Pentti Minkkinen

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• Professor
• Professor Emeritus at Lappeenranta – Lahti University of Technology LUT

Variography is an excellent tool for monitoring the long-range trend of continuous processes. Pierre Gy has presented a method that can be used for estimating the measurement variance of a lot mean as function of sampling frequency for different sampling modes: random, stratified, and systematic sample selections. The method involves the estimation...

There has been an extensive abuse of Gy's Formula during the entire history of applied TOS (Theory of Sampling), it being applied too liberally to almost any aggregate material conceivable for many material classes of extremely different compositions with significant (to large, or extreme) fragment size distribution heterogeneity, for example many...

Describes methods useful in controlling and estimating the the uncertainty of chemical measurements

This Guide aims to describe various methods that can be used to estimate the uncertainty of measurement, particularly that arising from the processes of sampling and the physical preparation of samples. It takes a holistic view of the measurement process to include all of these steps as well as the analytical process, in the case where the measuran...

Two contrasting multivariate data sets (a process data series vs. a 1-D geochemical soil profile) are analyzed to illustrate the benefits of using bilinear projection scores for variographic characterization instead of using individual variables. By using absolute variograms on a validated number of component scores, it is possible to make a combin...

Introduction: What is Weighting Error (WE)? •Questions: –Can WE be eliminated/minimized by increasing the number of samples? –Can WE be eliminated/minimized by sampling at fixed volume intervals? •Simulation studies •Real case examples

Official testing and sampling of large kernel lots for impurities [e.g., genetically-modified organisms (GMOs)] is regulated by normative documents and international standards of economic, trade and societal importance. The focus nearly always includes only analytical issues – omitting, with very few exceptions, proper accounting for sampling error...

Official testing and sampling of large kernel lots for impurities [e.g., genetically modified organisms (GMOs)] is regulated by normative documents and international standards of economic, trade and societal importance. In Part I, we reviewed current official guides and standards for sampling large contaminated kernel lots and the basic concepts of...

Part I reviewed the Theory of Sampling (TOS) as applied to quantitation of genetically-modified organisms (GMOs). Part II reanalyzed KeLDA data from a variographic analysis perspective and estimated Total Sampling Error (TSE) versus Total Analytical Error (TAE). Results from this analysis are here used as a basis for developing a general approach t...

Sampling is a key step in the analysis of chemical compounds. It is particularly important in the environmental field, for example for wastewater effluents, wet-weather discharges or streams in which the flows and concentrations vary greatly over time. In contrast to the improvements that have occurred in analytical measurement, developments in the...

Equations were determined for the calculation of the second stoichiometric (molality scale) dissociation constant, Km2, of glycine, in aqueous NaCl and KCl solutions at 298.15 K, from the thermodynamic dissociation constant, Ka2, of this acid and the ionic strength, Im, of the solution. The ionic strength of the solutions considered in this study i...

Sampling errors can be divided into two classes, incorrect sampling and correct sampling errors. Incorrect sampling errors arise from incorrectly designed sampling equipment or procedures. Correct sampling errors are due to the heterogeneity of the material in sampling targets. Excluding the incorrect sampling errors, which can all be eliminated in...

A project has been initiated by the International Union of Pure and Applied Chemistry (IUPAC) to create a glossary of concepts and terms in chemometrics. This will be accomplished by consultation with the community through the means of a wiki--a web site that can be modified by users (see http://www.iupacterms.eigenvector.com/index.php?title=Main_P...

The errors of analytical measurements, random as well as systematic errors nearly always are dependent on concentration, especially if the same method is used over a wide concentration range. Tests based on normal distribution are, therefore, seldom applicable to the original analytical quality control data; some data preprocessing is usually neces...

The effects of digitization and quantification in one- and two-dimensional signals on angle measure technique (AMT) texture analysis are described in order to find optimal corrections. AMT analysis with varying parameters has been carried out on simulated and real images as well on time-series data. All images and signals are of high resolution in...

Texture characterization plays an important role in image analysis as do signal complexity characterization for one-dimensional arrays (time series a.o.). One of the most effective approaches for this task is Angle Measure Technique (AMT) which simultaneously describes the complexity of images or signals at all scales. This approach is not widespre...

