An extraction-spectrophotometric determination of palladium with 4-(2-pyridylazo)resorcinol in the presence of diphenylguanidine

A new, sensitive spectrophotometric determination of palladium has been developed, based on the extraction of the red Pd(II) chelate with 4-(2-pyridylazo)resorcinol in the presence of N,N′-diphenylguanidine into n-butanol; the sensitivity of the method according to Sandell is S = 1.12 μg cm^?2, ?₅₃₀ = 9.4 × 10⁴ liters mol^?1 cm^?1, and palladium can be determined at concentrations from 0.21 to 1.91 μg ml^?1.     

Extractive spectrophotometric determination of nitrite in polluted waters

Nitrite is diazotised with p-nitroaniline in hydrochloric acid and coupled with 8-quinolinol in alkaline medium to give a purple azo dye (λ_max = 550 nm, ? = 3.88 × 10⁴ l mol^-1 cm^-1). Extraction of the dye into 3-methyl-1-butanol shifts the absorption maximum to 570 nm and improves the apparent molar absorptivity to 5.852 × 10⁴ l mol^-1 cm^-1. Beer's law is obeyed for 0.01–0.06 ppm nitrite. The Sandell sensitivity is 0.00078 μg cm^-2. The method is applicable to polluted waters.     

Photometric determination of calcium with antipyrylazo III

Antipyrylazo III or diantipyrylazo (3,6-bis(4-antipyrylazo)-4,5-dihydroxy-2, 7-napthalenedisulfonic acid) forms at PH 12.7 a complex Ca₂HL with calcium. The logarithmic overall stability constant, 10g β₂₁₁, is 23.99 ±0.03 (0.1 MNaClO₄,25°C).The effective molar absorptivity is 21,500 ±100 l mole^-1 cm^-1 at 605 nm. The complex can be used for a selective photometric determination of calcium(0.25–3.50μmole) if tri-and tetravalent ions are removed by extraction with cupferron (into chloroform) and transition divalent ions are masked with sodium cyanide. Only strontium (0.5 μmole) and EDTA (0.1 μmole) interfere seriously.     

Spectrophotometric determination of copper with α, β, γ, δ-tetraphenylporphine trisulfonate

Water-soluble porphyrin, α, β, γ, δ-tetraphenylphorphine trisulfonate (TPPS, H₂R), was found to be a very useful agent for both the direct spectrophotometric determination and the photometric titration of copper(II). The molar absorptivity of H₄R²⁺ at 434 nm is 5.0·10⁵ and the spectrophotometric sensitivity is 0.00013 μg Cu cm^?2 for A=0.001. Beer's law is followed in the range 0.006 μg–0.06 μg Cu ml^?1. Among twenty-two elements examined, only zinc(II) seriously interfered. Acid dissociation constants and salt effects on the spectra of TPPS were evaluated.     

The spectrophotometric determination of antimony in water,effluents, marine plants and silicates

A spectrophotometric procedure is described for the determination of antimony in natural waters (including sea water and effluents), algae and silicates. After a preliminary oxidative digestion for waters, or acid attack for algae and silicates, the element is quantitatively coprecipitated at pH 5.0 with hydrous zirconium oxide. The precipitate is dissolved in acid, and, after reduction with titanium(III) chloride, antimony is oxidized to antimony(V) with sodium nitrite. The ion pair of the SbCl₆^- ion with crystal violet is extracted with benzene and its absorbance is measured at 610 nm (molar absorptivity 74,000 l mol^-1 cm^-1). Extraction with toluene causes some loss of sensitivity. The detection limit is 0.005 μg l^-1; relative standard deviations are 0.5% and 1.1% for spiked distilled water (0.5 μg l^-1) and sea water (0.26 μg l^-1), respectively. A wide range of anions and cations cause no interference at levels many times those in natural waters. The technique can be adapted for application to marine algae and silicates; relative standard deviations are 1.8% and 2% for samples of Pelvetia canaliculata (0.19 μg Sb g^-1) and a Pacific Ocean red clay (1.08 μg Sb g^-1), respectively. Results for the U.S. Geological Survey Standard rocks GSP1 (2.7 ppm) and DTS1 (0.53 ppm) are in good agreement with those of earlier workers.     

