Simple optical readout for ethanol-chlorobenzene dosimetry system

Optical readout of the ethanol-chlorobenzene (ECB or Dvornik dosimetry system) is based on the development of coloured secondary complex of ferric thiocyanate which has a maximum absorption at 485 nm. The applicability of a rugged, hand-held, battery powered filter colorimeter operating at 480 nm has been investigated as a reader for this purpose. This simple reader performs very well within absorbance displaying an excellent linearity of absorbance with the concentration of Cl⁻ ions. It was shown, by choosing the appropriate dilution factor when preparing the secondary complex solution, the entire useful dose range of the dosimeter up to 2 MGy can be covered. The applicability of the same reader to some other liquid chemical dosimeters is also discussed.     

A new spot test for aromatic hydrazides using 2,3,5-triphenyl tetrazolium chloride

Summary A spot test using 2,3,5-triphenyl tetrazolium chloride for the detection of benzoic acid hydrazide, and itsm- andp-nitro derivatives, isonicotinic acid hydrazide, salicylic acid hydrazide and phenylacetic acid hydrazide is described. The method consists of treating 0.1 to 0.2 ml of 0.001 % hydrazide (for benzoic acid hydrazide a 0.0001 %) solution with 0.2 to 0.4 ml of 0.02M sodium hydroxide, 0.2 ml of 1% 2,3,5-triphenyl tetrazolium chloride and 0.2 ml of nitrobenzene oriso-butyl methyl ketone in a micro test tube. A reddish-brown colour in the organic phase confirms the presence of an aromatic hydrazide. The identification limits for benzoic acid hydrazide, itsm- andp-nitro derivatives, isonicotinic acid hydrazide, salicylic acid hydrazide, phenylacetic acid hydrazide respectively are: 0.2, 1.0, 1.0, 3.5, 3.0, 2.0g in 1 ml in nitrobenzene and 0.2, 0.2, 0.1, 3.0, 0.2, 1.5g in 1 ml iniso- butyl methyl ketone. The interference of various substances and anions has been studied.

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Zusammenfassung Eine Tüpfelreaktion mit 2,3,5-Triphenyltetrazoliumchlorid zum Nachweis von Benzoesäurehydrazid und dessenm- undp-Nitroderivaten, von Isonikotinsäurehydrazid, Salicylsäurehydrazid und Phenylessigsäurehydrazid wurde angegeben. 0,1 bis 0,2 ml einer 0,001% igen (bei Benzoesäurehydrazid einer 0,0001% igen) Lösung werden mit 0,2 bis 0,4 ml 0,02-m Natronlauge, 0,2 ml 1%iger Triphenyltetrazoliumchloridlösung und 0,2 ml Nitrobenzol oderi-Butylmethylketon in einem Mikroreagensglas behandelt. Rotbraune Färbung der organischen Phase zeigt die Anwesenheit eines aromatischen Hydrazids an. Die Nachweisgrenzen der angeführten Säurehydrazide in 1 ml Nitrobenzol betragen 0,2, 1,0, 1,0, 3,5, 3,0 bzw 2,0g, in 1 mli-Butylmethylketon 0,2, 0,2, 0,1, 3,0, 0,2 bzw. 1,5g Die störende Wirkung verschiedener Substanzen und Anionen wurde geprüft.

     

A new label dosimetry system

A new label dosimeter which changes its color by large radiation doses has been developed. The green color of the unirradiated dosimeter gradually turns to brown then to red at high doses. The label dosimeter was prepared with a peal-off paper backing, allowing it to stick by self-adhesion to a product box. Three types of dosimeters having different sensitivities to radiation doses were prepared. Correlations were established between absorbed doses and color scale or the green/red axis of the irradiated dosimeters, using a micro color unit equipped with a data station. The data were analyzed to determine the reproducibility of the reflectance measured from the label dosimeters exposed to different doses of γ radiation. These dosimeters showed great stability on extended storage before and after irradiation.Detailed measurements of absorbed dose extremes (D_min and D_max) in product boxes, processed in the Egypt Mega Gamma I radiation processing facility, were obtained using these dosimeters. These dosimeters are currently available in large quantities and are inexpensive, which makes them suitable for routine high-dose applications in radiation processing of materials.     

