4-(21-thiazolylazo) resacetophenone oxime. A new analytical reagent for the spectrophotometric determination of uranium (VI)

4-(2¹-Thiazolylazo) resacetophenone oxime forms a pink colored soluble complex with uranium(VI) in buffer solutions of pH 6.0. The colored complex has a maximum absorbance at the wavelength 572 nm and the color is stable for about 48 h. The system obeys Beer's law over the concentration range 0.2–6.0 g of uranium cm^–3. The molar absorptivity and the Sandell sensitivity of the complex are 6.2×10⁴ dm³.mol^–1.cm^–1 and 0.0038 g cm^–2, respectively. Effect of various diversions has been studied and the method was successfully applied for the determination of uranium in rock samples.     

Spectrophotometric determination of trace amounts of cadmium using Cd(II)-KI-Crystal violet system in the presence of triton X-100 and PVA

A new highly sensitive spectrophotometric method for determination traces of cadmium using Cd-(II)-KI-Crystal Violet system in the presence of Triton X-100-poly(vinyl) alcohol (PVA) mixture has been developed. The apparent molar absorptivity of the system is 1.77 × 10⁵ 1-mol^–1 cm^–1 and its Sandell's sensitivity is 6.35 × 10^–4 g·Cd·cm^2–. Beer's law is obeyed up to 0.32 g·Cd(II)·ml^–1. The method has been applied to determine Cd(II) in waste water, rice and pork meat samples with satisfactory results.     

3-Hydroxy-2-(2"-Thienyl)-4H-Chromon-4-one as a Spectrophotometric Reagent for the Trace Determination of Zirconium in an Aqueous Phase

A rapid, simple, selective, and sensitive method for the trace determination of zirconium has been developed based on the reaction of 3-hydroxy-2-(2"-thienyl)-4H-chromon-4-one in an hydrochloric acid medium to form a yellow–colored complex which is rendered water soluble by the micellar action of Triton X-100 and measured at 415 nm. Most of the metal ions do not interfere with the determination. Beer's law is obeyed in the concentration range 0–2.0 g/mL and the molar absorptivity of the complex is 2.73 × 10⁴L mol^–1cm^–1; Sandell's sensitivity is found to be 0.0034 g cm^–2. The method has been applied for the determination of zirconium in various samples, and satisfactory results have been obtained.     

Alternative spectrophotometric determination of niobium and tantalum with o-hydroxyhydroquinonephthalein in cationic surfactant micellar media

Summary The alternative and simultaneous spectrophotometric determination of niobium and tantalum was examined by using the colour development between o-hydroxyhydroquinonephthalein (Qnph) and niobium or tantalum in the presence of hexadecyltrimethylammonium chloride (HTAC) in strong acidic media. Beer's law was obeyed up to 10.0 g of niobium and up to 18.0 g of tantalum in a final volume of 10.0 ml. The apparent molar absorption coefficients for niobium and tantalum were 2.18×10⁵ and 2.09×10⁵ l mol^–1 cm^–1 with Sandell's sensitivities of 0.00042 g/cm² niobium at 520 nm and 0.00085 g/cm² tantalum at 510 nm, respectively. The alternative assay of niobium and tantalum was possible by using two methods: Method A — masking method with oxalic acid, Method B — acid adjusting-method using 50% sulfuric acid. These methods were 2–6-times more sensitive than other methods.Application of xanthene derivatives in analytical chemistry. Part XC. Part LXXXIX see ref [1]     

Electrochemical and solid-phase synthetic modification of glassy carbon electrodes with dihydroxybenzene compounds and the electrocatalytic oxidation of NADH

