Derivative Ultraviolet Spectrometry Research Articles

Residue behaviour and health risk assessment of chlorpyrifos and mancozeb in apple fruits and soil.

Mancozeb residue estimation was done using second derivative ultraviolet spectroscopy by Shimadzu ultraviolet-visible spectrophotometer, and chlorpyrifos was estimated by QuEChERS technique using GC-FPD. The persistence for chlorpyrifos was carried out at two locations, and for mancozeb, persistence studies were carried out at four locations. Initial deposits of mancozeb on apple fruits ranged from 1.33 to 1.63mg/kg at the recommended dose and from 2.55 to 3.26mg/kg at double the recommended dose at all four locations. Chlorpyrifos residues in apple fruits had an initial deposit of 0.94-0.99mg/kg at recommended dose and 1.75-1.92mg/kg at double the recommended dose. Mancozeb residues in apple fruit were below the detection limit (BDL) after 20days at recommended dose and after 25days at double the recommended dose at two locations, while mancozeb residue at the other two locations and the residues of chlorpyrifos at all locations reached BDL after 15 and 20days at recommended and double the recommended doses, respectively. Half-life of mancozeb varied from 3.07 to 4.02days at recommended dose and from 3.30 to 4.32days at double the recommended dose, whereas chlorpyrifos residues dissipated to half their initial concentration on 2.33-2.35days at recommended dose and 2.89-2.90days at double the recommended dose. The soil samples showed no presence of residues of chlorpyrifos and mancozeb at harvest. The risk assessment revealed that hazard quotient for the intake of mancozeb was in the range of 0.06-0.13% and 0.20-0.44% for rural and urban population, while for the intake of chlorpyrifos, hazard quotient was in the range of 0.10-0.12% for rural population and 0.33-0.38% for urban population, and theoretical maximum dietary intake (9.67 × 10-5mg/person and 3.18 × 10-4mg/person for rural population and urban population in case of mancozeb and 3.22 × 10-5mg/person and 1.06 × 10-4mg/person for rural population and urban population in case of chlorpyrifos) was also found to be less than maximum permissible intake (1.38mg/kg for mancozeb and 0.60mg/kg for chlorpyrifos). The results of risk assessment thereby indicated that apple consumption does not pose a risk to human health.

Combination of chromatographic and spectroscopic characterization based on primitive ultraviolet absorbance detection to fulfill advanced monitoring of dissolved organic matter in municipal wastewater treatment plant

Effective and affordable monitoring tool for dissolved organic matter (DOM) in municipal wastewater treatment plant (WWTP) is in great need. In this study, high-performance size exclusion chromatography (HPSEC) with ultraviolet absorbance (UVA) detection and ultraviolet (UV) spectrometry were complementarily combined for advanced characterization of DOM in a municipal WWTP. DOM in different process units were chromatographically characterized mainly by UVA at 210 nm (UVA210), 254 nm (UVA254), UVA ratio index (URI, UVA210/UVA254). Differential and derivative UV spectrometry were also used for DOM characterization. HPSEC URI chromatographic analyses helped to acquire rich chemical information of DOM components with primitive UVA detection. Influent HPSEC fractions Ⅰ, Ⅳ, Ⅴ− 2, which were proved to consist of protein and polysaccharides, low molecular weight organic acids and hydrophobic organics respectively, were readily removable. HPSEC fractions Ⅱ and Ⅲ were proved to contain mostly recalcitrant humic substances (HS). Effluent HPSEC fraction Ⅴ− 1 contained nonbiodegradable saturated organics. UV spectrometry complemented HPSEC characterization by revealing that saturated organics generated during sand filtration and second derivative peak height at 295 nm (SDPH295) could be surrogate for biodegradable organics concentration in influent. Measures for DOM control optimization of this WWTP were proposed based on the DOM characteristics revealed. This study proved practicability of achieving advanced DOM monitoring with cheap and convenient but primitive chromatographic and spectroscopic characterization with UVA detection which may provide basis for developing applicable equipment for organic pollutants monitoring of municipal WWTP.

