Spectrophotometric Determination Of Microgram Amounts Research Articles

Propericiazine as a Selective and Sensitive Reagent for the Spectrophotometric Determination of Microgram Amounts of Platinium in Minerals

Propericiazine(PPC) is proposed as a new sensitive and selective reagent for the spectrophotometric determination of microgram amounts of platinum. PPC forms a pink complex with platinum(IV) at room temperature (26 + 2 0 C) in hydrochloric acid - sodium acetate buffer medium containing copper (II) ions. The complexation is complete within 10 min. The complex exhibits an absorption maximum at 520 nm with a molar absorptivity of 1.204 X10 4 liters mol -1 cm -1 . Beer’s law is obeyed over the concentration range 0.5-12.2 ppm of platinum. A 50-fold molar excess of the chromogenic regent is necessary for the development of maximum colour Intensity. Job’s method of continuous variation, the molar ratio method, and the slope- ratio method indicate a 1:1 composition for the complex. The effects of pH, time, temperature, reagent concentration, order of addition of reagents and interference for various ions are reported. The reagent has been used successfully for the determination of platinum in minerals and alloys.

Spectrophotometric determination of microgram quantities of acetylsalicylic anhydride in acetylsalicylic acid.

Abstract A rapid and convenient method for the determination of an immunogenic impurity in acetylsalicylic acid, acetylsalicylic anhydride, is described. The method is based on the spectrophotometric measurement at 362 nm of 4-benzylidene-2-phenyloxazolin-5-one, formed in quantitative yield by allowing acetylsalicylic anhydride, pre-extracted from the acetylsalicylic acid by a benzene-aqueous phosphate buffer system, to react with a mixture of pyridine and sodium α-benzamido-cinnamate in ethanol for 30 min at 20°. The method is reproducible and permits determination of 0ṁ0005% of acetylsalicylic anhydride in acetylsalicylic acid. Applying the method to nine different commercial acetylsalicylic acid preparations, acetylsalicylic anhydride was found to be present in amounts ranging from 0ṁ0012 to 0ṁ024%.

Proteomics Characterization of Extracellular Space Components in the Human Aorta

The vascular extracellular matrix (ECM) is essential for the structural integrity of the vessel wall and also serves as a substrate for the binding and retention of secreted products of vascular cells as well as molecules coming from the circulation. Although proteomics has been previously applied to vascular tissues, few studies have specifically targeted the vascular ECM and its associated proteins. Thus, its detailed composition remains to be characterized. In this study, we describe a methodology for the extraction of extracellular proteins from human aortas and their identification by proteomics. The approach is based on (a) effective decellularization to enrich for scarce extracellular proteins, (b) successful solubilization and deglycosylation of ECM proteins, and (c) relative estimation of protein abundance using spectral counting. Our three-step extraction approach resulted in the identification of 103 extracellular proteins of which one-third have never been reported in the proteomics literature of vascular tissues. In particular, three glycoproteins (podocan, sclerostin, and agrin) were identified for the first time in human aortas at the protein level. We also identified extracellular adipocyte enhancer-binding protein 1, the cartilage glycoprotein asporin, and a previously hypothetical protein, retinal pigment epithelium (RPE) spondin. Moreover, our methodology allowed us to screen for proteolysis in the aortic samples based on the identification of proteolytic enzymes and their corresponding degradation products. For instance, we were able to detect matrix metalloproteinase-9 by mass spectrometry and relate its presence to degradation of fibronectin in a clinical specimen. We expect this proteomics methodology to further our understanding of the composition of the vascular extracellular environment, shed light on ECM remodeling and degradation, and provide insights into important pathological processes, such as plaque rupture, aneurysm formation, and restenosis.

Spectrophotometric Determination of Microgram Amounts of Aliphatic Amines with Quinalizarin

Spectrophotometric Determination of Microgram Amounts of Aliphatic Amines with Quinalizarin

Use of triphenylmethane dyes for the spectrophotometric determination of polymer flocculants in aqueous solutions

The interaction of anionic forms of triphenylmethane dyes (TPM) with cationic polymer flocculants (e.g., with polydiallyldimethylammonium chloride (PC)) yields inextricable ion pairs. This leads to a shift of absorption bands or a redistribution of their intensities in the TPM spectra and can be used for the spectrophotometric determination of microgram amounts of flocculants in aqueous solutions. Among 14 studied TPMs, erythrosine is the most promising dye. The corresponding procedure allows the determination of PC at a level of the maximum permissible concentration. To decrease the effect of impurities, the use of the standard addition method is recommended.

Detection and spectrophotometric determination of some phenols

We report the detection and spectrophotometric determination of microgram quantities of some phenols on the basis of their reaction with 1,5-diphenylcarbazide in presence of KMnO 4 .

