Phosphorus Detection

I. Koide, O. Noguclii, K. Okada, A. Yokoyama, H. Oda, S. Yamamoto and H. Kataoka, Detemination of amphetamine and methamphetamine in human hak by headspace solid-phase microexti action and gas cliromatogi aphy with niti ogen-phosphorus detection , J. Chromatogr. B707 99-104(1998). 

Maximum residue limit Mass spectrometry Tandem mass spectrometry Material safety data sheet North American Free Trade Act N-Hydroxysuccinimide Nitrogen-phosphorus detection Neomycin phosphotransferase II Optical density Office of Plant Protection and Quarantine... 

The presence of heteroatoms usually provides a convenient feature for improving selectivity by employing selective detection mechanisms. GC may then use flame photometric detection (FPD) for S and P atoms and to a certain extent for N, Se, Si etc. thermoselective detection (TSD) and nitrogen-phosphorus detection (NPD) for N and P atoms electron capture detection (ECD) for halogen atoms (E, Cl, Br, and 1) and for systems with conjugated double bonds and electron-drawing groups or atomic emission detection (AED) for many heteroatoms. 

ECD, electron capture detection NPD, nitrogen-phosphorus detection MS, mass spectrometry. 

The methyl ester of bispyribac is cleaned up by silica gel column chromatography. Bispyribac-methyl is determined by gas chromatography with nitrogen-phosphorus detection (NPD). 

Plants (cereals, cotton, potato, citrus, apple, pear, peach, grape, persimmon, apricot, chestnut), soil and water Gas-chromatographic determination [mass spectromet-ric detection (MSD), flame thermionic detection (FTD) or nitrogen-phosphorus detection (NPD)] for plant materials, water and soil... 

For cottonseeds, pyrithiobac-sodium is extracted with acetone-water (4 1, v/v). After filtration, the acetone is removed by evaporation under reduced pressure. The residue is adjusted to pH 1 and extracted with ethyl acetate. The extract is cleaned up by liquid-liquid partitioning and methylated with diazomethane. The methyl ester of pyrithiobac is purified by silica gel column chromatography. Pyrithiobac-methyl is determined by gas chromatography (GC) with nitrogen-phosphorus detection (NPD). 

Visible wavelength spectrophotometry Mass selective detection Nitrogen-phosphorus detection Electron capture detection UV detection... 

Universal and selective detectors, linked to GC or LC systems, have remained the predominant choice of analysts for the past two decades for the determination of pesticide residues in food. Although the introduction of bench-top mass spectrometers has enabled analysts to produce more unequivocal residue data for most pesticides, in many laboratories the use of selective detection methods, such as flame photometric detection (FPD), electron capture detection (BCD) and alkali flame ionization detection (AFID) or nitrogen-phosphorus detection (NPD), continues. Many of the new technologies associated with the on-going development of instrumental methods are discussed. However, the main objective of this section is to describe modern techniques that have been demonstrated to be of use to the pesticide residue analyst. 

The most common final separation techniques used for agrochemicals are GC and LC. A variety of detection methods are used for GC such as electron capture detection (BCD), nitrogen-phosphorus detection (NPD), flame photometric detection (FPD) and mass spectrometry (MS). For LC, typical detection methods are ultraviolet (UV) detection, fluorescence detection or, increasingly, different types of MS. The excellent selectivity and sensitivity of LC/MS/MS instruments results in simplified analytical methodology (e.g., less cleanup, smaller sample weight and smaller aliquots of the extract). As a result, this state-of-the-art technique is becoming the detection method of choice in many residue analytical laboratories. 

The residue-containing eluate from the GPC step is evaporated and analyzed by GC with nitrogen/phosphorus detection (NPD) (Modules D3 and D4) or mass spectrometry (MS) detection. For GC with electron capture detection (ECD) (Module Dl), the GPC eluate requires an additional cleanup on a small silica gel column. 

