Microdiffusion and spectrophotometric determination of fluoride in biological samples

Routine separation of fluoride from large numbers of biological samples (soft and hard tissues) is achieved by microdiffusion from perchloric acid and absorption by sodium hydroxide on filter paper in disposable polypropylene vials. Spectrophotometry with a modified lanthanum/alizarin complexone reagent allows rapid determination of fluoride. Up to 80 samples can be processed per day. Recoveries are in the range 88–102%. Results obtained by spectrophotometry and with the fluoride-sensitive electrode agree within 3–10% for various samples of krill and shrimp products.     

分光光度法测定水样中的硫离子

A new simple spectrophotometric method was proposed for the determination sulphur ion in water samples.In the medium of 0.05 mol/L HCl,sulphur anion turns mixed acid of the silicon and molybdenum into molybdenum blue.Its absorption maxima was found at the wavelength of 700 nm,with a molar absorptivity of 2.48×104L·mol-1·cm-1.Influencing factors such as the amount of reagent and reaction time were optimized,and the interferences from common aions were also investigated.This method was successfully used for t...     

Anion-exchange separation and spectrophotometric determination of thorium in geological samples

To determine thorium in geological samples it is first separated from all matrix elements by means of anion-exchange. After elution thorium is determined spectrophotometrically by using thoronol or arsenazo III. The suitability of the method for the determination of both trace and larger amounts of thorium was tested by analysing numerous geochemical standard samples with thorium contents in the range of 1-1000 ppm. In all cases very good agreement was obtained.     

Automated flow-injection spectrophotometric determination of nitrosamines in solid food samples

A spectrophotometric method using a flow-injection system is proposed for the determination of nitrosamines in foods (cured-meats). The method is based on the photochemical cleavage of the N-NO bond of the nitrosamine to yield the corresponding amine and nitrite. The nitrite is then detected spectrophotometrically, at 542 nm, by use of its reaction with a modified Griess reagent. Different linear ranges between 0.8 and 2000 ng mL(-1) are obtained for the method, depending on the time of exposure of the sample to the UV radiation. The relative standard deviation varies between 2.0 and 3.9% and the sample throughput is between three and seven samples per hour, depending on the experimental conditions. The proposed method was successfully applied to the analysis of N-nitrosodimethylamine in cured ham and loin, bacon, and sausages.     

Multisyringe flow injection spectrophotometric determination of uranium in water samples

A multisyringe flow injection analysis method for the determination of uranium in water samples was developed. The methodology was based on the complexation reaction of uranium with arsenazo (III) at pH 2.0. Uranium concentrations were spectrophotometrically detected at 649 nm using a light emitting diode. Under the optimized conditions, a linear dynamic range from 0.1 to 4.0 μg mL⁻¹, a 3σ detection limit of 0.04 μg mL⁻¹, and a 10σ quantification limit of 0.10 μg mL⁻¹ were obtained. The reproducibility (%) at 0.5, 2.5, and 4.0 μg mL⁻¹ was 2.5, 0.9, and 0.6%, respectively (n = 10). The interference effect of some ions was tested. The proposed method was successfully applied to the determination of uranium in water samples.     

Ion-exchange separation and spectrophotometric determination of vanadium in environmental samples

A selective and sensitive method for the extraction and spectrophotometric determination of vanadium(V) in microgram quantities is described. The molar absorptivity of the yellow vanadium(V)-caffeic acid-Aliquat 336 extract is 1.3 x 10(4) 1.mole(-1).cm(-1) at 370nm. The method is compared with the atomic-absorption spectrometric method and applied to the trace determination of vanadium in steel, alloys, a rock and environmental samples.     

Modifications of spectrophotometric methods for total phosphorus determination in meat samples

Spectrophotometric determination of total phosphorus in meat samples was modified using the molybdenum blue reaction with the following reducing agents: ascorbic acid (AA), hydrazine sulphate (HS), and mixture of hydroquinone and hydrazine sulphate (HHS). Proposed methods were validated by evaluation of statistical parameters such as: linearity, sensitivity, limits of detection (DL) and quantification (QL), precision, and accuracy, against the standard and malachite green (MG) modified procedures and by applying food certified materials. The values of within-day and between-days precision in meat samples for all tested reducing agents were better than 3.4 % and 4.2 %, respectively. The recoveries for CRMs analyses were between 92 % and 102.3 %. Obtained results suggest usefulness of the hydroquinone and hydrazine sulphate mixture in the determination of phosphorus ions.     

