Mechanism of interference with the Jaffé reaction for creatinine.

1987 ◽  
Vol 33 (7) ◽  
pp. 1129-1132 ◽  
Author(s):  
M H Kroll ◽  
N A Roach ◽  
B Poe ◽  
R J Elin
Keyword(s):  
Carbonyl Group ◽  
Equilibrium Constants ◽  
Molar Absorptivity ◽  
Reaction Products ◽  
Cyclic Ketones ◽  
Common Structure ◽  
Aliphatic Ketones ◽  
Rate Of Reaction ◽  
The Common

Abstract We investigated the mechanism of the Jaffé reaction for determination of creatinine by studying the spectrophotometric, kinetic, and equilibrium properties of the reaction of picrate with creatinine and with cyclic and aliphatic ketones. Absorbance spectra for the reaction products of picrate with all the ketones were superimposable with that of creatinine (Amax, 490 nm). Cyclic ketones not containing nitrogen had a molar absorptivity less than half that of creatinine and equilibrium constants approximately 0.01 that of creatinine. Aliphatic ketones, except for benzylacetone, had molar absorptivities similar to that of creatinine, but all of these compounds had equilibrium constants approximately a tenth or less that of creatinine. The common structure for all of the compounds reacting with picrate is the carbonyl group. The variable magnitude of interference for aliphatic and cyclic ketones is ascribable to the different rate constants, molar absorptivities, and equilibrium constants as compared with creatinine. Structures adjacent to the carbonyl group significantly affect the absorptivity and equilibrium constant, but steric hindrance is the major factor affecting the rate of reaction. We postulate that the carbonyl group is required for the Jaffé reaction, and we suggest a mechanism for the reaction.

Colorimetric Determination of Certain Phenothiazine Drugs by Using Morpholine and Iodine-Potassium Iodide Reagents

1986 ◽  
Vol 69 (3) ◽  
pp. 513-518 ◽  
Author(s):  
Adel F Youssef ◽  
Salwa R El-Shabouri ◽  
Fardous A Mohamed ◽  
Abdel Maboud I Rageh
Keyword(s):  
Potassium Iodide ◽  
Quantitative Estimation ◽  
Colorimetric Method ◽  
Molar Absorptivity ◽  
Dosage Forms ◽  
Colorimetric Determination ◽  
Reaction Products ◽  
Phenothiazine Drugs ◽  
Lower Molar

Abstract A colorimetric method was developed for the quantitative estimation of 11 phenothiazine drugs. The method is based on the interaction of unsulfoxidized drug with morpholine and iodine-potassium iodide reagents. The interaction for all studied phenothiazine drugs yields a blue product with 2 absorption maxima: one in the range of 620-640 nm with lower molar absorptivity and the other in the range of 662-690 nm with higher molar absorptivity. The color was stable for at least 10 h. The reproducibility and recovery of the method were excellent. The method was applied successfully to the analysis of various commercially available phenothiazines in different dosage forms. The results were comparable to those obtained by official procedures. The suitability of the method for detection and estimation of promethazine excreted in urine has been suggested by preliminary experiments. Reaction products have been isolated and identified.

Cefoxitin interferes with the "Clini-Skreen" column method for urinary 17-hydroxycorticosteroids.

1987 ◽  
Vol 33 (7) ◽  
pp. 1219-1222
Author(s):  
M H Kroll ◽  
A J Jackson ◽  
R J Elin
Keyword(s):  
Aqueous Solutions ◽  
Absorption Spectra ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Molar Absorptivity ◽  
The Other ◽  
Absorbance Maximum ◽  
Column Method ◽  
Apparent Concentration

Abstract Cefoxitin interferes with determination of urinary 17-hydroxycorticosteroids. The apparent concentration of hormone is increased from three- to 10-fold in samples from patients receiving cefoxitin when the Amberlite XAD-2 "Clini-Skreen" column is used. To determine the mechanism of interference, we reacted aqueous solutions of cefoxitin, cortisol, cortisone, and 11-deoxycortisol with phenylhydrazine; recorded the adsorption spectra; and determined the molar absorptivities and the equilibrium and rate constants. Also, we recorded the absorption spectra of phenylhydrazine with eight other cepha antibiotics and benzylpenicillin. Cortisol, cortisone, 11-deoxycortisol, and cefoxitin react with phenylhydrazine and absorb light with superimposable spectra and absorption maxima of 410 nm. The other antibiotics react with phenylhydrazine but absorbance maxima of the products vary, none being at 410 nm. Cortisol, cortisone, and 11-deoxycortisol react with phenylhydrazine 35-fold faster, have equilibrium constants ninefold greater, and have molar absorptivities 1.6 times that of cefoxitin. Thus, cefoxitin interferes with determination of urinary 17-hydroxycorticosteroids by forming a chromophore with the same absorbance maximum and with a molar absorptivity similar to cortisol, but much more slowly.

