The indirect determination of organic compounds by atomic absorption spectrometry

The feasibility of determining indirectly certain organic compounds by precipitation of insoluble silver compounds and determining the excess silver(I) by atomic absorption spectrometry (AAS) has been demonstrated. The determination of other compounds, such as alkylated barbiturates and mercaptans by similar methodology should be possible. Although direct AAS methods are preferable to indirect methods, the insolubility of many silver salts, the inherent sensitivity of the AAS method for silver, and the speed and convenience of AAS methodology suggests that under certain conditions, an indirect AAS method may be appropriate and the method of choice.     

Multiplexed immunoassay to detect anabolic androgenic steroids in human serum

A multianalyte enzyme-linked immunosorbent assay (ELISA) has been developed for the simultaneous detection of anabolic androgenic steroids (AAS) in human serum. The multiplexed method was developed according to a planar strategy in which the analytes are identified by their location in the microtiter plate. In the immunochemical procedure established here, human serum samples are mixed with a cocktail of antibodies and added to the distinct sections of a microplate biofunctionalized with different haptenized biomolecules. The cocktail of antibodies consists of a mixture of polyclonal antibodies raised against stanozolol (ST), boldenone (B), and tetrahydrogestrinone (THG). The whole immunochemical analytical procedure takes around 2 h including sample preparation, and many samples can be processed simultaneously to screen for the presence of the three AAS in a single run. Using this ELISA, ST, B, and THG can be detected and quantified individually. When used as a screening method, due to the cross-reactivity profiles of the immunoreagents used, the presence of up to 11 AAS can be detected simultaneously. The detectabilities achieved by this method in human serum are below the MRPLs (minimum required performance limits) proposed by WADA (World Anti-Doping Agency) and reference laboratories of the European Community.     

Coupling of ultrasonic nebulization to flame furnace atomic absorption spectrometry—new possibilities for trace element determination

The use of ultrasonic nebulization (USN) with desolvation system for sample introduction in flame atomic absorption spectrometry (F AAS) and flame furnace atomic absorption spectrometry (FF AAS) with a nickel tube is described. Polytetrafluorethylene (PTFE) adaptors were built to replace the pneumatic nebulizer for USN-F AAS measurements. For USN-FF AAS analysis, an alumina injector allowed the direct introduction of the dry aerosol into the nickel tube. The analytical performance of both systems is shown for Ag, Bi, Cd, Cr, Cu, Mn, Pb, Sb, Se, Tl and Zn. The results demonstrate that a sensitivity gain of up to 39 times can be achieved using USN-FF AAS, mainly due to the increase in residence time and to the absence of dilution of the analyte by the flame gases, as the atomization takes place inside the nickel tube. However, elements that require higher atomization temperatures, such as Cr and Mn, are more efficiently determined using USN-F AAS. To evaluate the accuracy of the proposed methods for the determination of trace elements, five certified reference samples were analyzed, and good agreement was, in general, achieved between certified and determined values at a 95% confidence level. The relative standard deviation was frequently below 5%, demonstrating good precision, particularly for USN-FF AAS. In this sense, coupling of USN with F AAS and especially with FF AAS has proved to be simple, safe, with high precision and good accuracy, also maintaining some of the most important features of F AAS, such as the high analytical frequency and the low running cost.     

悬浊液直接进样非火焰原子吸收法测定蔬菜样品中微量铬的研究

本文通过用直接悬浊液进样原子吸收法对新鲜蔬菜中铬的测定,研究了各种实验条件,并建立了实际测定新鲜蔬菜中微量元素的方法。该法将可用于食品。     

活血化瘀中药中无机元素含量测定

采用原子吸收分光光度法测定了丹参、红花草、益母草等活血化瘀中草药中多种无机元素的含量。结果表明,这些中草药中含有多种直接参与组织代谢的微量元素。     

Atomic absorption spectrometry — pregnant again after 45 years

Because atomic absorption spectrometry (AAS) seems to be so simple at first glance, its forthcoming end and replacement by more exciting techniques has been forecasted more than once over the past 45 years. However, AAS has received strong impetus again and again, e.g. by the introduction of the graphite furnace technique, and of flow injection, to mention but a few. Although more and more researchers, and even more instrument manufacturers are turning their back on AAS these days, this author believes that AAS is about to give birth to new offspring in the very near future. The most important ones are solid sampling and speciation analysis on the application side, a much deeper exploitation of the potential of flow injection analysis, the use of diode lasers as radiation sources, and the introduction of continuum-source AAS on the instrumental side. The latter could replace conventional line-source AAS in the foreseeable future because of its obvious advantages in essentially all analytical aspects.     