A new approach to the spectrophotometric determination of polyhexamethyleneguanidinium chloride

It has been demonstrated that the reaction of Phenol Red (PR) with polyhexamethyleneguanidinium chloride (PHMG) gives an ion associate and several aggregates. The composition of the latter ones was determined by spectrophotometry, turbidimetry, refractometry, and conductometry. The introduction of PHMG into PR solutions PR leads to the redistribution of the intensity of absorption bands and the appearance of extreme points corresponding to the regions of the maximal accumulation of the formed aggregates with the following stoichiometry: c _PR: c _PHMG = 8 (12, 16, 27, 54) : 1. A procedure has been developed for determining PHMG in disinfecting agent ‘Biopag-D’ employing the extreme points. The procedure provides PHMG the determination of PHMG with an error of 1%.     

A thin alanine-polyethylene film dosimetry system with diffuse reflection spectrophotometric evaluation

Characteristics of a new alanine dosimeter in the shape of a thin film, with the measurement of optical absorption of the CH₃CHCOO^– radical is described. That type of dosimeter, ALA/DRS (for diffuse reflection spectrophotometry) is compared, to an alanine dosimeter with EPR evaluation (ALA/EPR for short). In many respects the simple ALA/DRS version, as the alanine-polyethylene composite is superior. The paper shows the importance of the new experimental approach to free radical research in solid state radiation chemistry.     

Aqueous-ethanol nitro blue tetrazolium solutions for high dose dosimetry

The ions of nitro blue tetrazolium (NBT²⁺) in aqueous ethanol solution are readily reduced radiolytically first to monoformazan (MF⁺) and then to diformazan (DF) having high linear molar extinction coefficients at the absorption maxima of 522 and 570–610 nm. Spectrophotometric analysis then provides potential use in high-dose dosimetry over the dose ranges of 0.1–1 and 1–30 kGy. The solution is stable for the first 24 h after the irradiation.     

A new reagent system for the highly sensitive spectrophotometric determination of selenium

Highly sensitive and simple spectrophotometric determination of selenium is described for the determination of selenium(IV) using a new reagent leuco malachite green. The method is based on the reaction of selenium(IV) with potassium iodide in an acidic condition to liberate iodine, the liberated iodine oxidizes leuco malachite green to malachite green dye. The green coloration was developed in an acetate buffer (pH 4.2–4.9) on heating in a water bath (∼ 40 °C). The formed dye exhibits an absorption maximum at 615 nm. The method obeys Beer’s law over a concentration range of 0.04–0.4 μg mL⁻¹ selenium. The molar absorptivity and Sandell’s sensitivity of the color system were found to be 1.67 × 10⁵ L mol⁻¹ cm-¹ and 0.5 ng cm⁻², respectively. The optimum reaction conditions and other analytical parameters have been evaluated. The proposed procedure has been successfully applied to the determination of selenium in real samples of water, soil, plant material, human hair, and cosmetic samples. The results were compared to those obtained with the reference method. Statistical analysis of the results confirms the precision and accuracy of the proposed method. In addition, the developed method is cost-effective and involves easily accessible instrumentation technique which can be used by ordinary research laboratories.     

A new dosimetry system using a portable reader

A new dosimeter material has been developed which consists of a radiation sensitive layer on a reflective base, and utilises a portable microdensitometer for response measurement. The instrument, modified from a readily available hand-held unit, is a standard in the printing industry. The system was designed with the demands of ‘in plant’ use in mind, and is equally suitable for either gamma or electron beam irradiation. The dosimeter material develops an easily visible colour change, which is quantitative, highly reproducible and stable over the dose range of approximately 5–45 kGy. The results presented demonstrate the calibration and characteristics of the dosimetry system, and explore some of its potential.     

A sensitive method for the ultraviolet spectrophotometric determination of chloride

A new method for the determination of chloride ion is based on the formation of phenylmercury(II) chloride, its extraction into chloroform and reaction with sodium diethyldithiocarbamate to form phenylmercury(II) diethyldithiocarbamate. This complex has spectral maxima at 257 and 297 nm. either of which can he used for quantitative purposes. The molar absorptivities are 21.3·10³ and 6.5·10³ respectively. referred to the chloride ion. The method is especially suitable for the determination of trace amounts of chloride in aqueous solution and has been applied to samples of drinking water. Amounts of chloride in the range 0.04 0.32 p.p.m. can be determined in 250-ml aqueous samples with an average relative mean error of 12%. The method can be used also for bromide and iodide, and for organomercury(11) compounds. Interferences are minimal and the method compares favourably with the standard mercury(II) thiocyanate procedure.     

