Solid phase extraction cartridges for

A new technique has been developed to analyze a- and (3-endosulfan concentrations in human urine (Vidal et al. 1998). Samples are mixed with a buffer solution and then passed through solid phase extraction cartridges for analysis using gas chromatography-tandem mass spectrometry (GC-MS-MS). 

Other techniques to improve throughput are instrumentation based and may involve multiple HPLC systems. The simplest method involves the automated use of solid phase extraction cartridges for sample cleanup followed by direct injection into the mass spectrometer [114], Coupling of multiple HPLC systems to one mass spectrometer allows one column to equilibrate and separate while another column to flow into the mass spectrometer. Multiple HPLC systems may be configured such that the mass spectrometer is only exposed to each serial HPLC eluent as the analyte of interest is eluted [115,116]. Although multiple H P LC-based methods may increase throughput, they also typically decrease sensitivity and may confound data workup and interpretation. 

Andres, J. V., Falc6, P. C., and Hernandez, R. H., Determination of aliphatic amines in water by liquid chromatography using solid-phase extraction cartridges for preconcentration and derivatization, Analyst, 126, 1683-1689, 2001. 

F]fluorobenzaldehyde ([ F]FBA) was prepared within about 30 min in preparative yields of about 50% using solid-phase extraction cartridges for purification. Conjugation of various oxyamine acetate conjugated peptides ( Figs. 42.25 and O 42.26) was carried out in H20/MeOH (pH 2) in 60-80% yield (10 min) and peptide concentrations of 0.5 mm. 

Betalains are vacuolar plant pigments. Hence their hydrophilic nature is comprehensible. Although they are slightly soluble in ethanol and methanol, water is the best snited solvent both for stability and solnbility reasons. In contrast to the antho-cyanins, the betalains are even more polar as can be demonstrated by shorter retention times in RP-HPLC and lower solubilities in alcoholic solutions. The varying polarities may also be beneficially used to separate anthocyanins from betalains on an RP-18 solid-phase extraction cartridge (Stintzing, unpublished data). 

Abu Ruz S, Millership J, Heaney L, McElnay J. 2003. Simple liquid chromatography method for the rapid simultaneous determination of prednisolone and cortisol in plasma and urine using hydrophilic lipophilic balanced solid phase extraction cartridges. J Chromatogr B Biomed Sci Appl 798(2) 193-201. 

The volume of extract applied to the cartridge will depend mainly on sample quantity, its anthocyanin content, and the amount of sorbent packing in the column. Usually a sample volume of 5 to 10 ml is used for a Cl 8 solid-phase extraction cartridge containing 360 mg sorbent. 

C Crescenzi, A Di Corcia, G Passariello, R Samperi, Ml Turnes. Evaluation of two new examples of graphitized carbon blacks for use in solid-phase extraction cartridges. J Chromatogr A 733 41-55, 1996. 

When colours are added to a food system, their characterisation is often more difficult due to interferences from other materials in the food or difficulty with their extraction from the food. This is particularly the case for high-protein foods, which bind colours very tightly and can make their quantitative analysis very difficult. However, analysis for azo-dyes in soft drinks is generally straightforward using modern methods. There is less interference than in other food systems and as the colours are already in solution, and not bound to other materials, this makes the analysis easier. In some cases, the colours can be analysed without prior concentration and in others they have to be concentrated by solid-phase extraction methods, for example, Ci8 cartridges followed by elution with a small volume of methanolic ammonia. 

Chlorinated [407,408] and 2,4-dinitrophenoxy acid herbicides [409] have been determined. liquid chromatography particle beam mass spectrometry has been used as an analytical finish [408]. Crescenzi et al. [410] evaluated the feasibility of selectively and rapidly extracting herbicide residues in soils by hot water and collecting analytes with a Carbograph 4 solid-phase extraction cartridge set on-line with the extraction cell. Phenoxy acid herbicides and those non-acidic and acidic herbicides that are often used in combination with phenoxy acids were selected for this study. Five soil samples were... 

Orlando and Bonato [73] presented a practical and selective HPLC method for the separation and quantification of omeprazole enantiomers in human plasma. Ci8 solid-phase extraction cartridges were used to extract the enantiomers from plasma samples and the chiral separation was carried out on a Chiralpak AD column protected with a CN guard column, using ethanol-hexane (70 30) as the mobile phase, at a flow-rate of 0.5 ml/min. The detection was carried out at 302 nm. The method is linear in the range of 10-1000 ng/ml for each enantiomer, with a quantification limit of 5 ng/ml. Precision and accuracy, demonstrated by within-day and between-day assays, were lower than 10%. 

For certain procedures, a picture or illustration may be helpful. Accessories and Supplies A listing of all nonroutine items, such as the special filters, low-actinic autosampler vials, or solid-phase extraction cartridges required. 

The solvent extracts can be cleaned up by traditional column chromatography or by solid-phase extraction cartridges. This is a common cleanup method that is widely used in biological, clinical, and environmental sample preparation. More details are presented in Chapter 2. Some examples include the cleanup of pesticide residues and chlorinated hydrocarbons, the separation of nitrogen compounds from hydrocarbons, the separation of aromatic compounds from an aliphatic-aromatic mixture, and similar applications for use with fats, oils, and waxes. This approach provides efficient cleanup of steroids, esters, ketones, glycerides, alkaloids, and carbohydrates as well. Cations, anions, metals, and inorganic compounds are also candidates for this method [7],... 

Heymann, et al (24) have used solid phase extraction techniques for the isolation of pyrazines from wines. In this analysis, it was necessary to first distill the pyrazines from the wine and then pass the distillate through a Sep-Pak C-18 cartridge (Waters Assoc.). To speed the analysis, the distillate was forced through the cartridge at a rate of 30 ml/min. 

Sarin and soman have been shown to bind to a tyrosine residue present in a blood protein (51). The precise site of this residue has not yet been confirmed but it is associated with the albumin fraction. An LC/ESI/MS/MS (triple quadrupole) method was developed for its detection after digestion of the albumin fraction with Pronase and clean up on a C18 SPE (solid-phase extraction) cartridge. A... 

DEC and the internal standard (Istd), 1-diethylcar-bamyl-4-ethyl piperazine HC1 (E-DEC), were extracted from human plasma - that has been alkalised with carbonate buffer - after loading onto a conditioned Cl8 solid phase extraction cartridge, rinsed with water and eluted with methanol. After evaporation under a stream of nitrogen and reconstitution in methanol, 3 il. were injected into the GC system and detected using a flame ionization detector (FID). The retention time for DEC was 5.5 min and for the internal standard (E-DEC) it was 7.28 min. 

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