In the CHESS project, novel algorithms and variations of existing algorithms are developed for process data analysis, visualization, and monitoring. The algorithms are implemented in a variety of industrial applications under five test cases, including oil production, food production, process monitoring, plastics production, and environmental analy...

(E)- and (Z)-Urocanic acids are endogenous chemicals in the normal mammalian skin. The first and the second thermodynamic dissociation constants (pK a1 and pK a2) of urocanic acid isomers were determined using UV spectrophotometry in aqueous solutions. The values with standard deviation (pK a1 = 3.43 ± 0.12 and pK a2 = 5.80 ± 0.04) and (pK a1 = 2.7...

Chemical and process industries are nowadays required by regulations to estimate and control the level of their environmental discharges and many pollutants have legal limits that should not be exceeded. It is essential, therefore, to know the uncertainty of the measurements. For the laboratory measurements most laboratories have a quality control...

Sampling and uncertainty of sampling are important tasks, when industrial processes are monitored. Missing values and unequal sources can cause problems in almost all industrial fields. One major problem is that during weekends samples may not be collected. On the other hand a composite sample may be collected during weekend. These systematically o...

The standard pH of 0.05 mol·kg-1 potassium tetraoxalate was determined using the calculation method recommended by IUPAC (Pure Appl. Chem. 2002, 74, 2169−2200) at various temperatures from new Harned cell data and literature data. New data were obtained for 0.05 mol·kg-1 potassium tetraoxalate solution containing up to 1 mol·kg-1 KCl at temperature...

IntroductionEstimation and control of errors related to samplingComponents of the sampling errorWeighting errorIncrement delimitation and extraction errorsShort-term integration errorLong-range and periodic components of the integration errorsControl of random errorsUse of replicates to estimate random errorsControl of systematic errorsComparison t...

Real time monitoring of unit operations in manufacturing of pharmaceuticals is one of the main aspects included in the concept of process analytical technology (PAT). Crystallization is an important purification unit operation in manufacturing of pharmaceuticals. To obtain the desired product properties, e.g., size, shape and polymorphic form, the...

We evaluated 14 selected paper quality parameters using new image analytical techniques for characterization and monitoring of paper quality (multivariate AMT regression). We tested the technique on six major paper types. Of the parameters tested, 13 could be modeled with only minor optimization of the initial experimental image recording parameter...

Equations were developed for the calculation of the stoichiometric (molality scale) dissociation constants. Km, of ammonium ion in aqueous KCl solutions at 298.15 K from the thermodynamic dissociation constant, Ka, of this acid and the ionic strength, Im, of the solutions. Excess KCl was used in the solutions considered so that this salt in practic...

Ion mobility spectrometry based analysis has been found to provide a powerful and reliable tool as a portable gas detector of different chemical compounds and mixtures. The suitability of the spectrometer in food quality assay was studied in a case study, in which fish quality changes during cold storage were modelled. Hexane extracts of gills of v...

The Theory of Sampling (TOS) provides a description of all errors involved in sampling of heterogeneous materials as well as all necessary tools for their evaluation, elimination and/or minimization. This tutorial elaborates on—and illustrates—selected central aspects of TOS. The theoretical aspects are illustrated with many practical examples of T...

A large number of analyses is carried out, e.g., for process control, product quality control for consumer safety, and environmental control purposes. The sampling theory developed by Pierre Gy, together with the theory of stratified sampling, can be used to audit and optimize analytical measurement protocols. A careful optimization of the sampling...

Biological wastewater treatment is a complex, multivariate process, in which a number of physical and biological processes occur simultaneously. In this study, principal component analysis (PCA) and parallel factor analysis (PARAFAC) were used to profile and characterise Lagoon 115E, a multistage biological lagoon treatment system at Melbourne Wate...

Factors that determine accumulation of sediment-associated polychlorinated dibenzo-p-dioxins and furans and polychlorinated diphenyl ethers into semipermeable membrane devices (SPMDs) and benthic oligochaete worms (Lumbriculus variegatus) were examined. These factors included both physical-chemical and structural characteristics of the contaminants...

