bluuebunny/crossref_metadata_2025 huggingface dataset:
Cross‐reactivity of a commercial chemiluminescence immunoassay for human chorionic gonadotropin with the free β‐subunit
Authors: Luppa P. , Spöttl G. , Saller B. , Neumeier D. , Mann K.
Published: May 2005

An enhanced chemiluminescence immunoassay for the determination of serum human chorionic gonadotropin (HCG) in specimens from oncology patients has been assessed with respect to its cross‐reactivity with the free HCG ββ‐subunit (HCG‐β). The assay, standardized against the First International Reference Preparation 75/537, had a crossreactivity with the free β‐subunit of 625% (molar basis). Therefore this assay achieves high sensitivity for the detection of either intact HCG or free HCG‐β in serum of patients with seminomatous or nonseminomatous testicular cancers. Results of both assays, the in‐house immunoradiometric assay (+ HCG‐β) and the Amerlite HCG‐60 assay, showed a close correlation (R =0.854−0.960) when serum samples from tumour patients were analyzed. Moreover, the content of free β‐subunit determined in a specific HCG‐β assay, could be quantitatively measured in the enhanced chemiluminescence immunoassay. Thus, this assay is suitable for oncology use, but also highlights the limitations of measuring HCG in serum samples.
Determination of serum oxalate using peroxyoxalate chemiluminescence of free oxalic acid
Authors: Albrecht S. , Hornak H. , Freidt T. , Böhm W. D. , Weis K. , Reinschke A.
Published: May 2005

We describe a new sensitive and specific method for determination of oxalate in human serum. By using the chemiluminescence decay of monoperoxyoxalic acid very low concentrations of oxalate (200 nmol/L) can be determined. The mean serum oxalate level in apparently healthy controls was 14.5 ± 8.5 m̈mol/L. Supplementation of ascorbic acid leads to an increase in serum oxalate level. While serum oxalate concentrations of calcium oxalate stone formers (x = 16.4 ± 9.8 m̈mol/L) are not significantly different from the control group, an extreme increase of serum oxalate is evident in haemodialysis patients. The serum oxalate concentration decreased during dialysis treatment from 141.4 ± 32.1 m̈mol/L to 36.4 ± 12.7 m̈mol/L.
Flow injection chemiluminescence study of acridinium ester stability and kinetics of decomposition
Authors: Littig Janet S. , Nieman Timothy A.
Published: May 2005

Decomposition of phenyl acridinium‐9‐carboxylate is monitored using electrogenerated chemiluminescence in a flow system. The formation of the pseudobase from the acridinium ester [AE] is described by rate = k′1[AE] + k″1[AE][OH−]0.5, where k′1 = 0.020 ± 0.006 s−1 and k″1 = 2.1 ± 0.8 (L/mol)−0.5 s−1. Irreversible decomposition of the pseudobase is described by rate = k′2[AE][OH−], where k′2 = 20.1 ± 3.8 (L/mol s). These kinetic equations, plus measurement of variation in emission intensity for constant acridinium ester concentration, are used to predict the resulting emission intensity v. pH behaviour given various contact times (in the 0.25 to 25 s range) for the acridinium ester to be in an alkaline solution prior to initiation of the chemiluminescence reaction.
Improved preparation of leukocytes for chemiluminescent study of human phagocytic leukocyte‐generated reactive oxygen species
Authors: Saniabadi Abby R. , Nakano Minoru
Published: May 2005

Leukocyte oxidative function was investigated in a more physiological milieu than currently used in the chemiluminescence (CL) technique. Heparinized blood was mixed with 6% dextran‐T70 (9:1) and the leukocyte‐rich plasma obtained without centrifugation was used for the CL experiments (phagocyte count was adjusted to 0.7 × 106/mL with Hanks' buffer) (method A). In this medium, phagocytes responded to stimulation by opsonized zymosan, producing strong luminescence in the presence of 0.5 m̈ mol/L MCLA. CL was inhibited by superoxide dismutase, suggesting that the luminescence reaction was attributable to O. Granulocytes were also prepared by the usual method involving centrifugation and were then suspended in plasma (method B). Oxidative function of phagocytes prepared by the two methods was studied together with whole blood as aliquots diluted with Hanks' buffer up to a factor of 1000. Luminescence reached a peak value at a dilution factor of 16, but at very high dilutions luminescence decreased sharply. Significantly higher luminescence values were obtained with samples from method A. Luminescence of whole blood peaked at a dilution factor of 248 but it was less than the value obtained using samples prepared by method A or B. As samples prepared by method A contain all the leukocyte populations, platelets, residual red cells and plasma proteins, the assay of leukocyte‐generated reactive oxygens using CL is attained in more physiological conditions than method B in which leukocytes may be damaged owing to repeated centrifugation and hypotonic shock.
Processing biological images from very low light emissions
Authors: Bernroider Gustav
Published: May 2005

