Florisil cleanup with

Air Collect on hexylene glycol-alumina adsorbent sampler extract cleanup with Florisil GC/FPD 0.1 ng/m 53.4 Stanley et al. 1971... 

Note each lot of Florisil must be checked for acceptable recovery of flumioxazin prior to initiating the column cleanup procedure. Adjust elution volumes and/or the solvent mixture as necessary to achieve >90% recovery for this step. Sample cleanup with Florisil may not be required for some water samples. 

Macerated plant material is homogenized with a mixture of methanol and 1.2N hydrochloric acid (HCl) in water (4 1, v/v) and then with methanol. An internal standard solution is added to the filtrate and the filtrate is adjusted to a constant volume. A portion of the filtrate is rotary evaporated to dryness and hexane is added to the extract before a Florisil cleanup procedure is performed. The extract is dissolved in toluene for analysis by GC/MS in the negative chemical ionization (NCI) mode. 

Water/waste water Extract with methylene chloride exchange to hexane Florisil cleanup, if required GC/ECD 0.03 pg/L 99 EPA 1982... 

Food (fish, milk, butter, com oil) Extract with acetonitrile cleanup with Florisil elute with petroleum ether and ethyl ether/petroleum ether GC/ECD No data 80 Yurawecz an Puma 1986... 

Florisil Cleanup of chlorinated hydrocarbons, nitrogen, and aromatic compounds Has basic properties and may not be compatible with acids... 

Human milk Solvent extraction cleanup with sulfuric acid, Florisil GC/ECD 5 ppb >80 Jan 1983... 

Kimbrough [171] recommended the use of polar solvents with Florisil cleanup for the extraction of organochlorine insecticides from soil. 

Sulfur is found in many industrial wastes, marine algae, and sediment samples. Sulfur may mask the region of chromatogram, overlapping with peaks of interest. For example, in pesticides analysis, sulfur can mask over many pesticides such as lindane, aldrin, and heptachlor. Sulfur has a solubility similar to the organochlorine and organophosphorus pesticides and it cannot be separated by Florisil cleanup method. 

Aqueous samples are extracted with methylene chloride using a separatory funnel or a continuous liquid-liquid extractor. Solid samples are extracted with methylene chloride-acetone mixture (1 1) by either sonication or Soxhlett extraction. The methylene chloride extract should be finally exchanged to hexane or iso-octane or methyl tert-butyl ether. The latter solvents should be mixed with acetone during solvent exchange. The extracts should then be cleaned up by Florisil. Often Florisil cleanup reduces the percent recovery of analyte to less than 85%. A preliminary screening of the extract should, therefore, be done to determine the presence of interference and the necessity of florisil cleanup. Gel permeation cleanup also lowers the analyte recovery and thus is not recommended. If a FPD is used in the GC analysis, the presence of elemental sulfur can mask the analyte peaks. In such a case, sulfur cleanup should be performed. Sample extraction and cleanup procedures are described in Chapter 1.5. 

Aqueous samples repeatedly extracted with methylene chloride extracts combined and concentrated by evaporation of methylene chloride solvent exchanged to hexane florisil cleanup (for removal of interferences) extract analyzed on GC-ECD or GC/MS. 

Soils, sediments, or solid wastes extracted with methylene chloride by sonication or Soxhlett extraction extract concentrated exchanged to hexane (if florisil cleanup required) analyzed by GC-ECD or GC/MS. 

For florisil cleanup, column eluted with methylene chloride/hexane (1 9) and then with acetone/methylene chloride (1 9) mixture analyte eluted into the latter fraction. 

Determination of the intact CW agents in urine or blood may proceed by the methods commonly applied to water samples. Extraction with an organic solvent and subsequent cleanup with a Florisil column is a well-established procedure. Rather volatile, scheduled compounds can often be successfully recovered and purified from biological materials by means of dynamic headspace stripping and subsequent adsorption on Tenax tubes these tubes are then subjected to GC/MS analysis. 

For water, rat tissue, and fish samples, cleanup with deactivated Florisil (magnesium silicate containing 5% water) was performed. Column length was 300 mm and inner diameter 30 mm. A maximum of 0.6 g of lipidic sample per 20 g of Florisil was applied. The upper portion of column was packed with anhydrous sodium sulfate. TCBTs were eluted with 150 ml of hexane. A second elution with 100 ml of hexane/dichloromethane (85/15) was performed to determine whether any TCBT had been retained in the column. Both eluates were concentrated prior to chromatographic analyses [87]. 

Koistinen et al. [58] have applied a Florisil cleanup which uses a partially deactivated (1.25%) Florisil microcolumn (1 g) to separate PCDEs from PCDDs and PCDFs in abiota and biota extracts [33,57,113,114,123-125]. After sulfuric acid cleanup, PCDEs are eluted through a Florisil column together with PCBs using hexane (15 ml). PCDDs and PCDFs are retained in the column and can be eluted with dichloromethane (12 ml). 

