Additives, determination chromatography , with mass

Determination of trichothecenes in duplicate diets of young children by capillary gas chromatography with mass spectrometric detection. Food Additives and Contaminants, Vol. 22, No. 1, (January 2005), 48-55, ISSN 0265-203X. 

In addition, HPLC coupled with mass spectrometry (HPLC-MS) has been widely utilized for the analysis of folate. Liquid chromatography-tandem mass spectroscopic (LC-MS/MS) determination of pABA released by the acid hydrolysis of erythrocyte folates was previously described (Clifford et al. 2005), in which [ Cg]pABA was used as internal standard and derivatization of pABA with diazomethane was performed prior to analysis. 

Food Additives and Contaminants 15, No.3, 1st April 1998, p.346-54 PARTS-PER-TRILLION DETERMINATION OF STYRENE IN YOGHURT BY PURGE-AND-TRAP GAS CHROMATOGRAPHY WITH MASS SPECTROMETRY DETECTION Nerin C Rubio C Cacho J Salafranca J Zaragoza,University... 

Karasek et al. [1] determined hydrocarbons in benzene water extracts (pH7) of soil and in incinerator or fly ash by a variety of techniques including gas chromatography with flame ionization, electron capture and mass spectrometric detectors. Benzene water extractants were adjusted to pH4, 7 and 10 before the extraction in order to selectively extract various types of acidic and basic organic compounds in addition to hydrocarbons. 

Tan [71] devised a rapid simple sample preparation technique for analysing polyaromatic hydrocarbons in sediments. Polyaromatic hydrocarbons are removed from the sediment by ultrasonic extraction and isolated by solvent partition and silica gel column chromatography. The sulphur removal step is combined into the ultrasonic extraction procedure. Identification of polyaromatic hydrocarbon is carried by gas chromatography alone and in conjunction with mass spectrometry. Quantitative determination is achieved by addition of known amounts of standard compounds using flame ionization and multiple ion detectors. 

Structure elucidation of semiochemicals by modern NMR-techniques (including HPLC/NMR) is often hampered by the very small amounts of available material and problems in the isolation of pure compounds from the complex mixtures they are embedded in. Thus, the combination of gas chromatography and mass spectrometry, GC/MS, is frequently the method of choice. Determination of the molecular mass of the target compound (by chemical ionisation) and its atomic composition (by high resolution mass spectrometry) as well as a careful use of MS-Ubraries (mass spectra of beetle pheromones and their fragmentation pattern have been described [27]) and gas chromatographic retention indices will certainly facihtate the identification procedure. In addition, the combination of gas chromatography with Fourier-transform infrared spec-... 

In addition to food analysis, the environment is monitored to measure the degree of contamination that might be caused by the use of pesticides. These projects entail sampling of wild life, water sources, and soils. Wealthy countries can utilize highly sophisticated and expensive equipment, such as gas chromatography coupled with mass spectrometry, for residue determination and identification. However, since there is inter-... 

Size-exclusion chromatography has been recently applied, with success, to the analysis of biopolymers derived from biomass, as it is used for the determination of molecular mass distributions of polymeric compounds in general, because of its short analysis time, high reproducibility, and accuracy. This application of SEC has permitted the separation and further detection of polymeric and monomeric residues of biopolymers, as well as the estimation of the degree of polymerization and eventual uses of namral products as additives, not only in... 

The vahdity of assay results is best proved by tests for parallelism of the response curves for both calibrators and randomly selected samples from male and female subjects of various ages. In addition, comparison of extraction/ chromatography immunoassays should be validated by comparison with mass spectrometry methods. Direct immunoassays should not be used for female and prepubertal subjects, especially infants. These groups should be tested using an extraction immunoassay or an LC-MS/MS assay. It is important to note that both types of direct immunoassay demonstrate problems with functional sensitivity for low concentrations. Each lab should determine the low-end detection limit of their assay despite manufacturer claims. 

Zheng, B., Hinlelmann, H. Hyphenation of high performance liquid chromatography with sector field inductively coupled plasma mass spectrometry for the determination of ultra-trace level anionic and cationic arsenic compounds in freshwater fish. J Anal At Spectrom 2004,19, 191-195. Pergantis, S. A., Heithmar, E. M., Hinners, T. A. Speciation of arsenic animal feed additives by microbore high-performance liquid chromatography with inductively coupled plasma mass spectrometry. Analyst 1997, 122, 1063-1068. 

The method of analysis for the final determination of the seven CB congeners used by each of the participating laboratories was based on capillary gas chromatography with electron capture detection. In addition, mass spectrometry was used for compound identification and confirmation, but not for quantification. Each laboratory used their own proven procedures for the sample preparation, clean-up, method of injection, choice of carrier gas and chromatographic condition. The fish oils were dissolved in an appropriate solvent and analysed without any preliminary extraction from the matrix. 

Each laboratory was given a free choice of extraction, clean-up and conditions for the final determination. The latter, gas chromatography with high-resolution mass spectrometry, included choice of injection, capillary columns, ion masses monitored etc. [34]. In addition to the CRM, the participants received a calibrant solution containing the PCDDs/PCDFs of interest for this project as a control for their calibration procedure. 

The final determination of the CBs was performed by capillary gas chromatography with electron capture detection mass spectrometry was used as complementary technique to confirm the identity of each of the CBs determined. Each participant had validated its method by performing experiments on recovery, extraction efficiency, procedure blanks and detector linearity. The seven individual CB calibrants were supplied to the participants as pure, crystalline CRMs from BCR (CRMs Nos. 291,293, 294,295, 296. 297 and 298). Each laboratory was requested to prepare separate calibration solutions of the appropriate concentration, in iso-octane, to calibrate the detector and lying within its linear range. The use of at least one internal standard was mandatory the participants, however, were left free to select the internal standard(s) best suited to their methods. They had to verify that the selected compounds did not occur in the candidate reference material or did not interfere with compounds present in the material. A series of pure dichlorobenzylalkyl ethers (DCBEs) was made available to the participants but other internal standards were also accepted of which the list is given in the certification report [21] along with additional details on calibration procedures. 

---