Thiobarbituric acid-reacting substances derived from autoxidizing linoleic and linolenic acids

Seven pyridylazo dyes containing the m-tolylenediamine group were synthesized and their analytical potential for the determination of cobalt was studied spectrophotometrically. The molar absorptivities and selectivity of these reagents increased compared with those of PADAB. Cobalt(II) and 3,5-diCl-PADAT (5-[(3,5-dichloro-2-pyridyl)azo]-2,4-diaminotoluene) at pH 3 form a complex which is very stable even in the presence of strong mineral acids. The complex has two absorption maxima at 548 and 590 nm in hydrochloric acid (2.4 M) solution. The color is very stable and the system conforms to Beer's law; the optimal range for measurement in a 1-cm cell is 0.01–0.4 p.p.m. cobalt. In practice, this color reaction is specific. The molar absorptivity is 1.38 ·10⁵ 1 mol^-1 cm^-1 at 590 nm. The sensitivity is 0.00042 μg Co cm^-2 at 590 nm for log I₀/I= 0.001. The method was applied to the determination of cobalt in steel and waspaloy.     

Extraction—spectrophotometric determination of copper(II) with 4-(2-pyridylazo)resorcinol and a long-chain quaternary ammonium salt

A simple and highly sensitive extraction—spectrophotometric determination of copper (II) is described. The ion-associate formed between the copper(II)—4-(2-pyridylazo)-resorcinol (PAR) anion and tetradecyldimethylbenzylammonium chloride (TDBA) is extracted with chloroform at pH 9.7. The absorption maximum of the extracted species occurs at 510 nm, the molar absorptivity being 8.05 (± 0.07) × 10⁴ l mol^-1 cm^-1. Beer's Law is obeyed in the concentration range 0.1–0.5 μg Cu ml^-1. The composition of the ion-associate is estimated to be [Cu(PAR)₂(TDBA)₂]. The conditional extraction constant is log K'_ex ≈ 8. The interference of some cations and anions is studied. The method is suitable for analysis of waters.     

Extraction—spectrophotometric determination of traces of cadmium with 4-(2-pyridylazo)resorcinol and a long-chain quaternary ammonium salt

A simple and highly sensitive extraction—spectrophotometric determination of cadmium is described. The ion-associate formed between the cadmium-PAR anionic chelate and cetyldimethylbenzylammonium chloride (CDBA) is extracted with chloroform at pH 10. The absorption maximum of the extracted species occurs at 505 nm, the molar absorptivity being (9.82 ± 0.30) × 10⁴ l mol^-1 cm^-1. The optimal concentration range for measurements is 0.2–1.0 μg Cd ml^-1; Beer's law is obeyed. The composition of the ion-associate is estimated to be CdPAR₂-2CDBA. The conditional extraction constant is log K'_ex ≈ 8. The stability constant of the cadmium—PAR chelate in aqueous solution is log β₂ = 17.5 ± 0.3. Extraction with N-benzoyl-N-phenylhydroxylamine is used to avoid several interferences. Moderate amounts of zinc are masked with sodium hydroxide.     

Spectrophotometric determination of vanadium with n-benzoyl-o-tolylhydroxylamine

N-Benzoyl-o-tolylhydroxylamine is shown to provide a virtually specific reagent for the spectrophotometric determination of vanadium. The reddish-violet complex formed with the reagent in 4–8 N hydrochloric acid after extraction with chloroform shows absorption maxima at 510 mm, and obeyes Beer's law from 0.5 to 10 μg with an optimum range of 2–10 μg; the percent relative error is 2.7. The sensitivity is 0.0108 μg V/cm². The complex contains the metal and the reagent in a ratio of 1:2 and the dissociation constant is of the order of 10^-9.     

