Urine, buffering

Creatinine human serum/urine buffer dilution SEC... 

Fig. 17. (A) Reversed-phase HPLC isocratic separation of nucleosides in urine of colon cancer patient. (B) Reversed-phase HPLC isocratic separation of nucleosides in control urine. Sample 50 1 equivalent to 25/rl urine buffer 0.05. V/ NH4H2PO4, pH 5.10, with 50 ml methanol added per liter flow rate 1.0 ml/min detector 254 nm, 0.01 AUFS temperature 25°C. Reprinted with permission from Davis et al. (D2). Copyright by the American Association for Clinical Chemistry.

N-C Hj-morphine as internal standard. The internal standard was added to 10 ml urine, the urine buffered to pH 8.5 and extracted with chloroform isopropanol (4 1). The extraction residue was trimethylsilylated by adding 25 ul of N,0-bis(trimethylsilylJacetamide and heating at 60°C for about 1 h. About 2 ul was analyzed on a 3 % 0V-17 column at 230°C coupled direct to a Finnegan 1015 quadrupole mass spectrometer equipped with a chemical ionization source, which was operated at an ionizing energy of 100 eV, an ion repeller voltage of 0 V and a filament emission of 300 uA. The mass spectrometer was interfaced with a System Indus-... 

Mobile phase MeOH buffer 6 94 (serum) or 4 96 (urine) (Buffer was 100 mM KH2PO4 adjusted to pH 3.2 with phosphoric acid.)... 

Mobile phase A MeOH b iffer 17 83 containing 1 mM sodium hexylsulfate (Buffer was pH 7.4 phosphate buffer, ionic strength 0.05.) B MeOH buffer 35 65 (plasma) or 30 70 (urine) (Buffer was pH 7.4 phosphate buffer, ionic strength 0.05.)... 

Mobile phase MeOH buffer A 25 75 (plasma) or MeOH buffer B 20 100 (urine) (Buffer A was 0.1 mM Na2HP04 containing 0.1 mM NaH2P04 and 5 mM tetrabutylammonium bromide. Buffer B was 1 mM Na2HP04 containing 1 mM NaH2P04 and 5 mM tetrabutylammonium bromide.)... 

Sample preparation Condition a C2 Bond-Elut SPE cartridge with 1 column volume methanol and 1 column volume buffer. Add 1 mL of urine buffered with pH 6 100 mM phosphate buffer or plasma buffered with pH 8 100 mM phosphate buffer to the SPE cartridge, wash with 3 column volumes of water, wash with 1 mL of MeOH water 30 70, elute with 1 mL of MeOH water 60 40. Evaporate the eluate to dryness and take up the residue in 200 p,L mobile phase, inject an ediquot. 

The drug and its metabolite were extracted with ethylene dichloride from 0.5 ml of serum or urine buffered at pH 5 with an equal volume of citrate buffer. The layers were separated and the organic layer was blown to dryness with nitrogen. 

Mobile phase MeCN buffer 50 50 (plasma) or 43 57 (urine) (Buffer was 0.085% phosphoric acid adjusted to pH 6.5 with triethylamine.)... 

Mobile phase MeOH THF buffer A 50 5 63 (plasma) or MeCN THF buffer B 50 5 125 (urine) (Buffer A was 50 mM sodium dihydrogen phosphate containing 20 mM citric acid and 0.25 mM EDTA, adjusted to pH 2.0 with phosphoric acid. Buffer B was 50 mM sodium dihydrogen phosphate containing 20 mM citric acid and 0.25 mM EDTA,... 

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