Recent advances of liquid chromatography–(tandem) mass spectrometry in clinical and forensic toxicology

In the last decade, liquid chromatography coupled to (tandem) mass spectrometry (LC–MS(−MS)) has become a versatile technique with many routine applications in clinical and forensic toxicology. However, it is well-known that ionization in LC–MS(−MS) is prone to so-called matrix effects, i.e., alteration in response due to the presence of co-eluting compounds that may increase (ion enhancement) or reduce (ion suppression) ionization of the analyte. Since the first reports on such matrix effects, numerous papers have been published on this matter and the subject has been reviewed several times. However, none of the existing reviews has specifically addressed aspects of matrix effects of particular interest and relevance to clinical and forensic toxicology, for example matrix effects in methods for multi-analyte or systematic toxicological analysis or matrix effects in (alternative) matrices almost exclusively analyzed in clinical and forensic toxicology, for example meconium, hair, oral fluid, or decomposed samples in postmortem toxicology. This review article will therefore focus on these issues, critically discussing experiments and results of matrix effects in LC–MS(−MS) applications in clinical and forensic toxicology. Moreover, it provides guidance on performance of studies on matrix effects in LC–MS(−MS) procedures in systematic toxicological analysis and postmortem toxicology.

Aspects of matrix effects in applications of liquid chromatography-mass spectrometry to forensic and clinical toxicology—a review

Simplifying sample pretreatment: Application of dried blood spot (DBS) method to blood samples, including postmortem, for UHPLC–MS/MS analysis of drugs of abuse

A simple and sensitive method for the detection of arsenic(III) using a magnetic Fe3O4 nanoparticles and gold nanoparticles modified glassy carbon electrode (Au NPs/Fe3O4/GCE) was developed. The Fe3O4 nanoparticles were dropped onto a GCE and the gold nanoparticles were electrodeposited later. The resulting electrode surfaces were characterized with both field emission scanning electron microscopy (FESEM) and electrochemical impedance spectroscopy (EIS). Square wave anodic stripping voltammetry (SWASV) was performed for the determination of arsenic(III). The obtained results show that the sensitivity of arsenic(III) is significantly improved on Au NPs/Fe3O4/GCE in comparison with Au NPs/GCE. Under optimal conditions, the detection limit (S/N = 3) was 0.00097 μg L−1. In addition, the modified electrode exhibited excellent reproducibility and high stability. The developed method was successfully applied to determine arsenic(III) in real water samples with satisfactory results.

An electrochemical sensor based on a magnetic Fe3O4 nanoparticles and gold nanoparticles modified electrode for sensitive determination of trace amounts of arsenic(III)

Although more than 30 years has already passed since hydride generation (HG) via the reaction with NaBH4 (THB) was combined with inductively coupled plasma (ICP) and microwave induced plasma (MIP), and applied in optical emission spectrometry (OES) for measurements of As, Bi, Ge, Pb, Se, Sb, Sn and Te, it is still the technique of choice in lots of analytical tasks requiring determinations of trace and ultratrace levels of these elements. But even now, HG offers plenty of room for development and progression. The last couple of years brought several achievements that revitalize HG and open new areas of its application for ICP- and MIP-OES methods. New universal sample introduction interfaces, capable of operating as both conventional spray chambers for pneumatic nebulization (PN) and reaction cells and gas-liquid phase separators (GLSs) for HG, have made possible real simultaneous determinations of hydride and non-hydride elements. The scope of HG utilizing the reaction with THB has additionally been expanded to transition and noble metals, i.e., Ag, Au, Cu, Mn, Ni, Pd, Pt, Rh, Zn and other elements, which vapor species, possibly nanoparticles of reduced elemental forms, are formed and transported into the plasma prior to detection by OES. It also seems that HG is well suited for determinations of hydride and non-hydride forming elements from slurried sample solutions with no necessity for tedious and time-consuming preparations of samples aimed on their complete decomposition. Operation of HG in a flow injection (FI) mode and use of microcolumns (MCs) loaded with different sorbents was found to be very suitable for pre-concentration of hydride forming elements and their separation from transition metal ions being encountered as serious interferents in HG. By combining HG with high performance liquid chromatography (HPLC) or capillary electrophoresis (CE), speciation analysis of hydride forming elements was possible. This present review provides a literature survey on achievements in HG for ICP- and MIP-OES detection that have been made over the last few years. Different aspects of this technique, including design of HG reaction and separation systems, chemical reaction conditions, accompanying chemical interferences, means of their reduction, procedures of sample treatment for determinations of total concentrations and speciation forms of hydride and non-hydride forming elements in relevant samples, and figures of merit achievable with ICP and MIP, are described and discussed.

Recent achievements in chemical hydride generation inductively coupled and microwave induced plasmas with optical emission spectrometry detection

Simultaneous determination of five toxic alkaloids in body fluids by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry.

