Analytical Letters

Journal Information
ISSN / EISSN: 00032719 / 1532236X
Published by: Informa UK Limited
Total articles ≅ 10,910

Latest articles in this journal

, M. Valerio, R. Petrini
Published: 23 September 2022
Abstract:
Much importance has been given in the recent literature to the determination and speciation of mercury in contaminated mine waste and soil. Among mercury species, the concentration of elemental mercury is a key parameter for risk assessment. However, at present, a validated analytical method for the quantitation of Hg(0) in solid matrices does not exist. In the present study, the reliability of a thermal desorption technique in quantifying elemental mercury in Hg(0) amended silica glass, a reference shelf standard, and in a Hg(0)-bearing mineralized silicate rock, considered representative of mine tailings, has been addressed. Mercury release has been measured at variable temperature using a thermo-desorption method combined with a mercury vapor analyzer. The results allowed the peak temperature for the emission of free and matrix-bound Hg(0) components to be identified, suggesting that 100 °C represents a suitable temperature for Hg(0) isothermal release. Experiments with the shelf standard exposed to a specific sorbent keeping the temperature constant at 100 °C provided 90% and 98% Hg(0) recovery after 2 and 24 h, respectively. Experiments with the mineralized rock demonstrated that free elemental mercury was recovered after 6 h, while 60 h were required for the free and matrix bound Hg(0) release. The limits of detection and quantification of the method were 1.3 ng and 3.0 ng, respectively. This approach allows elemental mercury in solid matrices to be determined, allowing the quantification of Hg(0) in contaminated mine tailings and soil.
, Keisuke Morichika, Joseph Krueger, Hiroyuki Yokota
Published: 21 September 2022
Analytical Letters pp 1-10; https://doi.org/10.1080/00032719.2022.2123498

Abstract:
Immunohistochemistry (IHC) is a useful method for visualizing antigens in tissues using target-specific antibodies in drug discovery and clinical research. Color reactions with horseradish peroxidase enzymatic activity have been used for IHC. This method has a long history and is highly reliable when applied to in vitro diagnostics. However, an IHC method with high sensitivity is required for low-expression target molecules in antibody-drug conjugates and immunotherapy. Therefore, many studies have been conducted in recent years to improve the sensitivity using highly brilliant and light-resistant phosphor-integrated dots (PIDs). In this method, streptavidin-coated PIDs are linked via biotinylated antibodies and the target molecules are visualized (PID-AbL). PID-AbL is more sensitive than IHC with chromophores. Hence, this study aimed to improve the sensitivity and quantitative results of IHC by combining PIDs with a biotinylated tyramide linker (PID-TL). PID-TL is able to detect ultralow human epidermal growth factor receptor 2-expressed cells. Moreover, PID-TL may be applied to human tissue samples as well as in vitro diagnostic kits. This new approach may help detect low-expression target molecules for clinical research.
Yuangui Yang, Lvye Liu, Zhengtao Wang, Yan Jin,
Published: 21 September 2022
Analytical Letters pp 1-14; https://doi.org/10.1080/00032719.2022.2125525

Abstract:
An automated on-line solid-phase extraction (SPE) high-performance liquid chromatography (HPLC) method was developed for the determination of six protoberberine alkaloids in compound Chinese medicines containing Coptidis Rhizoma and Phellodendri Cortex. The sample solution extracted by acidic-methanol was loaded into the constructed system directly to perform enrichment and the purification of the analytes was performed automatically. A cation-exchanged sorbent based on turbulent chromatography was employed for on-line SPE to remove macro and neutral matrix interferences from samples. The target alkaloids were retained on the SPE column and eluted onto the trapping C18 column by a mobile phase of methanol/500 mM ammonium acetate (85:15) at a flow rate of 0.3 mL/min. Ion pair reverse phase high-performance liquid chromatography was employed to complete the determination of six analytes. The results showed the linear correlation coefficients for all analytes were above 0.999. The peak area of relative standard deviation in reproducibility measurements were from 0.55% to 2.39%. Recovery measurements spiked at two levels were from 92.71% to 104.28%. The reported method was suitable for the determination of six active alkaloids in multicomponent Chinese medicines containing Coptidis rhizoma and Phellodendri cortex.
Maria S. Synaridou, Vasilis Tsamis, Eleni Tsanaktsidou, Andreas Ouranidis, ,
Published: 19 September 2022
Analytical Letters pp 1-15; https://doi.org/10.1080/00032719.2022.2125003