Atomic absorption spectrometry (AAS) – a versatile and selective detector for trace element speciation

AAS as a highly sensitive and specific single element technique is ideally suited as a detector for speciation analysis. The combinations of chromatographic separation with element specific detectors (flame AAS, electrothermal AAS (ETAAS), hydride generation AAS (HGAAS)) provide powerful approaches to the determination of all species. Sample stabilisation is the area that requires most attention as it still represents the main source of problems encountered in speciation work. The correct speciation depends on how the sample is handled prior to analysis. Unfortunately, no universal procedure has been found. Anything that changes redox conditions, pH or complexation equilibrium is clearly unacceptable.     

Decolorization of vegetable oils: chlorophyll-a adsorption by acid-activated sepiolite

The adsorption characteristics of acid activated sepiolite (AAS) for the removal of chlorophyll-a (C(55)H(72)MgN(4)O(5)) from rapeseed oil was studied as a function of different sepiolite dosages and bleaching temperatures. A correlation has been shown between the adsorption capacity and a combination of AAS amount, bleaching temperature and oxidative reactions of chlorophyll-a. The adsorption equilibrium was found to follow the Langmuir isotherm model with a maximum adsorption capacity of 0.36 mg/g on AAS and K(L) value ranging from 6.11 to 19.51 kg/mg at 80 and 100 degrees C. It was found that AAS is an effective sorbent for the removal of chlorophyll-a molecule which is believed to adsorb as a protonated species onto SiOH groups at the edge in the tetrahedral sheet of sepiolite. These findings reveal that chlorophyll-a molecules not only adsorb onto the external surface of AAS but replace the released Mg(2+) ions in the octahedral sheet; they, depending on the pore size of AAS, are also incorporated in the channels and tunnels of sepiolite. A structural model is proposed to account for the orientation of chlorophyll-a in the sepiolite matrix.     

Mass spectrometric behavior of anabolic androgenic steroids using gas chromatography coupled to atmospheric pressure chemical ionization source. Part I: Ionization

The detection of anabolic androgenic steroids (AAS) is one of the most important topics in doping control analysis. Gas chromatography coupled to (tandem) mass spectrometry (GC–MS(/MS)) with electron ionization and liquid chromatography coupled to tandem mass spectrometry have been traditionally applied for this purpose. However, both approaches still have important limitations, and, therefore, detection of all AAS is currently afforded by the combination of these strategies. Alternative ionization techniques can minimize these drawbacks and help in the implementation of a single method for the detection of AAS. In the present work, a new atmospheric pressure chemical ionization (APCI) source commercialized for gas chromatography coupled to a quadrupole time‐of‐flight analyzer has been tested to evaluate the ionization of 60 model AAS. Underivatized and trimethylsylil (TMS)‐derivatized compounds have been investigated. The use of GC–APCI–MS allowed for the ionization of all AAS assayed irrespective of their structure. The presence of water in the source as modifier promoted the formation of protonated molecules ([M+H]⁺), becoming the base peak of the spectrum for the majority of studied compounds. Under these conditions, [M+H]⁺, [M+H‐H₂O]⁺ and [M+H‐2·H₂O]⁺ for underivatized AAS and [M+H]⁺, [M+H‐TMSOH]⁺ and [M+H‐2·TMSOH]⁺ for TMS‐derivatized AAS were observed as main ions in the spectra. The formed ions preserve the intact steroid skeleton, and, therefore, they might be used as specific precursors in MS/MS‐based methods. Additionally, a relationship between the relative abundance of these ions and the AAS structure has been established. This relationship might be useful in the structural elucidation of unknown metabolites. Copyright © 2014 John Wiley & Sons, Ltd.     

