Benedict's Test Research Articles

Structural and histochemical characterization of the osmophores in corollas of Asteraceae (tribes Onoserideae and Famatinantheae)

Osmophores are engaged in scent production and differ from other secretory structures by their product, site, duration, and anatomical structure. Whereas osmophores have been well-documented in flowers of several families, they are barely mentioned in the Asteraceae. The aims of this study are to: 1) determine the occurrence of osmophores in corollas of 39 species of the tribe Onoserideae and the only species of Famatinantheae with histochemical methods; and 2) analyze the morphology and structure of osmophores in these groups. Histochemical and histological techniques revealed osmophores in the marginal and in the central corollas of Famatinanthus Ariza & S.E. Freire and Plazia Ruiz & Pav. at the apex and margin of the corolla lobes, and at the sinuses. Osmophores were confirmed following positive staining reactions for TIOFH and TIOFH3 (Neutral Red, Oil Red O, and Iodine-Potassium-Iodide); the samples reacted negatively for Benedict's test for detecting reducing sugars. The osmophores found in this study are constituted uniquely by a papillose or non-papillose epidermis, or they extend into the mesophyll forming scent glands. In both cases, they are associated to stomata and starch grains. The corollas of the other species of Onoserideae did not react positively for osmophores.

Diagnosis of Galactosemia by Simple Technique in a Resource-Constraint Country

Galactosemia is an autosomal recessive inheritance and there is cellular deficiency of enzymes leading to defective/impaired metabolism of galactose resulting in toxic byproducts like galactilol, galactose-1-phosphate and galactonate that affect mainly liver, brain, kidneys, lens and gonads. Galactosemia appears as a rare metabolic cause of neonatal cholestasis syndrome (NCS). The classic disease manifestation after the first milk feeding varies in severity from an acute fulminant illness to a more common subacute illness beginning within the first few days of life. Neonatal sepsis is one of the presentations. Galactokinase deficiency results primarily in cataract formation and galactosuria. The preliminary diagnosis of galactosemia in sick neonates and suspected infants is made by Benedict test in several urine specimens and followed by dipstick test to exclude glycosuria. Gold standard test is demonstration of low enzyme activity in erythrocyte. Galactosemia can be detected by newborn screening methods like the Guthrie test using filterpaper blood samples. Classical form of galactosemia should be treated with an absolute galactose restricted diet without waiting for confirmation of the diagnosis. Here we report a case of a 50-dayold boy with features of neonatal cholestasis, diagnosed as galactosemia by using a simple cost effective method.
 J Enam Med Col 2020; 10(1): 43-48

Identification of exudates from callus of Mangrove Plant (Rhizophora apiculata BI) in vitro.

Rhizophora apiculata is species in mangrove vegetation. The mangroves leaves were the water-storage type. Induction of callus from the leaf of R. apiculata faced problems, i.e., browning phenomena and exudates. This research aimed to evaluate the production of exudates and their correlation with the browning of explant and to identify kind of compounds of exudates. The leaf that is used as explants was divided into the base and tip section was grown in Murashige and Skoog (MS) medium with the addition of NAA 1 mg/L, BAP 0,3 mg/L, and activated charcoal 12 g / L. The treatments included 24 hours placed in the dark and 24 hours placed under light, 16 hours placed in the dark and 8 hours under the light, 8 hours placed in the dark and 16 hours under the light; the treatments were repeated four times. Respond of explants were descriptively observed, while the exudates were analyzed by Benedict test. The results showed that light treatment could induce callus formation while 24-hour dark treatment could reduce browning. The novelty of this research lies upon the process of browning prevention using light duration treatment. Therefore, browning could be prevented, and mangrove culture could successfully produce callus. Not at all explants produced the exudates. Light treatment can be used to avoid exudates production. Some of the exudates consisted of carbohydrates. Nevertheless, another one consisted of a salt solution. These exudates made a disturbance in callus initiation of R. apiculata.

Testing Carbohydrate Substance as Flash Based Flipbook Learning Media

This study aims to produce a flash-based flipbook and find out the quality of flash-based flipbook products that are suitable for use as supporting learning media. The study consisted of preliminary research in the form of carbohydrate test practicum consisting of barfoed test, benedict test and iod / lugol test. The results of the study were developed into flash-based flipbook using macromedia flash and microsoft word 2010 through the data entry stage to the developer software, preparation of layouts and provision of activities on flash-based flipbook. The final product in the form of flipbook is flash-based. Flash-based flipbook was assessed by 1 material expert, 1 media expert, 1 science teacher, 3 peer reviewers, and tested on 10 junior high school students. The results of the evaluation of flashbased flipbook according to material experts were 90.87% (Very good), media experts 88.10% (Very good), peer reviewers 93.39% (Very good), biology teachers 75.00% (Good) , and 85.6% (Very good) student response. Based on this assessment, the flash-based flipbook that was developed is worthy of being used as a source of learning biology.

