Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

MS Detection

Eatty acids from commercial fats and oils, such as peanut oil, are extracted with methanolic NaOH and made volatile by derivatizing with a solution of methanol/BE3. Separations are carried out using a capillary 5% phenylmethyl silicone column with MS detection. By searching the associated spectral library students are able to identify the fatty acids present in their sample. Quantitative analysis is by external standards. [Pg.611]

The liquid chromatography - tandem mass spectrometry (LC/MS/MS) technique was proposed for the determination of corticosteroids in plasma and cerebrospinal fluid (CSF, liquor) of children with leucosis. Preliminai y sample prepai ation included the sedimentation of proteins, spinning and solid-phase extraction. MS detection was performed by scanning selected ions, with three chai acteristic ions for every corticosteroids. The limit of detection was found 80 pg/ml of plasma. [Pg.351]

In a study by Stresser and co-workers, the effect on tumor modulation by 227 has been investigated. HPLC on liver extracts from Fisher 344 rats revealed two major compounds, 3,3 -bisindolylmefliane (133) and a linear trimer, together with a < l(KX)-fold lower content of 4 in comparison with the two major substances. The HPLC isolate was derivatized with /V-methyl-/V-bis(trifluoroacetamide) that, upon MS detection, gave a compound identical to /V,W -ditrifluoroacetylindolo-[3,2-()]carbazole. The content of 4 in this system was estimated to be 0.(XKX)13% of the total dose of 227 given. Thus, it was concluded that the beneficial effect of oral distribution of 227 is due to the total content of derivatives formed (95MI5). [Pg.51]

One field study on the mass flow of secondary alkanesulfonates was conducted in the Zurich-Glatt municipal wastewater treatment plant [37]. The concentration of alkanesulfonates in samples of raw sewage and primary and secondary effluents was analyzed using the above-described SPE with C18 Empore disks and injection port derivatization with GC-MS detection. The con-... [Pg.174]

Table 5.2 Selected-reaction monitoring (SRM) transitions nsed for MS-MS detection of the pesticides studied in the systematic investigations on APCI-MS signal response dependence on eluent flow rate. Reprinted from J. Chro-matogr.. A, 937, Asperger, A., Efer, J., Koal, T. and Enge-wald, W., On the signal response of various pesticides in electrospray and atmospheric pressure chemical ionization depending on the flow rate of eluent applied in liquid chromatography-mass spectrometry , 65-72, Copyright (2001), with permission from Elsevier Science... Table 5.2 Selected-reaction monitoring (SRM) transitions nsed for MS-MS detection of the pesticides studied in the systematic investigations on APCI-MS signal response dependence on eluent flow rate. Reprinted from J. Chro-matogr.. A, 937, Asperger, A., Efer, J., Koal, T. and Enge-wald, W., On the signal response of various pesticides in electrospray and atmospheric pressure chemical ionization depending on the flow rate of eluent applied in liquid chromatography-mass spectrometry , 65-72, Copyright (2001), with permission from Elsevier Science...
Paganga, G. et al.. The polyphenolic content of fruit and vegetables and their antioxidant activities what does a serving constitute Free Radical Res., 30, 153, 1999. Maatta, K.R. et al.. High-performance liquid chromatography (HPLC) analysis of phenolic compounds in berries with diode array and electrospray ionization mass spectrometric (MS) detection Rihes species, J. Agric. Food Chem., 51, 6736, 2003. [Pg.84]

Lopes-Da-Silva, E. et al.. Identification of anthocyanin pigments in strawherry (cv Camarosa) hy LC using DAD and ESI-MS detection, Eur. Food Res. Technol., 214, 248, 2002. [Pg.505]

Detection UV detection represents the less expensive and the most widespread approach but is limited to analytes possessing chromophoric moieties. When the analyhcal cost is not an issue, MS detection should be used preferentially because of its quasi-universaUty and selectivity. [Pg.347]

