Fatty acid composition of Abies pindrow (West Himalayan fir).

The leaves of Abies pindrow, collected from Murree Hills, Punjab (Pakistan) revealed the presence of eleven fatty acids including eight saturated and three unsaturated fatty acids. They ranged from C(14) to C(24) and were detected as methyl esters by GC-MS technique. The saturated fatty acids were present in much greater proportion than unsaturated ones. Isopalmatic acid was found to be major saturated fatty acid and the oleic acid as predominant unsaturated acid. (+)-14-Methyl palmatic acid and (+)-Isosteric acid were the next higher saturated and unsaturated fatty acids respectively.

A rapid spectrophotometric method for the determination of trace level lead using 1,5-diphenylthiocarbazone in aqueous micellar solutions.

A very simple, ultra-sensitive and fairly selective direct spectrophotmetric method is presented for the rapid determination of lead(II) at ultra-trace level using 1,5-diphenylthiocarbazone (dithizone) in micellar media. The presence of the micellar system avoids the previous steps of solvent extraction and reduces the cost and toxicity while enhancing the sensitivity, selectivity and the molar absorptivity. The molar absorptivities of the lead-dithizone complex formed in the presence of the cationic cetyltrimethylammonium bromide (CTAB) surfactants are almost ten times the value observed in the standard method, resulting in an increase in the sensitivity of the method. The reaction is instantaneous and the absorbance remains stable for over 24 h. The average molar absorption coefficient was found to be 3.99 x 10(5) L mol(-1) cm(-1) and Sandell's sensitivity was 30 ng cm(-2) of Pb. Linear calibration graphs were obtained for 0.06-60 mg L(-1) of Pb(II); the stoichiometric composition of the chelate is 1:2 (Pb:dithizone). The interference from over 50 cations, anions and complexing agents has been studied at 1 mg L(-1) of Pb(II). The method was successfully used in the determination of lead in several standard reference materials (alloys and steels), environmental water samples (potable and polluted), biological samples (human blood and urine), soil samples and solutions containing both lead(II) and lead(IV) and complex synthetic mixtures. The method has high precision and accuracy (sigma = +/-0.01 for 0.5 mg L(-1)).

Ultra-trace level determination of hydroquinone in waste photographic solutions by UV-vis spectrophotometry.

A simpler UV-vis spectrophotometric method was investigated for hydroquinone (HQ) determination using KMnO(4) as oxidizing agent for conversion of HQ to p-benzoquinone (BQ) as well as signal enhancer. Various parameters such as analytical wavelength, stability time, temperature, pH, solvent effect and interference of chemicals were checked and parameters optimized by using 1mugml(-1) standard solution of HQ. Beer's Law was applicable in the range of 0.07-2mugml(-1) and 0.005-0.05mugml(-1) at 245.5nm and at 262nm for aqueous standard solutions of HQ with linear regression coefficient value of 0.9978 and 0.9843 and detection limit of 0.021mugml(-1) and 0.0016mugml(-1) HQ, respectively. Standard deviation of 1.7% and 2.4% was true for 1mugml(-1) and 0.03mugml(-1) HQ solution (n=11) run at respective wavelengths. The method was successfully applied to dilute waste photographic developer samples for free HQ determination.

The efficacy of nitrosonaphthol functionalized XAD-16 resin for the preconcentration/sorption of Ni(II) and Cu(II) ions.