Abstract:
A new multivitamin supplement containing fat (A and D3) and water soluble (C, B2, B3, B6 and B12) vitamins together with nutrients for young athletes was formulated and analyzed. Due to the complexity of the matrix (excipients: Aegina peanut butter, pomegranate juice, royal jelly and chocolate), a purification process was developed using a freezing and liquid extraction technique and optimized with central composite design (CCD) methodology. For the analysis of the samples, an efficient liquid chromatography (LC) gradient elution method was developed and validated, focusing on the stability of sensitive vitamins. After investigation, a diode array detector was chosen instead of electrospray ionization mass spectrometry (ESI-Q/MS) to determine the analytes. The most suitable chromatographic conditions were selected based on a D-optimal process where a mixture component (acetonitrile and phosphate buffer 20 mM) was cross-correlated with three factors: pH, flow rate, and column temperature. The analysis was performed on a cyano column (250 × 4.6 mm, 5 µm) and validated (recovery from 98.7 to 100.4; relative standard deviation 97.1%).
Daining Ding, , Yong Yin, Yunxia Yuan, Zhaozhou Li, Fang Li
Published: 19 September 2022
Analytical Letters pp 1-13; https://doi.org/10.1080/00032719.2022.2123922

Abstract:
The chlorophyll content and hardness are critical indicators for evaluating vegetable quality. To overcome the drawbacks of traditional detection methods, Raman spectroscopy was investigated for the determination of chlorophyll content and hardness in cucumbers. Cucumbers at different storage periods were analyzed and a successive projections algorithm – extreme learning machine (SPA-ELM) method was employed to establish a model for chlorophyll content and hardness. The Raman spectra were preprocessed to reduce noise and minimize the background fluorescence. Subsequently, SPA was used to select characteristic wavelengths for chlorophyll content and hardness using 19 and 26 characteristic wavelengths, respectively. ELM was employed to establish a model based on the selected characteristic wavelengths. The predicted results by ELM were compared with those obtained using partial least squares (PLS) and support vector machine (SVM). The results showed that the best accuracy was obtained using the SPA-ELM algorithm. The coefficients of determination (R2) of SPA-ELM model for chlorophyll content and hardness were 0.9569 and 0.9659. The root mean square error (RMSE) values were 0.0038 and 0.3570, respectively. A good correlation coefficient and small RMSE value were obtained, indicating the results to be highly accurate and reliable. Raman spectroscopy combined with SPA-ELM method was shown to rapidly and accurately evaluate the chlorophyll content and hardness of cucumbers.
Zheqi Fei, Baisen Chen, Xuemei Wei, , Xiyue Wang,
Published: 15 September 2022
Analytical Letters pp 1-14; https://doi.org/10.1080/00032719.2022.2122486

Abstract:
Developing highly efficient adsorbents toward trace pollutant analysis in complex biological samples is a challenge in analytical chemistry. Herein, NiO/ZnO-coated carbon microspheres (denoted by NiO/[email protected]) with a well-defined core–shell structure were prepared through hydrothermal treatment and subsequent pyrolysis in air to enrich malachite green (MG) and crystal violet (CV). Hydrophilic carbon microspheres played an important role in the formation of core–shell NiO/[email protected], which may lead to the deposition of Ni2+/Zn2+ upon the surface via acidic chelating ligands. Based on the Langmuir model, NiO/[email protected] demonstrated high adsorption capacities of 333.3 and 192.3 mg/g for MG and CV, respectively. Moreover, the NiO/[email protected] composite served as a dispersive solid-phase extraction adsorbent to determine MG and CV in aquatic products combined with ultra-high performance liquid chromatography. High linearity was obtained for analyte concentrations from 5 to 500 μg/L with correlation coefficients (r) exceeding 0.9991. The limits of detection of the method were 0.50 μg/L (MG) and 0.35 μg/L (CV) with relative standard deviations less than 7.47%. Furthermore, the developed method was employed to determine MG and CV in aquatic products.
Lúzio G. Bocalon, Marcos G. Tozatti, Ana H. Januário, Patrícia M. Pauletti, , Lucas A. Rocha, Eduardo F. Molina, ,
Published: 15 September 2022
Analytical Letters pp 1-15; https://doi.org/10.1080/00032719.2022.2120491

Abstract:
Drug delivery systems are technologies that have been vastly studied and applied to enhance existing therapies. For example, they allow the use of new approaches to already established drugs to improve the application of compounds with biological interest, such as augmenting their bioavailability. Betulinic acid (BA) is a triterpene that possesses interesting biological properties but its low solubility and low bioavailability have limited its applications. This work shows the obtention of BA and its incorporation process into two types of mesoporous silica, SN1(spherical) and SN2 (rod-shaped). Characterization of these materials through infrared, thermal analysis, scanning electron microscopy, and specific surface areas confirmed the presence of this triterpene in this silica matrix. Characterization of the BA release profile demonstrated that the probable mechanism of SN1 nanoparticles is a zero-order release system, whereas SN2 nanoparticles presented a non-Fickian diffusion. These results show the potential use of these nanoparticles as another approach in drug delivery systems for these types of compounds.
Cristiana Guerranti, Costanza Andreuccetti, Isabella Cenni, , Tania Martellini, Alessandra Cincinelli, Andrea Perico
Published: 13 September 2022
Analytical Letters pp 1-13; https://doi.org/10.1080/00032719.2022.2121405