Tomy et al. [ 14] extracted PCAs from fish and sediments by using DCM extraction, lipid removal by SX-3 Biobeads gel permeation chromatography (GPC) [53], and cleanup with Florisil column chromatography. Fractionation on Florisil was achieved by eluting with hexane (FI), which eluted all the PCBs, chlorinated benzenes, 4,4 -DDE, then with (15 85) DCM/hexane (F2), and finally with (1 1) DCM/hexane (F3). Fractions F2 and F3 contained PCAs along with 4,4 -DDT, toxaphene, cis- and frans-chlordane and other more polar organics, such as heptachlor epoxide and dieldrin. The mean percentage recovery of PCAs for this method was 85 %. 

Human milk (congener specific) Addition of surrogate congener standard PCB 46 and 142, extraction with hexane, cleanup with Florisil. HRGC/ECD 1 pg/g (PCB 200)-129 pg/g (PCB 48) No data Greizerstein et al. 1997... 

Addition of anhydrous sodium sulphate, concentration to 2.5 ml, cleanup with florisil, concentration to 2 ml in 10% diethyl ether in hexane and silylation... 

PAM 304 Fatty foods, animal tissue, fatty fish El. Extraction of fat with sodium. sulfaie, petroleum ether Cl. Acetonitrilc-pretroleum ether partitionii, Florisil column cleanup with three mixed ether eluani.s DG12/14 for residues with phosphorus... 

Fat extracted from tissue with solvent subjected to GPC and Florisil cleanup concentrated... 

Growth-enhancing substances An AOAC method is approved for the growth promoter melengestrol acetate in animal tissues by solvent extraction of fatty tissue and cleanup on a Florisil column with determination by GC-ECD. 

Column chromatography has been widely used for the cleanup of samples, either individually or after preliminary purification by solvent partitioning. An example of the latter is the quantitative TLC determination of the fungicides captan, folpet, and captafol in lettuce and apples (79). Samples were extracted by blending with acetone and the extracts were filtered, pesticides were partitioned from the aqueous filtrate with petroleum ether-methylene chloride (1 1), the organic layer was concentrated and diluted with acetone and petroleum ether, and the solution was chromatographed on an activated Florisil column with elution by 200 ml of 15% ethyl ether in petroleum ether followed by 200 ml of 50% ethyl ether in petroleum ether. The eluates were concentrated and aliquots spotted for TLC analysis. 

The Florisil cleanup of pesticides is an example of classical cleanup technique that has been used extensively for years. Prior to cleanup, the sample extract should be concentrated to 10 mL and be in hexane. A column containing 20 g of Florisil with a 2-cm layer of anhydrous sodium sulfate on top of the column is... 

The phthalate esters can also be determined by GCECD after an appropriate solvent extraction from aqueous or solid samples. USEPA Method 8061 lists 16 phthalate esters (13). Solid-phase extraction using C18 membrane disks can be used for aqueous samples, but the pH must be maintained between 5 and 7 to prevent hydrolysis of the phthalate esters. Solids or soils can be extracted by sonication or Soxhlet extraction using 1-1 methylene chloride-acetone. GPC or the Florisil cleanup may be necessary. Extreme care must be taken not to contaminate samples with phthalate esters that are ubiquitous in the laboratory. The solvent needs to be exchanged to hexane. Two megabore capillary columns that are connected by a Y in parallel are recommended for separation. Detection is accomplished by dual ECDs. The conditions for the GC are listed in Table 15.13. 

The primary method for detecting methyl parathion and metabolites in biological tissues is gas chromatography (GC) coupled with electron capture (BCD), flame photometric (FPD), or flame ionization detection (FID). Sample preparation for methyl parathion analysis routinely involves extraction with an organic solvent (e g., acetone or benzene), centrifugation, concentration, and re suspension in a suitable solvent prior to GC analysis. For low concentrations of methyl parathion, further cleanup procedures, such as column chromatography on silica gel or Florisil are required. 

HPLC has been recommended as a cleanup and fiactionation procedure for food samples prior to analysis by GC/ECD (Gillespie and Walters 1986). The advantages over the AOAC-recommended Florisil colunrn are that it is faster, requires less solvent, and gives better resolution. HPLC coupled with various detectors MS, MS/MS, UV/electrochemical detector, or UV/polarographic detection has been tested as a rapid, simplified separation and detection system to replace GC (Betowski and Jones 1988 Clark et al. 1985 Koen and Huber 1970). Recoveries, detection limits, and precisions were generally good, but further work is needed before the techniques are adopted for general use. 

For multi-analyte and/or multi-matrix methods, it is not possible to validate a method for all combinations of analyte, concentration and type of sample matrix that may be encountered in subsequent use of the method. On the other hand, the standards EN1528 andEN 12393 consist of a range of old multi-residue methods. The working principles of these methods are accepted not only in Europe, but all over the world. Most often these methods are based on extractions with acetone, acetonitrile, ethyl acetate or n-hexane. Subsequent cleanup steps are based on solvent partition steps and size exclusion or adsorption chromatography on Florisil, silica gel or alumina. Each solvent and each cleanup step has been successfully applied to hundreds of pesticides and tested in countless method validation studies. The selectivity and sensitivity of GC combined with electron capture, nitrogen-phosphorus, flame photometric or mass spectrometric detectors for a large number of pesticides are acceptable. 

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