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• The risk of bisphenols (BPA, BPF, and BPS) in thermal papers and canned food samples was assessed. • A method for determining bisphenols based on HPLC-DAD was developed and validated. • An integrated calibration method was modified and supported by the H-point standard addition method to compensate interference effects. • BPA concentration in canned food products was exceeded. • Risk factors connected to the receipts (BPF and BPS) proved harmful to cashiers due to long exposure time. The most crucial purpose of the measurement is to obtain a reliable result that reflects the actual qualitative and/or quantitative features of the tested material. The overriding goal of analytical chemistry is to obtain accurate results after compensating of various interference effects as well as non-linear calibration dependence. A new approach based on an integrated calibration method (ICM) supported by H-point standard addition method (HPSAM) has been used to improve the quality of analytical results. The proposed methodological approach was extended using the step-by-step dilution procedure, and five measurement conditions were used to eliminate multiplicative, additive, and non-linear interferences. On this basis, a set of estimations is obtained to improve the quality of the analytical results. The analytical usefulness of the proposed approach was tested on the example of the determination of three compounds from the group of bisphenols (BPs) using the chromatographic technique - HPLC-DAD (high-performance liquid chromatography with diode array detection). Compared to the reference method - fluorescence spectroscopy - the obtained results were characterized by excellent accuracy (RE=3 % in most cases). The developed methodology allowed to carry out a risk assessment on BPA, BPF, and BPS present in samples of shop receipts and canned food. Store clerks have been shown to be particularly vulnerable to PBF and BPS in receipts due to skin permeation (exposure factors were equal to 308.97 µg/g for BPF and 181.89 µg/g for BPS). Consumers should also pay close attention to the BPA found in canned food samples (the average concentration was equal to 20.61 µg/mL, and the tolerable daily intake was exceeded over 165.000 times). The analytical method and the methodological approach were evaluated using the RGB model and the AGREE approach - it was shown that the method can be successfully used for other analytical purposes (the method is White) and is environmentally friendly (Significance=0.63). [ABSTRACT FROM AUTHOR]

This work demonstrates a novel method for rapid determination of total solid content in viscous liquid (polymer-enriched) samples. The method is based multiple headspace extraction gas chromatography (MHE-GC) on a headspace vial at a temperature above boiling point of water. Thus, the trend of water loss from the tested liquid due to evaporation can be followed. With the limited MHE-GC testing (e.g., 5 extractions) and a one-point calibration procedure (i.e., recording the weight difference before and after analysis), the total amount of water in the sample can be determined, from which the total solid contents in the liquid can be calculated. A number of black liquors were analyzed by the new method which yielded results that closely matched those of the reference method; i.e., the results of these two methods differed by no more than 2.3%. Compared with the reference method, the MHE-GC method is much simpler and more practical. Therefore, it is suitable for the rapid determination of the solid content in many polymer-containing liquid samples. [ABSTRACT FROM AUTHOR]

Abstract: A method is described for characterization of sulfur compounds in unaged and aged whisky. The method is based on full evaporation dynamic headspace (FEDHS) of 100μL of whisky samples followed by selectable one-dimensional (1D) or two-dimensional (2D) retention-time-locked (RTL) gas chromatography (GC)–mass spectrometry (MS) with simultaneous element-specific detection using a sulfur chemiluminescence detector (SCD) and a nitrogen chemiluminescence detector (NCD). Sequential heart-cuts of the 16 sulfur fractions were used to identify each individual sulfur compound in the unaged whisky. Twenty sulfur compounds were positively identified by a MS library search, linear retention indices (LRI), and formula identification using MS calibration software. Additionally eight formulas were also identified for unknown sulfur compounds. Simultaneous heart-cuts of the 16 sulfur fractions were used to produce the 2D RTL GC-SCD chromatograms for principal component analysis. PCA of the 2D RTL GC-SCD data clearly demonstrated the difference between unaged and aged whisky, as well as two different whisky samples. Fourteen sulfur compounds could be characterized as key sulfur compounds responsible for the changes in the aging step and/or the difference between two kinds of whisky samples. The determined values of the key sulfur compounds were in the range of 0.3–210ngmL−1 (RSD: 0.37–12%, n =3). [Copyright &y& Elsevier]

Abstract: Gas and liquid chromatography (GC and LC) coupled to mass spectrometry (MS) serve as the most powerful analytical tools commonly used to monitor pesticide residues in food, among other applications. However, both GC–MS and LC–MS are susceptible to matrix effects which can adversely affect quantification depending on the analyte, matrix, sample preparation, instrumentation, and operating conditions. Among the approaches that reduce matrix effects, the most common in pesticide residue applications is matrix-matched calibration because it is relatively inexpensive and simple. Also, it has been shown to work well during method validation when fortified samples are exactly matched with samples used for calibration. However, the quality of matrix-matched results in real-world analyses depends on the consistency of matrix effects among diverse samples. In this study, the variability of matrix effects was measured for 38 representative pesticides in 20 samples each (including different varieties) of rice, orange, apple, and spinach extracted using the “quick, easy, cheap, effective, rugged, and safe” (QuEChERS) method for analysis by LC–MS/MS and low-pressure GC–MS. Using LC–MS/MS, only oranges gave >20% matrix effects for a few pesticides. GC–MS exhibited larger matrix effects, but as in LC–MS/MS, the differences were reasonably consistent among the 20 samples tested. Main conclusions of this study are that for the conditions utilized: (1) matrix-matching was not needed for most pesticides in the simpler food matrices; and (2) for the more complex orange matrix, acceptably accurate quantitative results were achieved by using matrix-matching even with a different sample of the same type. However, full confidence cannot be extended to matrix-matched results, and for consequential applications such as regulatory enforcement, confirmatory analyses using alternate quantitative determinations should also be conducted. [Copyright &y& Elsevier]