Hintelmann H, Falter R, Ilgen G and Evans RD (1997) Determination of artifactual formation of monomethylmercury (CHsHg ) in environmental samples using stable Hg isotopes with ICP-MS detection calculation of contents applying species specific isotope addition. Fresenius J Anal Chem 358 363-370. [Pg.253]

A number of biochemical markers not associated with the cell envelope allow the specific detection of individual microorganisms in environmental samples. These include secondary alcohols. For example, Mycobacterium xenopi can be detected through the hydrolysis of wax ester mycolates, which liberates 2-docosanol, a characteristic and dominant secondary alcohol, which can be detected at low levels by GC-MS. This biomarker was found to be very useful for the rapid detection of M. xenopi in drinking water (159,160). Results from the GC-MS detection of 2-docosanol were obtained within 2 days compared to the 12 weeks required for culturable detection of M. xenopi. The detection limit for this type of approach was found to be 10 colony-forming units (CFU) ml" drinking water. [Pg.390]

Residue analytical chemistry has extended its scope in recent decades from the simple analysis of chlorinated, lipophilic, nonpolar, persistent insecticides - analyzed in the first Si02 fraction after the all-destroying sulfuric acid cleanup by a gas chro-matography/electron capture detection (GC/ECD) method that was sometimes too sensitive to provide linearity beyond the required final concentration - to the monitoring of polar, even ionic, hydrophilic pesticides with structures giving the chemist no useful feature other than the molecule itself, hopefully to be ionized and fragmented for MS or MS" detection. [Pg.59]

Thus, organic solvent extraction methods for the extraction of pesticides from water samples can be replaced by the SPE method using Ci8 and PS-2. Ethobenzanid, clomeprop, naproanilide and their acidic metabolites are determined by a multi-residue analytical method using Cig or PS-2 cartridge extraction after acidification of the water samples with hydrochloric acid or other acidic media, followed by HPLC or LC/MS detection. [Pg.340]

Crescenzi et al. developed a multi-residue method for pesticides including propanil in drinking water, river water and groundwater based on SPE and LC/MS detection. The recoveries of the pesticides by this method were >80%. Santos etal. developed an on-line SPE method followed by LC/PAD and LC/MS detection in a simultaneous method for anilides and two degradation products (4-chloro-2-methylphenol and 2,4-dichlorophenol) of acidic herbicides in estuarine water samples. To determine the major degradation product of propanil, 3,4-dichloroaniline, the positive ion mode is needed for atmospheric pressure chemical ionization mass spectrometry (APCI/MS) detection. The LOD of 3,4-dichloroaniline by APCI/MS was 0.1-0.02 ng mL for 50-mL water samples. [Pg.341]

All previous discussion has focused on sample preparation, i.e., removal of the targeted analyte(s) from the sample matrix, isolation of the analyte(s) from other co-extracted, undesirable sample components, and transfer of the analytes into a solvent suitable for final analysis. Over the years, numerous types of analytical instruments have been employed for this final analysis step as noted in the preceding text and Tables 3 and 4. Overall, GC and LC are the most often used analytical techniques, and modern GC and LC instrumentation coupled with mass spectrometry (MS) and tandem mass spectrometry (MS/MS) detection systems are currently the analytical techniques of choice. Methods relying on spectrophotometric detection and thin-layer chromatography (TLC) are now rarely employed, except perhaps for qualitative purposes. [Pg.439]

As with GC, the combination of MS and MS/MS detection with LC adds an important confirmatory dimension to the analysis. Thermospray (TSP) and particle beam (PB) were two of the earlier interfaces for coupling LC and MS, but insufficient fragmentation resulted in a lack of structural information when using TSP, and insufficient sensitivity and an inability to ionize nonvolatile sample components hampered applications using PB. Today, atmospheric pressure ionization (API) dominates the LC/MS field for many environmental applications. The three major variants of API... [Pg.441]