Simultaneous determination of selenium and arsenic contents in different extracts of Radix Astragali by enhancement effect of ethanol in hydride generation-inductively coupled plasma-atomic emission spectrometry

The present invention relates to synthesis process and medicinal use of o-dihydroxyflavone-selenium complex. The o-dihydroxyflavone-selenium complex in the structure as shown may be applied in preparing health product, pesticide, plant growth regulator, feed additive, immunomodulator, antitumor medicine, antibacterial medicine, etc.

Method for preparing o-dihydroxyflavone-selenium complexes and medical use

Dichondra repens Forst is a Convolvulaceae plant. There are 5~8 species in the world and only one species in China. It is a traditional Chinese medicine, which has been known for a long time for its properties of heat-clearing, detoxicating, and damp elimination. It has been used in the treatment of diseases such as icterohepatitis, dysentery, and hydrops [1] in folk and clinical medicine. Extensive growth and cultivation of Dichondra repens Forst is now in progress and it has been exploited as a beverage food in China. Research [2] on the antibacterial activity of the decoction and tinctura from this plant against Bacillus diphtheriae and the antibacterial, anti-inflammation, and antinociceptive activity [3] of the n-butanol extract of Dichondra repens Forst has been conducted, and the chemical composition of Dichondra repens Forst has been reported [4, 5]. But there is not much attention devoted to the essential oil of Dichondra repens Forst and its antibacterial activities. Essential oils have demonstrated numerous biological actions, including antimicrobial activities [6, 7]. These properties are likely due to the many components of these complex mixtures and is facilitated by their ready dilusion across cell membranes. In this report, the chemical composition and antibacterial activities of the essential oil from Dichondra repens Forst is described. The essential oil was obtained from Dichondra repens Forst by steam distillation. The amount of components from the essential oil was calculated by the area normalization method. The separated components were identified by GC-MS. The antimicrobial activity of the essential oil has been tested by the method of disc-agar diffusion [8]. A total of 137 compounds were separated and 31 compounds were identified representing about 78.76% of the total oil. The chemical components and relative contents in the essential oil of Dichondra repens Forst are given in Table 1. The identified compounds mainly include 6-(methylamino)-phenanthren-3-ol (17.41%), (–)-trans-pinane (9.50%), ylangene (8.20%), isocaryophyllene (4.61%), phenol,2,6-dimethoxy(3.84%), 6-octadecenal (2.88%), 2-methyl-Z-4-tetradecene (2.56), 1H-cycloprop[e]azulene, decahydro-1,1,7-trimethyl-4-methylene (2.10%). The disc diameters of inhibition zones, minimum inhibitory concentrations (MIC), and minimum bactericidal concentrations (MBC) of Dichondra repens Forst essential oil for the microoganisms tested are shown in Table 2. The data obtained from the disc-agar diffusion method indicated that Bacillus diphtheriae had the strongest inhibition zone (23 mm), followed by β-hemolytic streptococci (22 mm), Enterococcus faecium (20 mm), and Escherichia coli (20 mm). Klebsiella pneumoniae exhibited a weak inhibition zone (8 mm). The results of MIC indicated the oil inhibited all microorganisms tested. Escherichia coli had the lowest MIC (0.80 μg/mL). The oil was demonstrated to have a strong bactericidal effect. The lowest MBC was 1.50 μL/mL for Escherichia coli. Escherichia coli presented the lowest MIC and MBC values. The strains that presented the biggest inhibition zones (diffusion method) are not always the most sensitive (values of MIC and MBC were lower) because the size of the inhibition zone does not reflect the antibacterial effectiveness of a compound, since it is affected by the solubility of the oil, the diffusion range in the agar, evaporation (it can affect the dose), etc. [9]. Some researchers reported that there is a relationship between the chemical structures of the most abundant compounds in the tested oil and the antimicrobial activity. The essential oils rich in phenolic compounds are widely reported to possess high levels of antimicrobial activity [10–15], which has been confirmed and extended in the present studies. The antimicrobial nature of the essential oil studied is apparently related to its phenolic components. The content of 6-(methylamino)phenanthren3-ol is the highest in the essential oil of Dichondra repens Forst (Table 1). The antimicrobial nature of the essential oil studied is apparently related to the 6-(methylamino)phenanthren-3-ol component.

Essential oil composition and antibacterial activity of Dichondra repens

A method for preparing electrochemical transducer of nanosilver particle includes preparing nanosilver sol-solution by reacting on NaBH4 solution with AgNO3 solution, drip-coating obtained sol-solution on silver plate electrode and forming electrochemical transducer of nanosilver particle by drying said electrode with air.

Li Lin

Papers

Simultaneous determination of five toxic alkaloids in body fluids by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry.

Simultaneous determination of selenium and arsenic contents in different extracts of Radix Astragali by enhancement effect of ethanol in hydride generation-inductively coupled plasma-atomic emission spectrometry

Method for preparing o-dihydroxyflavone-selenium complexes and medical use

Essential oil composition and antibacterial activity of Dichondra repens

Method for preparing electrochemical sensor of Nano silver particle, and application