Rapid Microdetermination Research Articles

Rapid Microdetermination of D-Galactose Anomers by β-D-Galactose Dehydmgenase and Mutarotase

Rapid Microdetermination of D-Galactose Anomers by β-D-Galactose Dehydmgenase and Mutarotase

Rapid Microdetermination of Partial Molar and Excess Molar Volumes

A new microscale procedure is given for the determination of partial and excess molar volumes of binary liquid mixtures.

Enzymic micro-determination of bronopol and its application to pharmaceuticals

A procedure is described for the rapid micro-determination of bronopol, based on the measurement of inhibition of a thiol protease, papain. The inhibition follows a linear relationship with concentration in the range 0.8–4.0 µg ml–1. The method utilizes the property of bronopol that is primarily responsible for its antimicrobial activity (ability to form disulfide bonds) and hence is also indicative of its antimicrobial potency. The method showed sensitivity towards the degradation of bronopol and can, therefore, be used in stability analysis. Results for the determination of bronopol in the presence of various pharmaceutical ingredients and also in the presence of much higher amounts of some antibiotics and anti-histamine and anti-inflammatory drugs confirmed the validity of the method in the determination of bronopol in complex pharamaceuticals.

Rapid Microdetermination of Amiodarone and its Metabolite N. Desethylamiodarone in Plasma by High-Performance Liquid Chromatography

Abstract A rapid microdetermination of amiodarone (A) and its metabolite, N. Desethylamiodarone (DA) in plasma by HPLC is described. 100μL of plasma are deproteinized by 200μL of acetonitrile containing triflupromazine as an internal standard. After centrifugation, 20pL of supernatant aliquot are injected into a Nucleosil octyl analytical column and eluted with a mixture of acetonitrile, 0.01 M sodium acetate pH 3.3 and triethylamine (84 : 16 : 0.1 v/v) at a flow rate of 2.0 mumin. Detection limit is 50 ng/mL for both compounds. Between run CVs range from 2.5 to 4.2%. No interference is observed either with endogenous substances or with a variety of drugs frequently used in cardiovascular therapy. This simple procedure is suitable for routine determination of plasma levels of amiodarone and desethylamiodarone in therapeutic monitoring or emergency toxicology.

Rapid Microdetermination of Hydroxyproline in Biomedical Samples by Flow Injection Analysis Using Cysteine as an Antioxidant

A new practical method for the rapid microdetermination of hydroxyproline (Hyp) in biomedical samples, such as tissue and urine, in the presence of a definite amount of cysteine as antioxidant was established by means of the modified KISO method using flow injection analysis. This method uses no organic solvent and requires only 9 min for each sample, which can be injected every 3 min (about 5 h is sufficient for 100 samples). A good linear relationship (r=0.99996) was obtained between the concentration of Hyp (0–80μg/ml) and the absorbance (0–0.514). In biomedical samples (hydrolyzates of rat stomach tissue), the recoveries (94.8–103.7%) and the reproducibility (the mean of RSD; 0.484% for ten kinds of rat tissues) were satisfactory. The correlation between values from this method and from the conventional KISO method was shown to be good enough (r=0.966) for hydrolyzate samples (N=95), when a proper amount of cysteine solution was added to both the sample and standard solutions and the concentration of the oxidant was optimized to Hyp contents.

Some observations on the rapid microdetermination of iodine in organic compounds

A small-scale method for the microdetermination of iodine in organic compounds is described. An interfacial voltaic cell is used as the indicator in combination with the Schöniger decomposition of sample. This method has the advantages of being simple, rapid, and economical and of having very sharp endpoints. The presence of nitrogen, fluorine, sulfur, phosphorus, boron, silicon, sodium, and potassium does not interfere with the microdetermination of organic iodine. The absolute error is ±0.2%.

Rapid and inexpensive microdetermination of serum fructosamine results in diabetics, uraemics, diabetics with uraemia and healthy subjects.

