Simple sugars, oligosaccharides, polysaccharides, and their derivatives, including the methyl ethers with free or potentially free reducing groups, give an orangeyellow color when treated with phenol and concentrated sulfuric acid. The reaction is sensitive and the color is stable. By use of this phenol-sulfuric acid reaction, a method has been developed to determine submicro amounts of sugars and related substances. In conjunction with paper partition chromatography the method is useful for the determination of the composition of polysaccharides and their methyl derivatives.C"1 OLORIMETRIC tests for reducing sugars and polysaccha-J rides have been known for a considerable time. The reagents such as 1-naphthol (S3) for carbohydrates in general; benzidine for pentoses and uronic acids (37, 49, 50); naphthoresorcinol for uronic acids (51); and resorcinol ( 43), naphthoresorcinol (39), and resorcinol disulfonic acid (31) for ketoses are well-known examples of colorimetric tests that may be carried out in acid solution. Such tests as these and modifications of them using aromatic amines and phenols (4, 33, 38) have recently gained added importance since the extensive development of partition chromatography for the separation and characterization of minute amounts of sugars and their derivatives (1, 4,

VOLUMETRIC procedures have been used for the quantitative detennination of sugars after separation by partition chromatography 1 • 2 • It has been our experience that these methods not only require considerable skill, but also they are lengthy and sensitive to slight variation of the conditions. We have therefore attempted to develop a simple quantitative colorimetric procedure. , Preliminary experiments showed that the anthrone 3 and the 0(-naphthol sulphonate• reagents give good .results with pure sggar solutions, but the presence of only traces of solvents such as butanol, phenol and propionic acid used in the chromatographic separation of the sugars rendered them useless.It was then discovered that phenol itself in the presence of sulphuric acid provides a simple rapid method for the quantitative colorimetric determination of ketoses and aldoses and their methyl derivatives on a sub-micro scale. The method, applicable to all carbohydrates with either a free or potential reducing group, is particularly useful for determining sugars which have been separated by partition chromatography using phenol-water as the solvent. The orange-yellow colour, produced by adding sulphuric acid (5 ml.) to the sugar solution (2 ml.) containing phenol, is permanent; its optical density (measured at 490 mµ for hexoses and hexuronic acids and their derivatives and at 475 mµ for pentoses and their derivatives) when referred to a standard curve gives the concentration of the sugar.This phenol-sulphuric acid reagent, which has enabled us to determine the composition of polysaccharides and their methyl derivatives on as little as 1 mgm. of material, thus offers an additional method for end-group analysis of polysaccharides 5 • The reaction is not limited to phenol, for certain amines such as N(l-naphthyl) ethylene diamine can replace phenol in the above reaction.In conjunction with the above colorimetric method, it has been found convenient to extract the sugars from the strips of paper cut from the chromatogram by simply immersing them in water.Since the extraction is carried out at room temperature, there is no danger of decomposing the sugars•. Substances in filter paper which interfere with the sugar analysis can be largely removed by three or four 'chromatographic' washings with water; washing with. dilute sodium hydroxide does not seem to improve the paper.Further details of this work.. and its application to the detennination of the structure of various polysaccharides will appear elsewhere.

An improved direct Injection nebulizer (DIN) Is used In a continuous-flow mode for Inductively coupled plasma mass spectrometry (ICP/MS). Precision In cases where the signal Is not limited by counting statistics Is typically 0.5% relative standard deviation (RSD), an Improvement by a factor of 4 over the precision obtained with conventional nebulizers. A rlnse-out time of only 15 s Is sufficient to reduce the analyte signal to 0.1% of Its steady-state value, even for memoryprone elements such as Hg and I. Relative detection limits are similar to those obtained with conventional pneumatic nebulizers. Since the sample flow rate Is only 120 µ min"1, the absolute detection limits are Improved by up to an order of magnitude. The refractory oxide Ion ratios (MO+/M+) are 3 times higher than with other nebulizers. Matrix effects caused by Na are comparable to those observed with other nebulizers.

