Multiple extraction procedure

Physical and chemical tests of the final product may need to address two concerns (1) whether the solidified waste exhibits any RCRA defined toxicity characteristics or could be delisted and (2) the potential long term fate of treated materials in the disposal environment. Three tests are available which address the first concern. These are the Extraction Procedure (EP Tox) (40 CFR 261, Appendix II, 1980) and the Toxicity Characteristic Leaching Procedure (TCLP) (40 CFR 261, Appendix II, 1986), and the Multiple Extraction Procedure Test (40 CFR 261, Appendix II, January 1989). It is important to note that these tests are not indicators of expected leachate quality but of potentials. A solidified product which cannot pass the appropriate test (EP Tox or TCLP) would be subject to classification as a hazardous waste. 

Federal Register - Multiple Extraction Procedure Test, Revised 40 CFR 261, Appendix II, January 1989. 

Multiple equilibrium model, 24 131 Multiple extraction procedure (MEP), 25 869... 

In order to determine the long term stability, a Multiple Extraction Procedure (MEP) was conducted on one of the most solidified samples according to USEPA SW-846, method 1320 for all eight metals as above. 8 >... 

In order to test the long term stability of the CHEMFIX process, the Multiple Extraction Procedure (MEP) was performed on the soil samples treated with the optimal, reagent ratio B. These results are illustrated in Table 6. 

Figure 11.4 Schematic representation of the multiple extraction procedure with the antibody-conjugated silica nanoparticles doped with magnetic nanoparticles (MNP) being added and extracted stepwise and the corresponding antibody-conjugated silica nanoparticles doped with fluorescent dyes (FNP) being added post-magnetic extraction of cell samples.40 (Reprinted with permission from J. E. Smith et al., Anal. Chem., 2007, 79, 3075-3082. Copyright 2007 American Chemical Society.) (See color insert.)...

The discussion on remaining sources of uncertainty which have arisen recently are the addition of an uncertainty component to the final certified value due to the precision of the recovery factor used to correct for extraction efficiency and purification [9] and somewhat the correction to dry mass. This debate is far from closed. It may be considered that the uncertainty of the recovery factor is reflected in the variability of the pretreatment procedure of the certification measurements. This is true if this uncertainty of the recovery factor as determined by e.g. spiking or multiple extraction procedures shows reproducibility close to the certification measurements. If not, as discussed above, the... 

The method procedures are very time-efficient by always using a well defined portion of the extracts, thus avoiding multiple extractions, time-consuming rinses and overloading of the chromatographic cleanup systems with co-extracted sample matrix. 

Once several target methods employing, e.g., LC/MS/MS techniques have been combined, a multi-residue method will evolve which includes the DEC S19 extraction procedures in combination with the generally applicable GPC cleanup and requires automatic multiple injections to circumvent the limitations of the limited HPLC peak capacity and the target-specific MS/MS methods. 

The extraction efficiencies using a blender and a shaker were compared and both methods gave similar results. A corn sample treated with radiolabeled carfentrazone-ethyl and collected from a metabolism study was used for comparison. Multiple samples can be extracted simultaneously if extraction is performed by shaking. In addition, since the extraction procedures in the residue study closely followed the extraction scheme in the metabolism study, the resulting extraction efficiencies from both studies were almost identical. 

IEC continues to have numerous applications to the detection and quantification of various inorganic ions.1 1 This is particularly true in water analysis.5-14 Inorganic ions in a variety of other sample types, such as food and beverages,1518 rocks,19-23 biological fluids, (blood, urine, etc.),24-31 pharmaceutical substances,32 33 concentrated acids,34 alcohols,35 and cleanroom air36 have also been analyzed by IEC. IEC has also been employed in isotopic separation of ions,37 including the production of radioisotopes for therapeutic purposes.3839 Typical IEC sample matrices are complex, and may contain substances that interfere with measurement of the ion(s) of interest. The low detection limits required for many IEC separations demand simple extraction procedures and small volumes to avoid over-dilution. Careful choice and manipulation of the eluent(s) may be needed to achieve the desired specificity, especially when multiple ions are to be determined in a single sample. 

