Chemical studies of anthocyanins: A review

The first part of this two-part review focused on the fundamental and diagnostics aspects of laser-induced plasmas, only touching briefly upon concepts such as sensitivity and detection limits and largely omitting any discussion of the vast panorama of the practical applications of the technique. Clearly a true LIBS community has emerged, which promises to quicken the pace of LIBS developments, applications, and implementations. With this second part, a more applied flavor is taken, and its intended goal is summarizing the current state-of-the-art of analytical LIBS, providing a contemporary snapshot of LIBS applications, and highlighting new directions in laser-induced breakdown spectroscopy, such as novel approaches, instrumental developments, and advanced use of chemometric tools. More specifically, we discuss instrumental and analytical approaches (e.g., double- and multi-pulse LIBS to improve the sensitivity), calibration-free approaches, hyphenated approaches in which techniques such as Raman and fluorescence are coupled with LIBS to increase sensitivity and information power, resonantly enhanced LIBS approaches, signal processing and optimization (e.g., signal-to-noise analysis), and finally applications. An attempt is made to provide an updated view of the role played by LIBS in the various fields, with emphasis on applications considered to be unique. We finally try to assess where LIBS is going as an analytical field, where in our opinion it should go, and what should still be done for consolidating the technique as a mature method of chemical analysis.

https://journals.sagepub.com/doi/pdf/10.1366/11-06574

Laser-induced breakdown spectroscopy (LIBS), part II: review of instrumental and methodological approaches to material analysis and applications to different fields.

We propose a data mining approach to predict human wine taste preferences that is based on easily available analytical tests at the certification step. A large dataset (when compared to other studies in this domain) is considered, with white and red vinho verde samples (from Portugal). Three regression techniques were applied, under a computationally efficient procedure that performs simultaneous variable and model selection. The support vector machine achieved promising results, outperforming the multiple regression and neural network methods. Such model is useful to support the oenologist wine tasting evaluations and improve wine production. Furthermore, similar techniques can help in target marketing by modeling consumer tastes from niche markets.

/pdf/modeling-wine-preferences-by-data-mining-from-3fxk2fcdej.pdf

Modeling wine preferences by data mining from physicochemical properties

Impedance biosensors are a class of electrical biosensors that show promise for point-of-care and other applications due to low cost, ease of miniaturization, and label-free operation. Unlabeled DNA and protein targets can be detected by monitoring changes in surface impedance when a target molecule binds to an immobilized probe. The affinity capture step leads to challenges shared by all label-free affinity biosensors; these challenges are discussed along with others unique to impedance readout. Various possible mechanisms for impedance change upon target binding are discussed. We critically summarize accomplishments of past label-free impedance biosensors and identify areas for future research.

/pdf/label-free-impedance-biosensors-opportunities-and-challenges-3b721lxxqy.pdf

Label-Free Impedance Biosensors: Opportunities and Challenges.

Applications of solid-phase microextraction in food analysis.

Guidelines for calibration in analytical chemistry. Part I. Fundamentals and single component calibration (IUPAC Recommendations 1998)

The terms recovery and apparent recovery are recommended to avoid confusion caused by the use of the term recovery to cover two distinct situations. These situations deal with: (a) the yield of a preconcentration or extraction stage of an analytical process (where recovery is recommended) and (b) the quantity observed value/reference value, obtained using an analytical procedure that involves a calibration graph (where apparent recovery is recommended).

Use of the term "recovery" and "apparent recovery" in analytical procedures (IUPAC Recommendations 2002)

: The correct use of the term “selectivity” and its clear distinction from theterm “specificity” are discussed. A definition of selectivity is given, and it is rec-ommended that the use of this term be promoted and that the use of the term“specificity” be discouraged. 1. INTRODUCTION A very important quality criterion of an analytical method is its capability to deliver signals that are freefrom interferences and give “true results”. The ability to discriminate between the analyte and interfer-ing components has, for many years, been expressed as the “selectivity” of a method and measurementsystem. One clear definition is the following: “ Selectivity of a method refers to the extent to which itcan determine particular analyte(s) in a complex mixture without interference from other componentsin the mixture” [1]. However, the same meaning has often been given to the term “specificity” [2].Following earlier concern about the use of these terms [3] IUPAC clarified this overlap by expressingthe view that “

Selectivity in analytical chemistry (IUPAC Recommendations 2001)

Provenance and authenticity of wines can be recognized on the basis of typical mineral and trace element patterns by means of chemometric methods. Therefore analytical methods were developed for the determination of As, Be, Co, Cs, Ga, Li, Nb, Ni, Rb, Te, Ti, W, Y, and Zr as well as Mo, Cd, Sb, Tl, U, and the rare earth elements in wines by inductively coupled plasma mass spectrometry (ICP-MS). For low risk of contamination or loss of analyte as well as depletion of sample amount and an easy sample pretreatment, direct measurement of diluted wines was studied. The accuracy of the analytical results was proven by recovery experiments by method comparison with standard addition methods and measurement of digested wines. In addition to applying statistical methods for characterizing the precision of the methods, the uncertainty of the measurements was estimated. Results for the elements mentioned above and additional 16 elements (Al, B, Ba, Ca, Cr, Cu, Fe, Mn, Mg, P, Pb, Si, Sn, Sr, V, and Zn) were evaluated by data analytical methods. Due to a specific choice of the analytes for multivariate statistical investigation a prediction rate by cross validation of 88.6% could be achieved.

Klaus Danzer

Papers

Guidelines for calibration in analytical chemistry. Part I. Fundamentals and single component calibration (IUPAC Recommendations 1998)

Use of the term "recovery" and "apparent recovery" in analytical procedures (IUPAC Recommendations 2002)

Selectivity in analytical chemistry (IUPAC Recommendations 2001)

Determination of trace elements in wines and classification according to their provenance.

Use of the terms "recovery" and "apparent recovery" in analytical procedures