Caffeine capillary

Caffeine in coffee, tea, and soda is determined by a solid-phase microextraction using an uncoated silica fiber, followed by a GC analysis using a capillary SPB-5 column with an MS detector. Standard solutions are spiked with G3 caffeine as an internal standard. 

Conte, E. D. Barry, E. E. Rubinstein, H. Determination of Caffeine in Beverages by Capillary Zone Electrophoresis, ... 

Diet soft drinks contain appreciable quantities of aspartame, benzoic acid, and caffeine. What is the expected order of elution for these compounds in a capillary zone electrophoresis separation using a pH 9.4 buffer solution, given that aspartame has pJC values of 2.964 and 7.37, benzoic acid s pfQ is 4.2, and the pfQ for caffeine is less than 0. 

Capillary GC was used to obtain high resolution profiles of 27 organic acids, caffeine, and sucrose in dimethylsulphoxide extracts of roast and ground coffees in a 60-min analysis.26 A shortened procedure is also reported for quantitative detection of 5-caffeoylquinic (5-CQA) and quinic (QA) acids and sucrose ng detection limits were achieved. Major commer-... 

Hieda et al. determined theophylline, theobromine, and caffeine in human plasma and urine by gradient capillary HPLC with frit fast atom bombardment (FAB) mass spectrometry with 7-ethyl theophylline as the internal standard.64... 

Hurst, W.J. and Martin, R.A. Jr, The quantitative determination of caffeine in beverages using capillary electrophoresis analysis, 21,389-91,1993. 

Hyotylainen, T., Siren, H., and Riekkola, M.L., Determination of morphine analogues, caffeine and amphetamine in biological fluids by capillary electrophoresis with the marker technique, J, Chromatogr., 735,439,1996... 

C.C.T. Worth, M. Wiessler and O.J. Schmitz, Analysis of catechins and caffeine in tea extracts by capillary electrokinetic chromatography. Electrophoresis 21 (2000) 3634-3638. 

Fig. 3.138. Electropherogams showing the separation of caffeine (1), aspartame (2), brilliant blue FCF (3), green S (4), sorbic acid (5), benzoic acid (6), saccharin (7), acesulfame K (8), sunset yellow FCF (9), quinoline yellow (10), carmoisine (11), ponceau 4R (12), black PN (13), using 20 mM carbonate buffer, pH 9.5 containing (a) no SDS, (b) 50 mM SDS, (c) 75 mM SDS. A 48.5 X 50 /tm I.D. fused-silica capillary was used and absorbance was measured at 200 nm. Reprinted with permission from R. A. Frazier et al. [184],...

Methanol eluent (2 X 25 mL) Measure the volume and remove 5 mL for humics analyses. Concentrate the remainder to dryness and solvent exchange to methylene chloride to a final volume of 1.0 mL spike with 20 /xg of internal standard. Analyze this fraction by capillary GC-FID for all Group I compounds with special emphasis on caffeine. 

Selected ion monitoring mass chromatogram showing caffeine and caffeine-D3 eluted from a capillary gas chromatography column. [From D. W. Hill, B. T. McSharry, and L. S. Trzupek, Quantitative Analysis by Isotopic Dilution Using Mass Spectrometry." J. Chem. Ed. 1988, 65, 907.]... 

Aucamp JP, Hara Y and Apostolides Z, Simultaneous analysis of tea catechins, caffeine, gallic acid, theanine and ascorbic acid by micellar electrokinetic capillary chromatography. J Chromatogr A 876 235-242 (2000). 

Edder et al. reported the capillary supercritical fluid chromatography of basic drugs of abuse, namely nicotine, caffeine, methadone, cocaine, imipramine, codeine, diazepam, morphine, benzoylecgonine, papverine, narcotine, and strychnine [25]. They compared the separation of these drugs on DBS and DB wax columns. The chromatographic conditions included a carbon dioxide mobile phase and a flame-ionization detector. It was noted that on the DBS column, all peaks other than methadone and cocaine were separated. With the exception of benzoylecgonine and papaverine, all other peaks were separated on a DB wax column. A reproducibility of less than 5% was obtained with an internal standard method. The detection limits obtained were within 10-50 ppm on both the columns. A linearity of >0.99 was obtained for methadone, codeine, and morphine in the concentration range 10-1000 ppm. 