Direct flame atomic absorption spectrophotometric determination of alkalis in geochemical samples

Flame atomic absorption spectrometry has been used for the estimation of the alkali metal content (as Na₂O and K₂O) in 95 reference materials with diverse matrices (including recently introduced Polish and Chinese standard samples awaiting certification through collaborative studies) using 1000 μg ml⁻¹ of lanthanum and 2000 μg ml⁻¹ of rubidium as matrix buffers for sodium and potassium, respectively. The ±t (Student's values for the samples with known recommended values (degree of freedom n − 1 = 9), at the 95% and 99% confidence levels) indicate that within the confidence levels 95–99% there is no statistical difference between the data presented and the reference data for most of the samples. The agreement between the reported data and the results obtained are generally good.     

停流-催化动力学光度法测定药物中的溴

研究了H3PO4介质中,溴离子催化KBrO3氧化丁基罗丹明B的褪色反应特性,测定了反应级数和表观活化能,拟定了反应的最佳条件,建立了停流-催化动力学光度法测定微量溴的新方法。在(27±0.05)℃反应4min测定的检出限为1.51×10-4g/L,线性范围为0~10.0mg/L。该方法用于药物中溴离子的测定,相对标准偏差为2.2%~2.3%,回收率为98%~102%。     

A simple spectrophotometric technique for determination of Irganox 1010 in polymeric samples

A simple spectrophotometric method is presented for the determination of tetrakis [methylene (3,5-di-tert-butyl-4-hydroxyhyrocinnamate)] methane (Irganox 1010) in polymeric samples. To a solution of Irganox 1010 in acetone is added concentrated sodium hydroxide solution and then it is shaken for a short time. The 2-phase system produced in the upper phase (acetone) is yellow colored. Absorbance of the colored phase is recorded in a quartz cell at 440 nm. Different parameters such as temperature, time after mixing solutions of Irganox 1010 and sodium hydroxide, and concentration of sodium hydroxide are studied. The linear dynamic range, limit of detection and correlation coefficient (r) are 25–1000 mg·L⁻¹, 10 mg·L⁻¹ and 0.996, respectively. The repeatability of this method is good (n = 6, C = 250 mg·L⁻¹, RSD = 3.26%). Correspondence: Mir Ali Farajzadeh, Department of Analytical Chemistry, Faculty of Chemistry, Tabriz University, Tabriz, Iran     

A new spectrophotometric method for the determination of hydrazine in environmental samples

Summary Hydrazine is determined spectrophotometrically by using veratraldehyde (3,4-dimethoxybenzaldehyde) as a new reagent. The reaction is based on the condensation of veratraldehyde with hydrazine in acidic medium. The resulting yellow coloured condensation product has maximum absorption at 410 nm. The colour system obeys Beer's law in the range of 0.065 to 0.3 g/ml of hydrazine. Molar absorptivity and Sandell's sensitivity are found to be 6.72×10⁴ l mol^–1 cm^–1 (±100) and 0.0004 g cm^–2, respectively. The method is successfully applied for the determination of hydrazine in polluted water, biological samples, in isoniazide tablets and in air. It is compared with other reported spectrophotometric methods and is found to be of comparable sensitivity.     

Solid-phase extraction and spectrophotometric determination of trace amounts of copper in water samples

A simple method for rapid and selective extraction, preconcentration and determination of copper as it's neocuproine complex by using octadecylsilica membrane disks and spectrophotometry is presented. Extraction efficiency and the influence of flow rates of sample solution and eluent, pH, amount of neocuproine and hydroxylamine hydrochloride, type and least amount of eluent for elution of copper complex from disks, break through volume and limit of detection were evaluated. Also the effects of various cationic interferences on percent recovery of copper were studied. Extraction efficiencies >99% were obtained by elution of the disks with minimal amount of solvent. The limit of detection of the proposed method is 0.12 ppb. The method was applied to the recovery and determination of copper in different water samples.     