Prevalence of Bovine Fasciolosis in Selected Dairy Farms of Addis Ababa, Ethiopia

A cross sectional study is carried out in selected dairy farms in and around Addis Ababa on the prevalence of fasciolosis in Ethiopia, in four sub-cities, locally called Kifele Ketemas. The dairy farms were under intensive and semi-intensive management systems. A total of 384 cattle were randomly selected and sampled which accounts for 95% (N=365) and 5% (N=19) of the samples for intensive and semi-intensive dairy farms, respectively. Fecal samples were examined using the direct fecal microscopic examination and Benedict's sedimentation tests. Out of 384 samples examined, 57 samples were found to be positive using both tests, giving a prevalence of 14.84% (N=57). The prevalence of fasciolosis in study areas (Kifele Ketemas) is 52.63% (N=30) in Yeka, 33.33% (N=19) in Bole, 10.35% (N=6) in Gullele and 3.51% (N=2) in Kality area. The prevalence of bovine fasciolosis in Yeka is significantly higher (P 0.05) is observed between the age groups. Keywords: Bovine; Fasciolosis; Prevalence; Chi-square; Addis Ababa; Ethiopia.

Optimization of Diagnosis and Treatment of Lactose Intolerance in Infants

The paper presents the results of a study of the Benedict test for deciding the diagnosis of lactose intolerance in children and the effectiveness of lactase drugs. Benedict test is one of the standard methods for the diagnosis of lactose intolerance in children. Drugs with lactase enzyme that helps break down lactose (hydrolysis) into two simple sugars, glucose and galactose, which simplifies digestion. Lactase drugs has been shown to be the best way to preserve natural feeding in children with lactose intolerance, since the lactase composition is involved in the breakdown and absorption of carbohydrates and proteins, produce essential vitamins for improving the health and immunity of the child, normalize the composition of the intestinal flora.

SIMPLE URINE METABOLIC SCRENING IN CHILDREN WITH REFRACTORY EPILEPSY IN ZAGAZIG UNIVERSITY CHILDREN'S

Background: Epilepsy is one of the most common serious neurological conditions and 20%to 30% of people with epilepsy have repeated seizures attacks that develop refractory epilepsy .The aim of the present study was to examine the inherited metabolic abnormalities in children with refractory epilepsy to provide early etiological and symptomatic treatment. Patients are to have refractory epilepsy if the application of two types of appropriate and tolerable antiepileptic drugs failed to completely prevent epileptic seizure following adequate duration of treatment and adequate doses of drugs Refractory epilepsy always has been a problematic issue in neurology particularly in the infantile period when the brain of children develops rapidly. An increasing number of children with refractory epilepsy are mainly focused on hereditary metabolic disorder .Since most inherited metabolic disorder are lacking in specific symptom, they are easily ignored or missed in clinical diagnosis. Methods: This study was applied to forty eight patients with refractory epilepsy by application of urine metabolic screen by using urine test strips ,Benedict test, ferric chloride test, Nitrosonaphthol test,Cyanide-nitroprusside test,2. 4 dinitrophenyl hydrazine test. Result: In our study regarding urine screening tests 42% of our cases had presented positive results in at least one of the urine screening tests. This denotes the importance of urine screening tests for early detection of metabolic diseases among cases of refractory epilepsy. Conclusion :Compared with the positive rate of the urine metabolic screening tests in high risk infants suggest probability of the presence of a metabolic disease, which will need further investigations

Food Analysis Labwork Guide as A Learning Media

This study aimed to produce practical guide labwork using a project-based learning models to know the quality of products and to produce practical guide that can be used as a learning media. The study consisted of a preliminary study in the form of carbohydrat tests such as: iodine test, seliwanoff's test and moore test. Lipid solubility test within alcohol, ether and chloroform. Protein tests: biuret test, test and xanthoprotein ninhydrin test. Vitamin C tests: benedict test and iodine test. The results of the research were developed into a practical guide with coreldraw x6 software applications and Microsoft Word 2010 through the stages of data entry into the software developer, the preparation of layout and provision of the activity in laboratory. The final result of the product was a user-based food testing laboratory project. The product guide assess by a subject expert, a media expert, a biology teacher, 5 peer reviewers, while experts responded that module classified into "very good" with a percentage of 85.80%. The assessment from 20 students of class XI and XII High School get a percentage rating of 78.60% with good quality.

