Gas chromatographic trace analysis of underivatized nitrophenols

Summary A method for the gas chromatographic trace analysis of underivatized nitrophenols in ground-water is presented. Using a highly de-activated separation system a satisfactory precision for their quantitative GC analysis could be achieved by avoiding condensation of the solvent and by fast injection of the sample. The reproducibility of the peak areas of eleven nitrophenols in ethylacetate was <5 % RSD. Using a nitrogen-phosphorus detector detection limits were in a range from 10 to 30 pg. Within the concentration range from 0.1 to 10 ng μl⁻¹ the calibrations were linear with correlation coefficients >0.992. The approach described was applied to the analysis of nitrophenols in ground-water near a former ammunition plant, after preconcentration by continuous liquid/liquid extraction with ethylacetate. Using a GC-MS technique and retention times various nitrophenols were identified and then quantified in the μg/L-range by applying NPD.     

多组分体系同时定性定量测定的逐步回归分析法

阐述了逐步回归分析法用于多组分体系同时定性定量分析的原理、实验及数据处理方法。分析了硝基酚类人工样、未知样及合成样。该法可用于仅知可能含有的组分范围的样品分析。     

Nitrophenol Derivatives Oxidized by Cerium(IV) Ammonium Nitrate (CAN) and Their Cytotoxicity

Oxidation of a series of phenols with cerium(IV) ammonium nitrate (CAN) in acetonitrile under mild conditions yields the mixture of corresponding nitrophenols. In the cases of methylphenols and hydroxy ‐carboxylic acids, the steric effect may reduce the nitration reaction. Compounds 3a and 4b showed selective activities to Hep 3B and Hep G2 cancer cell lines, respectively. Compound 2c showed selective activities to Hep G2 and MDA‐MB‐231 cancer cell lines. Furthermore, compound 10b showed selective activities to Hep G2, Hep 3B, MCF‐7 and MDA‐MB‐231 cancer cell lines.     

Cross‐linked starch‐based polymer as an SPE material for the determination of nitrophenols at trace levels in environmental water

SPE using a cross‐linked starch‐based polymer (CSMDI) as an adsorbent for the determination of four nitrophenols at trace levels from aqueous solution was investigated. The CSMDI was synthesized from native starch using 4,4′‐methylenebisphenyldiisocyanate as a cross‐linking agent in dry DMF. Parameters affecting the extraction efficiency including the pH of the water sample, type of eluent and its volume, flow rate, sample volume, and methanol content were investigated and optimized. The optimized results exhibited excellent linear relationships (R² > 0.995) for all the nitrophenols over the range of 2.0–200 ng/mL, with the RSD values in the range of 2.9–5.7% (n = 5). The LODs ranged from 0.08–0.34 ng/mL (S/N = 3) for the four nitrophenols tested under optimum conditions. The developed method has been successfully applied for the analysis of several real environmental water samples including tap, river, and reservoir water. These results indicated that the CSMDI had a tremendous potential for the enrichment and determination of nitrophenols at trace levels in environmental water samples.     

Rapid determination of mono and dinitrophenols by DPP, in the presence of lead and cadmium and using concentrated CaCl2 electrolyte

The contamination of drinking water and industrial wastewaters is a critical environmental problem. The nitrophenol, dinitrophenol, cadmium, and lead contaminants are classified as hazardous compounds. Their rapid determination may be obtained using differential pulse polarography with concentrated electrolyte. CaCl₂, which is very soluble to levels exceeding 5 mol l^–1, allows separation of coalescent peaks at 0.1 mol l^–1. A systematic study undertaken from 0.1 to 5 mol l^–1 shows good separation of lead and cadmium from the organic compounds, and optimization of the electrolyte concentration according to the objective is described. Preconcentration of real samples is necessary because pollution levels are usually very low.     

