Lipid removal

The eight samples are from burials distributed across the excavated area. In addition to these partitioned samples, bone powder that had the lipids removed was also available from three of the samples in the partitioned set (Burials 1, 8 and 20), as well as two other samples (Burial 17 and 24). These samples included bone from the entire cross-section. 

Ambrose (1990, 1993) found that for most samples well-preserved collagen had at least 3% carbon and 1% nitrogen. If this criterion is applied in this study, two of our 22 samples show aberrant values for carbon and one of 22 is aberrant for nitrogen, with three of the samples containing 1% nitrogen (Table 7.1). Of the three samples where we can compare bone with hpid-removed and lipids intact, both C and N concentrations are within acceptable limits in the lipid-removed sample, but substantially lower in most layers with lipid intact. The concentrations of both C and N are low, but within acceptable criteria, in the sample with well preserved histology (C = 5.11%, N= 1.77%). 

None of the elemental data show any correlation with collagen yield. When compared to yield, the correlation coefficients are non-significant for C N (r = 0.4), %C (r = 0.4) and %N (r = 0.2). All samples with low elemental values are from layers of bone that showed poor histological preservation. While low values tend to come from bone with poor histological preservation, many samples from bone of equally poor preservation produced acceptable values. Lipid removal generally improved both the yield characteristics and elemental values. 

Table 7.3. Summary of yield characierisdcs expressed relaUve to the standards recommended. Key 0 outer layer, M middle layer, 1 inner layer, L lipids removed (includes material from entire cross-section of bone). + meets criterion,...

Although the separation between some unwanted co-extractants and the analytes is well suited to an on-line system, high lipid or elemental sulfur loading is more effectively removed off-line. Most on-line systems at present work most effectively with low lipid contents [493,494], although some applications have overcome the problem of lipid removal. 

Jansson et al. [189] used the conventional approach of blending the solid particles with solvent after which an aliquot was taken to determine the volatile compounds (e.g., phenols and chlorobenzenes). A second fraction was taken after the lipid removal for determination of compounds sensitive to concentrated sulfuric acid. The bulk lipids were removed by oxidative dehydration with Si02 /H2S04 and further cleaned-up with GPC. The chloroparaffins were isolated at this stage. Separation on silica isolated the OCPs, and the organochlorines and organobromines were finally fractionated on active charcoal. 

Bergqvist, P.-A. Strandberg, B. R pe, C. 1998, Lipid removal using semipermeable membranes in PCDD and PCDF analysis of fat-rich environmental samples. Chemosphere 38 933—943. 

Strandberg, B. Bergqvist, P.-A. Rappe, C. 1998, Dialysis with semipermeable membranes as an efficient lipid removal method in the analysis of bioaccumulative chemicals. Anal. Chem. 70 ... 

Rantalainen, A.-L. Crewe, N.F. Ikonomou, M.G. 2000b, Comparison of three techniques for lipid removal from seal blubber Gel permeation, acid treatment, and dialysis with semipermeable membrane. Int. J. Environ. An. Ch. 76 31 7. 

Fish - [ANTIBIOTICS - CITLORAMPHENICOL AND ANALOGUES] (Vol2) -aquaculmral chemicals for [AQUACULTURE CHEMICALS] (Vol 3) -dewatering of (DEWATERING] (Vol 8) -food additives for [FOOD ADDITIVES] (Vol 11) -food packaging for [FOOD PACKAGING] (Vol 11) -lipid removal from [SUPERCRITICAL FLUIDS] (Vol 23) -mineral nutrients source [MINERAL NUTRIENTS] (Vol 16)... 

Biliaderis, 1989 Oomah and Mazza, 1998b). Flaxseed gum exhibited good foam stability at a level of 1% and maximum viscosity at pH 6.0-8.0 (Mazza and Biliaderis, 1989). Oomah and Mazza (1998b) reported that lipid removal significantly increased apparent viscosity values of flaxseed gum. Furthermore, viscosity of seed, cake, and flake samples was significantly related to protein (r = 0.97) and carbohydrate (r = 0.91) fractions, which were related to mucilage fraction of the seed. 

Adi pose ti ssue Extraction, bulk lipid removal, Florisil fracti onati on HRGC/MS 0.1 ng/g No data Mack and Stanley 1984... 

Other percentages can be selected, but a first elution with less than 10% acetonitrile is suitable to remove the hydrophilic compounds. After this first cleaning step, two successive more hydrophobic solutions are often used to have first the bulk of bioactive peptides and then the highly hydrophobic molecules in a different fraction. This step also allows lipid removal from the sample by an irreversible binding of the lipids to the single-use cartridge. 

Lipid removal Biobeads SX-3 Cyclohexane, dichloromethane Gel permeation (size exclusion)... 

Lipid removal using sulfuric acid washing is also effective but does result in loss of some analytes. The acid-treated extracts are then subjected to an adsorption column ffactionization step on silica or Florisil. 

The choice of the type of extraction technique, whether with chloroform-methanol or hexane-isopropanol, makes little difference in the total recovery of lipid. Removal of nonlipid contaminants can certainly be achieved with either of the aforementioned wash techniques. Thus the decision on the choice of the solvent for extraction rests solely with the investigator. 

The advantages of egg yolk antibodies with respect to the welfare of animals and to scientific and economic considerations are described in a recent review.50 Although antibodies issued from this source are mostly used in laboratories and for diagnostics, they must be extracted and purified from very complex mixtures. The presence of massive amount of insoluble material and lipids is the most important problem. The collected egg yolk must first be clarified and the lipid removed for a consistent chromatographic separation. Table 3 summarizes the most important characteristics of expression systems for antibody preparation with regards to the chromatographic separation. 

Ascites 1-10 20-25 Lipid removal High concentration of antibodies small volume of feed stock per animal... 

Lipid was removed from eel extract by a 15 galumina (A1203- 6H20) column and the concentrated sample was further cleaned up by means of a 1.8 g silica (Si02 -1.5%H20) column [91] Lipid removal from rat tissue extracts by shaking with 10 ml hexane solution with cone, sulfuric acid gave excellent results, as well [92]. 

Matrix Drying method Extraction method Extraction solvent Cleanup (lipid removal) Isolation Analysis technique Ref. 

Kuehl et al. [116] have used Celite-545 coated with concentrated sulfuric acid for lipid removal. They eluted fish extract using hexane through this column to a cesium silicate column. Acid treated silica gel is a common material for lipid removal of biota and abiota samples for PCDD/PCDF analyses [111, 112] and has been applied to human adipose tissue extracts for analysis of PCDE [132]. Silica impregnated with concentrated sulfuric acid packed on silica gel in a column has been applied as a second cleanup step [43,120,132]. A multi-silica gel column consisting of layers of silica (silica gel 60), silica impregnated with sulfuric acid (44%), silica, silica impregnated with sodium hydroxide (1 mol 1 ), silica, silica with silver nitrate (10%), and silica has been used for fish extracts by Birkholz et al. [120], The extract was eluted with 2% dichloromethane in hexane and was further purified on Florisil. 

In addition to lipid removal, Florisil column chromatography can be used for chromatographic cleanup and to separate PCDEs from other compounds such as PCBs, PCDDs, and PCDFs. Florisil has been used activated and after deactivation with water. An activated Florisil column has been reported to separate PCDEs... 

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 %. 

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