Spectrophotometric determination of nitrite in polluted waters using 3-nitroaniline

Nitrite reacts with 3-nitroaniline in the presence of hydrochloric acid to form a diazonium cation, which is subsequently coupled with N-(1-naphtyl)ethylenediammonium chloride to form a stable purple azo dye. The method is suitable for the determination of 0.01–0.80 μg ml^?1 nitrite. The reactions are very fast and require no control of temperature. The observed molar absorptivity and Sandell's sensitivity of the azo dye are 4.9 × 10⁴ l mol^?1 cm^?1 and 9.4 × 10^?4 μg cm^?2, respectively. The method is free from most interferences. The method has been applied successfully to polluted river water.     

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.     

Cytotoxic Podophyllotoxin Type-Lignans from the Steam Bark of <em>Bursera fagaroides </em>var. <em>fagaroides</em>

The hydroalcoholic extract of the steam bark of B. fagaroides var. fagaroides displayed potent cytotoxic activity against four cancer cell lines, namely KB (ED₅₀ = 9.6 × 10^-2 μg/mL), PC-3 (ED₅₀ = 2.5 × 10^-1 μg/mL), MCF-7 (ED₅₀ = 6.6 μg/mL), and HF-6 (ED₅₀ = 7.1 × 10^-3 μg/mL). This extract also showed anti-tumour activity when assayed on mice inoculated with L5178Y lymphoma cells. Bioactivity-directed isolation of this extract, afforded seven podophyllotoxin-type lignans identified as podophyllotoxin (1), β-peltatin-A-methylether (2), 5'-desmethoxy-β-peltatin-A-methylether (3), desmethoxy-yatein (4), desoxypodophyllotoxin (5), burseranin (6), and acetyl podophyllotoxin (7) by 1D and 2DNMR and FAB-MS analyses, and comparison with reported values. All the isolated compounds showed potent cytotoxic activity in the cell lines tested, especially compound 3, which exhibited greater activity than camptothecin and podophyllotoxin against PC-3 (ED₅₀ = 1.0 × 10^-5 μg/mL), and KB (ED₅₀ = 1.0 × 10^-5 μg/mL). This is the first report of the isolation of podophyllotoxin and its acetate in a Bursera species.     

Microwave spectrum,conformation, dipole moment and centrifugal distortion of glyoxylic acid

Microwave spectra of CHO-COOH and CHO-COOD are reported. The molecule has a planar equilibrium conformation with the two carbonyl groups trans to each other. A weak five-member intramolecular hydrogen bond is formed between the hydroxyl proton of the carboxyl group and the oxygen atom of the carbonyl group thus stabilizing the trans planar form. Other conformations having a statistical weight of 1 (cis and trans) are at least 1.3 kcal mol^?1 less stable, and rotamers with a statistical weight of 2 (e.g., gauche and skew) have at least 1.7 kcal mol^?1 higher energy. Four vibrationally excited states of CHO-COOH have been analyzed and relative intensity measurements yielded 167 ± 12 cm^?1 for the C-C torsional mode and 288 ± 26 cm^?1 for the lowest in-plane bending mode. The dipole moment was determined to be μ_a = 1.85 ± 0.03 D, μ_b = 0.20 ± 0.10 D, and μ_tot = 1.86 ± 0.04 D. A seven-parameter centrifugal distortion analysis has been carried out for the ground vibrational state of CHO-COOD and for the ground and three vibrationally excited states of CHO-COOH.     

Phenylmethoxybis(tetrazolium) ion-association complexes with an anionic indium(III) — 4-(2-pyridylazo)resorcinol chelate