Abstract: An ionic liquid-based single-drop microextraction (IL-SDME) procedure using IL as an extractant on-line coupled to capillary electrophoresis (CE) is proposed. The method is capable of quantifying trace amounts of phenols in environmental water samples. For the SDME of three phenols, a 2.40nL IL microdrop was exposed for 10min to the aqueous sample and then was directly injected into the capillary column for analysis. Extraction parameters such as the extraction time, the IL single-drop volume, pH of the sample solution, ionic strength, volume of the sample solution and the extraction temperature were systematically investigated. Detection limits to three phenols were less than 0.05μgmL−1, and their calibration curves were all linear (R 2 ≥0.9994) in the range from 0.05 to 50μgmL−1. And enrichment factors for three phenols were 156, 107 and 257 without agitation, respectively. This method was then utilized to analyze two real environmental samples from Yellow River and tap water, obtaining satisfactory results. Compared with the usual SDME for CE, IL-SDME–CE is a simple, low-cost, fast and environmentally friendly preconcentration technique. [Copyright &y& Elsevier]

Abstract: In common with all gas chromatography (GC) methods, comprehensive two-dimensional gas chromatography (GC×GC) has the potential to provide both qualitative and quantitative analysis. There are fundamental differences in the way one-dimensional (1D-GC) and GC×GC results are interpreted for these parameters. Since 1D-GC produces a single measured peak in the chromatogram, there is a single retention time, and associated with this a single peak response (either area or height). Peak area and height are related by peak width. GC×GC produces a series of modulated peaks at the detector. Thus, the peak metrics of retention, area and height for one component are now not simple single values for one peak, but rather are derived from the multiple peak distribution generated by the modulation process. The peak retention is interpreted in terms of two-dimensional coordinates in a retention plane. In this study, a brief background review to quantification in GC×GC is provided. Previous reviews cover aspects of quantitative GC×GC studies up to the year 2005, including different approaches to quantification, and reports of quantitative analysis with different detectors, for different compounds classes, and in different matrices. Other studies have developed chemometric approaches based on multivariate analysis to provide quantitative reporting of individual compounds. The coverage of the earlier reviews has been updated to include material that has been presented since 2005 and includes considerations of valve-based modulation. Recently the modulation ratio (M R) concept was proposed and intended to clarify the meaning of modulation number (n M) in GC×GC, which was shown to be a rather poorly defined parameter. Based on the prior studies that introduced this concept, the role of quantitative analysis is investigated here through calculation of the peak areas and peak area ratios of selected series of modulated peaks in GC×GC. The application of isotopically labelled reference compounds for polycyclic aromatic hydrocarbon (PAH) analysis is used here to develop the quantitative metric approach. It is shown that by selecting the two or three major modulated peaks for solutes and internal standards, comparing the response ratio with the sum of all modulated peaks and also with the reference non-modulated result, quantification is statistically equivalent. Thus, adequate quantitative analysis and calibration can be accomplished by using selected major modulated peaks for each compound. This may simplify quantitative interpretation of GC×GC data. [Copyright &y& Elsevier]

Abstract: In many studies of nonlinear or preparative chromatography, chromatographic signals must be recorded for relatively concentrated solutions and the detectors, that are designed for analytical applications and are highly sensitive, must be used under such experimental conditions that their responses are often nonlinear. Then, a calibration curve is needed to derive the actual concentration profiles of the eluates from the measured detector response. It becomes necessary to derive a relationship between the concentration of the eluent and the detector signal at any given time. The simplest approach consists in preparing a series of solutions of known concentrations and in flushing them successively through the detector cell, recording the height of the plateau response obtained. However, this method requires relatively large amounts of the pure solutes being studied and these are not always available or they may be most costly, although these solutions can be recovered. We describe and validate an alternative procedure providing this calibration from a series of peaks recorded upon the injection of increasingly large pulses of the studied compound. [Copyright &y& Elsevier]

Abstract: Matrix matching is used in analysis to compensate for matrix effects that influence analytical response. It has been a widely discussed topic in electro-spray mass spectrometry where the ionization suppression is a major problem in accurate quantitative analysis. However, the unique strength of mass spectrometry to detect and quantify accurately a co-eluting stable isotope labelled internal standard offers an easy solution to the ionization suppression problem. Given the fact that it is impossible to match the matrix of the calibration standards with all samples, mass spectrometry allows accurate quantitation without the need for matrix matching, as long as the internal standard co-elutes with the analyte of interest. If the analyte and internal standard co-elute, the slope of the calibration curve analyte response/internal standard vs. analyte concentration is independent of the matrix composition, eliminating the need for matrix matching. [Copyright &y& Elsevier]