We report the preparation, using electrochemical and solid-phase synthesis, and characterisation of a 26 member library of 13 dihydroxybenzene derivatives covalently attached to glassy carbon through ethylenediamine (EDA) and C₆H₄CH₂NH linkers. First, Boc-protected EDA or Boc–NHCH₂C₆H₄ were electrochemically attached to the GC surface. After Boc-deprotection, dimethoxybenzoyl chlorides were coupled to the EDA and C₆H₄CH₂NH linkers using solid-phase synthesis followed by deprotection of the methoxy groups to give the corresponding dihydroxybenzene compounds. Surface coverage and electrochemical parameters of the dihydroxybenzene modified electrodes were evaluated in parallel using cyclic voltammetry. The mid-peak potentials, E_mp, and surface coverages for the 13 dihydroxybenzene derivatives were found to be independent of the choice of linker. The mid-peak potentials of the immobilised dihydroxybenzene derivatives varied between 0.0 and 260 mV vs. SCE and their surface coverages varied between 0.07 and 1.1 nmol cm^− 2, depending on the pattern of substitution of the dihydroxybenzene ring. The electrocatalytic activities of the library were evaluated for mediation of NADH oxidation, and the ortho-dihydroxybenzene derivatives were found to have higher catalytic activity.     

Spectrophotometric and first-derivative spectrophotometric determination of cadmium witho-hydroxybenzenediazoaminoazobenzene (HDAA)

The synthesis ofo-hydroxybenzenediazoaminoazobenzene (HDAA) is described. Cadmium forms with HDAA in the presence of Triton X-100 a 13 complex, which gives a maximum absorption at 520nm with an apparent molar absorptivity of 1.97 × 10⁵1 · mol^–1 · cm^–1 in pH 10 borax buffer solution and 1.52 × 10⁵1 · mol^–1 · cm^–1 in ammoniacal medium. In both media, Beer's law is followed in the range of 0 –10 g of cadmium in 25ml of solution and the coefficients of variation do not exceed 1.5%. A derivative method has been employed to determine cadmium in certain waste water samples without separation.     

Extraction and spectrophotometric determination of uranium in phosphate fertilizers

An extraction and spectrophotometric method for determination of trace amounts of uranium in phosphate fertilizers is described. It is based on the extraction of uranium with trioctylphosphine oxide in benzene and the spectrophotometric determination of uranium with Arsenazo III in buffer-alcoholic medium. The maximum absorbance occurs at 655 nm with a molar absorptivity of 1.2·10⁴ l·mol^–1·cm^–1. Beer's law is obeyed over the range 0.6–15.0 g·ml^–1 of uranium(VI). The proposed method has been applied successfully to the analysis of phosphate fertilizers with phosphate concentrations of 45% P₂O₅.     

Spectrophotometric determination of micro amounts of beryllium in waste water with chromeazurol S (CAS) and cetylpyridinium chloride (CPC) after separation by dynamic adsorption on activated carbon

Summary A spectrophotometric method for the determination of microamounts of beryllium in waste water has been developed using CAS and CPC. The interference of foreign ions can be eliminated by separation with dynamic adsorption on activated carbon. Beer's law is obeyed for 0 to 0.7 g of Be in 25 ml of solution. The apparent molar absorptivity is 7.9×10⁴ l mol^–1 cm^–1 at 605 nm. The method has been used to determine beryllium in several industrial waste waters.     

A New Spectrophotometric Method for the Determination of Cerium Using Leuco Disulphine Blue

A new, simple, highly sensitive spectrophotometric method for the determination of trace amounts of cerium(IV) is described. The method is based on the oxidation of leuco disulphine blue (LDSB) to its blue form of disulphine blue by Ce(IV) in a sulfuric acid medium (pH 1.3–3.0); the absorbance of the formed dye is measured in an acetate buffer medium (pH 3.0–4.8) at 635 nm. The color system obeys Beer's law in the concentration range from 0.5 to 5.5 g mL^–1 cerium with a molar absorptivity of 1.75 × 10⁴ L mol^–1 cm^–1 and a Sandell's sensitivity of 0.008 g cm^–2. All variables were studied in order to optimize the reaction conditions. The developed method has been successfully applied to the determination of cerium in high purity rare-earth oxides, soil, natural water, plant tissue, human hair, and rock samples.     