Amberlite XAD-16 resin has been functionalized using nitrosonaphthol as a ligand and characterized employing elemental, thermogravimetric analysis and FT-IR spectroscopy. The sorption of Ni(II) and Cu(II) ions onto this functionalized resin is investigated and optimized with respect to the sorptive medium (pH), shaking speed and equilibration time between liquid and solid phases. The monitoring of the influence of diverse ions on the sorption of metal ions has revealed that phosphate, bicarbonate and citrate reduce the sorption up to 10-14%. The sorption data followed Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms. The Freundlich parameters computed are 1/n=0.56+/-0.03 and 0.49+/-0.05, A=9.54+/-1.5 and 6.0+/-0.5 mmol g(-1) for Ni(II) and Cu(II) ions, respectively. D-R isotherm yields the values of X(m)=0.87+/-0.07 and 0.35+/-0.05 mmol g(-1) and of E=9.5+/-0.23 and 12.3+/-0.6 kJ mol(-1) for Ni(II) and Cu(II) ions, respectively. Langmuir characteristic constants estimated are Q=0.082+/-0.005 and 0.063+/-0.003 mmol g(-1), b=(4.7+/-0.2)x10(4) and (7.31+/-0.11)x10(4)l mol(-1) for Ni(II) and Cu(II) ions, respectively. The variation of sorption with temperature gives thermodynamic quantities of DeltaH=-58.9+/-0.12 and -40.38+/-0.11 kJ mol(-1), DeltaS=-183+/-10 and -130+/-8 J mol(-1)K(-1) and DeltaG=-4.4+/-0.09 and -2.06+/-0.08 kJ mol(-1) at 298 K for Ni(II) and Cu(II) ions, respectively. Using kinetic equations, values of intraparticle transport and of first order rate constant have been computed for both the metal ions. The sorption procedure is utilized to preconcentrate these ions prior to their determination in tea, vegetable oil, hydrogenated oil (ghee) and palm oil by atomic absorption spectrometry using direct and standard addition methods.

Determination of preservatives in cosmetics and food samples by micellar liquid chromatography.

An analytical procedure has been developed for the analysis of benzoic acid, p-hydroxybenzoic acid, methyl-, ethyl-, propyl-, isopropyl-, and butyl esters of p-hydroxybenzoic acid by micellar liquid chromatography. After dilution in n-propanol the sample was directly injected onto a Lichrosorb ODS, 5 microm (250 x 4.6 mm ID) column and eluted with aqueous 2% Brij-35 adjusted to pH 3.0 with phosphoric acid:propanol (80:20 v/v) at a flow rate of 1 mL min(-1) and UV detection at 254 nm. A linear calibration curve was obtained simultaneously for each component in the range of 50-500 microg mL(-1) for benzoic acid and 5-150 microg mL(-1) for the other components; detection limits were within 25-250 ng mL(-1) corresponding to 125-1250 pg per injection (5 microL). The reproducibility in terms of average peak area and average retention time was obtained with coefficients of variation (CV) of 1.2% and 0.5%. The method was applied to analysis of these compounds in cosmetics (shampoos, hand lotions, creams, and bath foam) and food samples.

A simple spectrophotometric determination of trace level mercury using 1,5-diphenylthiocarbazone solubilized in micelle.

A very simple, ultra-sensitive and fairly selective non-extractive spectrophotmetric method is presented for the rapid determination of mercury(II) at ultra-trace level using 1,5-diphenylthiocarbazone (dithizone) as a new micellar spectrophotometric reagent (lambdamax = 490 nm) in a slightly acidic (0.07 - 0.17 M H2SO4) aqueous solution. The presence of a micellar system avoids the previous steps of solvent extraction and reduces the cost, toxicity while enhancing the sensitivity, selectivity and the molar absorptivity. The reaction is instantaneous and the absorbance remains stable for over 24 h. The average molar absorption coefficient and Sandell's sensitivity were found to be 5.02 x 10(4) L mol(-1) cm(-1) and 10 ng cm(-2) of Hg, respectively. Linear calibration graphs were obtained for 0.05 - 10 mg L(-1) of Hg; the stoichiometric composition of the chelate is 1:2 (Hg:dithizone). The method is characterized by a detection limit of 1 microg L(-1) of Hg. Large excesses of over 60 cations, anions and complexing agents (e.g. EDTA, tartrate, oxalate, citrate, phosphate, thiourea, azide, SCN-) do not interfere in the determination. The method was successfully applied to a number of environmental water samples (potable and polluted), biological samples (human blood and urine; milk and fish) and soils; solutions contained both mercury(I) and mercury(II) as well as complex synthetic mixtures. The method has high precision and accuracy (s = +/-0.01 for 0.1 mg L(-1)).