Existing representations for multiattribute ceteris paribus preference statements have provided useful treatments and clear semantics for qualitative comparisons, but have not provided similarly clear representations or semantics for comparisons involving quantitative tradeoffs. We use directional derivatives and other concepts from elementary differential geometry to interpret conditional mult...

A new simple and sensitive ratio-spectra first derivative spectrophotometric method was developed for the simultaneous determination of tapentadol hydrochloride (TPH) and paracetamol (PCM) in binary mixtures. The method depends on the use of the first derivative of the ratio-spectra obtained by dividing the absorption spectrum of binary mixture by a standard spectrum of one of the compounds. TP...

A new, simple, inexpensive, and sensitive method for the simultaneous spectrophotometric determination of Cu(II) and Pd(II) by H-point standard addition method and derivative spectrophotometry is described. 4Phenylpiperazinecarbodithioate (PPDTC) in an anionic micellar solution of SLS was used as a reagent at pH 4. The experimental parameters, such as pH, type of surfactant, concentration of re...

We determined methemoglobin in blood by zero-crossing-point first-derivative spectrophotometry. After lysis of erythrocytes, hemoglobin was converted into oxyhemoglobin and the first derivative spectrum was recorded between 405 and 425 nm. At the exact point where the first-derivative spectrum of oxyhemoglobin was zero ("zero-crossing point"), the first-derivative value of oxyhemoglobin and met...

vanadium is quantitatively retained on 2-nitroso-1-naphhthol-4-sulfonic acid tetradecyldimethlbenzyammonium chloride onto microcrystalline naphthalene in the ph range of 3.0-4.0 from a large volume of aqueous solutions of various alloys and synthetic samples. after filtration, the solid mass consisting of the vanadium complex and naphthalene was dissolved with 5.0 ml of dimethylformamide and th...

An abscisic acid derivative was formed by reaction with pentafluorobenzyl bromide which allowed highly sensitive detection by gas-liquid chromatography with electron capture detection. In comparison to the methyl ester derivative, the pentafluorobenzyl derivative of abscisic acid was four times more sensitive to electron capture detection and was stable at room temperature in the presence of ul...

Despite the fact that it was put on market more than 60 years ago, hydrochlorothiazide (HCT) is still one of most important antihypertensive drugs. Due to its chemical structure, which contains secondary aryl-alkyl-amino moiety, vulnerable formation N-nitrosamine drug substance-related impurity (NDSRI) N-nitroso-hydrochlorothiazide (NO-HCT). In our study, we reveal NO-HCT degrades rapidly at pH...