Equations were determined for the calculation of the stoichiometric (molality scale) dissociation constant, Km, of lactic acid in aqueous salt solutions at 291.15 and 298.15K from the thermodynamic dissociation constant, Ka, of this acid and from the ionic strength, Im, of the solution. The salt alone determines mostly the ionic strength of the sol...

Images from the scanning electron microscope (SEM) and the optical microscope are widely used in mineral processing to estimate the concentrations of mineral species. The aim of this study was to optimize the procedure used for the determination of concentration estimates from SEM images of ore and rock samples. The goal was especially to develop a...

Multivariate data analysis methods (4-way Candecomp-PARAFAC model solved with Multilinear Engine (ME-1)) were used to interpret the data of over two decades to study the changes in the water of Lake Saimaa in Finland. Earlier studies have shown that it is difficult to extract the natural background from the other sources of variation. By using the...

Equations were determined for the calculation of the stoichiometric (molality scale) dissociation constant Km of benzoic acid in dilute aqueous NaCl and KCl solutions at 25°C from the thermodynamic dissociation constant Ka of this acid and from the ionic strength Im of the solution. The salt alone determines mostly the ionic strength of the solutio...

Data are inherently multivariate in nature, and in many industrial processes the number of underlying correlation structures is very often much smaller than the number of measured variables. In other words, variables have redundancy, i.e. they carry the same kind of information, which often leads to a non-parsimonious and unstable model. To obtain...

Equations were determined for the calculation of the stoichiometric (molality scale) dissociation constant K_m of benzoic acid in dilute aqueous NaCl and KCl solutions at 25°C from the thermodynamic dissociation constant K_a of this acid and from the ionic strength I_m of the solution. The salt alone determines mostly the ionic strength of the solu...

The paper presents the results from the determination of the correlation functions between water quality indicators and the characteristics of uprising radiation. It studies the possibility of remote measurement not only of those parameters which have a direct effect on the value of the uprising radiation, such as the chlorophyll-a concentration, t...

Two novel approaches are presented which take into account the collinearity among variables and the different phenomena occurring at different scales. This is achieved by combining partial least squares (PLS) and multiresolution analysis (MRA). In this work the two novel approaches are interconnected. First, a standard exploratory PLS model is scru...

The application of FTIR spectroscopy was studied in mid-infrared region (MIR) and near-infrared (NIR) region in fusion synthesis of Ca-resinates as well as Ca/Mg-resinates. Predictive calibration models based on partial least squares (PLS) regression were developed to describe the relationship between the spectra and the acid value of laboratory sc...

Waste water treatment plants often need detailed information about the sources and levels of pollutants in sewage in order to maintain stable process conditions and to achieve permitted levels for hazardous compounds in their effluents. A high content of pollutants is usually traceable to industrial inputs. In this study the main objective was to s...

A partial least squares (PLS) regression is used to model and visualize the waste-water treatment process. The score values of PLS are submitted to both a fuzzy C-means (FCM) clustering and a possibilistic C-means (PCM) clustering. In this work, four concepts are presented. Firstly, a hidden path process modeling is illustrated. Secondly, the use o...

Single-ion activity coefficient equations are presented for the calculation of stoichiometric (molality scale) dissociation constants K m for acetic acid in aqueous NaCl or KCl solutions at 25°C. These equations are of the Pitzer or Hückel type and apply to the case where the inert electrolyte alone determines the ionic strength of the acetic acid...

Quite often, quality control models fail because, e.g., the mean values are changing continuously. These kinds of changes, e.g., process drifts due to seasonal fluctuations, are common in an activated sludge waste-water treatment plant in Finland. Different Fuzzy C-Means (FCM) clustering algorithms were tested in order to cope with these kinds of s...

A Kalman filter was developed to overcome the problems caused by process drifting. Different types of models were used to predict response variables of an activated sludge waste-water treatment plant. These models were constructed using MLR, PCR, and PLS. The MLR-type regression coefficients were calculated for both the PCR and PLS models. After th...

