Extraction compound recovery

Bierl [28] has described a procedure based on the micro-steam distillation and extraction technique for recovery and determination of low and medium-boiling chlorinated organic compounds. Recoveries of around 90%... 

Compounds Matrix Extraction technique Recovery (%) Relative standard deviation (%) Limit of detection (ng g-1)11 Reference... 

Preconcentration will only give precise results for quantitative work if the initial extraction technique gives high, or at least known and reproducible, recoveries of the desired compounds from the initial sample. As typically, several cycles are needed, and the solvent containing the extracted compounds must be concentrated to a small volume. This is normally carried out by evaporation under reduced pressure. Volatile compounds may be lost in this procedure. However, for many applications the compounds of interest... 

Analysis of data from the factorials indicates that pH has a consistently significant effect on compound recoveries. A summary of the effect of pH level on compounds used in the study is given in Table VI. There is also an interaction between pH and primary column sorbent type for some compounds. This interaction suggests that at low sample pH, a C18 column will produce the best extraction efficiencies for phenolic compounds. The effect of adding methanol to the sample before extraction clearly produced odd results when the recovery data from the 24 factorial was analyzed by using half-normal plots. This effect will be studied in future work. Additionally, different elution solvents will be examined as well as new sorbent phases as they become available. 

The results presented in Table VI for the 42 organochlorine pesticides extracted from spiked sand indicate that SFE with carbon dioxide worked reasonably well for 35 of the 42 compounds (recovery > 50 percent) from those 35 compounds, 30 compound had recoveries > 70 percent. Among the seven compounds with recoveries < 50 percent, two are very volatile (DBCP and hexachlorocyclopentadiene). Three of the remaining five compounds (chlorthalonil, captan, and endosulfan sulfate) gave very poor recoveries with carbon dioxide alone, probably because of their polarity however, in other experiments we have recovered them quantitatively from spiked sand with carbon dioxide modified with 10 percent methanol (1). Chlorobenzilate recoveries were poor, even when we used carbon dioxide with 10 percent methanol, and captafol was not tested with the carbon dioxide/methanol combination. 

Souchon, I., Afhes, V., Pierre, F.X. and Marin, M. (2004) Liquid-liquid extraction and air stripping in membrane contactor application to aroma compounds recovery. Desalination, 163, 39. 

The extracted compounds are collected into a vial that usually has in it a small volume of an organic collection solvent. The choice of collection solvent is important to ensure good recovery. Although there are many variables to consider when developing an extraction method by SFE, manufacturers of SFE instruments will provide information on the most appropriate conditions for a particular compound from a given matrix. Applications range from the extraction of fats and oils from foodstuffs to the... 

The organic solvent used in the extraction was supplied by Burdick Jackson (pesticide grade). Internal standards were added to the samples before the analysis. The recovery of the surrogate standard was used to monitor and evaluate potential losses in extracted compounds. 

Extraction and recovery of six representative compounds with polyurethane foams. Environ Sci Technol 12 791-795. 

Known amounts of adipic acid and 1,4-butanediol were dissolved in acidic methanol and analyzed in order to determine the extraction efficiencies. Extraction efficiencies, 79% for adipic acid and 76% for 1,4-butanediol, were calculated by dividing the slope of the calibration curve for extracted samples by the slope of the calibration curve for non-extracted samples. Bearing in mind the different characters of the extracted compounds, the recoveries obtained by this single-step extraction were good. Flirschlag and KOster earlier used SPE to extract hydroxyacids and dicarboxylic acids from aqueous media [94]. Their recovery for adipic acid was 67% using a SDB-1 column from... 

Extraction of free fatty acids from naturally occurring glycerides removal of HCl from chlorinated organic compounds recovery of aliphatic acids HE and HCl from aqueous solutions nitration of phenol solvent extraction in mineral processing interfacial polycondensation and esterification manufacture of organo-phosphate pesticides. 

Parameters of interest to determine for MIPs used as stationary phases in liquid chromatography are the retention factors [k = (t - t0)/to, where t is the retention of the analyte and t0 is the void], the separation factors (a = k1/k2, where k, and k2 are the retention factors of compound 1 and 2) and the resolution (R) [175, 176], For MIPs used as stationary phases in solid-phase extraction, the recovery is also of interest. 

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