Comparisons of Minicard ratings with ion chromatography sugar profiles of water extracts of cotton fibers and those of Minicard sticky spot materials

Specific levels of the carbohydrates melezitose and trehalulose deposited on the surface of cotton fibers are indicators of whitefly or aphid contamination. These deposits could cause stickiness problems during cotton ginning and textile processing. Cotton stickiness is highly complex, but surface carbohydrates may play the largest role in manifesting an issue. We utilized ion chromatography (IC) to identify and quantify nine sugars of interest present in the water extracts of 25 cotton samples to create sugar profiles for each sample: inositol, trehalose, glucose, fructose, trehalulose, sucrose, melezitose, raffinose and maltose. We compared the sugar profiles to the respective Minicard ratings of either NONE, LIGHT, MODERATE or HEAVY to draw correlations between the IC data and the rating. Trehalulose and melezitose in water extracts highly and positively correlate to Minicard ratings, confirming past researchers’ attribution of cotton stickiness to insect sugars. Trehalose and maltose also highly correlated, possibly due to their marker content in honeydew. Glucose and fructose moderately correlated to the ratings. IC studies of the collected Minicard sticky spot material found trehalulose and melezitose were the most prevalent sugars in HEAVY rated samples. Glucose and fructose were present in larger amounts in the MODERATE versus HEAVY rated samples. This result may indicate that the Benedict Test, which attributes these reducing sugars to stickiness, may not be sufficient for conjecturing a stickiness issue. When comparing the averages of the nine sugars present in water extracts versus those sugars contained in Minicard sticky spots, the overall distributions were very similar.

Effect of Varying Acid Hydrolysis Condition in Gracilaria Sp. Fermentation Using Sasad

Macroalgae or seaweed is being considered as promising feedstock for bioalcohol production due to high polysaccharides content. Polysaccharides can be converted into fermentable sugar through acid hydrolysis pre-treatment. In this study, the potential of using carbohydrate-rich macroalgae, Gracilaria sp. as feedstock for bioalcohol production via various acid hydrolysis conditions prior to the fermentation process was investigated and evaluated. The seaweed used in this research was from the red algae group, using species of Gracilaria sp. which was collected from Sg. Petani Kedah, Malaysia. Pre-treatment of substrate was done using H2SO4 and HCl with molarity ranging from 0.2M to 0.8M. The pretreatment time were varied in the range of 15 to 30 minutes. Fermentation was conducted using Sasad, a local Sabahan fermentation agent as a starter culture. Alcohol extraction was done using a distillation unit. Reducing sugar analysis was done by Benedict test method. Alcohol content analysis was done using specific gravity test. After hydrolysis, it was found out that acid hydrolysis at 0.2M H2SO4 and pre-treated for 20 minutes at 121°C has shown the highest reducing sugar content which has yield (10.06 mg/g) of reducing sugar. It was followed by other samples hydrolysis using 0.4M HCl with 30 minutes pre-treatment and 0.2M H2SO4, 15 minutes pre-treatment with yield of 8.06 mg/g and 5.75 mg/g reducing sugar content respectively. In conclusion, acid hydrolysis of Gracilaria sp. can produce higher reducing sugar yield and thus it can further enhance the bioalcohol production yield. Hence, acid hydrolysis of Gracilaria sp. should be studied more as it is an important step in the bioalcohol production and upscaling process.

Place of lactase deficiency in the pathogenesis of rotavirus infection and possibilities of its correction