Spectrophotometric determination of aniline in aqueous solution by azo-dye formation with diazotized p-nitroaniline

A simple, sensitive, and rapid Spectrophotometric method for the trace determination of aniline in aqueous solution is described. The method is based on coupling aniline with diazotizedp-nitroaniline in the presence of ethanol and sodium hydroxide to form an intense red water-soluble azo-dye which shows maximum absorption at 505 nm and greater stability and sensitivity in the presence of cetyltrimethylammonium bromide. Beer's law is obeyed over the aniline concentration range 0.2–2.4g/ml in the solution measured; the molar absorptivity is 3.46×10⁴l· mole^–1·cm^–1, and the relative standard deviation 1–2%, depending on the aniline concentration.     

Sensitive flotation-spectrophotometric method for the determination of vanadium (IV) with 3,5-dinitrosalicylic acid and rhodamine B

Vanadium(IV) is determined by reaction with 3,5-dinitrosalicylic acid and rhodamine B in weakly acidic medium. The flotation of the ternary ion-association complex is carried out with cyclohexane followed by dissolution in acetone for subsequent spectrophotometric determination. The molar absorptivity is 5.91×10⁵ l mole^–1 cm^–1 at 555 nm. Beer's law is obeyed in the range 0.05–1.5 g vanadium(IV) in 25 ml. The method is selective for vanadium(IV) in the presence of sodium fluoride and has been applied to standard reference materials.     

Direct and Derivative Spectrophotometric Determination of Thorium with 2,4-dihydroxybenzaldehyde Isonicotinoyl Hydrazone

A simple and sensitive spectrophotometric method is developed for the determination of throium in aqueous medium. The metal ion forms yellow coloured complex with 2,4-dihydroxybenzaldehyde isonicotinoyl hydrazone (2,4-DHBINH) in the pH range 2.0–8.0. The complex shows an absorption maximum at 390 nm. The absorbance of the complex is maximum at pH 5.5 Beer's law is obeyed in the range 0.30–7.00 g/ml of thorium(IV). The molar absorptivity and the Sandell's sensitivity of the method are 2.20· 10⁴ l·mol^–1·cm^–1 and 0.0106 g/cm^–2, respectively. The interference of various ions was studied. The composition of the complex is 1:1 {Th(IV) : 2,4-DHBINH}. The first derivative spectrum of the complex shows a zero cross at 391.2 nm and maximum amplitude at 415 nm. Thus a sensitive derivative spectrophotometric method for the determination of Th(IV) is proposed.     

Extraction and spectrophotometric determination of uranium(VI) withN-phenylcinnamohydroxamic acid

Uranium(VI) reacts withN-phenylcinnamohydroxamic acid to form an orange-yellow complex in the pH range 5.5–8.5. The orange-yellow complex, having the composition of 12 (metal:ligand), is quantitatively extractable into ethyl acetate. The spectrum of the complex exhibits a maximum absorption at 400 nm with a molar absorptivity of 6500 M^–1·cm^–1. The coloured system obeys Beer's law in the concentration range 2–40g·ml^–1 of uranium(VI). The photometric sensitivity of the colour reaction is 0.037 g·cm^–2 of uranium(VI). Most of the common ions do not interfere and the method has been found to be simple, precise, and free from the rigid control of experimental conditions. The method has been applied to the determination of uranium in synthetic matrices and potable water.     

Flotation-spectrophotometric method for the determination of mercury using iodide and brilliant green

This paper describes a sensitive spectrophotometric method for the determination of mercury, based on the flotation of a mercury iodide-brilliant green complex with cyclohexane at pH 5 and dissolution of the complex in acetone. The absorbance of the complex is measured at 625 nm. Beer's law is obeyed from 4–500 g/l of mercury. The method is highly sensitive ( = 5.96 × 10⁵ 1 mol^–1 cm^–1) and selective, as it is free from interferences by almost all cations and anions in the presence of EDTA. Furthermore, a two-level orthogonal array design as a chemometric method has been used for optimization of the various parameters involved. The method has been successfully applied to paper industry effluents.     

