Organophosphorus compounds determination

Cabal J., Kassa J., Severa J. A comparison of the decontamination efficacy of foammaking blends based on cationic and nonionic tensides against organophosphorus compounds determined in vitro and in vivo. Human Experimental Toxicology 22, 507-514(2003). 

Phosphorus from organophosphorus compounds, which are combusted to give mainly orthophosphate, can be absorbed by either sulphuric acid or nitric acid and readily determined spectrophotometrically either by the molybdenum blue method or as the phosphovanadomolybdate (Section 17.39). 

A plefhora of methods developed for the determination of triazine compounds in water, soil, crops, biological fluids, etc., have been reported in the literature, and several excellent reviews are available for the interested reader. " More method papers are published on the determination of triazines in water than for all other sample matrices combined (water > soil > crop). The majority of the water method reports relate to the determination of parent triazine compounds plus compounds from one or more other chemical classes of pesticides (e.g., phenoxy acids, carbamates, pheny-lureas, acetanilides, acetamides, organophosphorus compounds, etc.) for generalized multi-residue screening or monitoring purposes. Addressed in other more selective... 

Krikorian SE, Chom TA, King JW. 1987. Determination of octanol/water partition coefficients of certain organophosphorus compounds using high-performance liquid chromatography. Quant Struct-Act Relat 6(2) 65-69. 

The plutonium concentration in marine samples is principally due to environmental pollution caused by fallout from nuclear explosions and is generally at very low levels [75]. Environmental samples also contain microtraces of natural a emitters (uranium, thorium, and their decay products) which complicate the plutonium determinations [76]. Methods for the determination of plutonium in marine samples must therefore be very sensitive and selective. The methods reported for the chemical separation of plutonium are based on ion exchange resins [76-80] or liquid-liquid extraction with tertiary amines [81], organophosphorus compounds [82,83], and ketones [84,85]. 

Barcelo D, Porte C, Cid J, Albaiges J (1990) Determination of organophosphorus compounds in Mediterranean coastal waters and biota samples using gas-chromatography with nitrogen-phosphorus and chemical ionization mass-spectrometric detection. Int J Environ Anal Chem 38(2) 199-209... 

Dr. P. Jeffers at the State University of New York at Cortland is gathering information to determine the persistence of organophosphorus compounds in groundwater and the effects of various soils on the degradation and transport of these compounds. Both neutral and base hydrolysis processes will be evaluated. Transport studies in soil columns will be conducted to determine the mobility of diazinon in soils. 

Methods for Determining Biomarkers of Exposure and Effect. Section 2.6.1 reported on biomarkers used to identify or quantify exposure to diazinon. Some methods for the detection of the parent compound in biological samples were described above. The parent chemical is quickly metabolized so the determination of metabolites can also serve as biomarkers of exposure. The most specific biomarkers will be those metabolites related to 2-isopropyl-6-methyl-4-hydroxypyrimidine. A method for this compound and 2-(r-hydroxy-l -methyl)-ethyl-6-methyl-4-hydroxypyrimidine in dog urine has been described by Lawrence and Iverson (1975) with reported sensitivities in the sub-ppm range. Other metabolites most commonly detected are 0,0-diethylphosphate and 0,0-diethylphosphorothioate, although these compounds are not specific for diazinon as they also arise from other diethylphosphates and phosphorothioates (Drevenkar et al. 1993 Kudzin et al. 1991 Mount 1984 Reid and Watts 1981 Vasilic et al. 1993). Another less specific marker of exposure is erythrocyte acetyl cholinesterase, an enzyme inhibited by insecticidal organophosphorus compounds (see Chapter 2). Methods for the diazinon-specific hydroxypyrimidines should be updated and validated for human samples. Rapid, simple, and specific methods should be sought to make assays readily available to the clinician. Studies that relate the exposure concentration of diazinon to the concentrations of these specific biomarkers in blood or urine would provide a basis for the interpretation of such biomarker data. 

A number of instrumental analytical techniques can be used to measure the total phosphorus content of organophosphorus compounds, regardless of the chemical bonding of phosphorus within the molecules, as opposed to the determination of phosphate in mineralized samples. If the substances are soluble, there is no need for their destruction and for the conversion of phosphorus into phosphate, a considerable advantage over chemical procedures. The most important methods are flame photometry and inductively coupled plasma atomic emission spectrometry the previously described atomic absorption spectrometry is sometimes useful. 

More recent flame photometric methods rely on direct measurement of the phosphorus emission. If organophosphorus compounds are injected into a hydrogen flame, a continuous emission is obtained in the 490-650 nm region. A broad band system, with an intensity maximum at 526 nm, is superimposed on this background139 it is attributed to the HPO species formed in the flame. An early determination of phosphorus at 0.01-0.04 m concentrations was based on examination of the continuous emission standard and sample solutions were injected into the burner and the intensities were measured at 540 nm the calibration graph was linear down to the detection limit of 10 4 M phosphorus sodium or calcium, if present in the sample, interfered with the results140. 

The sensitivity of the gas chromatographic equipment is usually not the limiting factor in the detection and determination of the organophosphorus compounds found in natural environments. The extraction and clean-up procedures discussed earlier are the most important steps and the percentage recoveries probably play the primary role in this... 

With a molecular emission cavity flame detector, relying on measurement of the 526 nm emission of HPO (see Section II.C.l and III.B.3.b), nanogram amounts of phosphates or organophosphorus compounds can be assessed in automated systems160,348. Determination of m, the time elapsed between sample ignition and maximum emission, allows the resolution of ternary or more complex mixtures of insecticides. Dicrotophos, dimethoate, malathion and parathion mixed in aqueous solution were separated and identified in nanograms per millilitre concentrations348. 

In some instances a single organophosphorus substance or a mixture of very few such compounds are known to be present in a sample. In such cases separation and identification are not necessary and it may be expedient to use a simple method of limited applicability for their determination, rather than a sophisticated instrumental technique. Many procedures designed for the analysis of specific organophosphorus compounds of special interest have been published, of which only a few examples will be discussed here. 

Some general methods can also be adapted to the determination of individual organophosphorus compounds. For instance, the cholinesterase-inhibiting properties of methylparathion, dimethoate and their oxygen analogues were used for their determination a known amount of enzyme is incubated with the sample, then addition of a chromogenic agent such as p-nitrobenzenediazonium fluoroborate yields a... 

Numerous studies have applied gas chromatography to determine the concentration of CMPO and of a variety of organophosphorus compounds. The CMPO degradation products identified are summarized in Figure 8.4. 

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