Phosphorus Estimation

In Schloesing s test for free white phosphorus in phosphorus sesquisulphide the latter is shaken with light petroleum (b. pt. 45 to dissolve free phosphorus. The liquid is quickly filtered and an aliquot part evaporated in a vacuum at 15 to 20 The residue is oxidised with nitric acid and the phosphorus estimated. In order simply to detect the presence of phosphorus, the residue after evaporating off the petroleum is shaken with fine sand in a flask in the dark and carefully examined for phosphorescent glow,... 

Your colleagues who are responsible for the first step, the production of pure phosphorus, estimate that they can supply you with 1.09 X lO kg of phosphorus per day. The production manager asks you to figure out the maximum mass of P4O10 that can be made from this amount of phosphorus. The tools described in this chapter, in combination with the unit analysis method, enable you to satisfy this request. 

As noted in Table 2, between 40% and 75% of phosphorus buried in continental margin sediments is potentially reactive, and 90% to 100% of phosphorus buried in abyssal sediments is potentially reactive. The reactive phosphorus fraction of the total sedimentary phosphorus reservoir represents that which may have passed through the dissolved state in oceanic waters, and thus represents a true phosphorus sink from the ocean. The minimum reactive phosphorus burial flux was calculated as the sum of 0.4(sFjs) -I- 0.9 (sF ) the maximum reactive phosphorus burial flux was calculated as the sum of 0.75(sFes) -i- 1(sF ). Both the flux estimates and the % reactive phosphorus estimates have large uncertainties associated with them. 

The original methods have been modified to increase the accuracy of microbial phosphorus estimates on specific soils, and different protocols now exist for each step of the method (Table 7.2). Chloroform is most commonly used as fumigant, either gaseous, liquid or both. The non-carcinogenic hexa-nol is also effective as a fumigation biocide (McLaughlin et al., 1986) and must replace chloroform when certain brands of resin strips are used for extraction, since these are damaged by chloroform (Biinemann et al.,... 

Analytical characteristics of fish oils and whale oils, 134,139 Analytical methods anisidine value, 264 AOCS, 259 dilatation, 253 fat adulteration, 270 fat content, 250 free fatty acids, 260 gas chromatography, 265 hydroxyl value, 261 iodine value, 259 lUPAC, 249 NMR spectra, 250 pancreatic lipase hydrolysis, 267 peroxide value, 263 phosphorus estimation, 264 saponification value, 260 slip point, 251 solid fat, 255 standard, 250... 

A scheme of activation analysis usually includes a chemical separation process or the addition of a carrier . It is sometimes desirable to remove chemically, before activation, any elements which would cause interference. For example, the presence of sulphur or chlorine in the sample could cause inaccuracies in the estimation of phosphorus content due to reactions (13.216) and (13.217) taking place and providing extra radioactive phosphorus. In a similar manner silicon can also cause interference with the phosphorus estimation owing to the side reaction. 

Table 5. Estimated 1995 World Capacity of Elemental Phosphorus ...

When saccharin is treated with diethyl phosphorothiolothionate, the 3-ethylmercapto compound is obtained, rather than the expected organophosphorus compound (77 ACS(B)460). Treatment of saccharin with phosphorus pentoxide and amines gives 3-(substituted-amino)-1,2-benzisothiazole 1,1-dioxides, via an intermediate phosphate (81ZN(B)1640). Reduction of saccharin with zinc and hydrochloric acid gives 2,3-dihydro-l,2-benzisothiazole 1,1-dioxide, the method being used to estimate saccharin in foodstuffs (75MI41701). 

As just implied, the land-based phosphorus cycle is connected to the water-based cycle via the rivers and sewers. It has been estimated that, on a global scale, about 2 million... 

Feedbacks may be affected directly by atmospheric CO2, as in the case of possible CO2 fertilization of terrestrial production, or indirectly through the effects of atmospheric CO2 on climate. Furthermore, feedbacks between the carbon cycle and other anthropogenically altered biogeochemical cycles (e.g., nitrogen, phosphorus, and sulfur) may affect atmospheric CO2. If the creation or alteration of feedbacks have strong effects on the magnitudes of carbon cycle fluxes, then projections, made without consideration of these feedbacks and their potential for changing carbon cycle processes, will produce incorrect estimates of future concentrations of atmospheric CO2. 

Despite its relatively late discovery, phosphorus is the eleventh most abundant element in Earth s crustal rock. It has been estimated that world reserves of phosphate rock are sufficient to last for several hundred years. Virtually all phosphorus deposits contain apatite, whose general formula is Caj (P04)3 X, where X — OH, or Cl. Fluoroapatite is the least soluble, hence most abundant, of the three apatite minerals. Phosphorus Is found in aqueous systems as HPOq and H2 PO4 ions. In biological organisms, phosphorus is a component of nucleic acids and energy-shuttling molecules such as ATP. 

The simultaneous analysis of orthophosphate, glycerol phosphates, and inositol phosphates has been achieved by spectrophotometric analysis of the molybdovanadate complexes. Also, a sensitive and selective chemiluminescent molecular emission method for the estimation of phosphorus and sulphur is described, which is based on passing solutions into a cool, reducing, nitrogen-hydrogen diffusion flame. For organic compounds it was usually necessary to prepare test solutions by an oxygen-flask combustion technique. 

The dipole moment of tributylpliosphine varies from 1.49 to 2.4 D according to the solvent used. Inductive effects in phosphines have been estimated by comparing the calculated and observed dipole moments, and the apparent dipole moment due to the lone electron pair on phosphorus has been estimated. A method of calculating the hybridization of the phosphorus atom in terms of bond angles is suggested which leads to a linear relationship between hybridization ratio and lone electron pair moment. The difference between experimental and calculated dipole moments for para-substitued arylphosphines, phosphine sulphides, and phosphinimines has been used to estimate mesomeric transfer of electrons to phosphorus. 

Biological and Analytical Applications. - Phosphorus-31 n.m.r. continues to expand its application in the medical and biological fields20 and is now being applied to soil analysis.21 The problems involved in the use of FT 31P n.m.r. for quantitative determinations have been discussed.22 Samples of phosphinic carboxylic acids were cooled to -40°Cfor quantitative estimations.23... 

Water samples are acidified and extracted with solvent (Kawamura and Kaplan 1983 Muir et al. 1981). Clean-up steps may be used (Kawamura and Kaplan 1983). Methylene chloride is often used as the extracting solvent, and it may interfere with the nitrogen-phosphorus detector. In this case, a solvent-exchange step is used (Muir et al. 1981). Analysis by GC/NPD or GC/MS provides specificity (Kawamura and Kaplan 1983 Muir et al. 1981). Accuracy is acceptable (>80%), but precision has not been reported. Detection limits were not reported, but are estimated to be 0.05-0.1 pg/L (Muir et al. 1981). Detection limits at the low ppt level (ng/L) were achieved by concentrating organophosphate esters on XAD-2 resin. The analytes were solvent extracted from the resin and analyzed by GC/NPD and GC/MS. Recovery was acceptable (>70%) and precision was good (<10% RSD) (LeBel et al. 1981). 

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