Volume, extractable

Total volume to be extracted = Volume of vessel x f (f at the working vacuum from the above chart) Total volume to be extracted... 

Extraction of water with methylene chloride, removal of water from extract, volume reduction to 5 mL after solvent exchange to methyl-f-butyl ether... 

Investigate the influence of the relative reactor and extraction volumes. 

The resulting concentration value in micrograms per liter represents the concentration of the analyte in the injected sample. Using the concentration of analyte in the injected sample, the final extract volume, and the volume of water extracted, the concentration of analyte present in the water specimen can be calculated. The concentration (qgL ) of herbicide in the water specimen is calculated by multiplying the analyte concentration (qgL ) by the final volume (mL) and dividing by the water specimen volume (mL) ... 

Amount of sample injected (mg) initial aliquot weight (mg) final sample extract volume ( xL)... 

Vga = aliquot portion of the extract volume injected on to the CPC column (5 mL) Vge = Anal volume of CPC eluate after concentration (e.g., 5 mL)... 

FV = final extract volume (1.0 or 1.2 mL) of the pre-analysis diluted sample AV = aliquot volume of final extract used in pre-analysis dilution (0.2 or 0.6 mL) FX = final extract volume (10.0 mL)... 

Study the effect of the extraction stage on reactor performance by varying the magnitudes of the the mass transfer coefficient Ka, the equilibrium distribution ratio m, the recycle ratio R, the relative reactor and extraction volumes and solvent flowrate. 

Calculation of N. The composited samples are formed by combining a specified fixed mass of tissue (e.g., 1 gram) from each specimen. The entire composited sample is then extracted down to a prespecified final extract volume. Each analytical determination involves an injection of a small amount of the extract into the analytical Instrument. 

Sample Extraction and Cleanup. The sample extraction method has been described previously (27, 28). Prior to extraction, 100 pL of a dio-fluoranthene surrogate standard solution (0.82 ng/pL) was added to each sample. The XAD-2 resin was extracted for 24 h in a Soxhlet apparatus with -350 mL hexane/acetone (50/50 v/v). The extract volume was then reduced to -100 pL using rotary evaporation followed by evaporation... 

Experiment number Wavelength (nm) % Acetonitrile Sample extraction volume (ml)... 

The extract volume at which the odorant was most (AECA) or least (AEDA) perceived by gas chromatography-olfactometry... 

Diazinon has a finite vapor pressure (see Chapter 3) and thus will be present in the air. A method for diazinon in air has been reported that is based on the use of polyurethane foam (PUF) to adsorb the pesticide from the air as the air is pulled through the PUF (Hsu et al. 1988). The PUF is then Soxhlet-extracted and the extract volume reduced prior to capillary GC/MS analysis. An LOD of 55 ng/m3 (5.5 m3 sample) and recovery of 73% were reported. Another study was described in which the diazinon levels in indoor air were monitored following periodic application of the pesticide for insect control (Williams et al. 1987). In this method, air is pulled through a commercially available adsorbent tube to concentrate diazinon. The tube is then extracted with acetone prior to GC/NPD analysis. No data were provided for the LOD, but recoveries in excess of 90% were reported at the 0.1 and 1 pg/m3 levels. This paper also indicated that diazinon can be converted to diazoxon by ozone and NOx in the air during the sampling process. 

Sorbent Elution. The loaded extraction columns were disconnected and eluted with solvents individually. The elution procedure was as follows First, 1 column bed volume of pesticide-grade pentane was added to the sorbent to displace any residual water. Then, 3 column bed volumes of ethyl ether were added. The eluting solvents were collected in a 2-mL volumetric flask. The eluates from the primary and secondary columns were combined in the volumetric flask. The internal standard solution was added, and the final extract volume was adjusted to 2 mL. Air pressure was again used to push the solvents through the sorbents to avoid volatility losses. 

With A and C = Plant Specific Constants Vt = Total Extraction Volume [L]... 

Higher extraction volumes in high-pressure processes represent higher costs and attention must be paid to limiting them as far as possible. The main impact comes from the bulk density of the feed material (see Table 6.6-1). 

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