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Herbal medicines are more and more worldwide used. This fact certainly presents serious problems for the potential human health risks. This is due to the fact that the laws in force generally do not provide for strict quality controls of herbal medicines to certify the concentration of compounds and elements that may be hazardous for human health, and sometimes very severe or even lethal. Heavy metals have a decidedly substantial part of the contaminants in herbal medicines. The present review proposes an exhaustive focus on what are the metals of interest, and what is the state of the art about analytical methodologies suitable to detect these toxic metals in herbal medicines. This review would also be a stimulus to solicit International Organizations to fill the gap of the lack of strict and comprehensive laws regulating the maximum allowable concentrations for an increasing number of contaminants in these matrices, especially considering their enormous consumption.

Biofilms are communities of microorganisms adhering to a surface and embedded in an extracellular polymeric matrix, frequently associated with disease and contamination, and also used for engineering applications such as bioremediation. A mixed biofilm formed by bacteria and fungi may provide an optimal habitat for addressing contaminated areas. To exploit the potential of natural microbial communities consisting of bacteria and fungi, it is essential to understand and control their formation. In this work, a method to discriminate among bacteria of genera Bacillus, Pseudomonas, Rhodococcus with respect to the fungus Pleorotus in a biofilm by means of pyrolysis-gaschromatography-mass spectrometry and multivariate analysis is reported. Methylated fatty acids were chosen as biomarkers of microorganisms in the pyrolysates. In situ thermal hydrolysis and methylation was applied. Pyrograms were used as fingerprints, thus allowing for the characterization of whole cells analyzed without any sample pretreatment. Normalized pyrographic peak areas were chosen as variables for chemometric data processing. Principal components analysis was applied as a dataexploration tool. Satisfactory results were obtained in analyzing a real biofilm. The influence of growth medium on whole bacteria fatty acid cell composition was also explored.

On‐line, continuous chemiluminescence detection has been recently applied to gravitational field‐flow fractionation as a new method suitable for flow‐assisted assays based on the separation between the analyte in solution and the analyte bound to micrometer‐sized particles. In this work, flow field‐flow fractionation coupled with off‐line chemiluminescence detection is exploited for the development of flow‐assisted, multianalyte assays. Micrometer‐sized, polystyrene beads coated with enzymes suitable for chemiluminescence detection, such as horseradish peroxidase and alkaline phosphatase, are used as model samples. The high size‐based selectivity of flow field‐flow fractionation and specificity of chemiluminescence detection make possible, in a single run with very short analysis time, the simultaneous, high sensitivity detection of the different enzymes linked to beads of different size.

On-line, continuous chemiluminescence detection has been recently applied to gravitational field-flow fractionation as a new method suitable for flow-assisted assays based on the separation between the analyte in solution and the analyte bound to micrometer-sized particles. In this work, flow field-flow fractionation coupled with off-line chemiluminescence detection is exploited for the development of flow-assisted, multianalyte assays. Micrometer-sized, polystyrene beads coated with enzymes suitable for chemiluminescence detection, such as horseradish peroxidase and alkaline phosphatase, are used as model samples. The high size-based selectivity of flow field-flow fractionation and specificity of chemiluminescence detection make possible, in a single run with very short analysis time, the simultaneous, high sensitivity detection of the different enzymes linked to beads of different size.

A new procedure for calibrating ThFFF systems by using broad molecular weight standards based on a non‐linear least squares fitting of the fractogram to the Molecular Weight Distribution to derive the system calibration parameters is presented and explored by simulation. This procedure proved robust with respect to noise and it is able to account for detector nonlinearity. The effect of band broadening was evaluated and it was found that significant bias is observed only for polydispersities lower than 1.3. The method was experimentally validated by using polystyrene in decalin and was then applied to polypropylene under conditions of high temperature ThFFF (Tc= 394 K). It appears that the presented method can be useful in characterising polyolefins polymers for which monodisperse standards are not available.

Field-flow fractionation is a separation technique for macromolecular species; over more than 2 decades, it has been studied mostly for enhancing its separation capabilities in terms of wider applicability, improved selectivity, and reduced analysis time. Most of the efforts have been focused on qualitative aspects of fractionation, while the quantitative aspects have been scarcely exploited. However, a quantitative approach to field-flow fractionation is an unavoidable task in the framework of a general optimization of this technique, particularly when preparative applications are sought. In this work, an overview of quantitative aspects of gravitational field-flow fractionation for the analysis of supermicron particles is presented. In particular, a derivation of the Lambert–Beer law for flow-through measurements is applied to real-time conversion of the detector signal response into sample mass or concentration. In the proposed approach, particle size distribution curves are numerically related to sample mass and to the level of sample recovery derived together from a single fractionation. © 1997 John Wiley & Sons, Inc. J Micro Sep 9: 545–556, 1997

A standardless analysis method with electrothermal atomization/atomic absorption spectroscopy (ETA-AAS) measurements is proposed and applied to the determination of Pb in an urban environment (Bologna, Italy) and compared with results obtained in the same place and time, with the method dictated by Italian law, which is derived by European Community Directives. It was found that the difference previously observed between the two methods is due to the low efficiency of the 0.45-μm-pore-size paper filters, dictated by the official method. The uncovering of the error source validates the proposed method and highlights its accuracy. Moreover, the two methods can be conveniently combined to give two series of data relevant to pollutants associated with low- and high-dimension particles. This capability gives a much more precise picture of the hazard of a pollutant.

In previous works, it has been shown that a standard ultraviolet-visible detection system can be used for quantitative analysis of heterogeneous systems (dispersed supermicron particles) in field-flow fractionation (FFF) by single peak area measurements. Such an analysis method was shown to require either experimental measurements (standardless analysis) or an accurate model (absolute analysis) to determine the extinction efficiency of the particulate samples. In this work, an experimental design to assess absolute analysis in FFF through prediction of particles optical extinction is presented. Prediction derives from the semiempirical approach by van de Hulst and Walstra. Special emphasis is given to the restriction of the experimental domain of instrumental conditions within which absolute analysis is allowed. Validation by statistical analysis and a practical application to real sample recovery studies are also given.