Data collected from a paper mill using a WIC-100 process analyzer was divided into six classes, each representing a different kind of paper grade or quality. Each of the six classes were modeled separately by principal component analysis (PCA). The score values of the calibration data, together with the corresponding confidence limits and the traje...

The esterification of acetic acid with ethanol in the presence of a heterogeneous acid catalyst was monitored by near infrared (NIR) spectroscopy. A strong acid macroporous poly(styrene-co-divinylbenzene) based ion-exchange resin was used as catalyst. The liquid phase esterification was carried out in a stirred batch laboratory reactor at 60°C. Sam...

The component of the sampling error caused by taking discrete samples from a continuous process is the integration error, IE. This error can be estimated using P.M. Gy's variographic technique. This method involves the integration of the variogram. The variogram can be calculated from a time series of discrete samples. If the variogram is simple, i...

In this paper, a combined approach of partial least squares (PLS) and fuzzy c-means (FCM) clustering for the monitoring of an activated-sludge waste-water treatment plant is presented. Their properties are also investigated. Both methods were applied together in process monitoring. PLS was used for extracting the most useful information from the co...

The most common waste water purification method within Finnish pulp and paper industry is activated sludge method. Activated sludge method is a complex biological process, where several physical, chemical, and microbiological mechanisms simultaneously affect the purification result. There are tens of processes and control parameters determined at t...

Validation of an analysis method depends on the purpose of the method, the chosen technique and the procedure in question. Methods are used for different research, product development, process control and quality control purposes. The human and economical importance of results vary. Each of the techniques used, such as chromatography-(HPLC, HRGC, T...

The thermodynamic values of the first and second dissociation constants (Ka,1 and Ka,2) of glutamic acid were determined by a method developed recently. In this method, a simple equation of the Hückel type was used for activity coefficients of ionic species. The dissociation constants of this amino acid and the parameters for the activity coefficie...

Many variables are normally measured in an activated sludge waste water treatment plant. Some of them are strongly cross-correlated. Partial least squares (PLS) and principal component analysis (PCA) have been widely used with these kind of processes because they both can be used with redundant data sets. In PLS, variable interactions can be visual...

A predictive calibration model based on non-linear partial least squares (PLS) regression was developed to describe the relationship between the near-infrared (NIR) reflectance spectra and the acid value, hydroxyl value and water, content in polyesterification of dicarboxylic acids with diols. Two dicarboxylic acids and six diols were tested in dif...

Published experimental thermodynamic data at 298.15 K for aqueous mixtures of H2Ph, KHPh, and KCl, of KHPh, K2Ph, and KCl, and of KHPh and KCl, where H2Ph means phthalic acid, KHPh potassium hydrogen phthalate, and K2Ph dipotassium phthalate, were used to test the methods for calculation of the pH values of phthalate buffer solutions. Equations for...

The variogram as a function of the sampling interval can be calculated from the time series measurements. P. Gy has proposed some methods to estimate the value of the variogram vh(j) for sampling interval j=0. These methods and the method where the modified cubic spline is used for the modeling of the variogram and the auxiliary functions calculate...

Published thermodynamic data measured in aqueous mixtures of sodium or potassium dihydrogen phosphate with hydrogen phosphate and chloride at 25°C were used to test recently developed methods for calculation of the pH of phosphate buffer solutions. Equations for ionic activity coefficients are used in these methods. It is shown that all data used i...

This chapter uses multivariate methods, mainly principal component analysis (PCA), to interpret a large data set on aerosols and gaseous pollutants measured in the city of Kuopio. A very valuable feature of PCA is that the results can be presented as informative graphs, which greatly helps in interpretation of the results. Although the significant...

Thermodynamic properties of aqueous mixtures of sodium or potassium hydrogen phosphate, dihydrogen phosphate and chloride at 298.15 K were studied by means of a recently developed method where a simple equation is used for ionic activity coefficients. The experimental data for these studies were taken from the literature. It is shown that almost al...