Determination of partition coefficient and analysis of nitrophenols by three‐phase liquid‐phase microextraction coupled with capillary electrophoresis

A three‐phase hollow fiber liquid‐phase microextraction method coupled with CE was developed and used for the determination of partition coefficients and analysis of selected nitrophenols in water samples. The selected nitrophenols were extracted from 14 mL of aqueous solution (donor solution) with the pH adjusted to pH 3 into an organic phase (1‐octanol) immobilized in the pores of the hollow fiber and finally backextracted into 40.0 μL of the acceptor phase (NaOH) at pH 12.0 located inside the lumen of the hollow fiber. The extractions were carried out under the following optimum conditions: donor solution, 0.05 M H₃PO₄, pH 3.0; organic solvent, 1‐octanol; acceptor solution, 40 μL of 0.1 M NaOH, pH 12.0; agitation rate, 1050 rpm; extraction time, 15 min. Under optimized conditions, the calibration curves for the analytes were linear in the range of 0.05–0.30 mg/L with r²>0.9900 and LODs were in the range of 0.01–0.04 mg/L with RSDs of 1.25–2.32%. Excellent enrichment factors of up to 398‐folds were obtained. It was found that the partition coefficient (K_a/d) values were high for 2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2,4‐dinitrophenol and 2,6‐dinitrophenol and that the individual partition coefficients (K_org/d and K_a/org) promoted efficient simultaneous extraction from the donor through the organic phase and further into the acceptor phase. The developed method was successfully applied for the analysis of water samples.     

Separation of nitrophenols. Equilibriums in bi- and tri-phasic systems

The paper presents experimental data obtained in the study of liquid–liquid partition equilibriums in biphasic system in order to optimize the process of transport through bulk liquid membranes (triphasic partition systems). The partition equilibriums of some nitrophenols using chloroform as extraction solvent and membranary solvent, respectively, were studied. The influence of the pH on the partition equilibriums was investigated. The repartition constants and the pK_a values of the studied nitrophenols were calculated. Nitrophenols were transferred in triphasic system from a feed phase with pH 2, through a chloroform liquid membrane, into a receiving phase with pH 12, with efficiencies over 90%.     

示波中和滴定指示剂的研究（Ⅲ）

本文介绍了对酸性示波中和指示剂刚果红、百里酚兰和对、间、邻－硝基酚等指示滴定终点时切口随变化的原理的探讨。     

Development of a capillary electrophoresis system coupled to sequential injection analysis and evaluation by the analysis of nitrophenols

A combination of a laboratory-made capillary electrophoresis system and a sequential injection analysis equipment is described. For characterization, the system was successfully applied to the separation and quantification of nitrophenols. A blue LED was used as light source, and hydrodynamic injection was carried out by using a pressure-stable solenoid valve and an inflatable pressure reservoir. A good reproducibility of migration time (0.5%) and peak heights (5%) were obtained. The calibration by using peak heights was found to be linear up to 776?µmol?L^?1 for all three compounds. The system was robust and reliable for autonomous analysis without observation. All maintenance requirements including the conditioning of the capillary and flushing of both buffer reservoirs were carried out automatically. Instrumentation aspects of the capillary electrophoresis part are compared with former described hyphenated flow systems showing maximal operation versatility. Instrumental control and data evaluation were carried out using the software package AutoAnalysis.     

Study of mass transfer in a dynamic hollow‐fibre liquid phase microextraction system

The extraction characteristics of a dynamic hollow‐fibre liquid phase microextraction system were investigated by studying the mass transfer and diffusion rates of dinitrophenols from plasma samples over the liquid membrane (dihexylether). The measured diffusion coefficients were compared with theoretical values calculated from Stokes diameters. The diffusion mechanism was simulated by computer and the most polar compounds, 2,4‐dinitrophenol and 4,6‐o‐dinitrocresol, had associated diffusion coefficients that were close to the calculated theoretical values. 2‐sec‐Butyl‐4,6 dinitrophenol and 2‐tert‐butyl‐4,6‐dinitrophenol, the compounds with the highest log P values, were retained by the polypropylene membrane, which reduced the experimentally observed diffusion rates to about half of the theoretical values. The retention was most likely due to dispersive forces interacting with the pore inner walls. Extraction was linearly correlated with time for all compounds and the repeatability was high (RSDs 7–11%), even for the shortest extraction times. Method LOD as the amount injected ranged between 0.3 and 3.1 ng for an extraction cycle of 213 s.