Indirect spectrophotometric determination of chromium in aqueous samples with a novel chromogen ferene-TM

Summary An analytical procedure for the indirect determination of chromium at theg level in aqueous samples has been developed. It involves the use of a novel chromogen 3-(2-pyridyl)-5,6 bis(5-(2 furyl disulfonic acid))-1,2,4-triazine disodium salt (Ferene-TM), which forms an intensely blue tris chelate with iron(II) that absorbs at 593 nm with a molar absorptivity of 35,500 1 cm^–1 mol^–1. In an acidic system (pH1.0) chromium(VI) is reduced to chromium(III) in the presence of an excess of iron(II), which in turn decreases the absorption of the tris iron(II)-ferene-TM complex. The differential absorption data show a linear relationship for chromium(VI) in 0.01–1.0 ppm range. Many common cations and anions in micro concentration range do not influence the analytical response.

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Indirekte spektrophotometrische Bestimmung von Chrom in wärigen Lösungen mit dem neuen Farbreagens Ferene-TM

Zusammenfassung Ein Verfahren zur indirekten Bestimmung vong-Mengen Chrom in wäßrigen Proben wurde ausgearbeitet. Es beruht auf der Verwendung eines neuen Farbreagens 3-(2-Pyridyl)-5,6-bis(5-(2-furyldisulfonsäure))-1,2,4-triazin-dinatrium (Ferene-TM). Dieses bildet mit Fe(II) ein intensiv blau gefärbtes Tris-Chelat, das bei 493 nm eine molare Absorptivität von 35500 l· cm^–1·mol^–1 zeigt. Chrom(VI) wird bei pH 1,0 zu Cr(III) in Gegenwart eines Überschusses an Fe(II) reduziert, so daß die Absorption des erwähnten Tris-Chelates herabgesetzt wird. Die Absorptionswerte zeigen für 0,01 bis 1,0 ppm Cr(VI) ein lineares Verhältnis. Viele übliche Kationen und Anionen beeinflussen in Mikromengen das analytische Ergebnis nicht.

     

Selective spectrophotometric determination of paracetamol with sodium nitroprusside in pharmaceutical and biological samples

A novel simple method to determine paracetamol with good selectivity has been established by using sodium nitroprusside as the chromogenic reagent. The experiment indicates that sodium nitroprusside can react with paracetamol in a basic solution to form a product with colored O-nitrosamines. The maximal absorption wavelength (λ_max) and the apparent molar absorption coefficient of the product are 700 nm and 3.4 × 10³ L/mol cm, respectively. A Good linear relationship is obtained between the absorbance and the concentration of paracetamol in a wide range of 0.19–96 μg/mL. The linear regression equation is A = 0.01695 + 0.02240C (μg/mL), with a correlation coefficient of 0.9993. The detection limit (3σ/κ) is 0.10 μg/mL, and the relative standard deviation (RSD) is 0.90% (n = 11). The parameters with regard to determination are optimized, and the reaction mechanism is discussed. The method has been successfully applied to the selective determination of paracetamol in pharmaceutical and biological samples.     

Cloud point extraction and spectrophotometric determination of codeine in pharmaceutical and biological samples

Cloud point extraction process using non-ionic surfactant, Triton X-114, to extract codeine from aqueous solution was investigated. The method was based on the extraction of codeine and bromothymol blue from acetate buffer media to surfactantrich phase and formed a charge transfer-ion pair complex. The extracted surfactant-rich phase was diluted with ethanol and its absorbance was measured at 430 nm. The effect of different variables such as pH, Triton X-114 concentration, cloud point temperature and time was established. The calibration graph was linear in a wide range of 100–700 ng ml^?1 of codeine with r = 0.998 (n = 7). The detection limit based on three times standard deviation of the blank (3s) was 4.6 ng ml^?1 and relative standard deviation (R.S.D) is 2.15% for 500 ng ml^?1 codeine (n = 5). The proposed method was applied to the determination of codeine in acetaminophen codeine tablets and blood samples.     