Hydroxyamidines as New Extracting Reagents for Spectrophotometric Determination of Cadmium with 4-(2-Pyridylazo)naphthol in Industrial Effluents, Coal, and Fly Ash

1993 ◽  
Vol 76 (3) ◽  
pp. 604-608 ◽  
Author(s):  
Sumon Chakravarty ◽  
Manas Kanti Deb ◽  
Rajendra Kumar Mishra
Keyword(s):  
Spectrophotometric Determination ◽  
Environmental Samples ◽  
Present Method ◽  
Industrial Effluents ◽  
Molar Absorptivity ◽  
Binary Complex ◽  
Matrix Interference ◽  
Relative Standard ◽  
The Common

Abstract A simple, sensitive, and selective extractive spectrophotometric method for the determination of cadmium in trace quantities with N1-hydroxy-N1,N2- diphenylbenzamidine (HDPBA) and 4-(2-pyridylazo) naphthol (PAN) is described. The method is based on the extraction of cadmium with HDPBA into chloroform at pH 9.0 ± 0.2 and simultaneous spectrophotometric determination wiith PAN. The binary Cd(ll)-HDPBA complex extracted into chloroform has a molar absorptivity of 1.96 x 104L/ mol/cm at λmax 400 nm. The sensitivity of the yellow Cd(ll)-HDPBA complex was increased remarkably by the addition of PAN to the binary complex. With 6 different hydroxyamidines tested, the red-orange complex in chloroform exhibited maximum absorbance at 530-550 nm, with molar absorptivity values of 3.2-5.6 x 104L/mol/cm. The method adheres to Beer’s law up to 1.5 μg cadmium/mL organic phase. The detection limit of the method is 0.02 μg Cd/mL. Investigations of the effect of foreign ions revealed that the present method is free from matrix interference of most of the common ions (e.g., Fe(lll), Ni(ll), Cu(ll), Mn(ll), V(V), Co(ll), Al(lll), Cu(ll), Mg(ll), and Mo(VI)). The relative standard deviation for 10 repetitive analyses of the metal was 1.4%. The validity of the method was tested successfully with various environmental samples.

IONIZATION OF ORGANIC COMPOUNDS IN ACID I. ALIPHATIC KETONES

1960 ◽  
Vol 38 (11) ◽  
pp. 2109-2116 ◽  
Author(s):  
H. J. Campbell ◽  
J. T. Edward
Keyword(s):  
Sulphuric Acid ◽  
Carbonyl Group ◽  
Absorption Spectra ◽  
Organic Compounds ◽  
Acid Strength ◽  
Medium Effect ◽  
Ring Size ◽  
Cyclic Ketones ◽  
Aliphatic Ketones ◽  
Weak Peak

The changes in the ultraviolet absorption spectra of aliphatic ketones in aqueous sulphuric acid have been followed as the acid strength is increased from 0 to 98%. With increase in strength up to 65% the weak peak at about 270 mμ is shifted to shorter wavelengths by a medium effect. However, with further increase in acid strength the peak disappears altogether because of protonation of the carbonyl group. The pKBH+ values of several ketones have been calculated from the spectrophotometric results to be about −7. The pKBH+ values of cyclic ketones vary systematically with ring size. The significance of the present work to recent studies on the rate of enolization of acetone is discussed.

Garteur Group on Ground Vibration Testing: Results From the Test of a Single Structure by 12 Laboratories in Europe

1997 ◽  
Author(s):  
Etienne Balmès ◽  
Jan R. Wright
Keyword(s):  
State Of The Art ◽  
Ground Vibration ◽  
Structure Design ◽  
Modal Characteristics ◽  
Common Structure ◽  
Single Structure ◽  
The Common ◽  
Vibration Tests ◽  
Main Activity

Abstract In an effort to assess state of the art methodologies for the experimental determination of modal characteristics, 12 European groups, most of them working in the area of aircraft ground vibration tests for flutter certification, participated in a GAR-TEUR action group whose main activity was to have independent tests of a single representative structure. Design considerations for the common structure are first detailed. Estimates of frequency response functions and modal characteristics are then compared and show a level of consistency that is much higher than those reported in previous similar exercises.