Complex formation and liquid-liquid extraction were studied in systems containing indium(III), 4-(2-pyridylazo)resorcinol (PAR), phenylmethoxybis(tetrazolium) salt (MBT), water and chloroform. The following MBTs, which differ only by the number of -NO₂ groups in their cationic parts, were used: 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)bis(2,5-diphenyl-2H-tetrazolium chloride) (Blue Tetrazolium chloride, BT), 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)bis[2-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride] (Nitro Blue Tetrazolium chloride, NBT) and 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)bis[2,5-di(4-nitrophenyl)-2H-tetrazolium chloride] (Tetranitro Blue Tetrazolium chloride, TNBT). The composition of the formed ternary complexes was determined, In:PAR:MBT=1:2:2, and the optimum conditions for their extraction found: pH, shaking time, concentration of the reagents and the sequence of their addition. Some key constants were estimated: constants of extraction (K_ex), constants of association (β) and constants of distribution (K_D). BT appears to be the best MBT for extraction of the In(III)-PAR species, [In³⁺(OH)₃(PAR)₂]^4?, (Log K_ex=10.9, Log β=9.8, Log K_D=1.12, R%=92.7%). Several additional characteristics concerning its application as extraction-spectrophotometric reagent were calculated: limit of detection (LOD = 0.12 μg cm^?3), limit of quantification (LOD = 0.40 μg cm^?3) and Sandell’s sensitivity (SS =1.58 ng cm^?2); Beer’s law is obeyed for In(III) concentrations up to 3.2 μg mL^?1 with a molar absorptivity coefficient of 7.3×10⁴ L mol^?1 cm^?1 at λ_max=515 nm.      

Spectrophotometric determination of nitrite with p-nitroaniline and 2-methyl-8-quinolinol in hexadecyl-trimethylammonium bromide solution

Nitrite ion at low concentrations is determined spectrophotometrically by diazotization of p-nitroaniline and coupling of the diazonium salt with 2-methyl-8-quinolinol. The resulting dye is solubilized in hexadecyltrimethylammonium bromide micelles. The molar absorptivity is 4.72 × 10⁴ l mol^-1 cm^-1, and the Sandell sensitivity is 9.7 × 10^-4 μg cm^-2. Some interferences are reported, and preconcentration by evaporation is evaluated. The solubility of hexadecyltrimethylammonium bromide in water was determined as a function of temperature; the Krafft point is 19.6°C. Salting-in of the surfactant by potassium nitrate is described.     

Chlorophosphonazo-m-NO2, a new reagent for the spectrophotometric determination of cerium sub-group rare earth elements in the presence of yttrium sub-group elements

The synthesis of chlorophosphonazo-m-NO₂ is described. Cerium sub-group rare earth elements can be determined in the presence of 10–40 fold amounts of yttrium sub-group elements when the latter are masked by oxalic acid at pH 1.6. Under the experimental conditions employed, the apparent molar absorptivities of lanthanum and cerium at 666 nm are 9.5 × 10⁴ and 9.3 × 10⁴ l mol^-1 cm^-1, respectively. Beer's law is obeyed for 0–12 μg of lanthanum or cerium in 25 ml of solution. The coefficients of variation for La and Ce are 0.37% and 0.92%, respectively.     

Direct and Second Order Analogue Derivative Extraction-Spectrophotometric Determination of Iron with 2 (4, 5-Dimethyl-2-Thiazolylazo)-4, 6-Dimethylphenol

Abstract

An extraction-spectrophotometric method for the determination of trace amounts of iron based on its extraction into chloroform with 2-(4, 5-dimethyl-2-thiazolylazo)-4, 6-dimethylphenol has been developed, which allows the determination of 5–28 μg Fe (?₇₇₃ = 1.38×10⁴ 1. mol^?1. cm^?1). The use of second order analogue derivative spectrophotometry allows the determination of down to 0.2–5 μg, Fe. The methods are quite selective and have been applied to the determination of iron in mineral waters.     

Efficacy of selected triorganotin(IV) compounds on leaves against Phytophthora palmivora (Butler) Butler isolated from black pepper and cocoa