The most common (off-line) sample preparation procedures after protein precipitation are solid phase extraction and liquid-liquid extraction. Multiple vendors and available chemistries utilize 96-well plates for solid phase extraction systems and liquid-liquid extraction procedures. Both extraction process can prepare samples for HPLC/MS/MS assay. Jemal et al.110 compared liquid-liquid extraction in a 96-well plate to semi-automated solid phase extraction in a 96-well plate for a carboxylic acid containing analyte in a human plasma matrix and reported that both clean-up procedures worked well. Yang et al.111 112 described two validated methods for compounds in plasma using semi-automated 96-well plate solid phase extraction procedures. Zimmer et al.113 compared solid phase extraction and liquid-liquid extraction to a turbulent flow chromatography clean-up for two test compounds in plasma all three clean-up approaches led to HPLC/MS/MS assays that met GLP requirements. 

Tan [71] devised a rapid simple sample preparation technique for analysing polyaromatic hydrocarbons in sediments. Polyaromatic hydrocarbons are removed from the sediment by ultrasonic extraction and isolated by solvent partition and silica gel column chromatography. The sulphur removal step is combined into the ultrasonic extraction procedure. Identification of polyaromatic hydrocarbon is carried by gas chromatography alone and in conjunction with mass spectrometry. Quantitative determination is achieved by addition of known amounts of standard compounds using flame ionization and multiple ion detectors. 

The most recent modification of the NBD-Cl method involves a further improvement in its qualitative support (616). It involves the infusion of the extract employed for thin-layer chromatography via an electrospray interface into a mass spectrometer operating in the multiple-stage mass spectrometry mode, thus allowing confirmation of suspect results. The cleanup of the thyroid gland samples was also performed with a selective extraction procedure, based on the specific complex formation of the thiouracil, methylthiouracil, propylthiouracil and phenylthiouracil, tapazole, and mercaptobenzimidazole residues with mercury ions bound in a Dowex 1-X2 affinity column. 

The cleanup procedure used was discussed in the section entitled Resin Elution Concentration. The extraction procedure was not the optimum procedure that would result from the observations. The data indicated that a base extraction at pH >12 and a base-to-solvent ratio of 15 1 with multiple extraction steps were needed to maximize removal of the matrix interferences. However, the extraction efficiency must be balanced against minimal sample destruction and operational ease. 

Model Fitting to Mixing-Cell Data Multiple-site kinetic models have been used to describe pesticide and herbicide movement in soils (15,16,17), cesium migration in columns (18), and strontium migration in a sandy aquifer over a twenty-year time period (1L). The results of the selective extraction procedures in all experiments discussed here suggest that a multi-site model should provide a better fit of the data than a single-site model. This hypothesis is supported by the variances in Table I, with the possible exception of selenium. 

Chemometrics can also be used to overcome some of the intrinsic deficiencies of sequential extraction, such as non-specificity. Barona and Romero (1996a) used principal components analysis (PCA) to establish relationships between the amounts of metals released at each stage of a sequential extraction procedure and bulk soil properties, and demonstrated that carbonates played a dominant role in governing metal partitioning in the soil studied. The same workers employed multiple regression analysis to study soil remediation (see Section 10.11.1.1). Zufiaurre et al. (1998) also used PCA to confirm their interpretation of phase association and hence potential bioavailability of heavy metals in sewage sludge. 

With the need to provide PCR-amplifiable DNA, multiple approaches for incorporation of the extraction protocol onto microchips were examined. Recent development includes the implementation of a solid-phase extraction of DNA on a microchip [49]. The extraction procedure utilized was based on adsorption of the DNA onto bare silica. The silica beads were immobilized into the channel using a sol-gel network. This method made possible the extraction and elution of DNA in a pressure-driven system. 

Kolb [203] describes a stepwise gas-extraction procedure called multiple headspace extraction (MHE). Using this method, Kolb found that the determination can be performed with only two extractions. The volume of the sample was compensated for by adding a similar volume of an inert material such as glass beads. Ethylene oxide in surgical silk sutures was determined by this procedure. The extrapolated total area (four steps) was nearly identical to the total area value obtained using the two-step MHE process, 184 versus 183, respectively. 

Answer B (Amoxicillin). The multiple extractions can lead to bacteremia while the mitral valve stenosis and cardiac insufficiency place him at risk for developing endocarditis. The present American Heart Association guidelines indicate amoxicillin (3 gm 1 hour prior to procedure and 1.5 gm 6 hours after original dose.) Vancomycin would only be appropriate if the patient was allergic to penicillins. Tetracycline and cotrimoxazole are bacteriostatic and not effective against the viridans group of Streptococci, the usual causative organism. Imipenem is also inappropriate since its spectrum is too broad. 

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