Determination of Cadmium,Copper, Lead,and Zinc in Pilchard Sardines from the Bay of Boumerdés by Atomic Absorption Spectrometry

Fish are an important human food with increasing consumption in recent decades. Diet is the main route of exposure to heavy metals for human health. For this reason, many studies have been performed on the pollution by heavy metals in different species of fish. Our main objective was to evaluate the pollution by trace metals (Zn, Cu, Pb, and Cd) in sardine muscles collected from the bay of Boumerdés (Algeria). Flame atomic absorption spectroscopy (AAS) was used for the quantification of Cu and Zn. The quantification of Cd and Pb was achieved by graphite furnace (GF) AAS. The analysis revealed the presence of metal trace elements in the muscles of species at concentrations below the thresholds established by national and international regulations.     

树脂法分离纯化米洛培南

采用国产AAS大孔吸附树脂及D－280大孔脱色树脂对抗生素米洛培南制备母液进行分离纯化。实验表明，与日本Diaion公司生产的Diaion CHP20相比，AAS大孔吸附树脂对米洛培南具有更优良的吸附性能，使用D－280大孔脱色树脂对抗生素米洛培南制备母液进行脱色，未发现类似报道，分析结果证实，以上述方法制备的抗生素米洛培南收率高，纯度高，各项分析数据与文献报道相符。     

Analytical procedure for the determination of thorium, zinc and potassium in diet samples

Instrumental neutron activation analysis (INAA), and atomic absorption spectrometry (AAS) have been used for the determination of trace amounts of thorium, zinc, and potassium in diet samples. Interlaboratory comparison has been made. The z-scores show that INAA can be used to determine thorium and zinc whereas AAS can be employed to determine potassium in diet samples.     

Investigation of artifacts caused by deuterium background correction in the determination of phosphorus by electrothermal atomization using high-resolution continuum source atomic absorption spectrometry

The artifacts created in the measurement of phosphorus at the 213.6-nm non-resonance line by electrothermal atomic absorption spectrometry using line source atomic absorption spectrometry (LS AAS) and deuterium lamp background correction (D₂ BC) have been investigated using high-resolution continuum source atomic absorption spectrometry (HR-CS AAS). The absorbance signals and the analytical curves obtained by LS AAS without and with D₂ BC, and with HR-CS AAS without and with automatic correction for continuous background absorption, and also with least-squares background correction for molecular absorption with rotational fine structure were compared. The molecular absorption due to the suboxide PO that exhibits pronounced fine structure could not be corrected by the D₂ BC system, causing significant overcorrection. Among the investigated chemical modifiers, NaF, La, Pd and Pd + Ca, the Pd modifier resulted in the best agreement of the results obtained with LS AAS and HR-CS AAS. However, a 15% to 100% higher sensitivity, expressed as slope of the analytical curve, was obtained for LS AAS compared to HR-CS AAS, depending on the modifier. Although no final proof could be found, the most likely explanation is that this artifact is caused by a yet unidentified phosphorus species that causes a spectrally continuous absorption, which is corrected without problems by HR-CS AAS, but which is not recognized and corrected by the D₂ BC system of LS AAS.     

电热蒸发进样微波诱导等离子体原子吸收光谱法测定银和镉的研究

研究了以常压低功率氩微波诱导等离子体（ＭＩＰ）为原子化器的原子吸收光谱法（ＡＡＳ）测定银和镉。采用电热蒸发（ＥＴＶ）,浓Ｈ２ＳＯ４吸收去溶的进样方法。考察了微波前向功率,载气流量,去溶电压,去溶时间,蒸发电压,酸度对银,镉测定的影响。方法已用于试样分析。     

Applications of Transition‐Metal‐Catalyzed Asymmetric Allylic Substitution in Total Synthesis of Natural Products: An Update

Metal‐catalyzed asymmetric allylic substitution (AAS) reaction is one of the most synthetically useful reactions catalyzed by metal complexes for the formation of carbon‐carbon and carbon‐heteroatom bonds. It comprises the substitution of allylic substrates with a wide range of nucleophiles or S_N2′‐type allylic substitution, which results in the formation of the above‐mentioned bonds with high levels of enantioselective induction. AAS reaction tolerates a broad range of functional groups, thus has been successfully applied in the asymmetric synthesis of a wide range of optically pure compounds. This reaction has been extensively used in the total synthesis of several complex molecules, especially natural products. In this review, we try to highlight the applications of metal (Pd, Ir, Mo, or Cu)‐catalyzed AAS reaction in the total synthesis of the biologically active natural products, as a key step, updating the subject from 2003 till date.     