A method is described for the detection of nonreducinp glycosides. The chromatogram is first sprayed with a weak periodate solution whereby the a-glycol grouping is split and, at the same time, the periodate ion is reduced to iodate. Except for those small areas of the paper which contain the glycosides, the periodate solution remains largely unaffected. Hence upon spraying with benzidine, the glycosides are located by the appearance of white spots on a blue background, the latter arising from the oxidizing action of periodate on benzidine. The method is suitable for the detection of other carbohydrate compounds capable of being oxidized by periodate. Variation of the benzidine test enables certain carbohydrate compounds to be differentiated. HE location of minute amounts of reducing sugars on paper T chromatograms usually presents little or no difficulty and this is also true of reducing methylated sugars (2, 7 , fa). Nonreducing oligosaccharides, such as sucrose and alkyl glycofuranosides, may also be detected fairly easily by means of any one of a number of spray reagents that contain an amine and an acid capable of effecting fission of the glycosidic group (8, 3, 7 ) . Alkyl glycopyranosides, being relatively stable to acids, cannot be detected in this way and in this work the ammoniacal silver nitrate reagent (6, 8) has been only of limited use and furthermore the test is time-consuming. Because the reducing group in alkyl pyranosides is effectively masked, use has been made of the fact that when the periodate ion cleaves the a-glycol structure, it is itself reduced to iodate (9). A test with benzidine for the removal of periodate, rather than one for the formation of a dialdehyde ( 4 ) from the carbohydrate compound, has provided a awe, simple, and rapid procedure for locating glycopyranosides (IO). In order to accomplish this, the paper chromatogram. itre $prayed with a dilute solution of periodate followed by a benndine solution. The glycosides, which react vrith periodates, are located by the appearance of colorless spots on a blue background, which arises from the action of the periodate on benzidine.The periodate benzidine reagent is fairly sensitive (2 y of glucose, fructose, or ethylene glycol may be detected) but does not appear to be so sensitive for aldoses and ketoses as the Tollens xmmoniacal silver nitrate reagent (12) and those containing aromatic amines, such as aniline (ff), p-anisidine ( 7 ) , and X,Sdimethyl-p-aminoaniline ( 2 ) . Its value is in the detection of nonreducing carbohydrate compounds containing two or more hvdroxyl groups such as glycosides, alcohols, acids ( I ) , lactones (1 ), rrrtain partially methylated sugars, nonreducing oligosaccharidrs and polysaccharides. EXPERIMEYTAL Reagents. BENZIDINE REAGENT A. BENZIDINE RE.4GENT B. A saturated aqueous solution of potassium metaperiodate. Mix 1 volume of 0.1M benzidine in ethyl alcohol with 1 volume of 0.8N hydrochloric acid. Mix 10 volumes of 0.1M benzidine in 50 (volume) yo aqueous alcohol with 2 volumes of acetone and 1 volum...

SUMMARY The effects of fetal hypoxemia on renal hemodynamics and renal function were studied in two groups of chronically catheterized young (<120 days of gestation) and near-term lamb fetuses (>130 days). Fetal hypoxemia produced, in both groups, a significant decrease in renal blood flow (RBF) and a significant increase in the filtration fraction. However, the glomerular filtration rate (GFR) did not change significantly, suggesting that the renal vasoconstriction associated with fetal hypoxemia was more important at the efferent than at the afferent arteriolar level. In the group of near-term fetuses, the decrease in RBF correlated closely with changes in plasma renin activity (PRA) (r = -0.77). No changes in PRA were observed during hypoxemia in the group of young fetuses. After hypoxemia, reactive hyperemia associated with a significant increase in urinary prostaglandin excretion (PGE and PGF 2a ) was observed in near-term fetuses but not in young fetuses. It also was demonstrated that fetal hypoxemia produced a significant increase in fetal plasma concentrations of vasopressin associated with an antidiuresis in all but one near-term fetus and in 50% of the young fetuses, suggesting that the ability of the fetal kidney to reabsorb free water is more developed in near-term fetuses. Finally, fetal hypoxemia had no effect on mean arterial pressure and heart rate in young fetuses; however, in nearterm fetuses, a significant increase in blood pressure and a decrease in heart rate were observed. In summary, it appears that the response of the fetal kidney to hypoxemia depends on the degree of fetal maturation. Circ Res 48: 128-138. 1981