As opposed to strong light signals (>108 photons mm−2 s−1), the construction of images from object sources with low level signals (<102 photons mm−2 s−1) involves a probabilistic transfer‐ or point‐spread function. The resulting images carry considerable uncertainty or spread, restricting resolution and quantification. In this paper we propose various strategies how to recontruct object characteristics from very low light emissions by unfolding the imaging equation. Further, calibration techniques which help to associate light emissions with the decomposition of luminogenic substrates in a spatially selective way will be discussed.
CCD camera imaging for the chemiluminescent detection of enzymes using new ultrasensitive reagents
Authors: Akhavan‐Tafti Hashem , Schaap A. Paul , Arghavani Zahara , Desilva Renuka , Eickholt Robert A. , Handley Richard S. , Schoenfelner Barry A. , Sugioka Katsuaki , Sugioka Yumiko
Published: May 2005

We have designed and constructed an inexpensive imaging system based on charge coupled device (CCD) technology and utilized it to demonstrate the sensitivity and rapid detection possible with Lumigen® chemiluminescent reagents. We also report the development of two new chemiluminescent reagents, Lumi‐Phos® Plus and Lumigen PS. Lumi‐Phos Plus is an ehanced formulation for the rapid detection of alkaline phosphatase on membranes and in solution. It provides excellent images in blotting applications with exposures of under a minute. Lumigen PS represents a new generation of peroxidase detection reagents. The wide dynamic range with excellent linearity, higher signal and lower background than other chemiluminescent reagents make Lumigen PS of unsurpassed value in enzyme‐linked immunoassays and nuclic acid probe assays using HRP conjugates.
Low‐light image analysis of transgenic organisms using bacterial luciferase as a marker
Authors: Langridge W. , Escher A. , Wang G. , Ayre B. , Fodor I. , Szalay A.
Published: May 2005

Methods for measurement of a novel light‐emitting reporter gene system in bacteria, yeast, plant cells, plant tissues and intact plant organs are described. The principle underlying the assay procedures is the bacterial luciferase catalysed oxidation of reduced flavin mononucleotide (FMNH2) in the presence of the ten carbon aldehyde decanal, to yield FMN, decanoic acid, water and a photon of light at 490 nm which can be captured by X‐ray film, a photomultiplier tube or, for in vivo measurements, an image‐intensifier coupled to a video camera. This light measuring assay system is sensitive, easy to use, inexpensive, does not require radioactivity, and has been used successfully for rapid detection of bacterial transformants, the quantitative measurement of transient and stable gene expression in bacteria and yeast, and in vivo measurement of temporal and spatial gene expression throughout plant and animal development.
Use of lux genes in applied biochemistry
Authors: Hill Philip J. , Stewart Gordon S. A. B.
Published: May 2005

Bioluminescence has emerged in the last decade as a major tool for the study of bacterial adaptation and survival. In addition to the advantages of sensitivity and the real‐time, non‐invasive nature of this reporter, the imaging potntial of using low‐light and photon‐counting video cameras has been particularly influential in establishing its ascendancy over more traditional reporter systems. This review provides a reflection of personal activity in this field through applications in Food Microbiology and collaboration with colleagues both in the UK and beyond.
A method for measuring microquantities of DNA
Authors: Giachè Valentino , Pirami Laura , Becciolini Aido
Published: May 2005

Quantitative analysis of DNA content represents a critical step when only very small amounts of nucleic acids are available. The DNA content of a small RNA‐free sample can be measured in a simple and precise way using a two‐dimensional approach. DNA samples are spotted on the surface of an agarose gel containing ethidium bromide (EtBr) and the ultraviolet‐induced low‐light fluorescence emitted by EtBr molecules intercalated into the DNA is evaluated. The high sensitivity and reproducibility of this quantitative method has been obtained using an advanced analysis system capable of distinguishing low‐light fluorescent patterns, as in the case of DNA stained with EtBr, from the background. Use of an internal standard is necessary because the intensity of the signal is due to the aperture of camera diaphragm and to gel conditions. Using this two‐dimensional analysis system it is possible to obtain rapid and precise quantitation of as little as 2ng of DNA.
The enhancement of iron‐dependent luminol peroxidation by 2,2′‐Dipyridyl and nitrilotriacetate
Authors: Henley R. , Worwood M.
Published: May 2005

The generation of radicals from luminol and H2O2, in the presence of iron and iron chelates was monitored by measuring the chemiluminescence produced by further oxidation of these radicals. 2,2′‐Dipyridyl enhanced the production of chemiluminescence in the presence of FeSO4, farritin and haemosiderin but not FeCI3 or horseance of both FeSO4 and FeCI3 but not ferritin or haemosiderin. The enhancement of chemiluminescence by iron chelation may have analytical applications and the process by which these iron chelates are able to generate radicals from the nitrogenous base luminol may be similar to that responsible for their toxic effects on DNA.
The influence of age and sex on phagocyte chemiluminescence
Authors: McCafferty Ann C. , Cree Ian A. , McMurdo Marion E. T.
Published: May 2005

