction technique is suitable for sludge. This extiaction is frequently used to adapt the method (EPA 418.1) to soil samples. An infrared-based supercritical fluid extraction method for diesel range contamination (EPA 3560) is available. 

The surrogate compounds were mono-, tetra-, octa-, deca- C-PCBs, dg-naphthalene, C-PCP and C-phenol. The soil samples were dried with Na2S04 (60 g) and then Soxhlet extracted with hexane acetone (9 1) for 16 h. The extract was dried with sodium sulfate, concentrated, and split. While one portion was held for other analyses, the other portion was placed on a 3% deactivated silica gel column and eluted with increasing solvent polarity systems [hexane, followed by methylene chloride hexane (1 1), and then methylene chloride acetone (95 5)]. The extracts were combined and reduced to 1 mL, split and two internal standards added (tetrafluorobiphenyl and di2 Chrysene). The extracts were chromatographed on a 15-m DB-5 fused silica capillary column and detected with flame ionization (FID). Sludge samples were extracted according to the EPA sludge protocol (2) developed at Midwest Research Institute. 

Other extraction methods described for PBDEs in the literature are basically batch and Soxhlet extractions. The various clean-up methods for biological, sediment, and sewage sludge samples differ, depending on other compounds of interest which are determined simultaneously [1],... 

The Soxhlet and distillation experiments were carried out at an elevated temperature. The Soxhlet apparatus consists of an Allyhn condenser, a Soxhlet extraction tube, an extraction thimble for holding the sludge sample, and a 250 mb flask. Approximately 200 mLof hexane was used the extraction medium. A constant water temperature of 348 K was used to vaporize the hexane in the flask. The hexane vapor was condensed, percolated through the sludge sample, and returned to the flask. This process was repeated for 4 hours. The hexane extract in the flask was subsequently analysed for PCB content. 

Sludge and sediment (oil and grease) Sample is dried Soxhlet extraction Gravimetric... 

Samples of 1 gram of dried primary and dried wasted sludge were extracted in a Soxhlet extraction apparatus with 150 ml methanol for 4 hours. An aliquot of the methanol extract (20 ml out of a total volume of 200 ml) was passed over a small anion exchange column. The column was washed with 10 ml methanol before elution of the LAS with 3 ml of acidic methanol. The effluent was diluted to about 70 ml with water and the pH was adjusted to a value of 7. The solution was then brought to a value of 100 ml and an aliquot of 25 ml was passed over an octadecyl reversed phase SPE column. The sample was further treated as described above. The samples were kept in a dry state until analysis by HPLC. Prior to HPLC, the residues were dissolved in an acetonitrile/water 70/30 solvent mixture. 

The solid phase extraction-HPLC method described by Matthijs and De Henau (1987) was used to determine LAS in sludge amended soil samples. The procedure was however adapted to use a Soxhlet extraction with methanol to give a more complete recovery of LAS from soil samples (generally >90% compared with 84% for the original reflux technique). A Soxhlet extraction time of 4 hours resulted in high recoveries of LAS from spiked soil samples An increase in extraction time up to 16 horns did not consistently improve the recoveries (Table 2). 

Soxhlet extraction Semi-volatile and non-volatile organics from soils, relatively dry sludges and solid wastes Considered a rugged extraction method because it has very few variables that can adversely affect extraction recovery... 

Automated Soxhlet extraction Polychlorinated biphenyls, organochlorine pesticides and semi-volatiles from soils, relatively dry sludges and solid wastes Allows equivalent extraction efficiency to Soxhlet extraction in 2 h... 

FMAE was compared with pressurized-liquid, Soxhlet, and ultrasonic extraction for the analysis of sewage sludges. The optimum conditions for FMAE were determined to be 30 W, for 10 min in 30 ml of acetone HEX (1 1, v/v). Recoveries for certified reference marine sediment, CRM 1941a, were 75, 61, and 56% for FLA, B[b]F, and B[a]P, respectively. Activated copper bars were added to samples to remove sulfur. Mean recovery by FMAE was 70% compared to traditional Soxhlet extraction. FMAE recoveries exceeded those for ultrasonic extraction but better results were obtained by pressurized-liquid extraction (PEE) with the best results obtained by Soxhlet extraction. All extracts required column cleanup, concentration, and solvent exchange for RP-HPLC-FLD analysis. 

A comparison of sonication and Soxhlet extraction methods was made by Lopez-Avila et al. ° EPA methods 3550 and 3540 were used to extract some phthalate esters from solid samples, such as sandy loam soil and municipal sludge. The mean recoveries for the method 3540 (Soxhlet extraction) were, in general, similar to those obtained for method 3550 (ultrasonic extraction) however, its RSD was much higher. 

Typical solvents in Soxhlet extraction of PBBs, PBDEs, PBDFs, and PBDDs from soil, sediment, and sewage sludge samples have been hexane, toluene, and hexane acetone mixtures. 17,68,69 rpjjg extraction time has varied from 4 to 24 h. Before the extraction, the sample usually is mixed with anhydrous sodium sulphate or other drying agent. 

Neither soxhlet extraction nor steam distillation is designed to isolate volatiles from solids for subsequent determination. Slurrying the solids in water and then applying the PaT procedure has been reported A vacuum extractor with cryogenic concentration has been applied to both fish and sediment samples for determination of volatile priority pollutants PaT, LLE, and static headspace techniques have all been applied to the determination of volatiles in sludges from municipal waste treatment plants... 

A soil/sediment or contaminated sludge with a very high solids content can be extracted via Soxhlet extraction techniques or more conveniently via ultrasonic probe sonication into a mixture of TCTFE and a carefully weighed amount of soil/sediment/sludge. 

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