Flame photometric detector, volatile

In the case of crop residues, GC determination is carried out on the hydrolyzed product, i.e., methomyl oxime, instead of alanycarb to make effective use of its substantially higher response to the flame photometric detector. In order to prevent vaporization loss of methomyl oxime, ethylene glycol must be added prior to concentration in Section 6.3. In all other concentration operations, full account must also be taken of the high volatility of both alanycarb and methomyl oxime, especially in the process of removal of the last traces of solvents. Alanycarb residue in the sample is stable under storage condition at -20 °C for at least 100 days. 

The analysis of organosulphur compounds has been greatly facilitated by the flame photometric detector [2], Volatile compounds can be separated by a glass capillary chromatographic column and the effluent split to a flame ionization detector and a flame photometric detector. The flame photometric detector response is proportional to [S2] [3-6]. The selectivity and enhanced sensitivity of the flame photometric detector for sulphur permits quantitation of organosulphur compounds at relatively low concentrations in complex organic mixtures. The flame ionization detector trace allows the organosulphur compounds to be referenced to the more abundant aliphatic and/or polynuclear aromatic hydrocarbons. 

Organochlorine pesticides and OPPs have been determined mainly using GC, because of the stability and volatility that most of them show under chromatographic conditions and, particularly, the availability of element-selective detectors that display high selectivity for OCPs (electron-capture detector, ECD), and OPPs (flame photometric detector, FPD, and nitrogen phosphorus detector, NPD). Mass spectrometry-based detection is also more popular in GC than in HPLC (1,2,12,16). 

Lamkin et al. [276] studied in detail the GC analysis of silylated methylthiohydantoins of all protein amino acids. They effected the silylation with BSA-acetonitrile (1 3) at 100°C for 10 min. They separated the products in a simple column packed with 2% of OV-17 on Gas-Chrom Q at 145—230°C, and Fig. 5.20 illustrates the results. The authors used a flame photometric detector, sensitive to sulphur-containing compounds, in order to ensure sensitive and selective detection. Minor incidental peaks that were often noticed during the analysis of the samples obtained by the Edman degradation of proteins with the use of an FID did not appear and the peak of the solvent was not detected. The baseline stability was good and the response was linear over a range of two orders of magnitude of concentration. Asn and Phe were the only unresolved pair Arg, as in previous instances, did not form a volatile derivative. 

Jiemin, L., Ning, L., Meijuan, W., Guibin, J. Determination of volatile sulfur compounds in beverage and coffee samples by purge-and-trap on-line coupling with a gas chromatography-flame photometric detector. Microchim. Acta 148, 43 7 (2004)... 

Stevens, R.K., O Keefe, A.E. and Oilman, G.C., 1969. Absolute calibration of a flame photometric detector to volatile sulphur compounds at sub-parts per million levels. Env. Sci. Tech., 3 652-655. 

The use of the flame photometric detector in the sulfur-sensitive mode (attributed to the emission of S2 spectral species at 394 nm) is exemplified in measuring the sulfur-containing volatiles in physiological fluids [110], or breath of liver-disease patients [111]. A word of caution concerns the fact that co-eluting non-sulfur compounds may result in a diminished or quenched response of the measured species [112]. Hence, the need for maximum solute separation. The detector is responsive to nanogram amounts of sulfur-containing compounds, but the response increases with the square of sulfur content [112]. Merits of the flame photometric detector in the detection of phosphorus compounds is somewhat overshadowed by a similar capability of the thermionic detector. 

The analysis of volatile sulphur compounds is difficult as additional compounds may be formed if the sample is heated or exposed to light or oxygen. Headspace analysis by gas-liquid chromatography using a flame photometric detector is the most satisfactory technique although solvent extraction may be necessary for the less volatile compounds. The sulphur compounds which have been identified in beer are listed in Table 22.19. 

Volatile and aromatic components Separation of volatile components is achieved on either fused silica capillary columns or packed columns. Individual volatile components are detected with a FID and identified by the use of reference standards. Methods using specific detectors, such as the NPD, sulfur-specific flame photometric detector, and mass-selective detector (MSD) have also been used. The MSD has the additional advantage of providing structural identification of the individual components. 

GC offers excellent chromatographic resolution and can be coupled to a range of appropriate detectors for organotin detection such as MS, ICP-MS, atomic emission (AED), AAS, and flame photometric detectors (FPD). The main problem with GC is the low volatility of all organotin species except in the tetra-organotin forms. This means that a derivatization step is required prior to GC analysis. This typically involves alkylation of the sample. GC columns, which have been employed for organotin analysis are typically nonpolar PDMS fused silica columns such as HP-1 or the 5% phenyl equivalents such as HP-5. 

Sulfur compounds play a major role in determining the flavor and odor characteristics of many food substances. Often sulfur compounds are present in trace levels in foods making their isolation and quantification very difficult for chromatographers. This study compares three gas chromatographic detectors the flame photometric detector, sulfur chemiluminescence detector and the atomic emission detector, for the analysis of volatile sulfur compounds in foods. The atomic emission detector showed the most linearity in its response to sulfur the upper limit of the linear dynamic range for the atomic emission detector was 6 to 8 times greater than the other two detectors. The atomic emission detector had the greatest sensitivity to the sulfur compounds with minimum detectable levels as low as 1 pg. 

The SPTD was reprogrammed to send a start signal to the GC at the beginning of the desorption. A 60 m, 0.75 nun I.D., 5% phenyl, 95% dimethyl siloxane capillary column was cooled to 1°C to cryofocus the desorbed meat volatiles. The initial temperature was held at 1 C during the desorption 5 min period and then ramped to 150°C at 5°C per min. The temperature ramp was then increased to 250° C at 10° C per min. The effluent from the capillary was split to allow simultaneous detection of carbonyls by a flame ionization detector (FID) and the sulfur-containing components via a flame photometric detector (FPD). 

Crespo et a/. [18]. Mycobacterium avium and Mycobacterium kansasii, and a non-pathogenic fast growing species, Mycobacterium smegmatis, in Middlebrook M7H9 culturing media were followed online. To aid in the identification volatiles were collected in Tenax tubes and analysed with a gas chromatograph equipped with a flame photometric detector. Identification of VOCs was also based on isotopic ratios and CID results. 

Aroma of muskmelon, sulfur volatile sensory evaluation by GC-olfactometry, 36-47 Aroma threshold, determination, 81 Aroma volatiles in meat, sulfur-containing, See Sulfur-containing aroma volatiles in meat Artifacts, sulfur compounds in foods, 3 Atomic emission detector comparison to flame photometric and sulfur chemiluminescence detectors, 17,21... 

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