The process of ageing is associated with increased susceptibility to infection. Phagocytes form the primary defence mechanism against infecting microorganisms, but the influence of ageing on phagocyte function remains controversial. In this study we have applied a microtitre plate phagocyte chemiluminescence (CL) assay suitable for clinical use to compare phagocyte oxidative metabolism in younger healthy subjects (age 20–60 years) and healthy older (60–70 years) subjects. Polymorphonuclear leukocytes (PMNL) and monocytes were stimulated using phorbol myristate acetate (PMA), serum opsonized zymosan (SOZ), and non‐opsonized zymosan (ZYM) in the presence of both lucigenin and luminol. Monocytes showed a higher luminolenhanced CL response to PMA in males compared with females in the younger age group. No PMNL differences were observed between the sexes. Although no difference were found in relation to age when cells were stimulated with PMA and SOZ, significantly lower background (unstimulated) CL was obtained from PMNL with luminol. PMNL luminol‐enhanced CL responses were also lower in response to ZYM. The findings suggest a reduced response of PMNL from older subjects to minimal stimulation. This could be related to abnormalities in the triggering of the respiratory burst or myeloperoxidase release due to ageing. The influence of age and sex should be taken into account in clinical studies of phagocyte CL.
Enhanced chemiluminescence of lucigenin with epinephrine in cationic surfactant micelles containing periodate
Authors: Kamidate Tamio , Ichihashi Hiroyuki , Segawa Tadashi , Watanabe Hiroto
Published: May 2005

Epinephrine (EP) species involved in the lucigenin chemiluminescence (CL) were identified in alkaline solution by comparing the time course of the CL response and the formation of EP oxidation products. EP quinone and adrenolutine (AL) were found to be responsible for the lucigenin‐CL reaction. The mechanism of the lucigenin‐CL enhancement was investigated using cationic micellar hexadecyltrimethylammonium hydroxide (CTAOH), periodate, and a mixture of micellar CTAOH and periodate. The CL enhancement in the presence of micellar CTAOH and periodate could be explained in terms of increases in the oxidation rate of EP to EP quinone and the intramolecular oxidation rate of adrenochrome to AL.
Comparison of the performance of the borax buffer‐based HRP‐enhanced reagent and the ‘Lumi‐Phos 530’ chemiluminescence systems in the detection of biotinylated DNA
Authors: Cercek Bibijana , Roby Keith , Siaw Martin
Published: May 2005

A comparison of two chemiluminescence methods, the borax buffer‐based HRP‐enhanced reagent and Lumi‐Phos 530, applied to the detection of a biotinylated 30‐mer DNA slot blotted onto a nylon membrane, is presented. A streptavidin–HRP and streptavidin–ALP mediated detection system was used. The HRP‐enhanced system is up to 15‐fold greater with respect to the signal/background ratios than the Lumi‐Phos 530 system at 0.5 μg biotinylated DNA with at least a two‐fold improvement in detection sensitivity for 0.5 ng biotinylated DNA.
New enhancers for the chemiluminescent peroxidase catalysed chemiluminescent oxidation of pyrogallol and purpurogallin
Authors: Nozaki Osamu , Ji Xiaoying , Kricka Larry J.
Published: May 2005

The effects of various boronate compounds, 4‐biphenylboronic acid, 4‐bromobenzeneboronic acid, trans‐4‐(3‐propionic acid)phenylboronic acid and 4‐iodophenylboronic acid, on the horseradish peroxidase (HRP) catalysed chemiluminescent oxidation of pyrogallol and purpurogallin by peroxide were investigated. trans‐4‐(3‐Propionic acid)phenylboronic acid produced a 13.7‐fold enhancement in the peak light emission from the chemiluminescent HRP catalysed pyrogallol reaction (detection limit for HRP < 1.25 fmol). At low enhancer concentration a single peak of light emission was observed and as the enhancer concentration increased the time to peak light emission became progressively longer. The chemiluminescence showed two peaks at higher concentrations (> 54.3 μmol/L) and the individual peak times depended upon the concentration of the enhancer. All of the boronates enhanced peak light emission in the chemiluminescent HRP catalysed purpurogallin reaction. 4‐Biphenylboronic acid was the most effective and it enhanced peak light emission 314‐fold. The practical detection limit for HRP (Type VIA) using this enhancer was 4.18 pmol (peak emission at 20 minutes). This compound also enhanced peak light emission 232‐fold from a chemiluminescent HRP‐purpurogallin reaction in which molecular oxygen replaced peroxide as the oxidant.
Chemiluminescence response and adherence of neutrophils to cultured endothelial cells–influence of immunoglobulin G
Authors: Jonas Eleonore , Dwenger Alexander , Jonas Michael
Published: May 2005

The effect of different concentrations (0.87, 4.35, 8.7, 17.5, 25 and 35 mg/mL) of intravenous immunoglobulin G (Endobulin®) on neutrophil–endothelial cell interaction was studied using an in vitro model of human umbilical cord vein endothelial cells and human neutrophils. Because adherence of neutrophils to endothelial cells is an essential component in inflammatory processes leading to endothelial cell injury the influence of immunoglobulin G on adherence has been investigated.

A second aim of the present study was to determine changes in chemiluminescence response of neutrophils during adherence to endothelial cells. Production of oxygen‐derived metabolites, measured by chemiluminescence response of neutrophils, decreased significantly in the presence of 8.7 mg immunoglobulin/mL test during coincubation of neutrophils and endothelial cells (p < 0.025). The adherence of neutrophils to endothelial cells was significantly decreased at a concentration of 8.7 mg immunoglobulin/mL test (p < 0.025).