Simultaneous determination of iron and copper in waters by multiligand flow injection analysis

1988 ◽  
Vol 53 (7) ◽  
pp. 1461-1475 ◽  
Author(s):  
Vlastimil Kubáň ◽  
Dimitrii Borisovich Gladilovich
Keyword(s):  
Flow Injection ◽  
Flow Injection Analysis ◽  
Equilibrium Constants ◽  
Optical Characteristics ◽  
Array Detector ◽  
Reaction Products ◽  
Accuracy And Precision ◽  
Relative Standard ◽  
Acid Sample

Optical characteristics were measured and optimum conditions established for the simultaneous spectrophotometric determination of iron and copper with reagent mixtures of disodium bathocuproinedisulfonate (I) with disodium bathofenanthrolinedisulfonate (II) or ferrospectral (III) in static or dynamic (FIA) conditions. In the FIA method suggested, 30μl water samples containing Fe and Cu in concentration ratios 1 : 10 to 10 : 1 are injected into a stream of I-II mixed reagent at c(I) = 0·6 mmol l-1 and c(II) = 0·2 mmol l-1 in a medium of 0·1M formate buffer pH 3·5 and 0·01M ascorbic acid; for the two metals, present in concentrations of 4 to 40 μmol l-1, the relative standard deviations of determination do not exceed 2 and 5%, respectively. Alternatively, in the reverse FIA method using a multichannel diode array detector, 25 μl of the mixed reagent under the above conditions is injected into the acid sample stream; for samples containing Fe and Cu in concentrations of 1-43 μmol l-1 in ratios of 10 : 1 to 1 : 15, the relative standard deviation of determination is about 2%. The use of mixed reagents makes for a broader variability of the optical characteristics and conditional equilibrium constants of the reaction products as compared to methods employing a single nonselective reagent; owing to this, improved selectivity, accuracy and precision of determination are achieved with multicomponent flow injection analysis (MC-FIA).

Determination of the visible spectra of electrode reaction products in strongly absorbing media by diffusion-controlled chronoabsorptometry

1996 ◽  
Vol 74 (7) ◽  
pp. 1403-1408 ◽  
Author(s):  
David H. Jones ◽  
A. Scott Hinman
Keyword(s):  
Thin Layer ◽  
Electrode Reaction ◽  
Molar Absorptivity ◽  
Bulk Solution ◽  
Reaction Products ◽  
Optical Absorbance ◽  
Current Path ◽  
Diffusion Controlled ◽  
Visible Spectra

Chronoabsorptometry under diffusion-controlled conditions has been applied to determination of the difference in molar absorptivity between electrode reaction products and reactants. The technique allows complete determination of the ultraviolet–visible spectra of reaction products that are stable on the time scale of a few hundred milliseconds. The technique was implemented with a reflectance cell that employs quartz light pipes to minimize optical absorbance of the bulk solution without obstructing the current path between counter and working electrodes. The spectrum of one-electron oxidized chloro-(5,10,15,20-tetraphenylporphinato)Fe(III) is determined with the new technique and compared with that obtained by conventional thin-layer spectroelectrochemistry. Key words: spectroelectrochemistry, chronoabsorptometry, thin-layer spectroelectrochemistry.

Kinetics of the Metallation of Coproporphyrin-I in Water with Cadmium(II) and Manganese(II)

1998 ◽  
Vol 02 (02) ◽  
pp. 139-144 ◽  
Author(s):  
VITO BARTOCCI ◽  
RITA GIOVANNETTI ◽  
ENRICO CARSETTI
Keyword(s):  
Reaction Rate ◽  
Equilibrium Constants ◽  
Kinetic Method ◽  
Molar Absorptivity ◽  
Solution Properties ◽  
Alkaline Ph ◽  
Influence Of Temperature On ◽  
Kinetics Of ◽  
Coproporphyrin I

The reaction of 3,8,13,18-tetramethyl-21H,23H-porphine-2,7,12,17-tetrapropionic acid or coproporphyrin-I ( CPI ) with cadmium(II) was studied spectrophotometrically and its kinetic and equilibrium constants were determined. The influence of temperature on the reaction rate was also studied. At different ratios of [ CPI ]/[ Cd(II) ] two types of complex were formed: CdII ( CPI ) and ( CdII )2( CPI ); an investigation of the solution properties and the mechanism of aggregation of ( CdII )2( CPI ) at different pH were performed. It is verified that cadmium(II) accelerates the reaction of the incorporation of manganese(II) into CPI by the substitution of cadmium(II) with manganese(II) in the CdII ( CPI ) complex; the kinetics and mechanism of this substitution reaction at alkaline pH were studied. A sensitive kinetic method for the determination of cadmium(II) at ppb levels has been established; the molar absorptivity and the Sandell's sensitivity (for A = 0.001) of the recommended procedure at 458 nm and 300 s after the start of the reaction are (6.175 ± 0.026) × 105 1 mol−1 cm−1 and (1.820 ± 0.008) × 10−4 μg cm−2 respectively.