The most widely regarded approach to accomplish the determination of as many pesticides as possible in as few steps as possible is to use MS detection. MS is considered a universally selective detection method because MS detects all compounds independently of elemental composition and further separates the signal into mass spectral scans to provide a high degree of selectivity. Unlike GC with selective detectors, or even atomic emission detection (AED), GC/MS may provide acceptable confirmation of the identity of analytes without the need for further information. This reduces the need to re-inject a sample into a separate GC system (usually GC/MS) for pesticide confirmation. Through the use of selected ion monitoring (SIM), efficient ion-trap or quadrupole devices, and/or tandem mass spectrometry (MS/MS), modern GC/MS instruments provide LODs similar to or lower than those of selective detectors, depending on the analytes, methods, and detectors. [Pg.762]

MS detection does not necessarily require as highly resolved GC separations as in the case of selective detectors because the likelihood of an overlapping mass spectral peak among pesticides with the same retention time is less than the likelihood of an overlapping peak from the same element. Unfortunately, this advantage cannot always be optimized because SIM and current gas chromatography/tandem mass spectrometry (GC/MS/MS) methods, it is difficult to devise sequential SIM or MS/MS retention time windows to achieve fast GC separations for approximately > 50 analytes in a single method. [Pg.762]

As in HPLC, the coupling of MS detection with CE has provided an excellent opportunity for more selective analysis, but the much reduced flow rates, small injection volumes, limitations in the types of buffers used [since electrospray ionization (ESI) is used in capillary electrophoresis/mass spectrometry (CE/MS)], and need to... [Pg.781]

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. [Pg.1102]

HPLC and LC/MS. HPLC methodology coupled with ultraviolet (UV), fluorescence (FL), photodiode-array (PDA) and/or a mass spectrometry (MS) detection has been developed. In general, neonicotinoids can be determined by HPLC/UV. Typical HPLC operating conditions are given in Table 2. [Pg.1133]

The analytical methods summarized in this article are generally multiresidue methods for the determination of oxime carbamates in different sample matrices (crops, animal tissues, soil, and water). These methods include HPLC with fluorescence, MS, and MS/MS detection. [Pg.1146]

The purified sample extracts are concentrated and analyzed by reversed-phase HPLC with fluorescence, MS, or MS/MS detection as described in Sections 2.1 and 2.2. [Pg.1154]

Balogh, M.P and Li, J.B., HPLC Analysis of hypericin with photodiode-array and MS detection the advantages of multispectral techniques, LC-GC, 17(6), 558, 1999. [Pg.69]

Note that the interfacing of LC techniques with MS puts significant constraints on the solvents that can be used i.e., they must be volatile, with a low salt concentration, for MS compatibility. Narrow-bore columns, which use much smaller amounts of salt and organic modifier, appear to have potential for facilitating IEC-MS applications.40 Despite the excellent sensitivity of MS detection for most elements, however, there are cases where matrix effects can interfere. In this situation, combination of IEC with atomic emission spectrometry (AES) or atomic absorption spectrometry (AAS) may be preferable, and can also provide better precision.21 32 4142 Other types of... [Pg.288]


See other pages where MS Detection is mentioned: [Pg.103]    [Pg.229]    [Pg.265]    [Pg.280]    [Pg.334]    [Pg.335]    [Pg.422]    [Pg.178]    [Pg.271]    [Pg.438]    [Pg.204]    [Pg.345]    [Pg.345]    [Pg.345]    [Pg.57]    [Pg.346]    [Pg.401]    [Pg.644]    [Pg.740]    [Pg.764]    [Pg.1146]    [Pg.1161]    [Pg.59]    [Pg.288]    [Pg.398]    [Pg.433]   


SEARCH



CE-MS Detection

Coupling 2DLC with Online ESI-MS Detection

Detection in FT-ICR-MS

He MIP-MS detection of gas phase halogens

High-Throughput Sample Purification using MS-Detection

Inductively coupled plasma mass spectrometric ICP-MS) detection

MS detection enhancement factor

MS detection techniques

Mass spectrometric detection (MS)

Use of MS Detection

© 2024 chempedia.info