The present results indicate that this preparation of immunoglobulin G might exert a protective effect on neutrophil–endothelial cell interaction by decreasing adherence of neutrophils to endothelial cells and by scavenging reactive oxygen metabolites. Therefore, the current investigation points to a probable protective effect of immunoglobulin G in oxidative diseases, such as the adult respiratory distress syndrome.
Monitoring of spatial expression of firefly luciferase in transformed zebrafish
Authors: Mayerhofer R. , Araki K. , Szalay A. A.
Published: May 2005

The firefly luciferase gene attached to the cytomegalovirus promoter was transferred into zebrafish (Brachydanio rerio) by microinjection of fertilized eggs. Light emission could be monitored in vivo in eggs and throughout the early development of the fish by low‐light video‐image analysis. Gene expression was transient in most of the cases lasting for about 2 weeks. This gene cassette proved to be a very convenient and nondestructive transformation marker and the firefly luciferase gene appears to be a powerful tool for real‐time imaging of tissue‐specific gene expression in transgenic fish.
Expert system for knowledge‐based modelling of analytical laboratories as a tool for laboratory management
Authors: Klaessens Jo , Saris Theo , Vandeginste Bernard , Kateman Gerrit
Published: May 2005

An expert system (LABGEN) is presented for decision support in analytical laboratories by means of digital simulation. In an interactive manner, LABGEN constructs simulation models of laboratory organizations. It makes use of a database of model fragments and applies rules in order to prevent the user providing redundant information and to prevent inconsistent models being constructed. The models are written in the dedicated simulation language SIMULA. After compilation they can be used for simulation experiments. LABGEN can be applied to a wide range of laboratory organizations. An example of the application of LABGEN is presented.
A method for detecting potentially unreliable estimates when using the Burdick/Rayens model for estimating linear mixing proportions
Authors: Rayens William S.
Published: May 2005

In an earlier paper by Burdick and Rayens a model was developed which uses discriminant analysis to construct estimates of linear mixing proportions. In this paper a method is proposed for identifying potentially unreliable estimates when using the Burdick/Rayens model. It is also shown to be useful in detecting irregularities in the sample data. The methodology is based on the lengths of residual vectors and is demonstrated within the context of polychlorinated biphenyl mixtures.
Estimation of second‐order chemical kinetic parameters by using information‐based extended Kalman filtering
Authors: Barker Todd Q. , Brown Steven D.
Published: May 2005

The extended Kalman filter has been used to estimate initial reactant concentrations and rate constants for rate‐based chemical assays employing a second‐order chemical reaction. Application of first‐ and second‐order models to data permits reaction order identification by examining either the filter innovations or the evolution of the filter states. Because of non‐linearities in the second‐order kinetic model, repetitive filtering is necessary for convergence to reliable state estimates. Reduction of the filter calculation burden is investigated through the use of information‐based filter methods, and it is demonstrated that substantial decreases in the computational burden are possible without loss of filter accuracy. These decreases make possible the application of second‐order filters on large data sets, and they make real‐time filtering possible with a fast processor.
PLS regression methods
Authors: Höskuldsson Agnar
Published: May 2005

In this paper we develop the mathematical and statistical structure of PLS regression. We show the PLS regression algorithm and how it can be interpreted in model building. The basic mathematical principles that lie behind two block PLS are depicted. We also show the statistical aspects of the PLS method when it is used for model building. Finally we show the structure of the PLS decompositions of the data matrices involved.
Statistical F‐tests for abstract factor analysis and target testing
Authors: Malinowski Edmund R.
Published: May 2005

Fisher variance ratio tests are developed for determining (1) the number of statistically significant abstract factors responsible for a data matrix and (2) the significance of target vectors projected into the abstract factor space. F‐tests, developed from the viewpoint of vector distributions, are applied to various data sets taken from the chemical literature.
Chemical information from electroanalytical data. Part 1—Determination of system parameters for quasi‐reversible electron transfer reactions from cyclic voltammetric test data and data for the reduction of cerium (IV) bis(octaethylporphyrinate)
Authors: Scharbert Bernd , Speiser Bernd
Published: May 2005

Values of the peak potential, the peak current function and the peak potential difference are extracted from simulated cyclic voltammograms of a quasi‐reversible electron transfer reaction. Variations of the feature values are described by empirical functions of the model parameters α (transfer coefficient) and ψ′ (dimensionless form of the heterogeneous electron transfer rate constant ks) using multiple linear regression. These functions are used to determine the system parameters α and ks from test data sets of feature values. The predictive power of the features is discussed. It is shown that several features can be used simultaneously in the analysis. Also, α, ks, the formal potential E0 and the diffusion coefficient D can be estimated simultaneously. Experimental data from the metal‐centered one‐electron reduction of cerium (IV) bis(octaethylporphyrinate), Ce(OEP)2, are analyzed using the technique, and values of the system parameters for this electrochemical reaction are determined.
Program for processing of historical laboratory data based on fuzzy set theory as a tool for decision support
Authors: Klaessens J. , Van Schalkwijk J. , Cox P. , Bezemer R. , Vandeginste B. , Kateman G.
Published: May 2005

A computer program (FEA) is presented for processing historical laboratory data. It performs on a list of sample entries stored in a laboratory information management system. Using an algorithm which is based on fuzzy set theory, FEA classifies the entries into a limited number of clusters called sample types. The classification is fully user‐defined. The program transforms the historical data into a representation which is more suitable for studying the performance of the laboratory or which can be used as preparation for a simulation project.
Can image analysis provide information useful in chemistry?
Authors: Geladi Paul , Esbensen Kim
Published: May 2005