This paper describes a simple, reliable and inexpensive method for rapid determination of serum fructosamine. The assay is based on commercially available reagents and utilizes equipment accessible in most laboratories (i.e. an automated ELISA-reader interfaced with an IBM computer). In contrast to HbA1c determination, the fructosamine method presented can be used in diabetes complicated by uraemia. In the clinically relevant measuring range, fructosamine is uninfluenced by serum albumin concentration in diabetics with or without uraemia. Eighty microlitres of non-haemolysed capillary serum suffices for a duplicate determination. One year's storage of normal serum induced no change in serum fructosamine estimates. s-Fructosamine in 18 healthy subjects was 2.1 +/- 0.3 mmol/l (mean +/- SD) in venous blood and 2.2 +/- 0.4 mmol/l in capillary blood. In diabetics 3.4 +/- 0.6 mmol/l and 3.3 +/- 0.6 mmol/l (n = 38) were found. The method is well-suited for routine use in the diabetic out-patient clinic.

Microdetermination of cinchona alkaloids by atomic absorption spectroscopy

A sensitive and rapid microdetermination method has been developed for the determination of cinchona alkaloids via their mercury complex. Different parameters of the procedure have been thoroughly studied. The percentage recoveries for quinine, quinidine, cinchonine and cinchonidine were found to be 98.97 ±0.62, 99.06 ± 0.62, 98.90 ± 0.74, respectively. The results obtained are favourably compared to the official ones. The method is characterised by its specificity, accuracy and good precision.

A rapid microdetermination of phosphoserine, phosphothreonine, and phosphotyrosine in proteins by automatic cation exchange on a conventional amino acid analyzer

A cation-exchange chromatographic method for the separation and determination of phosphoserine, phosphothreonine, and phosphotyrosine in proteins after partial acid hydrolysis is described. The short column (0.6 × 8 cm) of an automatic amino acid analyzer was used and elution was carried out isocratically with 10 m m trifluoroacetic acid. The method is highly sensitive and each of the three O-phosphoamino acids can be accurately determined down to the 50-pmol level. Higher sensitivity may be obtained by the use of [ 32P]phosphate-labeled proteins. A correction factor for the decomposition of phosphoserine or phosphothreonine during acid hydrolysis can be deduced from the amount of inorganic phosphate recovered at the column void volume. The method is sensitive enough to be used for 32P-labeled proteins isolated by two-dimensional gel electrophoresis.

Characterization and determination of some?-amino acids using optical rotatory dispersion spectroscopy

The optical rotatory dispersion spectra of 16α-amino acids have been recorded over wave lengths down to 200 nm. The linear relationship between the molecular rotation in 0.1N HCl and the concentration permits the rapid and simple microdetermination of variousα-amino acids in the range of 0.2 to 500 mg/ml with an average recovery of 98%. The data on the molecular rotation of the various acids and their relation with the nature of the substituent groups are also presented.

Rapid Microdetermination of D-Glucose Anormers by?β-D-Glucose Dehydrogenase and Mutarotase

Rapid Microdetermination of D-Glucose Anormers by?β-D-Glucose Dehydrogenase and Mutarotase

Microdetermination of Naphthionic Acid in Serum and Amniotic Fluid

A simple, rapid, sensitive, and reproducible microdetermination of naphthionic acid (NA) in serum and amniotic fluid is described. The detection limit of the method is 1 ng NA in 20 microL serum, and 3 ng NA in 50 microL amniotic fluid. The concentration of nonderivatized NA was measured by fluorescence spectrophotometry (excitation 328 nm, emission 420 nm) of the supernate, after precipitation of proteins with absolute ethanol and heating for 30 min at 75 degrees C. Standard deviations of determinations for 2, 10, and 50 ng NA in 20 microL serum were 10.1, 7.59, and 7.64%, respectively. An analyst can perform about 100 determinations daily; results are available within 2 hr of sampling. A modification of the procedure to permit quantitation of NA in urine is also described.

A rapid microdetermination of chlorine dioxide in the presence of active chlorine compounds

A titrimetric and spectrophotometric procedure has been developed for the determination of ClO 2 in water samples. The procedure is rapid, accurate, and free of normal interferences present in water. It is based upon the reaction of ClO 2 with substituted halophenol indicators.