A new procedure for the spectrophotometric determination of uranium(VI) in the presence of a large excess of thorium(IV)

Spectrophotometric determination of microgram amounts of U(VI) with 2-(5-Bromo-2-Pyridylazo)-5-diethylaminophenol (Br-PADAP), originally developed by Johnson and Florence has been modified to enable the determination of U(VI) in the presence of a large excess of Th(IV). The effects of thorium, tri- n-butyl phosphate (TBP) and ethanol on the estimation of uranium have been studied in detail and are presented in this paper. This modified method can be applied for the analysis of U(VI) both in aqueous and organic samples containing a large excess of Th(IV) (Th:U=10 000:1).

Sequential Spectrophotometric Determination of Microgram Amounts of Nitrate and Nitrite in Mixtures

This paper describes three new methods: the first may be used for the determination of nitrite; the second is applicable to determination of nitrate; and the third permits sequential determination of both nitrite and nitrate in mixtures with no prior separation. For the determination of nitrite and nitrate in synthetic mixtures containing 1:5 to 5:1 ratios of the ions, in tap water, and in river water, mean recoveries (for 3 to 22 μg of added NO−3and NO−2) are 96.1 and 98.1% (n= 15) and coefficients of variation are 2.2 and 2.5% for NO−3and NO−2(n= 5), respectively.

Pentachlorophenol preconcentration using quinolin-8-ol immobilized on controlled-pore glass and flow spectrophotometric determination

A pentachlorophenol preconcentration method using a microcolumn (20 × 2.5 mm i.d.) filled with quinolin-8-ol (oxine) immobilized on controlled-pore glass (CPG) is proposed. The method is based on retention at pH 1 and elution at pH 3 with acetonitrile—water (80 + 20). Maximum retention of pentachlorophenol was 180 μg per gram of oxine—CPG. The breakthrough volume was 100 ml. The good ability for retention and elution allows the flow spectrophotometric determination of microgram amounts of pentachlorophenol. The calibration graph was linear from 4.0 to 25 μg for a sample volume of 100 ml, the repeatability using a single column for 12 μg of pentachlorophenol was 1.2% (R.S.D., n = 4), and the reproducibility between five different microcolumns for the same concentration level was 1.6%. The 3σ detection limit was 2.5 μg and a preconcentration factor of 250-fold was obtained. Common cations and other phenols do not interfere significantly.

Modification of an ultraviolet spectrophotometric method for the determination of trace amounts of phenols with iodine monobromide

A procedure for the spectrophotometric determination of microgram amounts of phenols by reaction with iodine monobromide was improved and its application extended. The reactions of 28 individual phenols were investigated and the precision and sensitivity of the method were enhanced when iron(III) sulfate was used as a catalyst. The adverse effects of reducing compounds were removed by addition of potassium bromate and interferences from some organic acids were decreased by preliminary extraction into cyclohexane. Interferences from phenylamine compounds proved more intractable and could not be removed by preliminary extraction. Rinsing the organic phase with anhydrous sodium sulfate powder dispersed any emulsion formed. Standard mixtures of phenols are proposed as standards for the analysis of waste water and whisky for total phenol content.

Spectrophotometric determination of microgram amounts of ampicillin with chloranil

Ampicillin trihydrate (12.5–750 μg) is determined spectrophotometrically using chloranil as π-acceptor at pH 9. The method is relatively accurate (with a recovery of 100 ± 1.0%) and precise (RSD ⩽ 1.7%) and can be used successfully for capsules and ampoules.

Spectrophotometric determination of microgram amounts of vitamin B 1 with chloranil

Vitamin B 1 (20–200 μg) is determined spectrophotometrically using chloranil as π-acceptor at pH 9. The method is relatively rapid (10 min standing time), simple (the reaction occurs at room temperature), precise (RSD = 1.7%), and relatively accurate (error ⩽ ±3.0%).

Rapid analysis of cation-exchangeable property in acidic soil: III. Sensitive spectrophotometric determination of microgram amounts of exchangeable magnesium with xylidyl Blue I in the presence of cetyltrimethylammonium bromide (CTAB)

A simple and sensitive procedure for Spectrophotometric determination of exchangeable magnesium has been developed. At 0.15 – 0.375 N ammonia, magnesium reacts with xylidyl Blue I in the presence of CTAB to form a colored ternary complex, which has an absorption maximum at 524 nm. The molar absorption coefficient is 2.2 × 10 4 liters · mol −1 · cm −1. The Beer rule will be valid for concentrations from 0 to 8 μg/20 ml magnesium. The method has been used for rapid determination of microgram amounts of exchangeable magnesium in acidic soil with good reproducibility.