Rotavirus infection is one of the causes of the lactase deficiency. The pathogenesis of the lactase deficiency in this disease has been actively studied recently. But the dynamic changes of clinical and laboratory signs of the lactase deficiency in early age children on the background of rotavirus infection and methods of their correction are still not well investigated.The aim of research: tо enhance the effectiveness of treatment of rotavirus infection in early age children through the study of clinical and laboratory parameters of lactase deficiency gravity and development of the method of its correction.Materials and methods: the research bases on the results of examination of 40 children aged 1 to 18 months suffered with rotavirus infection, who were breastfed. 20 of them had been accepted basic and symptomatic therapy and were in the first group of observation. The second group consisted of another 20 at the same age patients with rotavirus infection, received drug lactase along with this therapy. All the children of the investigation groups had Benedict test (determining the content of carbohydrates in the faeces ) and pH-metry faeces and clinical, biochemical, immunochromatographic and bacteriological tests.Results: The most part of children had increased levels of carbohydrates in faeces on the day of hospitalization due the clinical manifestations of the disaccharidase deficiency (osmotic diarrhoea, flatulence, intestinal colic): on the day of hospitalization Benedict test result was 0,6±0,3%; increased to 1,0±0,3% on the third day and remained at the same level (0,9± 0,3%) on the fifth day of the observation.Strongly acidic faeces pH (5,3±0,2)was recorded on the day of hospitalization in absolute majority of patients (80% - 16 children). On the third day of the disease this rate was 5,3±0,2 and was strongly acidic in 75%, and only on the fifth day of the rotavirus infection there were observed the raising of the acidity of faeces to 5,6±0,3.The analysis of clinical and laboratory parameters of lactase deficiency in patients suffered with rotavirus depending on the type of treatment (with and without drug lactase) pointed to some differences between groups of observation. The duration of diarrhea in children from the second group was significantly lower (5,5±1,0 days) than the duration of the first patient group (7,7±1,2 days, p<0.05) as the duration of flatulence and rumbling gut 3,2±0,9 and 3,5±1 compared with 4,7±1,6 and 4,6±1,0 respectively (p<0.05).The levels of carbohydrates in the feces of children from the first and second groups were not statistically different with each other on the first day (0,6±0,3% and 0,7±0,4%, respectively) and on the third day of hospital stay (1,0±0,3% and 0,9±0,3% respectively). However, the indicators of the Benedict test had been decreased almost two times (0,5±0,1%) in children from the second group on the fifth day of treatment compared with patients of the first group (0,9±0,3%, p<0.05).Children of both groups had strongly acidic pH of the faeces (less than 5.5) on the day of hospitalization. There was a normalization of this indicator in 65% (13) patients of the second group and only in 35% (7 children) of the first group. On the fifth day of the observation 95% and 80% of children, respectively, had a normal acidity of the faeces (5,5-6,9).Conclusion: all infants, who were breastfed, on the background of rotavirus infection had clinical and laboratory signs of the secondary lactase deficiency of varying severity: diarrhea, flatulence, decreased pH of feces to 5,3±0,2, increased level of carbohydrates in the faeces to 1,0±0,1%. The additional purpose of the lactase in the therapy of rotavirus infection helps to reduce the manifestations of secondary lactase deficiency. The rapid acceleration of the leveling of diarrhea syndrome and flatulence occurs by the normalization of samples acidity and by reducing of the level of carbohydrates in the faeces (on the fifth day of illness).

Usefulness of Benedict's test for the screening of galactosemia

BackgroundBenedict's test for the screening of galactosemia presents a high false-positive rate, which puts into question its usefulness. MethodsWe evaluated the results of Benedict's test as screening strategy for galactosemia, and the patients' definite diagnosis in our hospital in the last 25years. We also assessed the most prevalent clinical conditions among the false-positive cases. ResultsApart from glycosuria, many non-galactosemic newborns with heart alterations, prematurity, icterus and sepsis usually lead to false-positive results using Benedict's. No false-negative case for Benedict's test was reported in our hospital. ConclusionsA better approach in terms of cost-effectiveness, sensitivity and specificity is needed for an effective screening of galactosemia.

HIDDEN NANO CHEMISTRY IN BENDICT GLUCOSE TEST

From centuries, different manufacturers are using different technology for blood glucose monitoring. Since 1908, Benedict's test is utilized for only qualitative analysis of the urine/blood sample of patients suspected for diabetics mellitus. Based on this fact, we have now experimentally proved that presence of nanosized cuprous oxide equivalent to the reduced sugar present in any biological fluid can be utilized for both the qualitative and quantitative analysis of even trace amount of sugar in different species using fluorescence spectroscopy.

History and Vision: What is Important for Patients with Diabetes?