Images can contain chemical information and many chemical methods can generate image data. For an efficient extraction of chemical data from images, data analysis techniques are necessary. It is a great advantage to be able to work on multivariate images. Many imaging techniques allow the extraction of chemical information. Inorganic analytical chemistry seems to have the longest tradition here, but organic chemistry and biochemistry may soon be catching up. Also large data arrays from non‐imaging techniques can be combined with image analysis in a useful way, provided certain conditions are fulfilled.
Evolving factor analysis applied to flow injection analysis data
Authors: Gemperline Paul J. , Hamilton J. Craig
Published: May 2005

Evolving factor analysis is used to estimate the concentration profiles and spectra of Bi3+ and the bismuth chloride complexes BiC12+ through BiCl formed by injection of bismuth perchlorate into a flowing stream of 1·0 mol 1−1 HCl. The estimated spectra compare favorably with previously published spectra of the complexes.
PLS response surface optimization: The CARSO procedure
Authors: Clementi Sergio , Cruciani Gabriele , Curti Gianluca , Skagerberg Bert
Published: May 2005

The paper presents a procedure to obtain response surfaces with non‐designed data. The method is based on PLS modelling of the expanded X‐matrix followed by transformation of the PLS loadings into polynomial coefficients and detection of the co‐ordinates of the best response within the experimental domain. The results are presented both graphically and numerically. The procedure is validated on an optimization study of the yield of an organic reaction.
Display aspects in hierarchical clustering
Authors: Henrion André , Henrion René , Henrion Günter
Published: May 2005

Ultrametric inter‐object distances found by hierarchical clustering may be used to generate and appropriate constellation of points in a plane. A configuration of points which reproduce the ultrametric distances in a low‐dimensional space as closely as possible can be found by Torgerson's method of multidimensional scaling. The resulting display supports the cognition of clusters very well, and for this purpose it seems to be superior to, for instance, the frequently applied principal components display. In certain situations dedrograms are expected to become simpler to interpret when such complementary ‘cluster display’ is also consulted. An example from analytical chemistry is presented.
Multicomponent determinations by a membrane‐discriminated gas phase analyzer and successive regression in the fiduciary region
Authors: Petersen Kaj , Lopez Jorge L. , Dasgupta Purnendu K.
Published: May 2005

A membrane‐discriminated gas phase analyzer is proposed for multicomponent determinations. Nitrogen gas flows countercurrent through outer and inner channels in a tube‐in‐tube arrangement. The only communication between the two channels occurs through a 500 μm aperture covered by a porous PTFE membrane. A mixture of organic compounds (up to four components) is injected into the inner channel by a heated backflushed injector and the sample components diffusing into the outer channel are monitored by a flame ionization detector (FID). A calibration set, consisting of pure components, binary, ternary and quaternary mixtures (a total of 64 samples), provides the known data base: temporal profiles of the FID output as a function of sample composition. Although the overall response behavior is not a linearly additive function of individual analyte concentrations, the use of successive inverse multiple linear regression (while continually altering the choice of the calibration samples considered for the forward regression, on the basis of the most recent values of the predicted unknown sample composition) is shown to yield analytical results for unknown samples that are in good agreement with their true values.
Resolution of multicomponent fluorescent mixtures by analysis of the excitation–emission–frequency array
Authors: Burdick Donald S. , Tu Xin M. , McGown Linda B. , Millican David W.
Published: May 2005

Fluorescence lifetime provides a third independent dimension of information for the resolution of total luminescence spectra of multicomponent mixtures. The incorporation of this parameter into the excitation–emission matrix (EEM) by the phase modulation technique results in a three‐dimensional excitation–emission–frequency array (EEFA). Multicomponent analysis based on the three‐dimensional EEFA brings a qualitative change for the resolved spectra, i.e. individual spectra can be uniquely resolved, which is impossible with any two‐dimensional analysis. In this paper we present a method for analyzing the EEFA. We show mathematically that with the three‐dimensional analysis of the EEFA individual spectra and lifetimes can be obtained. Our algorithm is developed in mathematical detail and is demonstrated by its application to a two‐component mixture.
Enhancing the deconvolution of noisy chromatographic data by Jansson's method
Authors: Crilly Paul Benjamin
Published: May 2005

In previous papers Jansson's method was found to be successful at deconvolving severely overlapped gas chromatographic peaks. In the most recent paper the method was evaluated with respect to quantitative accuracy, peak area and retention time repeatability. The problems associated with deconvolving noisy data and some alternatives which can improve the ability of Jansson's method to deconvolve noisy data are discussed. These alternatives include presmoothing the data with a nine‐point, third‐order polynomial filter and data reblurring. This paper will test these methods on peaks with various degrees of resolution and signal‐to‐noise ratios.
A new approach to confirmation by infrared spectrometry
Authors: De Ruig W. G. , Weseman J. M.
Published: May 2005

In the series of analytical techniques for identification of chemical substances, infrared spectrometry presents by far the highest information content. However, the information is most complicated too. It concerns a multitude of band positions, band intensities and band shapes, which, moreover, can be disturbed by matrix and other effects. The high redundancy, however, allows conclusions to be made by a qualitative, subjective procedure.

