Cyclic voltammograms of 1 mM caffeine in perchloric acid
solution (pH 0.56) at carbon paste electrode modified with various mass percentages (%w/w) of anthraquinone was recorded at a scan rate of 100 mV[s.sup.-1].
was found to be the desirable medium for bromination of the investigated drugs by NBS; additionally it contributed in drugs solubility and also increased NBS potential for INC oxidation.
All the experiments started with the registration of the voltammograms of nickel in perchloric acid
. After that the necessary amounts of halide salt were added.
Sodium and Potassium were determined by taken 5ml of 1:1 nitric acid concentrate + perchloric acid
, 5ml of concentrated sulphuric acid and 1g sample PKOC mixed in a digestion flask and placed on electro-thermal heater for an hour.
The reagents used were analytical grade and included sodium hydroxide (NaOH), disodium monohydrogen phosphate [(Na.sub.2][HPO.sub.4].2[H.sub.2]O),potassiumdihydrogenmonophosphate ([KH.sub.2][PO.sub.4]), perchloric acid
(HCl[O.sub.4]), methanol, distilled water and pyrazinamide standard (Sigma Chemical Co., St Louis, Mo).
After another five-minute centrifugation, the pellet of insoluble macromolecules is washed with 5 ml of 95% ethanol, and the nucleic acids are extracted with 5 ml of 5% perchloric acid
(PCA) for 20 minutes at 70 [degrees]C.
Standard solutions (1 mmol/L) were prepared in 0.1 mol/L perchloric acid
and diluted to the desired concentration.
Diphenyl sulphoxide (Lancaster), sodium perchlorate, perchloric acid
and other chemicals are all of AnalaR grade and used as such.
Nitrogen was analysed by microkjeldahl digestion with sulphuric acid and distilled with boric acid, and phosphorus was analysed by digestion with nitric acid and perchloric acid
, and determined by photometry.
Approximately 50 mg of liver was weighed and homogenized in 500 [micro]L 0.1 M sodium acetate (pH 5.5), and cellular proteins were precipitated by addition of 312 [micro]L 10% perchloric acid
. After centrifugation (2,000 x g, 10 min, 4 [degrees] C), each supernatant was transferred to a clean tube, neutralized by addition of 140 [micro]L 1 M sodium phosphate (pH 11.5), and diluted with 1 mL deionized [H.sub.2]O.
Iiyama and Wallis (1988) introduced the use of perchloric acid
into the original reaction mixture to help ensure the complete solubilization of cell wall samples.
(PCA) and chloroform homogenates of 30 males or 30 females (N = 2 or 3) for nuclear magnetic resonance (NMR) analysis were made according to Heinstra et al.