Plant samples are homogenized with sodium hydrogencarbonate aqueous solution to prevent decomposition of the analytes during homogenization. Imibenconazole and its primary metabolite, imibenconazole-debenzyl, are extracted from plan materials and soil with methanol. After evaporation of methanol from the extracts, the residues are extracted with dichloromethane from the residual aqueous solution. The dichloromethane phase is cleaned up on Florisil and Cig columns. Imibenconazole and imibenconazole-debenzyl are determined by gas chromatography/nitrogen-phosphorus detection (GC/NPD). 

Water samples are directly partitioned with dichloromethane (DCM). The DCM exAact is then rotary evaporated and driven to dryness with a sAeam of niAogen. The dry residue is dissolved in acetone and analyzed by gas chromatography/nitrogen-phosphorus detection (GC-NPD). 

Quantitation of tebuconazole residue in water extracts is also performed by the calibration technique. Construct a new calibration curve of 0.5-, 1-, 2-, and 5-mg L equivalent tebuconazole standard solutions for each set of analyses. Inject 5- o.L aliquots of the standard solutions. The injection volume should be kept constant as the peak area varies with the injection volume by nitrogen-phosphorus detection. Plot the peak area against the injected concentrations of tebuconazole. 

Gas-chromatographic determination [mass spectromet-ric detection (MSD) or nitrogen-phosphorus detection (NPD)] for plant materials, soil and water... 

A Multi-residue analytical method (for plants) is used for rice, citrus and tomato. Buprofezin and p-OH-buprofezin (as the acetylated derivative, p-AcO-buprofezin) are analyzed simultaneously using gas chromatography/nitrogen-phosphorus detection (GC/NPD). 

Residues are extracted with acetone. The extract is rotary evaporated to remove acetone, the concentrated residue is diluted with 5% aqueous sodium chloride, and residues are partitioned into dichloromethane. The extract is then concentrated and purified on a silica gel column. Residues of pyriproxyfen are quantitated by gas chromatography with nitrogen-phosphorus detection (GC/NPD). For citrus, a hexane-acetonitrile solvent partition step is required for oil removal prior to the dichloromethane partition step. 

GC = gas chromatography GPC = gel permeation chromatography MS = mass spectrometry NPD = nitrogen/phosphorus detection... 

The most commonly used and widely marketed GC detector based on chemiluminescence is the FPD [82], This detector differs from other gas-phase chemiluminescence techniques described below in that it detects chemiluminescence occurring in a flame, rather than cold chemiluminescence. The high temperatures of the flame promote chemical reactions that form key reaction intermediates and may provide additional thermal excitation of the emitting species. Flame emissions may be used to selectively detect compounds containing sulfur, nitrogen, phosphorus, boron, antimony, and arsenic, and even halogens under special reaction conditions [83, 84], but commercial detectors normally are configured only for sulfur and phosphorus detection [85-87], In the FPD, the GC column extends... 

The detector can be made to respond to phosphorus compounds only by earthing the jet, which is at a negative potential for simultaneous nitrogen and phosphorus detection, and altering the flow rates of the flame gases. If... 

PDMS = polydimethylsiloxane. PA = polyacrylate. CW = Carbowax. DVB = divinylbenzene. FID = flame ionization detection. NPD = nitrogen-phosphorus detection. TSD = thermionic-specific detection. LOQ = limit of quantitation. LOD = limit of detection. TCA = trichloroacetic acid. PICI-MS = positive ion chemical mass spectrometry. SIM = selected ion monitoring. 

De la Torre, R. et al. 1998. Quantitative determination of tricyclic antidepressnts and their metabolites in plasma by solid phase extraction (bond-elut TCA) and separation by capillary gas chromatography with nitrogen-phosphorus detection. Ther Drug Monit. 20 340. 

Seto Y, Tsunoda N, Ohta H, et al. 1993. Determination of blood cyanide by headspace gas chromatography with nitrogen phosphorus detection and using a megabore capillary column. Analytica ChimicaActa 276 247-259. 

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