IR is often used to prove the equality between a sample and a reference material, e.g. in quality control of a production process. In forensic control, the question to be answered is mostly not to prove equality, but whether or not the presence of a compound in a sample, e.g. a drug, can be proved. Moreover, testing has to be performed according to objective rules.

To fulfil these requirements, a new retrieval algorithm, the ‘Adequate Peaks Search’, is presented. It concerns representing the reference spectra by sets of adequate peak positions and the sample spectrum by a set of all peak positions, whereafter the cross‐sections of the sample set and the reference sets are determined. The concept ‘adequate peak’ is defined and criteria have been formulated to evaluate the results into a positive (presence of the analyte is proved) or negative (presence is not proved) conclusion.

The detection limit when the Adequate Peaks Search (APS) method was applied was four to seven times lower than that attained by a number of experts.
An approach to obtaining an optimal design in the non‐linear least squares determination of binding parameters in a complex biochemical system
Authors: Crisponi Guido , Nurchi Valeria , Ganadu M. Luisa
Published: May 2005

The design of an experiment for the determination of binding parameters in the association between a ligand and a macromolecule with two groups of non‐interacting binding sites is proposed. In the Gauss–Newton non‐linear least squares treatment the standard deviation of each parameter is given as the product of two terms: one depending on the experimental error and the other, the diagonal element of the dispersion matrix, depending only on the independent variables of the system. In order to reach an optimal experimental design, these diagonal elements of the information matrix have to be minimized. In our approach this is achieved by searching those values of the independent variable which maximize the determinant of the information matrix. Furthermore, the limits of validity of the model are deduced from an analysis of the diagonal elements of the information matrix obtained under optimal conditions.
Target factor analysis: UV spectrophotometry for the simultaneous determination of six amino acids
Authors: Zhongxiao Pan , Siqing Xia , Shengzhu Si , Maosen Zhang , Leming Shi , Xinan Liu
Published: May 2005

The UV spectra of mixture solutions consisting of tyrosine, tryptophane, phenylalanine, cystine, histidine and 3,4‐dihydroxyl phenylalanine have been measured. The numbers, identities and concentrations of the amino acids in the mixtures have been determined successfully using target factor analysis. The effects of the wavelength range and the selected sampling interval on the results are discussed. Twenty‐five synthetic mixture samples have been analysed successfully. The average recoveries are 98.9 for Tyr, 96.5 for Trp, 105.6 for Phe, 98.1 for Cys, 98.9 for His and 106.4 for Di‐phe. The results obtained are in good agreement with those obtained by the Kalman filter method.
Use of the Wronskian determinant in the study of multicomponent systems
Authors: Koinis S. P. , Tsatsas A. T. , Katakis D. F.
Published: May 2005

The use of Wronskian determinants in the study of multicomponent systems is proposed. The general theory is presented and applied to the spectrophotometric determination of the number of linearly independent components–absorbers. A detailed study of a two‐component system is presented and analysed. Numerical methods for smoothing and differentiation of digitized spectra via cubic splines are used.
The use of a ratio method as an alternative to constrained deconvolution
Authors: Crilly Paul Benjamin
Published: May 2005

This paper will consider the use of an iterative ratio technique called Gold's ratio method as an alternative to iterative constrained deconvolution methods for the restoration of overlapped and noisy chromatograpic peaks. The study will consist of first describing the technique and then evaluating its performance with respect to Jansson's deconvolution procedure. A Hewlett‐Packard 5890A gas chromatograph will be used to generate most of the test data. The evaluation criteria will include convergence rates, peak area errors and variances, retention time variances and noise performance.
Rank‐order analysis for robust multiresponse, multiblock comparisons: Evaluation of herbicide interactions
Authors: Duewer David Lee , Clark Robert D.
Published: May 2005

Studies of interactions among bioactive compounds are often difficult to interpret unambiguously. A priori assumptions about the nature of such interactions can seriously distort analysis of the data. By applying a rank order analysis appropriate to the naturally ordinal scale of response to xenobiotic insult, several co‐herbicides were successfully identified from among numerous candidates in an experiment involving multiple blocks, rates and species. Moreover, underlying herbicide interactions were substantiated and identified which were not apparent by more traditional parametric analysis.
Comparison of measurement methods based on a model for the error structure
Authors: Nilsson Göran
Published: May 2005

Comparison of methods is a technique often used for investigation of systematic errors of measurement methods. As concerns the design and analysis of such comparisons, much variety of opinion and practice exists. In one approach a few specimens are measured several times by different operators in different laboratories (reproducibility conditions) and in another approach several specimens are measured on one or a few occasions by one operator in the same laboratory (repeatability conditions). In this paper a model for the error structure of measurements is formulated and it is emphasized that one has to distinguish between two types of systematic errors: the first type depends only on the level of the measured quantity and the second type is specific for the separate specimens. On the basis of this model the information which can be obtained from the different designs of method comparisons is discussed. A new approach for the analysis of method comparisons with many specimens is also proposed.
Simple validatory tools for judging the predictive performance of parafac and three‐way PLS
Authors: Smilde Age K. , Doornbos Durk A.
Published: May 2005

