Analysis of atmospheric particular matter and water using atomic emission spectrometry with inductively-coupled plasma and two-jet plasmatron

Summary A method for the atomic emission spectrometric analysis of air and water with inductively coupled and two-jet direct current plasmas has been developed. The method has been applied to the determination of impurity contents with good accuracy and sensitivity.     

Profiling primaquine metabolites in primary human hepatocytes using UHPLC‐QTOF‐MS with 13C stable isotope labeling

Therapeutic efficiency and hemolytic toxicity of primaquine (PQ), the only drug available for radical cure of relapsing vivax malaria are believed to be mediated by its metabolites. However, identification of these metabolites has remained a major challenge apparently due to low quantities and their reactive nature. Drug candidates labeled with stable isotopes afford convenient tools for tracking drug‐derived metabolites in complex matrices by liquid chromatography‐tandem mass spectrometry (LC‐MS‐MS) and filtering for masses with twin peaks attributable to the label. This study was undertaken to identify metabolites of PQ from an in vitro incubation of a 1:1 w/w mixture of ¹³C₆‐PQ/PQ with primary human hepatocytes. Acquity ultra‐performance LC (UHPLC) was integrated with QTOF‐MS to combine the efficiency of separation with high sensitivity, selectivity of detection and accurate mass determination. UHPLC retention time, twin mass peaks with difference of 6 (originating from ¹³C₆‐PQ/PQ), and MS‐MS fragmentation pattern were used for phenotyping. Besides carboxy‐PQ (cPQ), formed by oxidative deamination of PQ to an aldehyde and subsequent oxidation, several other metabolites were identified: including PQ alcohol, predictably generated by oxidative deamination of PQ to an aldehyde and subsequent reduction, its acetate and the alcohol's glucuronide conjugate. Trace amounts of quinone‐imine metabolites of PQ and cPQ were also detected which may be generated by hydroxylation of the PQ/cPQ quinoline ring at the 5‐position and subsequent oxidation. These findings shed additional light on the human hepatic metabolism of PQ, and the method can be applied for identification of reactive PQ metabolites generated in vivo in preclinical and clinical studies. Copyright © 2013 John Wiley & Sons, Ltd.     

Fluoropropenoates as dienophiles in the Diels-Alder reaction

Several fluorinated alkenes were prepared from known ethyl (R)-2-fluoro-4,5-dihydroxyisopropylidine-2-pentenoate (1). The fluoroalkenoates were tested as dienophiles with several dienes and showed cycloaddition only with the very reactive diene, 1,3-diphenylisobenzofuran (5). Fluorobutenolide 2 reacted with 5 to produce the endo-syn adduct 9 in a highly stereoselective manner.     

Using a two-jet arc plasmatron for determining the trace element composition of powdered biological samples

Weak effects of organic matrix and the chain length of the organic substituent on the analytical line intensities of the elements in the exciting emission spectra in a two-jet arc plasmatron were found. Using animal organs, hair, and plants as examples, it was demonstrated that the plasmatron is promising for determining trace elements in powdered biological samples without sample dissolution.     

Comparison of the Content of Several Elements in Seawater,Sea Cucumber Eupentacta fraudatrix and Its High-Molecular-Mass Multiprotein Complex

Metal ions and other elements play many different critical roles in all biological processes. They can be especially important in high concentrations for the functioning of organisms living in seawater. It is important to understand how much the concentrations of different trace elements in such organisms can be higher than in seawater. Some marine organisms capable of rapid recovery after different injuries are fascinating in this regard. Sea cucumbers Eupentacta fraudatrix can completely restore all organs and the whole body within several weeks after their division into two parts. Here, for the first time, a comparison of the content of different elements in seawater, sea cucumber, and its very stable multiprotein complex (2000 kDa) was performed using two-jet plasma atomic emission spectrometry. Among the 18 elements we found in sea cucumbers, seawater contained only six elements in detectable amounts, and their content decreased in the following order: Mg > Ca > B > Sr ≈ Si > Cr (0.13–930 µg/g of seawater). The content of these elements in sea cucumbers was higher compared with seawater (-fold): Ca (714) > Sr (459) > Cr (75) > Si (42)> B (12) > Mg (6.9). Only four of them had a higher concentration in the protein complex than in seawater (-fold): Si (120.0) > Cr (31.5) > Ca (9.1) > Sr (8.8). The contents of Mg and B were lower in the protein complex than in seawater. The content of elements additionally found in sea cucumbers decreased in the order (µg/g of powder) of P (1100) > Fe (47) > Mn (26) > Ba (15) > Zn (13) > Al (9.3) > Mo (2.8) > Cu (1.4) > Cd (0.3), and in the protein complex, in the order of P (290) > Zn (51) > Fe (23) > Al (14) ≈ Ni (13) > Cu (7.5) > Ba (2.5) ≈ Co (2.0) ≈ Mn (1.6) > Cd (0.7) >Ag (0.2). Thus, sea cucumbers accumulate various elements, including those contained in very low concentrations in seawater. The possible biological roles of these elements are discussed here.     