Simple and rapid micro-determination of sulfinpyrazone (Anturan) in biological fluids by reversed-phase high-performance liquid chromatography

Simple and rapid micro-determination of sulfinpyrazone (Anturan) in biological fluids by reversed-phase high-performance liquid chromatography

Rapid Microdetermination of Oxygen in Blood by Ox gen Electrode

Rapid Microdetermination of Oxygen in Blood by Ox gen Electrode

Rapid microdetermination of fatty acids in biological materials by gas-liquid chromatography

Total and free fatty acids in general ranging from lauric to nervonic acid were separated and quantitated based on an internal standard method as methyl esters by “on column” methylation with trimethyl-(α,α,α-trifluoro- m-tolyl) ammonium hydroxide (TMTFTH) in a gas chromatographic system. This study represents an application of a method published by MacGee and Allen and a change to an internal standard technique. For the determination of the total fatty acids the sampls were saponified with KOH-CH 3OH, acidified with H 2PO 4, and then the fatty acids were extracted into hexane. An aliquot of the hexane extract was then extracted with TMTFTH and chromatographed. For determination of free fatty acids the sample was acidified with H 3PO 4, immediately extracted with hexane and processed as described earlier. The relative standard deviation of 1.4 to 4.2% illustrates the precision of the method and the recovery of the fatty acids ranged from 88.5 to 100.5%. This method was applied to the determination of fecal fatty acids in conjunction with an interdepartmental study on “High protein diet in colon cancer” at the University of Missouri. In addition, the applicability of the analytical procedure (with small modifications) was shown for a wide variety of biological materials (serum, milk, skin tissue, fungal spores, food homogenates, beef tissues, and tumor cell cultures). The analyses were performed on different gas chromatographs by different analysts.

Fluorometric determination of acetaldehyde and its related compounds with o-phenylphenol

In the presence of nitrite ion, the reaction between acetaldehyde and o-phenylphenol in sulfuric acid was found to progress instantaneously at room temperature, causing an enhancement of fluorescence intensity. A simple and rapid microdetermination of acetaldehyde was thus established. Applications of the proposed method were examined in order to quantitate lactic acid and muramic acid which easily liberate acetaldehyde when heated with sulfuric acid. By this method, 1–10 nmol of acetaldehyde, 1.1–22.5 nmol of lactic acid, and 2.1–23.2 nmol of muramic acid in a 200-μl sample can be determined with precision. Besides glyceraldehyde, α-hydroxyearboxylic acids, and aliphatic aldehydes, the other compounds tested did not interfere with the determination of lactic acid. Furthermore, except for amino sugars, there was no interference in the assay for muramic acid by naturally occurring alcohols, amines, amino acids, carboxylic acids, and sugars. The interference of amino sugars can be completely removed by treatment with ion-exchange resin.

Polarographic method for rapid microdetermination of cholesterol with cholesterol esterase and cholesterol oxidase.

Cholesterol concentrations in serum are enzymatically determined rapidly by use of a polarographic oxygen analyzer with a circuit modified to record simultaneously the amount and rate of oxygen consumption. The final assay system, assessed from the oxygen consumption value that we found to be optimum, consists of 1 ml of sodium phosphate buffer (0.6 mol/liter, pH 7.0) containing NaN3 (10 mg/liter), Triton X-100 surfactant (10 ml/liter), 0.4 U of cholesterol ester hydrolase, and 0.6 U of cholesterol oxidase. Oxygen consumption and cholesterol concentration are linearly related to 8.0 g/liter, and only 10 mul of serum is required. Replicate analyses of pooled serum by the present method demonstrated the following inter-run precision: mean = 1731 mg/liter, SD = 22.3 mg/liter, CV = 1.3%. Bilirubin and ascorbic acid were without effect on the present method, unlike the enzymatic colorimetric methods.

Rapid microdetermination of silicon in rice plant

A direct method of estimation of silica in rice plant tissues is reported. This involves the digestion of finely ground plant samples with concentrated nitric acid in corning-glass conical flasks followed by dissolution in Na2CO3 in stainless-steel beakers; the plant silica is thereby converted into molybdenum reactive form which is estimated colorimetrically. This method represents an improvement over the time consuming fusion procedure followed ordinarily and also dispenses with use of platinumware. re]19740501

Coulometric microdetermination of peroxides—II: Organic peroxides

An iodometric method for the rapid microdetermination of organic peroxides, utilizing electrochemical reduction in the iodine-iodide system, has been developed. After complete reaction between peroxide and iodide in an acidic semi-aqueous medium the iodine produced is reduced at a rotating platinum electrode, at constant potential. Electronic integration is used. Organic peroxides of different reactivities have been analysed by making use of the increased rate of reaction at elevated temperatures. Accurate and precise results were obtained for samples at the 1-mg level and the total time of analysis varied from 8 to 20 min, depending on reactivity.