Cloud-point extraction,preconcentration, and spectrophotometric determination of palladium in water samples

The possibility of using Thio-Michler's Ketone (TMK), 4,4′-bis(dimethylamino) thiobenzophenone, for palladium(II) concentrated by micellar extraction at the cloud-point temperature, and later spectrophotometric determination, was investigated. Under the optimum conditions, preconcentration of 50?mL of water samples in the presence of 0.1% (w/v) octylphenoxy polyethoxy ethanol (Triton X-114), 2?×?10^?6?mol?L^?1?TMK and 1?×?10^–3?mol?L^?1 buffer solution (pH?=?3.0) gave the limit of detection of 0.47?ng?mL^?1, and the calibration graph was linear in the range of 2–50?ng?mL^–1. The recovery under optimum working conditions was higher than 97%. The proposed method has been applied to the spectrophotometric determination of palladium(II) in natural water samples after cloud-point extraction with satisfactory results.     

Diazotized reagent for spectrophotometric determination of glyphosate pesticide in environmental and agricultural samples

A new sensitive spectrophotometric method for the determination of glyphosate herbicide in environmental and agricultural samples is developed. The reaction is based on diazotization followed by coupling of glyphosate with p-dimethyl amino benzaldehyde. The resulted complex absorption spectra was observed at λ_max = 420 nm. The effects of other metal ions and pesticides were also tested for selective determination of glyphosate. The analytical parameters were optimized and have been successfully applied for determination of glyphosate in various environmental samples such as soil, water and vegetables. This method has a lower limit detection of 6 μg of glyphosate. Beer's law is obeyed over the concentration range of 6.0 μg–24.0 μg glyphosate in 25 mL of the final solution at 420 nm. The standard deviation and relative standard deviation calculated are 0.0055 and 1.023, respectively. The molar absorptivity of the colored system is 1.91 × 10¹⁰ L mol^?1cm^?1 and Sandell's sensitivity is found 0.408 × 10^?5 μg cm^?2. The proposed method is simple, sensitive, highly reproducible and time saving as compare to those complicated time consuming methods.     

分散液相微萃取-分光光度法测定水样中痕量肼

建立了分散液相微萃取-分光光度法测定痕量肼的新方法.在0.2 mol/L HCl介质中,以对二甲氨基苯甲醛(PDAB)为显色剂,三氯甲烷为萃取剂,乙醇为分散剂分离富集溶液中痕量肼.优化了反应酸度、萃取剂与分散剂的选择和用量、显色剂用量、显色时间和萃取时间等影响因素.最佳实验条件下,方法的线性范围0.80~120μg/L(r=0.999 5),检出限0.26μg/L.应用于实际水样测定,回收率在98.0%~103.4%之间,RSD在2.7%~3.2%之间.     

Solid-phase extraction and spectrophotometric determination of mercury with 6-mercaptopurine in environmental samples

A highly selective, sensitive and rapid method for the determination of trace amounts of inorganic mercury based on the reaction of Hg (II) with 6-mercaptopurine and the solid phase extraction of the complex on C18 membrane disks was developed. The 6-mercaptopurine selectively reacts with Hg (II) to form a complex in the pH range of 5-8. This complex was preconcentrated by solid phase extraction with C18 disks. An enrichment factor of 100 was achieved. The molar absorptivity of the complex is 0.26 x 10(-6) L. mol(-1) cm(-1) measured at 315 nm. The Beer's law is obeyed in the concentration range of 0.002-0.048 microg mL(-1). The relative standard deviation for eleven-replicated measurement of 0.04 microg mL(-1) is 1.5 %. The detection limit is 0.001 microg mL(-1) in the water samples. The advantage of the method is that the determination of Hg (II) is free from interference of almost all the cations and anions found in environment and wastewater samples. The determination of Hg (II) in water samples of different origins and marine sediment were carried out by the present method and cold vapor atomic absorption spectrometry (CVAAS). Also the method's accuracy was investigated by using SRM 2709. The obtained results by the present procedure were in good agreement with those of the CVAAS and certified value, so that the applicability of the proposed method was confirmed for the real samples.