Chromatography photometric detection

A practical method for low level perchlorate analysis employs ion chromatography. The unsuppressed method using a conductivity detector has a lower detectable limit of about 10 ppm. A suppression technique, which suppresses the conductivity of the electrolyte but not the separated ions, can further improve sensitivity (110,111). Additionally, ion chromatography can be coupled with indirect photometric detection and appHed to the analysis of perchlorates (112). 

The ionic or polar substances can be seperated without any reaction on specially treated chromatographic columns and detected refractometrically. This is necessary because alkyl sulfosuccinates show only small absorption in the UV-visible region no sensitive photometric detection can be obtained. Separation problems can arise when common steel columns filled with reverse phase material (or sometimes silica gel) are used. This problem can be solved by adding a suitable counterion (e.g., tetrabutylammonium) to the mobile phase ( ion pair chromatography ). This way it is possible to get good separation performance. For an explanation of separation mechanism see Ref. 65-67. A broad review of the whole method and its possibilities in use is given in an excellent monograph [68]. 

Boraiko C, Yoder R, Cooper J, Lieckfield R Jr, Remski M (2004) Sampling and analysis of butyltin compounds in air using gas chromatography and flame photometric detection. Journai of Occupational and Environmental Hygiene, 1 (1 ) 50-56. 

Jiang GB, Xu FZ, Zhang FJ (1999) Dioctyltin and tributyltin detection at trace levels in water and beverages by capillary gas chromatography with flame photometric detection. Fresenius Journal of Analytical Chemistry, 363(3) 256-260. 

Liu JM, Jiang GB, Zhou QF (2001) Comprehensive trace-ievei determination of methyitin compounds in aqueous sampies by cryogenic purge-and-trap gas chromatography with fiame photometric detection. Analytical Sciences, 7(11) 1279-1283. 

Baynes RE, Bowen JM. 1995. Rapid determination of methyl parathion and methyl paraoxon in milk by gas chromatography with solid-phase extraction and flame photometric detection. J Assoc Off Anal Chem 78 812-815. 

Stan H-J, Mrowetz D. 1983. Residue analysis of organophosphorus pesticides in food with 2-dimensional gas chromatography using capillary columns and flame photometric detection. J High Resol Chromatog Chromatog Comm 6 255-263. 

Each sample was fortified with chlorpyrifos, as a reference standard, to determine the recovery during each extraction. Three portions of solvent were used, and the combined extract for each sample was dried with sodium sulfate. Analyses employed gas chromatography/flame photometric detection. Limits of detection for vegetation and animal tissues were 0.2 and 0.007 pg respectively. Recoveries from fortified samples were 82%. Diazoxon occurrence was infrequenf and at trace concentrations. 

In multi-residue analysis, an analyte is identified by its relative retention time, e.g., relative to aldrin when using ECD or relative to parathion or chlorpyrifos when using a flame photometric detection (FPD) and NPD. Such relative retention times are taken from corresponding lists for the columns used. Further evidence for the identity of an analyte is provided by the selectivity of the different detectors (Modules D1 to D3), by its elution behavior during column chromatography (Modules Cl and C2) and in some cases even by the peak form in a gas chromatogram. In a specific analysis for only some individual analytes, their retention times are compared directly with the corresponding retention times of the analytes from standard solutions. 

Oxime carbamates are not directly amenable to gas chromatography (GC) because of their high thermal instability, which often leads to their breakdown at the injection port or in the column during analysis. Analysis of oxime carbamates by GC with sulfur detection or flame photometric detection involves oxidation of the intact insecticides or alkaline hydrolysis to form the more volatile but stable oxime compound. Enzymatic techniques have been reported for the analysis of these compounds. Enzyme-linked immunosorbent assay (ELISA) has been used to determine aldicarb and its sulfone and sulfoxide metabolites and methomyl in water, soil, and sediment samples. 

AFID = alkali-flame ionization detection FID = flame ionization detection FPD = flame photometric detection GC = gas chromatography IGEFET = interdigitated gate electrode field-effect transistor ITMS = ion trap mass spectrometry MIMS = multiphoton ionization mass spectrometry MS = mass spectrometry... 