Up to the mid-1950s, evaluating the degree of glycemic control relied upon determining the concentration of glucose in the urine while acknowledging the inherent difficulties in interpretation. Progress was made from the original Benedict's test, when Benedict's solution was added to the urine sample to be tested, followed by the addition of the urine sample to a reagent tablet (Clinitest) or powder (Gelatest), and finally, in the 1960s, to a variety of urine glucose test strips, i.e., test-tape/Glukotest, Clinistix, Dreypak, and Combur-Test (glucose, protein, and pH value). The quest to produce blood glucose test strips was realized later in the 1960s, with refinements made during the following decade resulting in the introduction of Dextrostix and the Reflotest strips for use with reflectance meters and then the Haemo-Glukotest for visual determination. It was soon realized that patients were capable of using such meters, thereby introducing the concept of self-monitoring of blood glucose (SMBG). Initially, there was considerable opposition by the profession, which soon evaporated when the benefits of SMBG were clearly demonstrated in the mid- to late 1970s by Sînksen et al. (1978), Walford et al. (1978), and Cohen et al. (1980) in their pivotal publications. Early experience of introducing the patient to the concept of self-care using SMBG achieved a dramatic and sustained improvement in glycemic control, being preferred to urine testing in terms of both its execution and meaningfulness of the test result. Despite early concerns, SMBG's value in the management of the pregnant woman with diabetes was quickly realized and universally adopted. Further developments have centered on refining the test strips, blood sampling techniques (thereby reducing the volume of blood samples required), accuracy of glucose determination, and time from sampling to results. Currently there is reasonable consensus, based on evidence, about the use of SMBG in insulin-treated persons with diabetes, whereas considerable debate continues about its role in non–insulin-treated subjects with type 2 diabetes.

Diuretic effect of milk coffee on white rat (Rattus norvegicus) with variation of milk types

Bistani DA, Listyawati S, Setyawan AD. 2007. Diuretic effect of milk coffee on white rat (Rattus norvegicus) with variation of milk types. Biofarmasi 5: 8-15. Caffeine content in coffee is a mild diuretic which increase glomerule filtration and reduce natrium reabsorbtion in renal tubule. Some people mix milk into the coffee because they do not like the bitter taste from caffeine. Milk contains glucose which can cause osmotic diuretic and increase urine excretion. The aim of this research was to find out the diuretic effects of orally intakes of coffee-milk on white male rats (Rattus norvegicus) with a variation of milk kind. This research was done in Biology Sub Laboratory, Central Laboratory of MIPA UNS, Surakarta, Central Java. A Completely Randomized Design with five groups and four replications to each group was used in this study. The treatments applied for those groups were: (i) aquadest (group I), (ii) coffee solution (group II), (iii) coffee + sweetened condensed milk solution (group III), (iv) coffee + soymilk solution (group IV), and (v) coffee + skim milk solution (group V). The parameters used for the physical characteristics of urine were volume, colour, clearness, pH value and density. The parameters used for the chemical characteristics were the glucose analysis by Benedict test for qualitative and spectrophotometry for quantitative, and the analysis of NaCl content by Fantus method. The data were analyzed by using the analysis of variance (Anova) and continued with Duncan Multiple Range Test (DMRT) at a significance level of 5%. The results showed that a variation of milk kind was not effect on volume, colour, clearness, pH value, density, and glucose content after 4 hours of treatments, but effect on NaCl content after 4 hours of treatments.

Amperometric sensor for glucose based on electrochemically polymerized tetraruthenated nickel-porphyrin

Glassy carbon and gold electrodes were modified with tetraruthenated Ni-porphyrin by electropolymerization in alkaline medium and characterized by cyclic voltammetry, UV–vis spectroscopy and MAC-mode scanning probe microscopy (SPM). The half-wave potentials and current intensities associated with the Ni III/Ni II process were strongly pH-dependent. The modified electrodes were successfully employed as sensors for glucose in alkaline medium, based on the catalytic activity of the Ni III/Ni II centers. Glucose quantification was carried out by means of cyclic voltammetry or amperometry coupled to batch injection analysis (BIA). The BIA-amperometry technique revealed more efficiency than cyclic voltammetry, lowering the detection limit to 3.6 × 10 −7 mol L −1, and providing a larger, linear working range (2.5 × 10 −6 to 1.0 × 10 −3 mol L −1), better repeatability (RSD = 1.1% for 25 injections of 2.5 × 10 −5 mol L −1), and higher sampling frequency (60 samples h −1). The new sensor was successfully employed for the analysis of glucose in parentheral nutrition solutions and the results were in good agreement with the ones obtained by spectrophotometry, utilizing a modified Benedict's test.

What should we measure in the diabetic patient and how does this respond to therapy?