Determination of trace elements in bone by two-jet plasma atomic emission spectrometry

This paper describes an analytical method for trace element determination in bone tissues. The study of the influence of the bone matrix showed that the addition of 25% ground bone to graphite powder with introduced impurities did not affect the analytical signal of elements in the spectral excitation in a two-jet plasma. On basis of these investigations a method for direct multielement analysis of bone tissues was suggested. The sample preparation procedure consisted in mixing powdered bone (particle size 30 μm or less) with a spectroscopic buffer (graphite powder plus NaCl) in ratio 1:3 or to a greater extent depending on the analyte concentration. Reference samples based on graphite powder were used for construction of calibration curves. The NaCl concentration in analyzed and calibration samples was 15 wt%. The effect of particle size was revealed from the determination of Ba, Sr, and Mg. To eliminate this effect, treatment of the samples with nitric acid was proposed. The validation of the technique was confirmed by comparison of the analysis results of a bone sample with those obtained by inductively coupled plasma atomic emission spectrometry after wet acid digestion. The limits of detection estimated for 20 elements were the following (μg g^-1): 0.1 (Ag), 1.0 (Al), 1.0 (Ba), 0.1 (Be), 1.2 (Bi), 0.4 (Cd), 1.0 (Co), 0.2 (Cu), 0.6 (Cr), 1.9 (In), 2 (Fe), 0.3 (Ga), 0.4 (Mn), 0.4 (Mo), 0.7 (Ni), 1.0 (Pb), 0.7 (Sn), 0.8 (Tl), 5 (Sr), 1.0 (Zn).     

Simultaneous determination of Fe, P, Ca, Mg, Zn, and Cu in whole blood by two-jet plasma atomic emission spectrometry

Availability of many biological samples in ample quantity for biomedical investigations sometimes is very restricted. Therefore, there is the need for the simple techniques allowing the analysis of small amount samples. In the present work the two-jet plasma atomic emission spectrometry techniques for the determination of Fe, P, Ca, Mg, Zn, and Cu in whole blood are proposed. The first technique is developed for direct analysis of freeze-dried blood. The sample preparation consisted in a dilution of blood powder (particle size 20 μm or less) with a spectroscopic buffer (graphite powder containing 15 wt.% NaCl). For the analysis of liquid whole blood, previous carbonization (not ashing) of blood evaporated on graphite powder was applied. Calibration samples based on graphite powder containing 15 wt.% NaCl were used. The validation of the techniques was confirmed by the use of different sample preparation procedures (wet acid digestion and dry carbonization), the analysis of IAEA A-13 reference material (freeze-dried bovine whole blood), and the comparison of the results obtained by the proposed technique with the results of the stripping voltammetry technique. Just 20-50 μL of whole blood is quite enough for all determinations. The proposed techniques were successfully applied for the simultaneous determination of Fe, P, Ca, Mg, Zn, and Cu in whole blood of living experimental rats and mice and human blood.     

Solid sampling in analysis of animal organs by two-jet plasma atomic emission spectrometry

A study of high-power two-jet plasma capabilities for the direct multi-elemental analysis of animal organs was undertaken. The experimental conditions chosen allow the direct analysis of different animal organs after drying and grinding to powder (particle size 20–200 μm). It was found that evaporation efficiency of the samples depends on the particle size and thermal stability of tissues and can be improved by reduction of a carrier gas flow. Calibration samples based on graphite powder and a tenfold dilution of powdered samples with buffer (graphite powder containing 15% NaCl) were used. 5–10 mg of the sample was quite enough to get the detection limits of elements at the level of 0.1–10 μg g^? 1. A prior carbonization procedure (not ashing) makes it possible to decrease the detection limits of elements by an order of magnitude. The validation of the techniques was confirmed by the analysis of certified reference materials NIST 8414, BCR 278R and NCS ZC 81001 as well as by using different sample preparation procedures.     

Determination of Trace Elements in Different Powdered Samples by Atomic Emission Spectrometry with Spectral Excitation in a Two-Jet Arc Plasmatron

The effects of operating parameters and easily ionized additives on the analytical signal in the region before the confluence of plasmatron jets were studied. It was shown that the effective atomic excitation temperature in this region is independent of the concentration of NaCl (0–50%) in the graphite powder. A method was proposed for the direct atomic emission determination of trace elements in powdered samples. In this method, multielement analysis of various samples, such as graphite concentrates of trace impurities, soils, bottom sediments, plants, and humic acids can be performed under unified conditions using a unified set of reference samples without sample mineralization and dissolution. At the stage of sample preparation, a finely divided sample is mixed with a spectroscopic buffer (graphite powder doped with NaCl). The detection limits for several dozen elements in their direct determination varied from 10^–6 to 10^–4 wt % at a relative standard deviation (RSD) of no worse than 15%.