Within a case study ‘Ecobalance’, the fate and effects of various chlorinated and non-chlorinated organic compounds and some heavy metals discharged from pulp and paper mills into water, sediment and aquatic animals were studied in a recipient area of southern Lake Saimaa, SE Finland. The main aim of the project was to find an empirical link betwee...

Interlaboratory comparisons are frequently carried out in analytical laboratories either as a part of their quality assurance procedures or as an important part of analytical method development. The total analytical error is usually composed of three components: the random measurement error, laboratory bias and sample—laboratory interaction. The si...

A simple equation originating from the Debye-Huckel theory was used for activity coefficients of ionic species in thermodynamical studies of weak acids in aqueous solutions at 298.15 K. The equation was tested with experimental results of galvanic cells with and without a liquid junction. Of the cells of the latter type, those containing a hydrogen...

Ordinary least squares (OLS), partial least squares (PLS) and principal component regression (PCR) were compared in the calibration of a process analyzer with and without variable selection. The leave-one-out cross-validation procedure was used in selecting variables for the OLS, PLS and PCR models and for the PCR models with component selection. I...

Eight well-known equations presented for thermodynamic activities in aqueous NaCl and KCl solutions at 298.15 were tested with the most reliable experimental results of the isopiestic determinations reported in the literature. Usually the equations tested do not predict these data very well. Only the two-parameter Pan equation with the parameter va...

Ammonium nitrate solid phase transition paths between phases IV, III and II were explained and predicted on the basis of X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC) data by applying partial least-squares regression (PLS) and principal component analysis (PCA). The samples were clustered according to their different tr...

The cryoscopic data reported in the literature for aqueous NaCl solutions were systematically recalculated. In these calculations, it was found that most of the measured freezing points up to the molality of 0.45 mol-kg-1 can be predicted within experimental error by a two-parameter equation of the Huckel type. The two parameters of this Huckel equ...

Fifteen 48-hour and two 24-hour aerosol samples were collected in the summer of 1985 during a Baltic Sea cruise on the Soviet marine research vessel Akademik Shuleykin. The expedition was part of the Soviet-Finnish programme for scientific and technical co-operation. The geometric means of the concentration of the different elements expressed as ng...

Minkkinen, P., 1989. SAMPEX — a computer program for solving sampling problems. Chemometrics and Intelligent Laboratory Systems, 7: 189-194.Chemical analysis nearly always involves sampling. With heterogeneous solids the sampling error may be the largest source of error which determines the overall reliability of the analysis. To help analysts to e...

Partial least squares modelling in latent variables (PLS) is proposed for the solution of water pollution source apportionment problems. SIMCA, principal component analysis (PCA), and PLS are applied to the water quality monitoring data collected from Lake Saimaa, Finland. PCA is used to investigate the origin of the effluents and discriminant PLS...

The evaporation of potassium from phlogopite was investigated by roasting phlogopite with different chemical reagents. The possible reactions between reactants and the sample at different temperatures were investigated by thermogravimetry. Gypsum, calcite, sodium chloride, activated carbon, calcium chloride and fluoride were used as chemical reacta...

Chemical analysis is a multi-stage process, which starts with primary sampling and ends with evaluation of the resuts. Especially in trace analysis and microanalysis of solid materials, sampling can far outweigh all other sources of error. For estimating the reliability of complete analytical procedures, a method is needed which can be used to esti...

The partial least-squares method was applied to data collected at a municipal waste-water treatment plant to estimate the relationship between the process parameters and effluent quality. The main reason for poor treatment efficiency was the so-called bulking phenomemon of the activated sludge. The PLS model of the data presenting a normal period o...

To ensure the reliability of results, analytical laboratories require a continuous qualitycontrol program which must take account of both systematic and random errors. Analyses of reference materials can be used to estimate systematic errors but estimates of random errors (precision) tend to be optimistic, mainly because reference materials cannot...

A simple and general standard-addition method for a single-component determination is presented. The method uses two independent variables for the calculation of the analyte concentration (the amount of sample taken and the amount of analyte added) and one dependent variable, the response. The sensitivity and the response of the blank can also be e...

III CAC - Meet. of the chemometrics soc. Lerici, IT, 26 - 29 May 1986. Abstract, 112 - 113