scholarly journals Extraction-Spectrophotometric Determination of Lidocaine Hydrochloride in Pharmaceuticals

2017 ◽  
Vol 9 (4) ◽  
pp. 49 ◽  
Author(s):  
Lazeeza Sattar Omer ◽  
Rasul Jameel Ali
Keyword(s):  
Molar Absorptivity ◽  
Ion Pair ◽  
Lidocaine Hydrochloride ◽  
Colored Complex ◽  
Eriochrome Black T ◽  
Accuracy And Precision ◽  
Relative Standard ◽  
The Common ◽  
Detection And Quantification

Simple, selective and highly detectable spectrophotometric method has been developed and validated for the determination of Lidocaine hydrochloride in standard and commercial solutions .The method is based on the formation of a soluble colored Lidocaine hydrochloride-eriochrome black T ion-pair complex at pH 1.80. The colored complex was extracted quantitatively into chloroform and measured at 508 nm. Beer’s law was obeyed in the concentration range of 0.10-10 mg L -1 with molar absorptivity of 2.3623 x104 L mol-1 cm-1.The limits of detection and quantification were 0.024 mg L -1, and 0.100 mg L -1 respectively. Using Job’s continuous variations method, the stoichiometry of the ion-pair complex was found to be 1:1. Intra-day accuracy and precision of the method were estimated with a relative error (0.57%), and the relative standard deviation (0.25-1.23). This developed method has been successfully employed to determine concentration of Lidocaine hydrochloride in injection and spray without interference by the common co-formulated substances.The numerical results obtained using both proposed and official methods were in concordance with each other.

Solvent and crown ether/cryptand effects on the oximate-promoted 1,2-elimination from β-phenylmercaptoethyl p-nitrophenolate. Formation and reactivity of a crown ether-complexed potassium oximate ion pair

1994 ◽  
Vol 72 (2) ◽  
pp. 437-447 ◽  
Author(s):  
Erwin Buncel ◽  
Anurag Kumar ◽  
Hai-Qi Xie ◽  
Robert Y. Moir ◽  
J. Garfield Purdon
Keyword(s):  
Crown Ether ◽  
Metal Ion ◽  
Equilibrium Constants ◽  
Spectrophotometric Study ◽  
Ion Pair ◽  
Rate Coefficients ◽  
Complexing Agents ◽  
Specific Rate ◽  
Reaction Products ◽  
Rate Of Reaction

The reactions of β-phenylmercaptoethyl p-nitrophenolate (1) with three potassium oximates, viz. potassium 2,3-butanedione monoximate (BDOK), acetophenone oximate (APOK), and acetone oximate (AOK) have been investigated in two nonhydroxylic dipolar aprotic solvents, tetraglyme and dimethyl sulfoxide (DMSO). The reaction products, as determined by 1H NMR spectroscopy, were p-nitrophenoxide ion and phenyl vinyl sulfide, in accord with an elimination process. A kinetic spectrophotometric study showed that in tetraglyme, the addition of oxime and water in small amounts drastically decreased the rate of reaction of 1 with APOK as a result of hydrogen-bonding interactions with the oximate anion. In tetraglyme as solvent the addition of 2.2.2 cryptand greatly enhanced the reactivity of the oximates but the macrocyclic crown ether DC-18-C6 had much smaller effect on rate. The results are consistent with formation of a crown ether-complexed potassium oximate ion pair, which is much less reactive than the free anion formed in the presence of 2.2.2 cryptand but more reactive than the potassium oximate ion pair. The kinetic data were analyzed to obtain specific rate coefficients for reaction of APOK as the dissociated anion, the ion-paired species, and as the crown ether-complexed oximate; equilibrium constants for potassium oximate ion pair formation and for the crown ether-complexed ion pair were obtained. In DMSO as solvent the rate of reaction remained unaffected on addition of the metal ion complexing agents, indicating that ion pairing is not important in this solvent. The reactivity of the free oximate anions in both solvents increased in the order BDOK < APOK < AOK, which parallels the pKa's of the corresponding oximes in DMSO. The unusually high reactivity of oximates in the low polarity tetraglyme compared to polar DMSO could be explained on the basis of stabilization of the transition state in tetraglyme. Trends in kTG/kDMSO for the oximates follow reactivity–selectivity considerations.

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