The methods PARAFAC and three‐way PLS are compared with respect to their ability to predict reversed‐phase retention values. Special attention is paid to simple validatory tools, the meaning and use of which are explained.
Principal variations in the chemical composition of peat: Predictive peat scales based on multivariate strategies
Authors: Hämäläinen Markku , Albano Christer
Published: May 2005

The principal properties, here called the ρ‐scales, of peat have been calculated on the basis of chemical analysis. The scales were derived from quantitative contents of carbohydrates, Klason lignin, amino acids, amino sugars and conventional chemical peat measurements. The variation in the chemical parameters was compressed using principal component analysis (PCA). Partial least squares (PLS) regression was used for prediction of botanical, microbial, physical and dewatering data. A rapid estimation of the scales has been made from near‐infrared (NIR) spectroscopy and offers, indirectly, rapidly obtainable, chemically interpretable, biological information. A reduced scale based on carbohydrate data was also tested. The ρ‐scales offer an interface between different areas of peat research. Strategies are outlined for the selection of a subset of chemical measurements among the variables used for characterization. A multivariate strategy based on these ideas is discussed.
A new receptor model: A direct trilinear decomposition followed by a matrix reconstruction
Authors: Zeng Yousheng , Hopke Philip K.
Published: May 2005

In many cases, monitoring data for ambient airborne particles can be organized in the form of a three‐way data table with one way for chemical species, one for sampling periods and one for sites. A direct trilinear decomposition followed by a matrix reconstruction (DTDMR) is developed to analyze such a data table as a whole. The three‐way data set is composed into three two‐way matrices by a direct trilinear decomposition (DTD). The column vectors of each of the matrices are called ‘source profiles’, ‘emission patterns’ and ‘site coefficients’ respectively. Particulate sources are identified by examining both their source profiles and emission patterns. After the sources have been identified, emission patterns and site coefficients are used to produce a three‐way matrix that gives estimates of mass contributions of sources to the samples collected at every site in every period. By simulation study, not only has the method been verified, but a good indicator has been found that shows the number of factors (i.e. sources) in the system. Unlike other receptor models, DTDMR does not require source profile data and does not involve trial‐and‐error procedures. Since DTDMR identifies sources based on variations in two dimensions, it has a higher potential to distinguish two sources that have similar chemical compositions. The DTDMR model has provided excellent results with simulated data and has been applied in a real world three‐way data set.
Data analysis with minimal assumptions
Authors: Mandel John
Published: May 2005

The computer has made it possible to scrutinize data rapidly by means of graphics. This should be done prior to the application of any model to the data, since the model must be validated before using it as a means of analyzing the data. The procedure is illustrated in terms of two examples of real experimental data.
Advances in second‐order calibration
Authors: Wang Yongdong , Borgen Odd S. , Kowalski Bruce R. , Gu Ming , Turecek Frantisek
Published: May 2005

Several multivariate methods are now available for the calibration of second‐order or hyphenated instruments (e.g. GC/MS). When applied to bilinear data, it has been shown that calibration can be performed in the presence of unknown interferences ‐ a significant advantage over first‐order calibration. In this paper, non‐bilinear rank annihilation (NBRA), a method which has the potential of handling, second‐order non‐bi‐linear data, is studied through theoretical analysis and computer simulation. It is found that the second‐order advantage can be carried over to non‐bilinear data if a property defined as net analyte rank (NAR) holds for the analyte of interest. The net analyte signal (NAS) is defined accordingly for second‐order calibration and the analogy to and difference from lower‐order calibration are discussed. With NAS, some analytical figures of merit such as signal‐to noise ratio, selectivity, sensitivity and limit of determination can be calculated for second order calibration. An application to MS/MS data is also given.
Finding suspected causes of measurement error in multivariate environmental data
Authors: Stapanian Martin A. , Garner Forest C. , Fitzgerald Kirk E. , Flatman George T. , Nocerino John M.
Published: May 2005

Environmental data are usually multivariate, with the variables conforming to some correlation structure. Occasionally, measurements which do not conform in structure or magnitude may occur in one or more variables. It is important (1) to characterize these discordancies in terms of the disturbed variables and the direction and magnitude of the anomalous error and (2) to associate each discordant observation with a specific cause of measurement error in order to prevent further mismeasurement. We describe a procedure for identifying suspected causes of discordant observations in otherwise multinormal data sets. Variables are assigned to groups, each of which is associated with a specific cause of measurement error. Discordant observations are identified with the generalized distance test or the multivariate kurtosis test. Suspected causes of measurement error are identified by repeating the tests with one of the groups of variables omitted in each analysis. The procedures are evaluated with simulated data sets having a correlation structure similar to that of a large environmental data set.
A test of significance for partial least squares regression
Authors: Wakeling Ian N. , Morris Jeff J.
Published: May 2005