Spectrophotometric determination of uranium(VI) with 1-(2′-thiazolylazo)-2-naphthol in the presence of Trition X-100

Uranium(VI) reacts with 1-(2-thiazolylazo)-2-naphthol to form a red-coloured chelate in the pH range 5.3–7.2, maintained by 0.04 M acetate buffer. Absorbance of the sparingly soluble complex, solubilized and stabilized by Triton X-100, is measured after 30 min and it is stable for at least 16 hours. The complex exhibits maximum absorbance at 575 and 625–630 nm, but absorbance at longer wavelengths is not stable. The 12 complex obeys Beer's law over the concentration range 0.4–6.4 g of uranium(VI) per cm³, has molar absorptivity 3.36·10⁴ dm³·mol^–1·cm^–1, Sandell sensitivity 7.0 ng·cm^–2, formation constant (log K) 9.32 and coefficient of variation ±0.77%. Effect of 60 ions has been studied and selectivity improved considerably in presence of CDTA. The method has been applied for determination of uranium content in a rock sample.     

Extraction-spectrophotometric determination of chromium with Nitrotetrazolium Blue

The interaction of Cr(VI) and Nitrotetrazolium Blue has been examined. A 12 NTB (CrO₃Cl)₂ ion-associate is formed and is extractable into 1,2-dichloroethane. The optimum conditions have been established. The molar absorptivity at 260 nm was (8.2 ± 0.06) × 10⁴L mol^–1cm^–1. Beer's law was obeyed in the range 0.01–0.4 g ml^–1 Cr(VI). A sensitive and selective method for determination of micro-quantities of Cr(VI) in soils and steels is suggested.     

Polarographic and spectrophotometric determination of isocarboxazid and tranylcypromine sulphate through treatment with nitrous acid

Two methods are described for the determination of two widely prescribed antidepressants, namely isocarboxazid and tranylcypromine sulphate as the pure drugs and in dosage forms. Both methods involve prior treatment with nitrous acid. In the Spectrophotometric method, the two derivatives obey Beer's law over the concentration range 1–20 g/ml. The derivatives are polarographically reducible withE _1/2 values of –0.84 and –0.73 V for isocarboxazid and tranylcypromine sulphate, respectively. The calibration plots are linear over the range 4.3 × 10^–5–3.0 × 10^–4 and 1.1 × 10^–5–1.65 × 10^–4 mol/1 for isocarboxazid and tranylcypromine sulphate, respectively. The results obtained for assays for the two drugs compare satisfactorily with those given by the official methods.     

A sensitive spectrophotometric method for the determination of trace amounts of uranium (VI) using o-hydroxypropiophenone isonicotinoyl hydrazone

The reaction between uranium (VI) and o-hydroxypropiophenone isonicotinoyl hydrazone (OHPINH) has been investigated in HCl-sodium acetate buffers and a highly sensitive and simple procedure for the determination of uranium (VI) is suggested. The yellow colored complex showed maximum absorption at 380 nm in buffer solutions of pH 3. Beer's law is obeyed in the range of 0.47–17 g ml^–1. The molar absorptivity and Sandell sensitivity are found to be 1.15×10⁴ dm³ mol^–1 cm^–1 and 0.02 g cm^–2, respectively. The composition of the complex is found to be 11 between metal and reagent.     

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.     

2-(2-Thiazolylazo)-p-cresol as a spectrophotometric reagent for vanadium determination in the presence of ascorbic acid

The present work describes the use of 2-(2-thiazolylazo)-p-cresol (TAC) as a spectrophotometric reagent for vanadium determination. TAC reacts with vanadium(IV) in the presence of ascorbic acid, forming a red complex with absorption maximum at 525 nm. The following parameters were studied: complex stability, pH effect, amount of TAC, amount of acetate buffer, HEDTA effect, order of addition of reagents and Beer's law validity. TAC can be used for vanadium determination in the pH range 4.6–6.0, with molar absorptivity of 2.11 × 10⁴Lmole^–1 cm^–1 (at525nm). Beer's law is obeyed up to 2.0 g mL^–1. Many cation interferences can be easily eliminated by using HEDTA as a masking agent. Steel reference standards were used to test the proposed procedure and the accuracy and precision obtained were satisfactory.