Several triorganotin(IV) compounds and Terrazole® 35 WP were screened for their in vitro antifungal activity against three isolates of Phytophthora palmivora. Two isolates (isolates Phy. 2 and Phy. 334) were obtained from black pepper (Piper nigrum L.) and one isolate (isolate Phy. 56) from cocoa leaves (Cacao theobromae). ED₅₀ values for radial growth of the isolates ranged from 0.09 to 1,700 μg cm^?3 for the triorganotin(IV) compounds and from 3.46 to 1 227 000 μg cm^?3 for Terrazole®. Diphenylbutyltin bromide exhibited the highest antifungal activity against the three isolates of P. palmivora with ED₅₀ values ranging from 0.30 to 0.73 μg cm^?3. Diphenylbutyltin bromide was equally effective against a freshly isolated virulent culture of P. palmivora (isolate Phy. 346) from black pepper leaves in Sarawak, East Malaysia, yielding an ED₅₀ value for radial growth of 0.87 μg cm^?3 and a probit-log concentration regression line slope value of 1.04. In vitro efficacy of diphenylbutyltin bromide against isolate Phy. 346 using detached healthy pepper leaves showed 40–75% infection of leaves at 100 μg cm^?3 and no infection at 500 μg cm^?3. Diphenylbutyltin bromide at 100 μg cm^?3, however, inhibited the diameter of lesion by 43.3–73.7% compared with the untreated controls. Black pepper leaves treated with Terrazole® at 778 μg cm^?3 exhibited 5.3–33.3% inhibition of lesion diameter compared with the untreated controls, where 90–100% of the leaves were infected. Concentrations of diphenylbutyltin bromide of 1000–2500 μg cm^?3 caused some injury lesions on the leaves. From the results obtained, it appears that diphenylbutyltin bromide could be used as a protective spray or drench against P. palmivora infection of black pepper at 100–500 μg cm^?3.     

Stark quantum beat spectroscopy of polyatomic molecules

We derive analytical expressions for Stark quantum beat signals of polyatomic molecules and discuss them with regard to molecular and geometrical parameters. The general treatment is specified for near prolate asymmetric rotor molecules and a method for determining rotational constants and all components of the dipole moment of electronically excited polyatomic molecules is presented. The method is tested and illustrated for the vibrationlessS ₁ state of deuterated propynal (HC ≡ CCDO,C _s symmetry) and its lowest frequency non-totally symmetric state 12¹. The results of the vibrationless state are compared with structural data reported in the literature. For the 12¹ state we obtainA=1.5004(43) cm^?1,B=0.16131(34) cm^?1,C=0.14623(34) cm^?1, and the components of the electric dipole moment in the molecular plane μ _a =?0.88(2)D, μ _b =1.03(2)D. Furthermore, it is shown that the modulation depth of Stark quantum beat signals can be utilized to quantify the contribution of the individual components of the transition moment to the total emission.     

Cumulative author index: Vol. 126(1977)–150(1978)

The synthesis of μ-[phenyl(dicyclohexylphosphonio)ethenidyl]-μ-(diphenylphosphido)hexacarbonyldiiron, Fe₂(CO)₆[CC(PCy₂H)Ph](PPh₂) via nucleophilic attack by dicyclohexylphosphine at the β-carbon atom of the σπ-acetylide in Fe₂(CO)₆(CCPh)(PPh₂) is described. This complex, which contains a one-carbon 3-electron bridging ligand has been characterised by microanalysis, infrared, mass, Mössbauer and ³¹P NMR spectroscopy and by a single crystal X-ray structure determination. Crystals are monoclinic, space group P2₁/c with a 10.932(3), b 8.983(2), c 38.644(6) Å, β 94.48(2)°. With four molecules per unit cell and a formula weight of 764.4, the calculated density of 1.342 g cm^?3 agrees with the measured value of 1.34 g cm^?3. The structure was solved by heavy atom methods and refined by least squares techniques with iron and phosphorus atoms having anisotropic thermal parameters, to R and R_w values of 0.068 and 0.075 respectively. In the binuclear molecule an ironiron bond of length 2.550(2) Å is bridged by a diphenylphosphido group and the carbon atom of an unusual dipolar ligand Cy₂(H)P⁺C(Ph)C^?. In the bridging one-carbon-3-electron ligand the coordinated carbon atom is trigonal and the atoms P(1), C(8), C(31), C(7) are virtually coplanar. Structural parameters are compared with those of other complexes containing bridging one-carbon, 3-electron and two-carbon, 3-electron ligands. Nucleophilic attack by phosphorus and nitrogen nucleophiles on σπ-acetylides appears to be a general route to these ligands.