Abstract:
A new method for the determination of five trace metals (Pb, Co, Cd, Cr, and Ni) in make-up products was developed. Quantification of the metals was performed by inductively coupled plasma – mass spectrometry (ICP-MS). The specificity, precision, applicability range and linearity, the minimum detection limit, repeatability, trueness, and uncertainty of the method were assessed by a top-down approach. The method was applied to 90 cosmetic products in the Italian market and only Pb and Cd were always lower than limits for cosmetic products proposed by the Istituto Superiore Sanità (Italian National Institute for Health, ISS). The metal concentrations allowed the evaluation of the risk levels of exposure to these elements. Except for a few cases, the calculated margin of safety (MOS), margin of exposure (MOE), and lifetime cancer risk (LCR) values were all below the risk threshold levels. Based on the maximum concentrations of metals determined in the cosmetics, the dose of systemic exposure (SED) ranged from 8.00 x 10−12 to 3.39 x 10−7 mg/kg/d. The risk was also described from the hazard index (HI). The metals in each cosmetic product show an MOE higher than the threshold limit except for Cr in eyeshadow.
Mansoor Khan,
Published: 9 September 2022
Analytical Letters pp 1-13; https://doi.org/10.1080/00032719.2022.2121406

Abstract:
Mercury (Hg) is a toxic heavy metal discharged into the environment by many human and natural sources. Therefore, the precise and accurate determination of trace mercury in samples is of immense importance. In this regard, a spectrophotometric method has been developed for the quantification of Hg (II) in water, hair, and fish using deep eutectic (choline chloride, ChCl + decanol) solvent-based liquid-liquid microextraction (DES-LLME). All of the relevant parameters, including pH (9), volume of 1-(2-pyridylazo)-2-naphthol (PAN) (300 µL), ratio of choline chloride and decanol (1:1), volume of DES (400 µL), volume of tetrahydrofuran (THF) (400 µL), and sample volume (40 mL) were optimized. The low limits of detection (LOD) (0.09 µg L−1) and quantification (LOQ) (0.325 µg L−1) demonstrate that the developed approach is highly sensitive. High preconcentration (PF) and enhancement factors (EF) of 50 show that the developed protocol is highly efficient. The relative standard deviation (RSD) is 6.32%, indicating that the method is reproducible. The method was validated by the analysis of TMDA-53.3 water and NCSZC81002B hair certified reference materials with high recoveries of 97% and 93%, respectively. The method was also employed for the analysis of tap water, dam water, river water, hair, and tuna fish with satisfactory recoveries from 95% to 102%. The developed approach was compared with literature methods on the basis of the limit of detection.
Ziwei Zhang, Jin Yuan, Huiling Zheng, Zelin Liu, Guangqiu Lu, ,
Published: 7 September 2022
Analytical Letters pp 1-17; https://doi.org/10.1080/00032719.2022.2119245

Abstract:
Lead pollution may cause serious damage to environment safety and human health, especially to children’s growth. In this work, by using double stranded DNA (dsDNA) as the recognition element, a simple and effective electrochemical DNA sensor has been developed on a full carbon-based substrate, reduced graphene oxide/carbon paper (rGO/CP), to accomplish the rapid, sensitive and selective determination of Pb2+. Carbon paper (CP) provides a suitable substrate for the sensor with high portability and low cost, while rGO is easily electrodeposited onto CP and serves as both the signal amplification element and the molecular bridge between DNA and CP. Because of its high specific surface area and unique conjugated giant π structure, rGO tightly binds with DNA through π-π stacking and hydrophobic interactions, thereby providing loading of high quantities of DNA. The specific coordination between DNA and Pb2+ further improves the sensitivity of the sensor. The results demonstrate that rapid electrochemical enrichment of Pb2+ is achieved using the constructed CP/rGO/DNA electrode with a linear relationship between the peak current and the concentration of Pb2+ from 1 pM to 100 pM and a detection limit of 1 pM. In addition, this approach shows good selectivity and satisfactory repeatability for river water analysis. A promising sensitive, low-cost, simply-fabricated, and portable full carbon-based electrochemical biosensing platform has been therefore provided for lead determination.
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