DNA complexed with TAT peptide and condensed using calcium possesses unique structural features compared to PEI polyplexes

Complexes of the TAT peptide with plasmid DNA (pDNA) show unusually high transfection efficiency when condensed via "soft" calcium cross links. In this study, we characterize the structure of pDNA within TAT complexes and compare it with that of branched polyethylenimine (PEI, 25 kDa) complexes. Dynamic light scattering (DLS), second derivative ultraviolet absorption spectroscopy, extrinsic dye fluorescence, Fourier transform infrared (FTIR) spectroscopy, circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC) were employed to access various aspects of the structure of the pDNA. TAT complexes showed the highest transfection efficiency at an N/P ratio of 25 in A549 cells. FTIR and CD spectra of complexes demonstrated that the pDNA remained in the B conformation when associated with TAT or PEI. DSC showed that both TAT and PEI stabilized all forms of pDNA, with TAT increasing the melting temperature of pDNA compared to PEI complexes. Second derivative ultraviolet spectroscopy of TAT complexes showed a substantial reduction in the absorbance and an increase in the wavelengths of the peaks of pDNA at N/P>13; however, a clear correlation between pDNA structure and transfection efficiency was not readily apparent.

Direct determination of U(VI) in TBP-kerosene extracts using first derivative ultraviolet spectroscopy

The extractive first order derivative spectrophotometry is a selective method for the separation and determination of U(VI) using tri-n-butyl phosphate (TBP), which combines the roles of solvent and complexing agent. The complex is formed by extracting U(VI) from an aqueous 6M sodium nitrate solution at initial pH 3.0 into a 25% solution of TBP in kerosene. This extraction also separates U(VI) from many diverse ions that interfere. After extraction, the determination of uranium shows good accuracy and precision with relative standard deviation of 1.5% (n = 5) at 20 ppm using zero-order spectrum at lmax = 250 nm. Calibration curve was also found to obey Beer's law in the range of 10-100 ppm with 3.33 ppm detection limit. However, these accuracy and precision have been improved to give relative standard deviation of 0.7% (n = 5) at 20 ppm with a lower detection limit of 2.24 ppm using the first-derivative spectrum at l = 263 nm comparing to the normal one.

Fourier transform infrared and second derivative ultraviolet spectrometry in determining polystyrene‐poly(4‐methylstyrene) blend composition

AbstractPolymer blend usage has increased in recent years as the blends provide a convenient means for modifying polymer properties. It is often necessary to determine the percents or ratios of the polymers present in a blend. One blend of interest is the immiscible blend of polystyrene (PS) and poly(4‐methylstyrene) (P4MS). The percentages were determined by two methods: Fourier transform infrared (FTIR) spectroscopy and second derivative ultraviolet (UV) spectroscopy. The peak ratio versus percent polymer technique was used in both methods. For the FTIR, the ratio of the absorbance values for the out‐of‐plane CH para‐substituted bending vibration of P4MS at 813 cm−1 and the out‐of‐plane monosubstituted CH bending vibration for PS at 757 cm−1 were ratioed. For derivative UV, the vibrational structures of the aromatic secondary bands were used: the 269 nm minimum for PS and 275 nm minimum for P4MS. The derivative UV method gave considerably better results and also had the advantage of requiring less sample due to its greater sensitivity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3400–3403, 2006

Use of Fourier transform infrared and second derivative ultraviolet spectrometry in determining polystyrene–poly(4‐vinylpyridine) blend composition

AbstractPolymer blend usage has increased in recent years as the blends provide a convenient means for modifying polymer properties. It is often necessary to be able to determine the percentages or ratios of polymers present in a blend. One blend of interest is the immiscible blend of polystyrene (PS) and poly(4‐vinylpyridine) (P4VP). The percentages were determined by two methods: Fourier transform infrared (FTIR) spectroscopy and second derivative ultraviolet (UV) spectroscopy. The peak ratio versus percentage polymer technique was used in both methods. For FTIR, the ratio of the absorbance values of the out‐of‐plane CH bending vibration of P4VP at 822 cm−1 and the aromatic C  C stretch for PS at 1493 cm−1 were ratioed. For derivative UV, the vibrational structure of the aromatic secondary bands was used: 269 nm minimum for PS and the 271 nm maximum for P4VP. Both methods gave excellent and comparable results. The derivative UV determination had the advantage of requiring less sample due to its greater sensitivity. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2422–2426, 2005

Reversed-phase high-performance liquid chromatography on-line with the second and fourth derivative ultraviolet spectroscopy as a tool for identification of milk proteins

This paper reports the possibilities of high-performance liquid chromatography on-line with photodiode-array detection for identification of bovine milk proteins. The application of this method for qualitative analysis of milk proteins on the basis of UV spectra discriminants is described. These discriminants characterise the most frequently occurring extrema of derivatives of UV spectra of proteins separated using HPLC.The measurements have been carried out in the wavelength range of 270–300nm, corresponding to the absorbance of aromatic amino acid residues. The experiment has allowed to estimate the minimal value of absorbance, at which a given protein may be identified and to determine the method specificity, i.e. statistical significance of differences between discriminants characterising the spectra of individual proteins.The findings show the possibility that milk proteins, except αs1-casein (αs1-CN) and αs2-casein (αs2-CN), can be distinguished also proving the method robustness. This means that the method is independent of environmental interference, such as the temperature influence in 20–30°C range, a change of column, the content of acetonitrile and trifluoroacetic acid in the solvent and a sample concentration.The method presented is suitable for identification of individual proteins in such preparations as calcium caseinate, sodium caseinate, milk protein coprecipitate and whey protein concentrate.

