Determination of estrogenic steroids in surface water and wastewater by liquid chromatography-electrospray tandem mass spectrometry

An analytical method is presented which permits trace level determination of 17alpha-ethynylestradiol (EE2), 17beta-estradiol (E2), and estrone (E1). Using this method, the estrogenic steroids were analyzed in drinking water, surface water, and wastewater (sewage influents and effluents) at concentrations down to 0.1 ng/L. Sample volumes between 100 and 500 mL are concentrated using automated solid-phase extraction. Analysis is performed by liquid chromatography with detection by tandem mass spectrometry. Applying simple clean-up procedures and internal standard calibration, recovery losses resulting from matrix-dependent ion suppression during electrospray ionization could be compensated for all of the investigated compounds. Recoveries around 100% were obtained for all analytes after correction using the internal standards. Limits of quantification (LOQ) were between 0.1 and 0.4 ng/L for purified sewage, surface, ground, and drinking water and between 1 and 2 ng/L in the case of raw sewage. Water treatment by wastewater treatment plants (WWTPs) or by a surface water treatment plant affected the removal of all estrogenic steroids. Thus, E1, E2, and EE2 were removed in the municipal WWTPs to the extent of 93%, 93%, and 80%, respectively. In the effluents of the WWTP in Ruhleben (Berlin, Germany), E1, E2, and EE2 were detected at the low ng/L level. E2 and EE2 were, however, not present in the Berlin surface water above the LOQ (0.2 ng/L). E1 was the only compound that could be detected in surface water samples. After additional surface water treatment it was still detectable but only at trace-level concentrations with a mean value of 0.16 ng/L.     

Forensic classification of ballpoint pen inks using high performance liquid chromatography and infrared spectroscopy with principal components analysis and linear discriminant analysis

Several varieties of blue ballpoint pen inks were analyzed by high performance liquid chromatography (HPLC) and infrared spectroscopy (IR). The chromatographic data extracted at four wavelengths (254, 279, 370 and 400 nm) was analyzed individually and at a combination of these wavelengths by the soft independent modeling of class analogies (SIMCA) technique using principal components analysis (PCA) to estimate the separation between the pen samples. Linear discriminant analysis (LDA) measured the probability with which an observation could be assigned to a pen class. The best resolution was obtained by HPLC using data from all four wavelengths together, differentiating 96.4% pen pairs successfully using PCA and 97.9% pen samples by LDA. PCA separated 60.7% of the pen pairs and LDA provided a correct classification of 62.5% of the pens analyzed by IR. The results of this study indicate that HPLC coupled with chemometrics provided a better discrimination of ballpoint pen inks compared to IR. The need to develop a suitable IR method for analysing blue ballpoint pen inks has been emphasized and it is hoped that the development of such a method would indeed provide a valuable tool for the non-destructive analysis of blue ballpoint pen ink samples for forensic purposes.     

Polyhydroxy pregnanes from Dregea volubilis

Three new polyhydroxy pregnanes named dregealol (1), volubilogenone (2) and volubilol (3) were isolated from the flowers of Dregea volubilis, and their structures elucidated from extensive 2D NMR analysis. The structure of volubilol (3) was confirmed by X-ray crystallographic studies. The known pregnane derivatives drevogenin D, iso-drevogenin P and 17α-marsdenin were also isolated.     

On-line photo-derivatization with flow injection and liquid chromatography-atmospheric pressure electrospray mass spectrometry for the identification of indoles

The application of on-line photochemistry with flow injection (FI) and liquid chromatography (LC) in conjunction with atmospheric pressure electrospray mass spectrometry (LC-APESI-MS) for the identification of similar indole derivatives is reported here. The photo-transformation of the indole compounds is strongly affected by the substituent groups on the aromatic and heterocyclic rings. Upon photolysis for 2.5 min, the mass spectrum of tryptamine (Try) which has no OH substituent on the aromatic ring does not differ greatly from that obtained without photolysis. However, after photolysis of serotonin (Ser) which has one OH group on C5 of the aromatic ring, the mass spectrum indicates the formation of dimers and higher molecular weight ions. The fragmentation pattern of 5-hydroxytryptophol (Phol) without photolysis resembles that of Ser with a base peak of m/z 160. Upon photolysis using MeOH-H₂O (10/90), Phol is found to form a base peak at m/z 375 (100%) and a major peak at m/z 214 (66%) in addition to other ions with lower abundance. Melatonin (Mel) and tryptophan (Phan) upon photolysis are found to form high molecular weight ions with a relative low abundance. The mass spectrum of indole-3-acetic acid (Inaa) with on-line photolysis also shows different ions that are not formed without photolysis.     

