Mass spectrometry low-resolution

In this core, concentrations of PCBs (determined as Aroclor 1254 and 1260, by high resolution gas chromatography, electron capture detection and high resolution gas chromatography-low resolution mass spectrometry) were <30 ng and those of total DDT (p,p DDT + p,p DDD + p,p DDE) <5 ng g Campesan et al. (21) in 11 sediment samples from Valle di Brenta, determined by GC-ECD the following mean concentrations (ng gd.w.) ... 

P.C. Jurs, B.R. Kowalski and T.L. Isenhour, Computerized learning machines applied to chemical problems. Molecular formula determination from low resolution mass spectrometry. Anal. Chem., 41 (1969)21-27. 

Huber, J.F.K., Kenndler, E., Reich, G. (1979). Quantification of the information content of multi-dimensional gas chromatography and low resolution mass spectrometry in the identification of doping drugs. J. Chromatogr. 172, 15-30. 

Bay, Massachusetts. Gas liquid chromatography was used to detect hydrocarbons present at different depths in the sediment, while low resolution mass spectrometry was employed to measure concentrations of paraffins, cycloparaffins, aromatics and polynuclear aromatics. Their data show that the concentrations of total and saturated hydrocarbons decreased with increased depth, and it was noted that identification and quantification of hydrocarbons in oil-contaminated sediments is required if the fate of these compounds in dredge spills is to be determined. 

Gas chromatography Liquid chromatography Infrared spectrometry Low resolution mass spectrometry... 

Finally, low resolution mass spectrometry (LRMS) is applied to each separation fraction which exceeds a specified concentration when referred to the sample sources. The present levels are 0.5 fig/rn for gas streams, 1 mg/kg for solids, and 0.1 mg/1 for liquids. The selection of this particular technique, firmly in the middle of a transition between Levels 1 and 2, caused many philosophical problems concerning its proper use. The original Level 1 scheme did not contain LRMS. It has been included in the modified strategy to prevent potential triggering of Level 2 efforts based on large amounts of suspicious, but innocuous, oiganics. However, LRMS can be costly if constraints are not placed on how frequently it is applied. 

Additional analysis of these samples using the liquid chromatographic separation, total chromatographable organics, infrared, and low resolution mass spectrometry demonstrated that the sampling and analysis scheme produced reproducible data as shown in Table IV. 

Covaci A, de Boer J, Ryan JJ, et al. 2002. Determination of polybrominated diphenyl ethers and polychlorinated biphenyls in human adipose tissues by large-volume injection-narrow-bore capillary gas chromatograpy/electron impact low-resolution mass spectrometry. Anal Chem 74(4) 790-798. 

Detection of a spot at the right Rf value Detection of a spot at the intersection of Rf values Low-resolution mass spectrometry... 

Pyrolysis of Sodium-Tetramethylammonium Zeolite Omega. Preliminary calcinations of the Q zeolites showed that intracrystalline diffusion restrictions interfered greatly with transport both of oxygen and of calcination products. Under mild conditions, coking was observed, and even under favorable conditions (550° C, thin beds, good venting) the reaction was slow. Some samples of zeolite were pyrolyzed under vacuum, and the products were identified by low resolution mass spectrometry. 

Low Resolution Mass Spectrometry in Combination with the GLC—TMSi Method... 

The quantitation is performed by the internal standard method. The SIM response for the isomers at their primary characteristic m/z are compared against the internal standard(s). A detection limit in the range of 2 to 5 ppt (0.002 to 0.005 pg/L) can be achieved for aqueous samples concentrated as above and analyzed using low resolution mass spectrometry method. A lower detection limit in 0.01 to 1 ppt range may be achieved by HRMS technique. 

Smith RM, O Keefe PW, Hilker DR, et al. 1989. Ambient air and incinerator testing for chlorinated dibenzofurans and dioxins by low resolution mass spectrometry. Chemosphere 18 585-592. 

Gas chromatography-low resolution mass spectrometry was used to determine if TCDD is in the samples (12). The GC column used was a 6 ft. x 2 mm i.d. glass 2.5% BMBT liquid crystal on 100/120 mesh Chromosorb WHP (Altech Assoc.) at 225°C. In Figure 3 is shown the output from a standard and typical human milk extract run on an LKB-9000 with a SI-150 (System Industries) data system equipped with a computer controlled multiple ion detector (Ledland, Inc.). The entire extract was... 

Figure 3. Gas chromatography-low resolution mass spectrometry grams for 2,3,7,8-TCDD standard and human milk extract ((—...

Hummel, R. A., and Shadoff, L. A. (1980). Specificity of low resolution gas chromatography-low resolution mass spectrometry for the detection of tetrachlorobenzo-p-dioxin in environmental samples. Anal. Chem. 52, 191-192. 

In cases when congener-specific information is not necessary, other simpler methods can be used. EPA Methods 608 and 8082a use GC/ECD to determine the concentration of PCBs in terms of Aroclor (Federal Register, 1984 US EPA, 2007). EPA Method 680 (US EPA, 1985) uses GC/MS (low resolution mass spectrometry) to determine the homolog concentration of PCBs. 

PCDE analyses can be performed by high resolution gas chromatography (HRGC) combined with low resolution mass spectrometry (LRMS) or using HRGC combined with high resolution mass spectrometry (HRMS). For example, a Hewlett Packard 5970 mass selective detector system, which is a qua-drupole mass analyzer, has been used as an LRMS instrument in Finnish studies [33, 57, 113, 114, 122-125, 139]. Compared to LRMS, HRMS is more sensitive, allows less sample cleanup, and eliminates interference more effec-... 

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