Simultaneous determination of oxybenzone and 2-ethylhexyl 4-methoxycinnamate in sunscreen formulations by flow injection-isodifferential derivative ultraviolet spectrometry

A flow injection procedure was developed for the simultaneous determination of two UV filters (oxybenzone and 2-ethylhexyl 4-methoxycinnamate) in sunscreen formulations, based on the isodifferential approach. The use of the second derivative spectra allowed a selective determination of the analytes free from matrix interferences and without pretreatment of samples. Standard solutions of the analytes were analyzed by the proposed procedure in order to select the appropriate wavelengths to solve the mixture. After this, the procedure was validated using commercial sunscreen formulations the concentrations of which were determined by an HPLC procedure. The two procedures gave comparable results. The sensitivity for oxybenzone determination by the proposed method was (9.2±0.1)×10 −5 ml μg −1, and the limit of instrumental detection was 0.5 μg ml −1. Determination of 2-ethylhexyl 4-methoxycinnamate had a sensitivity of (4.6±0.1)×10 −5 ml μg −1 and a limit of detection of 2.1 μg ml −1. The proposed flow injection procedure allowed on-line dilution of samples, and a sampling frequency of 360 h −1. The accuracy, speed and selectivity of the procedure make it suitable for this type of formulations.

Evaluation of a second derivative UV/visible spectroscopy technique for nitrate and total nitrogen analysis of wastewater samples

A method for nitrate analysis based on second derivative UV/Visible spectroscopy was developed by Simal et al. (1985: Simal J., Lage M. A., and Iglesias I. (1985) Second derivative ultraviolet spectroscopy and sulfamic acid method for determination of nitrates in water. J. Assoc. Analyt. Chem. 68, 962–964) and Suzuki and Kuroda (1987: Suzuki, N. and Kuroda R. (1987) Direct simultaneous determination of nitrate and nitrite by ultraviolet second-derivative spectrophotometry. Analyst 112, 1077–1079), and later modified for the analysis of total nitrogen in aqueous samples of varying nitrate:organic nitrogen ratios ( Crumpton et al., 1992 : Crumpton W. G., Isenhart T. M. and Mitchell P. D. (1992) Nitrate and organic N analyses with second-derivative spectroscopy. Limnol. Oceanogr. 37, 907–913). The procedure uses the second derivative of the absorption spectrum for nitrate (NO − 3), which has a peak at ∼224 nm that is proportional to the NO − 3 concentration. Samples for total N analysis are first oxidized to NO − 3 by persulfate digestion. The objectives of this study were to: (1) test the accuracy and precision of the second derivative method through the use of NIST-traceable wastewater check samples; (2) determine whether the second derivative method for nitrate analysis can be used for wastewater samples and whether the method compares favorably with other currently used nitrate analysis methods; and (3) use the method to analyze wastewater samples containing a range of nitrate and total nitrogen concentrations. Our results indicated that the method needed to be modified to include a longer digestion time (60 min) and dilution of samples prior to digestion (if needed). With the modified method, nitrogen recoveries were not significantly different ( P≥0.05) from samples with known N concentrations. In addition, nitrate concentrations in constructed wetland and wastewater samples analyzed by both second derivative spectroscopy and ion chromatography were not significantly different. Total nitrogen concentrations in wastewater samples also compared favorably to the same samples analyzed by Kjeldahl digestion. The method is faster, simpler, requires smaller sample volumes, and generates less waste than many EPA-approved methods of N analysis, and may offer a suitable alternative to current methods for analysis of nitrate and total N in wastewater samples.

Simultaneous Analysis of Pyridoxine and Melatonin in Tablet Formulation by Derivative Ultraviolet Spectroscopy

A method for simultaneous analysis of pyridoxine and melatonin by second and third derivative UV - spectroscopy, the “zero - crossing” technique, is described. The determination has been carried out in 0.1 mol dm−3 hydrochloric acid solution and the concentration range of 2 – 10 μg/ml pyridoxine and 0.5 – 3.5 μg/ml melatonin. Lower limits of detection at the 95% confidence level were 0.26 μg/ml for pyridoxine and 0.05μg/ml for melatonin The advantages of the proposed method include its application for the assay and in-vitro dissolution studies of pyridoxine and melatonin from two different tablet formulations.