Partial least squares (PLS) regression is a commonly used statistical technique for performing multivariate calibration, especially in situations where there are more variables than samples. Choosing the number of factors to include in a model is a decision that all users of PLS must make, but is complicated by the large number of empirical tests available. In most instances predictive ability is the most desired property of a PLS model and so interest has centred on making this choice based on an internal validation process. A popular approach is the calculation of a cross‐validated r2 to gauge how much variance in the dependent variable can be explained from leave‐one‐out predictions. Using Monte Carlo simulations for different sizes of data set, the influence of chance effects on the cross‐validation process is investigated. The results are presented as tables of critical values which are compared against the values of cross‐validated r2 obtained from the user's own data set. This gives a formal test for predictive ability of a PLS model with a given number of dimensions.
Constrained background bilinearization with a generalized simulated annealing algorithm
Authors: Xie Yulong , Wang Jihong , Liang Yizeng , Ge Kai , Yu Ruqin
Published: May 2005

Generalized simulated annealing (GSA) is an optimization technique for locating the global optimum. In this paper GSA was used as the optimization procedure in the constrained background bilinearization (CBBL) of two‐way bilinear data in order to reduce the possibility of sinking into local optima. The behaviour of the algorithm and its comparison with the modified Powell algorithm were studied by simulations and real fluorescence excitation–emission data for organic dye mixtures.
The geometry of multivariate object preprocessing
Authors: Deming Stanley N. , Palasota John A. , Nocerino John M.
Published: May 2005

The geometric properties of three common object‐preprocessing transformations (constant sum, or closure; constant length, or normalization; and maximum value, or ratioing) are investigated. An argument is made for using absolute values in the constant sum and maximum value transformations. In general, each transformation distorts the shape and dimensionality of patterns in the data: transformed data lie on (C‐1)‐dimensional surfaces in the original C‐dimensional space. A data set that has been closed by one of these transformations can be reopened if a vector containing the constant sums, constant lengths or maximum values of the original objects was retained. Transformed data sets may be freely interconverted among these three transformations without the loss of information.
Non‐linear least squares refinement with constraints. Evaluation through curve fitting on emulated XPS‐like spectra and application to the analysis of carbon fibres
Authors: Ceipidor Ugo Biader , Cataldi Tommaso R. I. , Desimoni Elio , Salvi Anna Maria
Published: May 2005

A non‐linear least squares iterative refinement has been implemented which shows high performance on a multiple‐peak spectrum including baseline or background. Constraints as well as links within a range are introduced to drive the mathematical optimization: each peak parameter (i.e. height, position, Gaussian/Lorentzian mixing ratio and HWHM on both left and right sides) has assigned to it an allowed range of variation and can be strained to be correlated with other parameters belonging either to the same peak (symmetrical peaks) or to other peaks (doublets, triplets, etc.). Peak shapes typical of XP spectra are used and applications in the field of XPS are discussed. Through emulated curves with Poisson distributed noise, the accuracy and precision of back‐calculated (refined) parameters have been estimated. Moreover, a confidence level calculated from X2 and degrees of freedom has been suggested to check the overall fitting of experimental curves where the signal‐to‐noise ratio is a priori unknown. An application to real C ls XP spectra is described as an example and a list of suggestions is given to match operator requirements. Finally, features of NLLSRC are discussed with respect to other approaches.
Direct distance measures in factor analysis spectral resolution
Authors: Neal Sharon L.
Published: May 2005

A factor analysis algorithm that estimates the spectra of mixture components using the set of most dissimilar rows and/or columns is described and illustrated. This algorithm uses the distance as a measure of spectral similarity and is suitable for application to a variety of the bilinear matrix‐formatted data types produced by hyphenated and multidimensional analytical techniqes. The algorithm requires that the data matrix contain at least one row or column that corresponds to the pure spectrum of each component to effect accurate spectral resolution. The performance of the method is illustrated using the resolution of excitation and emission spectra of up to four components from experimental fluorescence excitation‐emission matrices (EEMs). In the case of the EEM, characteristic bands in an emission spectrum effect resolution of the excitation spectrum of the corresponding component, while characteristic bands in an excitation spectrum lead to resolution of the corresponding emission spectrum. The use of the set of most dissimilar rows and columns to evaluate the degree of overlap in the component spectra and compare the quality of row and column solutions is also described.
Comments on the DATa ANalysis (DATAN) algorithm and rank annihilation factor analysis for the analysis of correlated spectral data
Authors: Booksh Karl S. , Kowalski Bruce R.
Published: May 2005

It is shown that the DATa ANalysis (DATAN) algorithm can be expressed in terms of rank annihilation factor analysis (RAFA). Subsequent advances in RAFA are applied to DATAN to eliminate the problems and restrictions associated with DATAN. The extension of DATAN in terms of the trilinear decomposition algorithm is discussed.
PCB method applied to material design—computer‐aided synthesis of BiPbSrCaCuOF superconductor
Authors: Liu Hong‐Lin , Chen Yu , Chen Nian‐Yi
Published: May 2005

An inverse mapping method called PCB (principal component backing), in which the point representing an unknown sample from a low‐dimensional principal component subspace is back‐projected to the high‐dimensional original feature space, is proposed. Two sorts of boundary conditions, non‐linear inverse mapping and linear inverse mapping, are used to obtain an accurate solution in the PCB method. The method is applied to the material design of high‐Tc superconductors, predicting the composition and process conditions for the synthesis of F‐doped Bi‐based materials. Samples in the ‘optimal’ region with the highest Tc of the Bi‐based ceramics have been predicted.