Feasibility of a liquid-phase microextraction sample clean-up and liquid chromatographic/mass spectrometric screening method for selected anabolic steroid glucuronides in biological samples

Anabolic androgenic steroids (AAS) are metabolized extensively in the human body, resulting mainly in the formation of glucuronide conjugates. Current detection methods for AAS are based on gas chromatographic/mass spectrometric (GC/MS) analysis of the hydrolyzed steroid aglycones. These analyses require laborious sample preparation steps and are therefore time consuming. Our interest was to develop a rapid and straightforward method for intact steroid glucuronides in biological samples, using liquid-phase microextraction (LPME) sample clean-up and concentration method combined with liquid chromatographic/tandem mass spectrometric (LC/MS/MS) analysis. The applicability of LPME was optimized for 13 steroid glucuronides, and compared with conventional liquid-liquid extraction (LLE) and solid-phase extraction (SPE) procedures. An LC/MS/MS method was developed for the quantitative detection of AAS glucuronides, using a deuterium-labeled steroid glucuronide as the internal standard. LPME, owing to its high specificity, was shown to be better suited than conventional LLE and SPE for the clean-up of urinary AAS glucuronides. The LPME/LC/MS/MS method was fast and reliable, offering acceptable reproducibility and linearity with detection limits in the range 2-20 ng ml(-1) for most of the selected AAS glucuronides. The method was successfully applied to in vitro metabolic studies, and also tested with an authentic forensic urine sample. For a urine matrix the method still has some unsolved problems with specificity, which should be overcome before the method can be reliably used for doping analysis, but still offering additional and complementary data for current GC/MS analyses.     

High-resolution continuum source electrothermal atomic absorption spectrometry — An analytical and diagnostic tool for trace analysis

The literature about applications of high-resolution continuum source atomic absorption spectrometry (HR-CS AAS) with electrothermal atomization is reviewed. The historic development of HR-CS AAS is briefly summarized and the main advantages of this technique, mainly the ‘visibility’ of the spectral environment around the analytical line at high resolution and the unequaled simultaneous background correction are discussed. Simultaneous multielement CS AAS has been realized only in a very limited number of cases. The direct analysis of solid samples appears to have gained a lot from the special features of HR-CS AAS, and the examples from the literature suggest that calibration can be carried out against aqueous standards. Low-temperature losses of nickel and vanadyl porphyrins could be detected and avoided in the analysis of crude oil due to the superior background correction system. The visibility of the spectral environment around the analytical line revealed that the absorbance signal measured for phosphorus at the 213.6 nm non-resonance line without a modifier is mostly due to the PO molecule, and not to atomic phosphorus. The future possibility to apply high-resolution continuum source molecular absorption for the determination of non-metals is discussed.     

High reliability atomic absorption spectrometry of major and minor elements in biological materials

Summary Reliable analytical information is of fundamental importance for decisions of far-reaching impact in many regulatory, medical and scientific areas and disciplines. It is however at times elusive. Although the technique of atomic absorption spectrometry (AAS) as become widely established in analytical laboratories throughout the world for the determination of inorganic elements, only few AAS-based methods have reached official status and even fewer have attained reference method status. Research is underway to delineate impacts of a number of parameters on method performance to lead to protocols for standard and reference flame AAS (FAAS) methods for the reliable measurement of major and minor levels of elements of nutritional and toxicological pertinence in clinical and biological materials. Factors investigated include preparation of standards, calibration techniques, sampling and sample decomposition, solution preparation, instrumental parameters, and measurement protocols. Examples of some pronounced effects of sample decomposition and calibration techniques are presented as well as indications of the excellent performance of well-applied AAS procedures determined by use of standard reference materials and comparison with other techniques of analysis. Reference will be made to the determination of the major and minor nutrient elements Na, K, Mg, Ca, Mn, Fe, Cu and Zn in plant biological reference materials.Formerly at Plant Research Centre, Agriculture Canada, Ottawa, Ontario K1A OC6, CanadaContribution No. 1030 from Plant Research Centre