Neotetrazolium chloride: a new reagent for spectrophotometric determination of manganese

The interaction of Mn(VII) and the Neotetrazolium chloride has been examined. The ion-associate formed is extracted into 1,2di-chloroethane. The optimum conditions have been established. The molar absorptivity of the complex is (9.1+/-0.08)x10(5) l mol(-1) cm(-1). The sensitivity of the method is 6.04x1010(-5) mug cm(-2). It is possible to extract and determine manganese in the presence of large number of cations and anions. The characteristic values for the extraction and the aqueous phase equilibria were determined: extraction constant K(ex)=3.21x10(9), distribution constant K(D)=33 and association constant beta=9.72x10(7). The method is applicable to analysis of soils and steels.     

A simple method for the spectrophotometric determination of chloride by solvent extraction as chromyl chloride

Summary A simple and direct method for the spectrophotometric determination of chloride, based on the formation of chromyl chloride and its extraction into carbon tetrachloride has been developed. The absorption spectrum of the organic extract shows two bands at 300 and 415 nm; Beer's law is obeyed at both wavelengths over the range 20–320g of chloride. The best conditions for the spectrophotometric determination of chloride are determined and a procedure is recommended. Interferences from some of the most common anions are studied.

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Zusammenfassung Eine neue Methode für die Bestimmung von Chloridionen wurde angegeben. Sie beruht auf der Bildung von Chromylchlorid und dessen Extraktion mit Tetrachlorkohlenstoff. Der Extrakt hat spektrale Maxima bei 300 und 415 nm. Das Beersche Gesetz ist zwischen 20 und 320g Chlorid erfüllt. Die besten Bedingungen für die spektrophotometrische Bestimmung wurden ermittelt und ein Verfahren empfohlen. Störungsmöglichkeiten einiger üblicher Anionen wurden untersucht.

     

Polymer-based triphenyl tetrazolium chloride films for ultraviolet radiation monitoring

Ultraviolet (UV) radiation monitoring films were prepared from solutions of polymers (polyvinyl, alcohol, PVA, or polyvinyl butyral, PVB), containing triphenyl tetrazolium chloride dye (TTC). These films have a pronounced response to the main UV radiation spectral regions [UV-A (400–320 nm), UV-B (320–280 nm), and UV-C (280–180 nm)] showing different sensitivities. PVA/TTC film has its maximum sensitivity in the UV-A region, while PVB/TTC film has its maximum sensitivity in the UV-C region. Both films have almost the same sensitivity in the UV-B region. The radiation-induced colour change is analysed spectrophotometrically at the maximum of the visible absorption band peaking at 492 nm wavelength. The measurement uncertainty of estimating ultraviolet radiation energy incident per unit area on the films is found to be about 3.5% (1 σ). The study of the effect of radiance exposure, incident wavelength, and storage conditions have been carried out to characterise the use of these films for actinometric monitoring artificial ultraviolet radiation sources which are used for medical and industrial applications.     

Muscle and plastic equivalent glass dosimeter for high-dose dosimetry

The alkali-silicate glass dosimeter is made up of 66.8% SiO₂, 31.2% Li₂O, 2% K₂O. It is nearly colourless before irradiation and then takes on an amber colour with increasing doses of gamma-radiation. This colouration is represented by the appearance of broad absorption bands at 405 nm and 600 nm wavelengths. The change in absorbance is linear with the absorbed dose in the range 0.1–4.5 kGy, when measured at its 405 nm absorption band maximum. This glass dosimeter simulates low-z plastics and muscle tissue in terms of gamma-ray absorption properties over broad radiation spectra (0.1 MeV to 10 MeV).     

