Comparison of cholesterol values from venous blood and skin puncture blood is difficult, because biological differences between both materials may be concealed or increased by the preanalytical imprecision of skin puncture. In 12 adults, we studied the variance of cholesterol and urea determination in 8 blood samples obtained by the puncture of 8 fingers and compared the results with the 8-fold...

Urea is the most widely used nitrogen (N) fertilizer in direct-seeded, delayed-flood rice production. Urea fertilizer is susceptible to loss as ammonia gas to the atmosphere if not flooded in a timely manner. A urease inhibitor [i.e. N-(n-butyl) thiophosphorictriamide; NBPT] is recommended when a timely flood cannot be established. Recent research has indicated that when relative humidity (RH) ...

Purpose. Reverse iontophoresis is an alternative to blood sampling for the monitoring of endogenous molecules. Here, the potential of the technique to measure urea and potassium levels non-invasively, and to track their concentrations during hemodialysis, has been examined. Materials and Methods. In vitro experiments were performed to test (a) a series of subdermal urea and potassium concentrat...

In a recent number of this Journal,’ a new method for the estimat,ion of urea in urine was described. This method consists in the conversion of the urea into ammonium carbonate by means of the urease of the soy bean, and an estimation of the alkalinity before and after the conversion by means of standard acid and methyl orange. The procedure is not directly applicable to the est,imation of urea...

Several techniques are used to increase the aqueous solubilities of poorly water soluble drugs. Hydrotropic solubilization technique is one of them. In the present investigation hydrotropic solution of Urea (10M) has been used as a solubilizing agent to solubilize poorly water soluble drug. Fluvoxamine maleate shows maximum absorbance at 271 nm. Beer’s law was obeyed in the concentration range ...

A method is described for the direct colorimetric determination of urea in biological fluids. The method depends on the reaction (first described by Wheatley, 1948) between urea, diacetylmonoxime, and phenylanthranilic acid in the presence of controlled amounts of oxidant; chloride ions are included to sensitize the reaction; manganous ions stabilize the resultant colour; and phosphate enables ...

In this method for serum and urinary urea determination, the same reagent is used without predilution of urine samples. The method is based on the pH increase resulting from the ammonia released by urease hydrolysis of urea. o-Cresolphthalein complexone is used to monitor the pH change colorimetrically. Urea concentration and absorbance at 570 nm are linearly related for concentrations as great...

Since the ammonia undergoes a 3-electron change, 1 mole is equal to 3 equivalents of the generated titrant. Recently we (lescril)ed an improved cud-point (letection for this system and applied it to titration of as little as 1.4 g. ammonia (2). This method has been extended to titration of ammonia formed by the action of urease on urea in blood and urine. In urine samples, ammonia may be titrat...