Fig. 3.6. Electrochromatogram of benzylamine (I), caffeine (II) and benzoic acid (III). Efficiency values of 4642, 76331, and 6399 plates per column were obtained respectively for I, II, and III. Electrochromatography was performed at 15°C with an applied voltage of 25 kV on a 25 cm, 100 pm i.d., 3 pm Hypersil Phenyl packed capillary. Mobile phase ACN-50 mM triethanolamine phosphate, pH 2.5-H20 (6 2 2 v/v/v). Sample concentration was 100 pg ml 1 of each component, 5 kV/5s injection. Detection at 214 nm. From [63]. Reproduced with permission of The Royal Society of Chemistry...

Take a melting point of your solid. First, scrape the caffeine from the bottom and sides of the flask with a microspatula and collect a sample of the solid in a capillary tube (review Experiment 15 for the technique). Pure caffeine melts at 238°C. Compare your melting point (6) to the literature value. 

A mixture of four fluoroquinolones (including ciprofloxacin hydrochloride) was determined by high performance capillary electrophoresis using caffeine as an internal standard [58], A portion of the solution was... 

Except for theophyllin, the solubilities are similar at a dissolution temperature (Td) and a dissolution pressure (Pd) of 65°C and 250bar, respectively, the mole fractions are of 2.5e-4 for anthracene, 5e-4 for caffeine and 6.5e-4 for salicylic acid. Theophyllin is an order of magnitude lower, with a value of 0.2e-4. The mole fractions allow one to estimate the maximum production rate for the experimental set up. Assuming a recovery of produced particles of 100%, and no dilution required for processing, the production rates are 1.0, 1.2, 0.5 and 0.04 g/h for caffeine, salicylic acid, anthracene and theophyllin, respectively (conditions Pd = 220bar, Td=65°C, capillary =1.5cm x 75pm flow rate of liquid C02=11.2ml/min)... 

Rodopoulos N, Norman A. Determination of caffeine and its metabolites in urine by high-performance hquid chromatography and capillary electrophoresis. Scand. J Clin Lab Invest 1994 54 305-15. 

Bohn et al.17 used glass capillary gas chromatography in investigations of illicit heroin samples and obtained good separation of heroin, 6-0-monoacetylmorphine, acetylcodeine and caffeine on a 12 m by 0.3 mm I.D. glass capillary coated with Triton X 303 (Merck) and temperature programming from 200°C to 250°C. 

Floberg et al. applied glass capillary gas chromatography for the analysis of theophylline and caffeine in plasma. The alkaloids were analyzed as such, or after derivatization. 

A number of heroin seizures in Munsterland (G.F.R.) were analyzed by Bohn et al. with glass capillary gas chromatography. With a 12 m long column by 0.3 mn I.D. coated with Triton X 350 and temperature programming (200-250°C) a good separation was obtained for heroin, 6-0-acetylmorphine, morphine, acetyl codeine, caffeine and the internal standard, dotriacon-tan. The heroin samples contained heroin (19.1-58.2 %), 6-0-acetylmorphine (1.0-7.3 %), acetylcodeine (2.4-9.8 %), caffeine (26.5-64.3 %) and strychnine (0-1.26 %). 

Glass capillary gas chromatography was used by Christophersen and Rasmussen also for heroin. Whereas morphine, codeine, mono-acetyl morphine and ethylmorphine were derivatized with N,0-bis(trimethylsilylJacetamide with flash heater derivatization, heroin was not derivatized, but it was well separated from the other compounds mentioned, as well as caffeine and strychnine, which were found in the heroin samples analyzed. 

In their publication on the gas chromatography of alkaloids on capillary columns, Massin-gill and Hodgkins11 also chromatographed caffeine. A 100 feet long capillary coated with... 

Christophersen and Rasmussen10 included caffeine in a study on glass capillary gas chromatography of narcotic drugs, using SE-30 as stationary phase and temperature programming up to 250°C. 

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