A new spectrophotometric method for the determination of nadolol

A new spectrophotometric method has been developed for the assay of nadolol in pure form and in tablets. The assay procedure is based on a derivatization methodology employing 4-carboxyl-2,6-dinitrobenzene diazonium ion (CDNBD) as a diazo coupling reagent. The azo dye formed between nadolol and CDNBD absorbed visible light at the wavelength maximum of 416 nm (λ_max) demonstrating a bathochromic shift from the absorption maximum of nadolol. Optimization studies established an optimal reaction time of 10 min at 60 °C. The assays were linear over 1.25–10 μg ml^?1 of nadolol, and the reaction occurred by a 3:1 reagent/drug stoichiometric ratio. The method is found to be selective and has a lower detection limit of 0.29 μg ml^?1. Recovery studies over three days gave mean recovery of 101.4% (RSD 3.0%). This new method has been successfully applied in the determination of nadolol and nadolol/bendroflumethiazide tablets with accuracy and precision similar to the official (USP) HPLC procedure (p > 0.05). The new procedure has the advantages of high sensitivity, lower limit of detection and could find application as an in-process quality control method for nadolol.     

A new reagent for the spectrophotometric microdetermination of cadmium

2,2′-Dipyridyl-2-pyridylhydrazone (DPPH) allows a simple, rapid, and sensitive spectrophotometric microdetermination of cadmium in aqueous solution. The yellow 1:2 metal-to-ligand complex formed has a molecular extinction coefficient of 5.5 × 10⁴ liters mole^?1 cm^?1 at the absorption maximum of 444 nm. The determination of cadmium is carried out at pH 12.3 ± 0.2. Beer's law is obeyed over the concentration range of 0.2 to 2 ppm and the Sandell sensitivity of the color reaction is 0.002 μg of cadmium/cm² for an absorbance of 0.001.     

A new label dosimetry system based on pentacosa-diynoic acid monomer for low dose applications

The dosimetric characteristics of γ-radiation sensitive labels based on polyvinyl butyral (PVB) and a conjugated diacetylene monomer, 10,12-pentacosa-diynoic acid (PCDA) have been investigated using reflectance colorimeter. Two types of labels (colourless and yellow) based on PCDA monomer were prepared using an Automatic Film Applicator System. Upon γ-ray exposure, the colourless label turns progressively blue, while the yellow colour label turns to green then to dark blue. The colour intensity of the labels is proportional to the radiation absorbed dose. The useful dose range was 15 Gy-2 kGy depending on PCDA monomer concentration. The expanded uncertainty of dose measurement of the colourless label was 6.06 (2σ).     

A new spectrophotometric method for the determination of dimethyl formamide

Summary The spectrophotometric determination of dimethyl formamide comprises hydrolysation to dimethyl amine and reaction with carbon disulphide to dithiocarbamate, which gives a yellow complex (_max=430 nm) with copper(II). Standard deviation was ±0.0086 g/ml. There are no interferences from various copollutants.     

A new spectrophotometric method for assay of chloramphenicol

Summary Ninhydrin in the presence of SnCl₂ in 0.2M citrate buffer (pH 5) is proposed as a new reagent for the Spectrophotometric assay of chloramphenicol (CP), CP esters and CP in pharmaceutical formulations such as tablets, capsules, eye drops, eye ointments, ear drops and injections. The method is based on hydrolysis of chloramphenicol with 4M NaOH and subsequent treatment with ninhydrin reagent. The resulting violet colour exhibits maximum absorption at 570 nm. The Beer's law limits, molar absorptivity, effect of time and reagent concentration, and interference studies are reported.

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Eine neue spektrophotometrische Methode zur Bestimmung von Chloramphenicol

Zusammenfassung Für die spektrophotometrische Bestimmung von Chloramphenicol (CP) und CP-Estern in pharmazeutischen Präparaten (Tabletten, Pillen, Augentropfen, Augensalben, Ohrentropfen und Injektionspräparaten) wurde als neues Reagens Ninhydrin mit SnCl₂ in 0,2M Citratpuffer (pH 5) vorgeschlagen. Das Verfahren beruht auf der Hydrolyse von CP mit 4M NaOH und nachfolgender Behandlung mit dem Ninhydrinreagens. Die sich dabei ergebende Violettfärbung hat ihr Absorptionsmaximum bei 570 nm. Die Gültigkeitsgrenzen des Beerschen Gesetzes, die molare Absorbanz, der Einfluß der Zeit und der Reagenskonzentration sowie die Störfaktoren wurden angegeben.