High performance liquid chromatography extraction procedures

Unfortunately, the dose-survival times for the DSP toxins in the mouse assay fluctuate considerably and fatty acids interfere with the assay, giving false-positive results consequently, a suckling mouse assay that has been developed and used for control of DSP measures fluid accumulation after injection of the shellfish extract. Considerable effort has been applied recently to development of chemical assays to replace these bioassays. As a result a good high performance liquid chromatography (HPLC) procedure has been developed to identify individual PSP toxins (detection limit for saxitoxin = 20 fg per 100 g of meats 0.2 ppm), an excellent HPLC procedure (detection limit for okadaic acid = 400 ngg 0.4 ppm), a commercially available immunoassay (detection limit for okadaic acid=lfg per 100 g of meats 0.01 ppm) for DSP, and a totally satisfactory HPLC procedure for ASP (detection limit for domoic acid = 750 ngg 0.75 ppm). 

High performance liquid chromatography (HPLC) has been by far the most important method for separating chlorophylls. Open column chromatography and thin layer chromatography are still used for clean-up procedures to isolate and separate carotenoids and other lipids from chlorophylls and for preparative applications, but both are losing importance for analytical purposes due to their low resolution and have been replaced by more effective techniques like solid phase, supercritical fluid extraction and counter current chromatography. The whole analysis should be as brief as possible, since each additional step is a potential source of epimers and allomers. 

Residue analytical methods for neonicotinoids in crops, soil and water samples have been developed. The basic principle of these methods consists of the following steps extraction of the crop and/or soil samples with acetone or the other organic solvent, cleanup by liquid-liquid partition or column chromatography, and quantitative analysis by high-performance liquid chromatography with ultraviolet detection (HPLC/UV). Simple column cleanup procedures are used to improve the accuracy and sensitivity of these methods. 

Dye identification is of great interest in textile studies. The classical procedure requires a hydrolysis step and other extraction techniques, followed by identification of the individual compounds present after separation by a chromatographic technique, e.g. high-performance liquid chromatography [Novotna et al. 1999, Szostek et al. 2003]. However, ToF-SIMS can be an alternative method, avoiding the phase of extraction which is always a time consuming and delicate step because of the possible destruction of the molecular structure of the sample [Ferreira et al. 2002]. The development of ToF-SIMS for dye detection has been reported in different studies. 

Brown and Rhead [307] improved the sensitivity of high-performance liquid chromatography to 0.2 xg/l. This procedure consists ofbromination, extraction of the a, /i-dibromopropionamide with ethyl acetate, and quantification using high-performance liquid chromatography with ultraviolet detection. Samples... 

A.V. Loskutov, C.W. Beninger, G.L. Hosfield and K.C. Sink, Development of an improved procedure for extraction and quantitation of safranal in stigmas of Crocus sativus L. using high performance liquid chromatography. Food Chem. 69 (2000) 87-95. 

C. Sottani, R. Turci, L. Peibellini and C. Minoia, Liquid-liquid extraction procedure for trace determination of cyclophosphamide in human urine by high-performance liquid chromatography tandem mass spectrometry. Rapid Communications in Mass Spectrometry RCM 12(16), 1063-1068. 1998. 

The reaction of sulfite with formaldehyde to form hydroxymethylsulfonate (HMS), which is very stable under the controlled conditions of this assay, was used as the first step in an analytical procedure to determine food-borne sulfite. The effect of mobile-phase pH on the stability of HMS during high-performance liquid chromatography was studied. It was found that on-column HMS dissociation to formaldehyde and bisulfite increased with the pH of the mobile phase therefore the relatively low pH 4.7, at which the dissociation of HMS was approximately 2%, was selected for the analysis. In addition, the release of sulfite from its reversibly bound forms in wine and other foods was examined as a function of the pH of the extraction medium by following the appearance of HMS formed from the reaction of the freed sulfite with formaldehyde. The rate of dissociation of the reversibly bound sulfite was relatively slow at pH 3 but very rapid at pH 7. 

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