Dry ashing extraction

Air Collection of particulate matter onto filter dry ashing extraction AAS 0.1 pg/m3 93 Scott et al. 

Method 7.11b. Determination of potassium in piant materiai by fiame photometry (dry ashing extract)... 

Wet ash filter extract electrodeposit on platinum disk Evaporate wet ask filter extract, electrodeposit on platinum disk Wet ash filter extract el elctrodeposit on platinum disk Dry ash reduce valance State extract electrodeposit on platinum disk Dry ash extract reduce valence state coprecipitate with lanthanum f1uori de... 

Air Sample collection on cellulose filter, dry ashed, solvent extracted Biphasic liquid scintillation 1 pCi 95% Bomben et al. 1994... 

Feldman and co-workers117) described a procedure for determining as little as 10 ppb of chromium in serum. The normal level is 30 ppb. At least 2 ml of serum are digested or dry ashed and treated with not permanganate to oxidize chromium to chromium(VI). The chromium(VI) is extracted from 3M HC1 into 5 ml MIBK in the cold. This method has been used to measure chromium levels in studies relating this element to diabetes. Thousands of analyses have been performed. Devoto (198) dry ashed 10 ml of blood and extracted the chromium with 5 ml of 10 % tributyl phosphate in MIBK. Recently, Feldman 119) has determined... 

Willis determined the physiological level of bismuth in urine to be about 0.02 ppm by using the same procedure he described for lead 93). Devoto ls°) dry ashed 100 ml of urine and extracted bismuth with APDC into 5 ml of MIBK. 

These samples are prepared by either wet or dry ashing. Many of the metals can be determined in aqueous solution, but for the more trace ones, solvent extraction procedures similar to those described above are resorted to. Similar sample preparation procedures apply to plants. The elements... 

Bur, and Gin Trash Samples and Ash Contents of the Dried Aqueous Extracts of these Samples (21)... 

Average ash content of dried aqueous extracts (range), %... 

These data show that the ash content of the dried aqueous extracts tend to be higher than the original for all three types of samples. The increase is especially high for the condenser trash samples and is quite similar to the behavior of plant parts (21). There is also a trend that as the particle size becomes smaller, the ash content increases. The ash content of the electrostatic precipitator dust was particularly high (41.3%). 

The cotton plant parts investigated include bract, leaf, stem and bur. The ash fraction was taken as a reasonably accurate measure of the inorganic fraction. Bract has the highest ash fraction (ca. 18%), followed by leaf (ca. 16.5%), bur (ca. 7.5%) and stem (ca. 7.2%). The ash fraction of dried aqueous extracts of each of these plant parts was ca. 35% which is considerably higher than the ash fraction of the raw samples, was noted that high variations occur in the ash fraction of samples as a function of growing location and year of harvest. 

Table 6.10 Structural analyses results of shell samples (wt.% of dry, ash and extractive-free...

Bones spiked with tracer dry ashed, Th coprecipitated with Fe-hydrox1de, cleaned up by complexatlon and solvent extracted and electrodeposited. 

Dry ash bone, dissolve ash in acid, clean-up by solvent extraction and Ion-exchange method, develop color with Arsenzazo 111. 

Element Fresh bottom ash Ivsimeter extracted pore water and leachates (Chandler el al. 1997 Cranncll et al. 2000) Aged boiiuiit ash extracted pore waters (Mciina 1997) Dry and semi-dry scrubber residues low LS (0.0-0.2) column leachates (Chandler et al. 1997) Wet scrubber residue low LS 10.0-0.2) column leachates (Chandler et al. 1997)... 

Extraction Dry ash redissolve Extract with ethanol and Remove co-extractives on... 

In an official method [83] for determining zinc in plant material, the sample is digested with perchloric acid 60% nitric acid 70%, m/v 1 4, followed by 2 M hydrochloric acid. Alternatively, the plant material is dry ashed and the residue dissolved in 6 M hydrochloric acid. The extract is evaluated by AAS at the 213.9 nm emission line. See also Sect. 7.34.1,7.34.4 and 7.34.7. 

Analytical values for the eight coals after treatment with 2 M HN03 are given in Table III. The reported values are the averages of four determinations (duplicate determinations on different days). A comparison of the dry ash values for the HNOj-extracted residues described in Table III to the dry ash values for the raw coals described in Table I reflects the reduction in mineral matter caused by extraction of the raw coals with 2 M HN03. Carbonates, sulfates, and other minerals dissolve in the acid solution used to extract pyrite. 

QF samples contained 15% (w/w) starch and 17% cellulose (Table 1). The total carbohydrate composition was 65%. Protein and oils accounted for 12%. The components measured account for 78% of the dried material, the residual material (not tested for) includes ash, extractables, lignin, and lipids. The composition of the QF was, as expected, similar to that found for corn fiber. Corn fiber and QF are both derived from the pericarp and tip portions of the kernel. Most notably, the QF contained approx the same amount of residual starch, which suggests that the modified milling process is as effective at separating starch from the pericarp as a full steeping protocol. Starch recovery is significantly improved compared to previous results for which the starch content of the QF was 42-46% w/w (2). The current study used an improved process that included an additional starch washing step. 

A common result of the sample preparation is the dissolution of the entire sample, producing a clear solution. The digestion method must be selected to suit the type of sample, the metals being determined, and finally, the analytical method. Of the methods listed above, most require a liquid sample, except for x-ray fluorescence, which often is used on solid samples. Wet digestion in acid solution, dry ashing, and extraction of the analytes from... 

Some analysts prefer to use dry ashing techniques, ashing up to 20 g sub-samples in silica basins.7 Care is then needed to make sure that losses onto siliceous ash residue or by adsorption onto the basin, which are serious problems for copper and cobalt especially, are circumvented. This may be done by extracting the residue at least twice with dilute nitric acid under infrared lamps. If the residue is finally diluted to ca. 25 ml with dilute nitric acid, numerous trace elements may be determined. For some elements, however, preconcentration and sensitivity enhancement by solvent extraction may still be necessary. Details of... 

When samples are dry ashed for Sn determination, it is theoretically possible to volatilize the metal during the process, just as for Cd and Pb. This does not seem to be the case in practical work, though. Results from dry ashing have compared very well with results obtained with other techniques, such as HC1 extraction or the dithizone method. It is crucial, however, that the ashes are dissolved in HC1 and not HNO3. 

Sodium and potassium are extracted from solid samples by wet digestion or dry ashing followed by acid dissolution of residue, and are determined by flame AAS using an air—acetylene flame. Liquid samples are aspirated after dilution. 

---