卡尔曼滤波紫外光度法同时测定饮料中苯甲酸及糖精的研究

在酸性条件下，用乙醚萃取、蒸干乙醚后，用ＮａＨＣＯ３溶解残渣，从复杂的样品中分离出苯甲酸和糖精，测定它们在２４５～２８１ｎｍ之间的紫外吸收，运用卡尔曼滤波算法计算两者的浓度，用新息序列监测干扰物质分离的程度。此法简化了许多分离手续，用于饮料分析，结果满意。     

Automated at-line solid-phase extraction-gas chromatographic analysis of micropollutants in water using the PrepStation

A fully automated at-line solid-phase extraction-gas chromatography procedure has been developed for the analysis of aqueous samples using the PrepStation. The sample extract is transferred from the sample preparation module to the gas chromatograph via an autosampler vial. With flame-ionization detection, limits of determination (S/N=10) of 0.05–0.13 μg/l were obtained for the analysis of HPLC-grade water when modifying the PrepStation by: (i) increasing the sample volume to 50 ml, (ii) increasing the injection volume up to 50 μl, and (iii) decreasing the desorption volume to 300 μl. The HP autosampler had to be modified to enable the automated “at-once” on-column injection of up to 50 μl of sample extract. The amount of packing material in the original cartridge had to be reduced to effect the decrease of the desorption volume. The total set-up did not require any further optimization after having set up the method once. The analytical characteristics of the organonitrogen and organophosphorus test analytes, i.e. recoveries (typically 75–105%), repeatability (2–8%) and linearity (0.09–3.0 μg/l) were satisfactory. The potential of the system was demonstrated by determining triazines and organophosphorus pesticides in river Rhine water at the 0.6 μg/l level using flame-ionization and mass-selective detection. No practical problems were observed during the analysis of more than 100 river water samples.     

Fluorinated nitroxides as ESR probes of solvation

Some newly synthesized fluorinated nitroxides, such as t-butyl perfluoroalkyl nitroxides Bu^tN(O) R_f (R_f=CF₃, 5; C₂F₅, 6; n-C₃F₇, 7) and s-butyl perfluoroacyl nitroxides Bu^sN(O) COR_f (R_f=CF₃, 9; n-C₃F₇, 10) have been employed as ESR probes of solvation in different common organic solvents. In aprotic solvents, the measured a_N values for each of the nitroxyl probes show a linear correlation with the cybotactic polar solvent parameters E_T (Dimroth) and Z (Kosowar), i.e. a_N=bE_T+c, and a_N=b′Z+c′. The physical significance for the slope (b or b′), the slope×E_T or slope×Z, the extrapolated intercept on a_N axis, c or c′, are linked, respectively, to the sensitivity of a specific nitroxide toward solvation, the magnitude of the overall solvation effect on the a_N value, and the intrinsic a_N value of each nitroxide in the ideal gaseous state. The intercept on the a_N axis may also serve as a new measure of electronegativity for perfluoroalkyl groups, CF₃, C₂F₅, n-C₃F₇, and perfluoroacyl groups, CF₃CO, n-C₃F₇CO. In protic solvents, i.e. alcohols and carboxylic acids, however, a_N values of all the probes, kept almost no change with the increase in E_T and Z. Furthermore, the plots of a_N versus non-cybotactic solvent constants, such as dipolar moment (μ) and dielectric constant (ε), all show random variations.     

Complexity of flow time minimization in a crossdock truck scheduling problem with asymmetric handover relations

We address a novel truck scheduling problem arising in crossdocking logistics, in which inbound trucks carry items (pallets) which must be sorted and loaded onto outbound trucks. We minimize the utilisation of the warehouse by focusing on the synchronisation between the different related trucks. The problem is to assign the trucks to the doors of the warehouse and sequence them, in order to minimize the total time spent in the system by the pallets. We discuss the complexity of the problem, showing that even with a single door the problem is NP-hard in general, and discuss some special cases.     

New results on multi-dimensional linear discriminant analysis

Fisher linear discriminant analysis is a well-known technique for dimensionality reduction and classification. The method was first formulated in 1936 by Fisher. In this paper we concentrate on three different formulations of the multi-dimensional problem. We provide a mathematical explanation why two of the formulations are equivalent and prove that this equivalency can be extended to a broader class of objective functions. The second contribution is a rate of convergence of a fixed point method for solving the third model.