Sass S, Parker GA. 1980. Structure-response relationship of gas chromatography-flame photometric detection to some organophosphorus compounds. J Chromatogr 189(3) 331-349. 

AAS = atomic absorption spectroscopy CdS04 = cadmium sulfate GC/ECD = electrochemical gas chromatographic detection GC/FPD = gas chromatography with flame photometric detection HC1 = hydrochloric acid H2S = hydrogen sulfide NaOH = sodium hydroxide NR = not reported PAS = photoacoustic spectroscopy... 

Radford-Knoery J, Cutter GA. 1993. Determination of carbonyl sulfide and hydrogen sulfide species in natural waters using specialized collection procedures and gas chromatography with flame photometric detection. Anal Chem 65 976-982. 

Garra and Muth [80] and Wasik and Brown [81] characterised crude, semi-refined, and refined oils by gas chromatography. Separation followed by dualresponse detection (flame ionisation for hydrocarbons and flame photometric detection for S-containing compounds) was used as a basis for identifying oil samples. By examination of chromatograms, it was shown that refinery... 

Valkirs et al. [105] have conducted an interlaboratory comparison or determinations of di- and tributyltin species in marine and estuarine waters using two methods, namely hydride generation with atomic absorption detection and gas chromatography with flame photometric detection. Good agreement was obtained between the results of the two methods. Studies on the effect of storing frozen samples prior to analysis showed that samples could be stored in polycarbonate containers at - 20 °C for 2 - 3 months without significant loss of tributyltin. 

DAGAN, S., Comparison of gas chromatography-pulsed flame photometric detection-mass spectrometry, automated mass spectral deconvolution and identification system and gas chromatography-tandem mass spectrometry as tools for trace level detection and identification, J. Chromatogr., A., 2000,868,229-247. 

Owing to the short path length, the sensitivity of photometric detection in CE is limited. For this reason, procedures are necessary to enhance the sensitivity. This can be achieved by sample pre-concentration, improvement of the optical design and/or alternative capillary geometries [66]. Sample pre-concentration can be done off- or on-column. The off-column procedures are well described in the literature and have been applied extensively in chromatography [67]. The on-column procedures are more specific to CE and are therefore briefly discussed. 

Muller [76] has described a gas chromatographic method for the determination of tributyltin compounds in sediments. The tributyltin compounds are first converted to tributylmethyltin by reaction with ethyl magnesium bromide, and then analysed using capillary gas chromatography with flame photometric detection and gas chromatography-mass spectrometry. Tributyltin was found in samples of sediment and these results demonstrated that the technique has detection limits of less than 0.5pg L 1. 

GC = gas chromatography FPD = flame photometric detection MS = mass spectrometry SIM = selected ion moni tori ng... 

AFID = alkali flame ionization detector ECD = Electron capture detection EPA = Environmental Protection Agency FPD = flame photometric detection GC = gas chromatography GPC = gel permeation chromatography HRGC = high resolution gas chromatography NPD = nitrogen- phosphorus detection SPE = solid phase extraction device... 

Chromatographic systems have one thing in common most depend on spectro-photometric detection devices, i.e., ultraviolet (UV), visible, fluorescent, and midrange infrared (MIR) spectrometers. High-performance liquid chromatography (HPLC) has been used to, in essence, purify (separate) the constituents from the matrix, then introduce them to a spectrometer for identification or quantification. One reason that spectrometers were not placed in a production setting... 

Miyahara M, Suzuki T, Saito Y. 1992. Multiresidue method for some pesticides in lanolin by capillary gas chromatography with detection by electron capture, flame photometric, mass spectrometric, and atomic emission techniques. J Agric Fd Chem 40 64-69. 

M De Paoli, TM Barbina, R Mondini, A Pezzoni, A Valentino. Determination of organophosphorus pesticides in fruits by on-line size-exclusion chromatography-liquid chromatography-gas chromatography-flame photometric detection. J Chromatogr 626 145-150, 1992. 

Clark and Lesage [76] have described a method for the determination of elemental sulfur in soils using gas chromatography with flame photometric detection after the sulfur is reacted to form Ph3PS. 

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