Particulate total digestion

Table 2.7 lists techniques used to characterise carbon-blacks. Analysis of CB in rubber vulcanisates requires recovery of CB by digestion of the matrix followed by filtration, or by nonoxidative pyrolysis. Dispersion of CB within rubber products is usually assessed by the Cabot dispersion test, or by means of TEM. Kruse [46] has reviewed rubber microscopy, including the determination of the microstructure of CB in rubber compounds and vulcanisates and their qualitative and quantitative determination. Analysis of free CB features measurements of (i) particulate and aggregate size (SEM, TEM, XRD, AFM, STM) (ii) total surface area according to the BET method (ISO 4652), iodine adsorption (ISO 1304) or cetyltrimethylammonium bromide (CTAB) adsorption (ASTM D 3765) and (iii) external surface area, according to the dibutylphthalate (DBP) test (ASTM D 2414). TGA is an excellent technique for the quantification of CB in rubbers. However, it is very limited in being able to distinguish the different types of... 

It is seen by examination of Table 1.11(b) that a wide variety of techniques have been employed including spectrophotometry (four determinants), combustion and wet digestion methods and inductively coupled plasma atomic emission spectrometry (three determinants each), atomic absorption spectrometry, potentiometric methods, molecular absorption spectrometry and gas chromatography (two determinants each), and flow-injection analysis and neutron activation analysis (one determinant each). Between them these techniques are capable of determining boron, halogens, total and particulate carbon, nitrogen, phosphorus, sulphur, silicon, selenium, arsenic antimony and bismuth in soils. 

Mn(II) and Fe(II) were determined by differential pulse voltammetry (9, 30). The determinations were carried out within a few hours after sampling. Total dissolved and particulate Fe and Mn (after digestion of the particulate matter in a microwave digestion unit with HN03-HC1) were measured by flame or graphite furnace atomic absorption spectrometry. 

The separation of waterborne metals into filterable and nonfilterable categories may be done if desired. This requires filtration of the water sample as soon after collection as possible, and certainly before any acid is added to the sample. The metals in natural water samples are often sorbed on particulate matter in a larger quantity than is present in solution. The particles may be filtered out and analyzed separately by digesting the filter in acid. On the other hand, if the total metal content of the water sample is required, the entire unfiltered sample is acidified and digested. 

Air (total chromium) Particulate matter collected on cellulose ester filter, digested with aqua regia ICP-AES 1 pg/m3 87-102% at 0.5-100 pg Lo and Arai 1988... 

The results of sequential leaching experiments and the bioaccumulation studies reveal a selective assimilation of certain chemical forms of some trace metals by molluscs. There seems to be a relationship between seawater-soluble chromium levels and accumulation of the element in the kidneys of exposed bivalves. Particulate forms of chromium, while present in the digestive glands, do not appear to have been assimilated by the organisms, even though much of the total chromium was dissolved by a relatively mild extractant -25% acetic acid. Thus, an estimation of the bioavailability of particulate metals based on their solubility in dilute acetic acid can be erroneously high, at least for herbivorous filter feeders. 

Air Air particulate collection on glass fiber filter digestion in HNO3 ICP-MS (total uranium) 0.1 pg/L in final solution No data Boomer and Powell 1987... 

Because the Se in the SSW samples could be present in many ways, such as particulate, all total Se measurements were carried out on unfiltered samples of the water. These samples were digested prior to any total Se measurements by using a procedure that employed a combination of hydrogen peroxide and nitric acid to convert all of the selenium to soluble selenium. 

PP is the total phosphorus associated with particulate matter. Total phosphorus in the particulate matter is determined by either wet ashing or perchloric acid digestion methods. PP often includes inorganic forms such as phosphate sorbed onto suspended clay particles, and suspended crystalline and amorphous precipitates of PO with Ca, Mg, Al, and Fe. Inorganic phosphorus associated with PP is termed as PIP. Particulate matter is extracted with 1M HCl and filtered solutions are analyzed for orthophosphate as described above. 

Filters For total particulate/aerosol sampling, the open- or close-faced 37 mm filter cassette is the most popular in many countries. A newer type of sampler for inhalable dust is the lOM sampler with a 25 mm filter. Many studies have shown that the lOM sampler provides the best reference for inhalable aerosol. Other samplers that are emerging for this purpose are Respicon, and the Button samplers. There are several types of filters commonly used for this purpose glass fiber, mixed cellulose ester fiber (MCE), and poly(vinyl chloride) (PVC) filters. They are selected based on their ability to collect material and their suitability for laboratory analysis. For example, PVC filters are normally used for gravimetric analysis and MCEs are used when a chemical analysis is needed followed by digestion or extraction. 

Dissolve the lyophilized proteolytic digests in at least 6 p pH 1.9 buffer or pH 4. 72 buffer (for electrophoresis at pH 1.9 and pH 4.72, respectively) or deionized water (for electrophoresis at other pH s), using a vortex mixer (the final volume depends on the total number of counts per minute in the sample). Centrifuge the sample briefly in a microcentrifuge to ensure that any residual particulate matter is not applied to the plate. 

For the determination of TE concentrations in particulate material by wet chemical methods, total decomposition methods (digestion with strong acids), moderate extraction (with weak acids) or sequential material dissolution are commonly used. Often, simultaneously with the determination of TE, several of the major and minor constituents of the samples are determined to collect the necessary background information on sample origin, mineralogical composition, binding forms or potential bioavailability of the TE. 

PN is included in the TON, if unfiltered samples are digested by these analytical methods, and it might be determined as difference between TON and DON. However, a more accurate determination of PN requires the analysis of the particulate collected by filtration independently with respect to the determination of dissolved nitrogen forms, as PN often constitutes only a small fraction of the total nitrogen in the natural waters. The digestion of PN collected on filters can be achieved by KD and PO methods, but the most important technique used for this analysis is the HTO method (Figure 14.1). 

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