Determination of Iron in Drug Biochemical and Biological Samples as a Thiocyanato Mixed Ligand Complex with Hydroxyamidine

Abstract N-Hydroxy-N-o-tolyl-N′-phenylbenzamidine (HTPB) is presented as a new sensitive and highly selective reagent for determination of iron in drug, biochemical and biological samples in presence of thiocyanate. The red organge Fe(III)–HTPB–SCN mixed ligand complex is quantitatively extracted into benzene. The extraction of iron(III) as thiocyanato mixed ligand complex is quantitative in the acidity range between 0.2–0.7 M (1M=1 mol dm−3) hydrochloric acid. The effective molar absorptivity of the complex is 12000 l mol−1 cm−1 with Sandell’s sensitivity of 0.0046 μg of iron per cm2. On the basis of this sensitive color reaction, a simple, rapid, selective, and highly reproducible method for the extractive spectrophotometric determination of microgram amounts of iron in various drug, biochemical and biological samples has been developed. The method is free from most of the common metal ions and commonly used sequestering agents.

Sensitive spectrophotometric determination of vanadium with 2-(5-bromo-2-pyridylazo)-5-diethyl-aminophenol (5-Br-PADAP)

A new sensitive and highly selective method is described for the spectrophotometric determination of microgram amounts of vanadium(V). First, vanadium is isolated by extraction withN-benzoyl-N-phenylhydroxylamine (BPHA) in chloroform from about 4M hydrochloric acid medium. Then, chloroform is evaporated and the residue mineralized with mixture of cone. perchloric and nitric acid. Finally, a colour reaction of vanadium(V) separated with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) in an acetate buffer (pH 4.5) gives a molar absorptivity of 5.48×104l·mol−1·cm−1 at 585 nm. The proposed method was applied for the determination of traces of vanadium in aluminium samples. The results obtained show a good precision and accuracy of the method.

Atomic absorption spectrophotometric determination of microgram quantities of copper in tea after solvent extraction.

An atomic absorption spectrophotometric method is described for determining trace amounts of copper in tea. The method is based on the solvent extraction of the metal as tetraiodocuprate (I), from 2 M HCl solutions of tea samples which contain 12% (w/v) KI, into methylisobutyl ketone. The organic extracts, containing the ion-association complex of copper are atomized into an air-acetylene flame. The limit of detection is 1.14 micrograms g-1 Cu.

Spectrophotometric determination of microgram amounts of platinum

2-Ethyl-10-[3-(dimethylamino-2-methyl)propyl]phenothiazine hydrochloride (ethylisobutrazine hydrochloride) forms an orange-red complex with platinum(IV) at room temperature (26 ± 2 °C) in hydrochloric acid-sodium acetate buffer medium containing copper(II) ions. The complexation is complete within 10 min. The complex exhibits an absorption maximum at 529 nm with a molar absorptivity of 1.90 × 10 4 liters mol −1 cm −1. Beer's law is obeyed over the concentration range 0.4–7.8 ppm of platinum. A 50-fold molar excess of the chromogenic reagent is necessary for the development of maximum color intensity. Job's method of continuous variation, the molar-ratio method, and the slope-ratio method indicate a 1:1 composition for the complex. The effects of pH, time, temperature, reagent concentration, order of addition of reagents, and interference of various ions are reported. The reagent has also been used successfully for the determination of platinum in minerals and alloys.

Prochlorperazine bismethanesulfonate: Sensitive and selective reagent for the spectrophotometric determination of microgram amounts of osmium

Prochlorperazine bismethanesulfonate (PCPMS) is proposed as a new sensitive and selective reagent for the spectrophotometric determination of microgram amounts of osmium. PCPMS forms a red-colored species with osmium(VIII) or osmium(VI) instantaneously at room temperature in 5 M phosphoric acid medium. The red species exhibits maximum absorbance at 529 nm. Beer's law is valid over the concentration range 0.05–3.6 ppm for osmium(VIII) and 0.15–6.4 ppm for osmium(VI). Sandell's sensitivity of the reaction is 2.89 nm cm −2 for osmium(VIII) and 4.24 ng cm −2 for osmium(VI). The effects of time, temperature, acidity, order of addition of reagents, reagent concentration, and diverse ions are investigated. The application of the proposed method in the determination of osmium content in synthetic ores has been explored.

Spectrophotometric determination of microgram amounts of adrenaline with chloranil

Adrenaline (10–700 μg) is determined by using chloranil as a π-acceptor at pH 9.O. The method is rapid, simple, precise (r.s.d. < 2.5%), and accurate (the error better than ±2%).

Application of Azure C for the extractive spectrophotometric determination of microgram amounts of penicillin

A simple, accurate, and rapid method for the quantitative determination of penicillin is proposed. The method is based on the formation of a blue penicillin-Azure-C ion-pair that can be extracted into chloroform in phosphate-citric acid buffer. The molar absorptivities for sodium penicillin G and potassium penicillin V at 635 nm were 5.46 × 10 3 and 2.19 × 10 4 l/mol/cm, respectively. Beer's law was valid over the concentration range of 4–80 μg ml for sodium penicillin G and 3–55 μg ml for potassium penicillin V. Maximum absorbance was obtained almost instantaneously and was stable for several days. The method was successfully applied to pharmaceutical preparations.