Diphenyldichlorophosphonium trichloride-chlorine solvate 1:1, [PPh2Cl2]+Cl(3)(-).Cl2: an ionic form of diphenyltrichlorophosphorane. Crystal structures of [PPh2Cl2]+Cl(3)(-).Cl2 and [(PPh2Cl2)+]2[InCl5](2-)

An ionic form of diphenyltrichlorophosphorane, namely, diphenyldichlorophosphonium trichloride isolated as a dichlorine solvate (1), was obtained by treating PPh(2)Cl(3) with excess chlorine. The identity of this species was established by single-crystal X-ray analysis and (31)P, (1)H, and (35)Cl NMR and Raman spectra. Bis(diphenyldichlorophosphonium) pentachloroindate (2) was obtained by the reaction of diphenyltrichlorophosphorane with indium trichloride in dichloromethane for comparison purposes. Its identity was determined by (31)P NMR spectra and single-crystal X-ray analysis.     

Interesting interferences in a direct serum creatinine reaction

A spectrophotometric study on a direct picric acid reaction for creatinine in severely jaundiced serums is described. A problem appears to be caused by the oxidation of bilirubin which minimizes rising absorbance when using continuous measurement. Simple examples of interferences with the kinetic mode are shown along with the hitherto unreported interference of the drug, Cephalothin, which also undergoes a picric acid reaction. A procedure in which a delta absorbance is obtained after decolorization of the Jaffé complex by acidification is shown as one available means for obviating the bilirubin effect. However, the theory that Jaffé-reactive interferences do not decolorize with the same acid treatment is not totally applicable when the drug, Cephalothin, is present.     

Interference study on precipitating reagents used in a sensitive color reaction for high-density lipoprotein cholesterol determination

A spectrophotometric study was carried out which describes the effect of the inclusion of potassium ferrocyanide into an enzyme reagent system as a protective device against the competitive interaction of bilirubin in the indicator reaction. A previously described system for depicting how bilirubin interacts competitively in a modified 4-aminoantipyrene-phenolic peroxidase-peroxide coupled reaction was used as a template to judge the effectiveness of the protective action. The results obtained indicate that the protection is not total, but that the close approximation may make this a worthwhile modification in procedure to consider for the determination of total, free, and/or high density lipoprotein cholesterol. At the same time it might be inferred that the interference of bilirubin can be diminished chemically for other oxidase-peroxidase coupled systems. A search for even better solutions to this interference problem may be possible. For us, this lead has pointed the way in other similar directions.In addition, this study reports on a preliminary investigation as to the site of coupling of phenolic compounds with 4-aminoantipyrene.     

A spectrophotometric study on the interaction of hemoglobin in a diazo coupling reaction of neonatal bilirubin: I. Interaction of bilirubin and hemoglobin in the Jendrassik-Grof diazo blank reagents

Studies of difference spectra have revealed a dynamic interaction of bilirubin and hemoglobin in the alkaline Jendrassik-Grof diazo blank reagent. The similarity obtained for difference spectra with respect to shape and peak maxima and peak minima of various ferriprotoporphyrin-containing biomolecules, such as hemin, methemoglobin, cyanmethemoglobin, and catalase implicated ferriprotoporphyrin in this interactive process. Further time studies of these mixtures seem to suggest an oxidation-reduction type of reaction, resulting in the formation of ferroprotoporphyrin and presumably the concomitant oxidation of bilirubin.     

Essential serum trace metals: I. Determination of iron

Studies of serum iron determination have been described using sensitive color reagents of high molar absorptivities. Each selective reaction for iron is strengthened by means of complexing molecules which eliminate trace metal interferences. One ligand. 4-(2-pyridylazo)-resorcinol, exhibits two sensitive peaks, either of which can be used to determine iron quantitatively if an interference is present at one wavelength, or to qualitatively help ensure by ratio measurement that iron is the only metal determined. The second ligand, 2,4-bis(5,6-diphenyl-1,2,4-triazin3-yl) pyridinetetrasulfonic acid, is not only sensitive but has the capability of measuring iron, copper, or both by a judicious choice of selective conditions. Each compound has a useful potential in either discrete sampling or on-stream automation.     

Study of various substrates for peroxidase-coupled peroxide oxidations

It would appear from this study that the sodium sulfonates of 2, 4-dichloro- and 2, 4-dibromophenol when employed in the presence of 4-AAP produce useful and sensitive, colorimetric, cosubstrate systems. What may prove to be of equal importance is the relatively high initial rate of the coupling reactions, as it has been suggested (29, 30) that this might help alleviate interference by competitive proton donors.As long as the general structure of the phenols is maintained, increased aromaticity tends to add stability to the chromogen. This is, of course, an asset when performing equilibrium analysis.The use of MBTH, in the presence of either aromatic amines or alcohols, appears to have little obvious merit. Apart from the continual increase in absorbance of the blank, that is, a spontaneous coupling of the cosubstrates, as well as the comparatively high blank absorbance, this material does not seem to be as sensitive as some of the other reactions studied.     

Fenofibrate and fenofibric acid analysis by capillary electrophoresis

A capillary electrophoresis method has been developed to measure fenofibrate in capsules based on micellar electrokinetic capillary chromatography with detection at 280 nm using a borate buffer containing sodium dodecyl sulfate (SDS). However, the metabolite of this drug (fenofibric acid) in serum and whole blood was analyzed by capillary zone electrophoresis (CZE) in a borate-carbonate buffer using acetonitrile stacking. The analysis is rapid, < 7 min with no interferences. Incubation of fenofibrate in whole blood caused hydrolysis of the ester bond with the release of fenofibric acid.     

Enzymic determination of cerebrospinal fluid lipid fractions

Colorimetric peroxidase-coupled procedures for the determination of several cerebrospinal fluid (CSF) lipid classes are described. These methods were modified to increase the effectiveness of each cerebrospinal fluid lipid assay by using the sample as the primary diluent for a highly concentrated reagent in an inverse concentration technique. Direct enzymic assays for the determination of CSF cholesterol (free and total), choline phospholipids, and triglycerides were adapted from existing assays to require less than 0.5 ml of sample per assay. This made determinations of the several lipid analytes possible even when samples were from pediatric specimens. In a study model, 51 pediatric CSF samples were analyzed for these lipid constituents. Mean values and standard deviations were determined. Within and between-run studies were performed by sampling from a pool of cerebrospinal fluid specimens. Within-run coefficients of variation for the several proposed procedures were less than 3% while the between-run findings for all of the procedures were less than 5%.