Diabetes is characterized by hyperglycaemia and by the development of complications. The criteria for diagnosis have been revised and published by the World Health Organization (WHO). In a symptomatic patient, a random plasma glucose concentration of ≥11.1 mmol l−1 is diagnostic. For asymptomatic patients, two diagnostic tests are required. A fasting glucose level ≥7 mmol l−1 confirms the diagnosis (providing this is supported by a second diagnostic test). The 75 g oral glucose tolerance test, as recommended by the WHO, is used for diagnosis in borderline cases or for academic studies. A plasma glucose concentration ≥11.1 mmol l−1 at 2 h following oral glucose confirms the diagnosis (Table 1). Table 1 Values for diagnosis of diabetes mellitus and other categories of hyperglycaemia.

The Use of a "Qual" Centrifuge for Greatly Simplifying and Speeding the Study of Milk

Laboratory study of the constituents of milk is almost always slowed by difficult separation of relatively large amounts of curd and whey by filtration. In the two-and-one-half hour experiment described, only 5 mL of skim milk is used and the curd is separated from the whey by using a simple qual centrifuge. Casein and serum proteins are quickly isolated as solids in essentially-quantitative yields in a procedure utilizing only two 13 x 100 mm test tubes and a 50 mL beaker along with the centrifuge and a hotplate. Protein solutions are prepared in the test tubes in which they were isolated and subjected to a variety of classical tests, the most dramatic of which is the Hopkins-Cole test which shows the presence of tryptophan in casein and its absence in serum protein. An essentially-quantitative yield of solid lactose is obtained by evaporation of the supernatant liquid obtained from the serum protein centrifugation. A lactose solution is subjected to Benedict's and Barfoed's tests, identifying it as a ...

Facile enzyme immobilization and assay technique using polyethyleneimine-cellulose thin-layer chromatography as a solid support

In the search for a plate-shaped solid support for enzyme immobilization, we found commercially obtainable polyethyleneimine (PEI)-cellulose thin-layer chromatography (TLC) plates to have adequate physical and chemical properties for enzyme immobilization. Through Benedict's, Tollen's and ninhydrin tests, the PEI-cellulose coating proved to have enough physical strength and amine concentration, and its properties could be maintained nearly constantly during the processes of enzyme immobilization. To confirm that the PEI-cellulose TLC plate was a suitable support for enzyme immobilization, alkaline phosphatase was immobilized using glutaraldehyde as a crosslinking reagent. The activity of the immobilized alkaline phosphatase was assayed with a reiterative method using p-nitrophenyl phosphate as a substrate. By analyzing Lineweaver-Burk plots from the results of successive assays, we proved the immobilized alkaline phosphatase to be reusable many times.

Laboratory experiments on the actions of digestive enzymes

Saliva is a mixture derived from the secretions of three pairs of glands: the parotid, submaxillary and sublingual, as well as from small mucous glands scattered diffusely over the mucosa of the mouth. The amount secreted in normal adult human is between I to 1.5 litres in 24 h. The composition of saliva (pH 6.2 to 7.4) is 99.5% water and 0.5% organic and inorganic solids. The principal organic components are glycoproteins. Other proteins (eg albumin, globulin) as well as carbohydrates are also present. The principal inorganic components are calcium, sodium, potassium, magnesium and phosphorus. The amylase present in saliva hydrolyses the a(1-*4) linked Dglucose units in polysaccharides. At a pH of about 6-7 and in the presence of chloride ions, a-amylase catalyses the hydrolysis of starch to the disaccharide maltose with the intermediate formation of various dextrins. Starch and higher dextrins give a blue colour with iodine, the intermediate dextrins give a reddishbrown colour, while the lower dextrins and maltose give no reaction with iodine. Thus, the action of a-amylase can be followed by observing the time taken to reach the point at which the reaction mixture no longer gives a colour with the iodine solution, the 'achromic point'. The maltose produced in the reaction can be detected by the Benedict's test. Materials and apparatus (1) 0.1 M sodium phosphate buffer pH 6.7; (2) 0.5% starch solution. (Prepared by mixing 5 g of soluble starch with about 50 ml of the above phosphate buffer to a smooth paste which was added quantitatively to 500 ml of boiling phosphate buffer. The mixture was allowed to boil for 1 rain, cooled and made up to 1 litre with the phosphate buffer); (3) 2.5 mM iodine solution in 3% potassium iodide; (4) 1% NaCI; (5) Benedict's reagent. (Prepared by dissolving 173 g of sodium citrate and 100 g of anhydrous sodium carbonate in about 800 ml of water with heating. The solution was filtered and, with stirring, 17.3 g of copper sulphate dissolved in 100 ml water was added slowly. The final solution was made to 1 litre.); (6) 37°C water bath; (7) Boiling water bath; (8) Several white tiles and glass rods.