Hydrolysis of Benzodiazepines in a Microwave Oven and Ultraviolet Derivative Analysis of Their Benzophenones

Oxazepam, clonazepam, lorazepam, nitrazepam, prazepam, and dipotassium chlorazepate have been quantitatively hydrolyzed in 6 M HCL to their respective benzophenones using a microwave oven with 520 W power and a digestion time of 8 mm. The hydrolysis yield obtained in each case corresponds to 103, 117, 98, 115, 97, and 97%, respectively. Chlorazepate has been used as a test molecule to evaluate the effect of the digestion parameters, such as power and digestion time, on the hydrolysis yield. To determine benzophenones in the presence of benzodiazepines, in order to establish the hydrolysis yield, derivative ultraviolet spectrometry has been employed, using the isodifferential approach.

APPLICATION OF NORMAL AND DERIVATIVE ULTRAVIOLET ABSORPTION SPECTROSCOPY FOR THK DETERMINATION OF AROMATIC HYDROCARBONS IN GAS OILS

ABSTRACT Ultraviolet absorption spectroscopy, has an immense potential for characterization of aromatic hydrocarbons in distillate petroleum fractions. The second derivative ultraviolet spectroscopy has improved the understanding of complex aromatic structures, such as polynuclear aromatics, which are present in gas oil fractions. Normal and second derivative ultraviolet spectroscopy of gas oils and their separated fractions are discussed in detail and conclusions are drawn regarding mono-di-and polynuclear aromatics in various gas oils.

Determination of nitrate in soil by second derivative ultraviolet spectrometry

Abstract A second derivative UV‐spectrometry method is described for the determination of nitrate in soils. Ammonium, nitrite, and urea may be determined in the same extract. The method generally requires no pretreatment of soil extracts, and hence is very rapid. It is largely free from interferences. Recoveries of added nitrate in four soils by the proposed method compared favourably with the phenoldisulphonic acid method.

Multiple Interacting Factors Determine Precision in Derivative Ultraviolet Spectrometry

Theory and experiment show that the precision of quantitative derivative ultraviolet spectrometry depends on the choice of derivative order, degree of smoothing, convolution method of smoothing or derivatization, and power of the reference beam. Except for work describing the simultaneous effect of wavelength range and derivative order, investigations have been made by varying the level of one factor at a time. Adjustment of a single factor at a time is not an efficient way of establishing optimum conditions for analysis, particularly in derivative ultraviolet spectrometry.

Identification of styrene copolymers and a terpolymer by second derivative ultraviolet spectroscopy

AbstractA method for distinguishing styrene copolymers and a terpolymer by second derivative ultraviolet spectroscopy will be described. The polymers were dissolved in chloroform except for one which was dissolved in 2‐butanone. Concentrations of about 5 g/L were used. The polymer solutions were applied to the removable windows of divided, quartz cells and were allowed to dry to a thin film. The ultraviolet region was scanned from 300 to 230 nm. Then thinner films were used, and the 240–200 nm region was scanned. The second derivative spectra that resulted could be distinguished easily. This technique allows rapid, sample preparation and identification of these copolymers and the terpolymer.

Identification of structurally similar polymers by second derivative ultraviolet spectroscopy

Identification of structurally similar polymers by second derivative ultraviolet spectroscopy

A review of sampling methods for polyaromatic hydrocarbons in air.

The recent literature describing sampling methods and development of sampling techniques for airborne PAH is reviewed. Aspects of sampling such as particle sizing and the types of collection media for particle bound and gaseous PAH are discussed. Findings on formation of artifacts during sampling for PAH as a result of reactions with copollutants existing in air are summarized. Effects of sampling conditions such as flow rate, temperature, humidity and sampling duration are reviewed. Developments reported for both passive sampling for PAH and for direct measurement techniques, such as second derivative ultraviolet absorption spectrometry and synchronous luminescence, are also noted.

Determination of aspirin and salicylic acid in aspirin suppositories by second derivative ultraviolet spectrometry.

Determination of aspirin and salicylic acid in aspirin suppositories by second derivative ultraviolet spectrometry.

Quantitative determination of the ligand in Phenyl-Sepharose FF with proton nuclear magnetic resonance and derivative ultraviolet spectroscopy

Quantitative determination of the ligand in Phenyl-Sepharose FF with proton nuclear magnetic resonance and derivative ultraviolet spectroscopy

Arson analysis by second derivative ultraviolet spectrometry

Methode superieure a la chromatographie en phase gazeuse pour les analyses lors d'incendies criminels avec utilisation d'activation par produits petroliers