Characterization by gas chromatography-mass spectrometry of diterpenoid resinous materials in Roman-age amphorae from northern Greece.

A combined gas chromatography-mass spectrometry approach has been used for the characterization of two lumps of resin and 17 adsorbed residues on Roman-age vessels, mainly amphorae, from northern Greece. The data show that a diterpenic resin from plants of the Pinacae family is the main component of the tarry material associated with the analyzed archaeological samples. The identification and mass spectrometric fragmentation of several characteristic diterpenoid biomarkers is discussed.

Development of a sequential injection system for trace mercury determination by cold vapour atomic absorption spectrometry utilizing an integrated gas-liquid separator/reactor.

A simple and robust time-based on-line sequential injection system for trace mercury determination via cold vapour atomic absorption spectrometry (CVAAS), employing a new integrated gas-liquid separator (GLS), which in parallel operates as reactor, was developed. Sample and reductant are sequentially loaded into the GLS while an argon flow delivers the released mercury vapour through the atomic absorption cell. The proposed method is characterized by the ability of successfully managing variable sample volume up to 30ml in order to achieve high sensitivity.

On-line liquid-liquid extraction system using a new phase separator for flame atomic absorption spectrometric determination of ultra-trace cadmium in natural waters.

A robust flow injection (FI) on-line liquid-liquid extraction (LLE) preconcentration/separation system associated with a newly designed gravitational phase separator, coupled to flame atomic absorption spectrometry (FAAS) was developed. The performance of the system was illustrated for cadmium determination at the mugl(-1) level. The non-charged cadmium complex with ammonium pyrrolidine dithiocarbamate (APDC) was extracted on-line into isobutyl methyl ketone (IBMK).

Gallium trace on-line preconcentration/separation and determination using a polyurethane foam mini-column and flame atomic absorption spectrometry. Application in aluminum alloys, natural waters and urine.

A sensitive and selective flow injection time-based method for on-line preconcentration/separation and determination of gallium by flame atomic absorption spectrometry at trace levels was developed. The on-line formed gallium chloride complex is sorbed onto a polyether-type polyurethane foam mini-column, followed by on-line quantitative elution with isobutyl methyl ketone and direct introduction into the flame pneumatic nebulizer of the atomic absorption spectrometer. All chemical and flow variables of the system as well as the possible interferences were studied.

On-line preconcentration and determination of copper, lead and chromium(VI) using unloaded polyurethane foam packed column by flame atomic absorption spectrometry in natural waters and biological samples.

A simple, sensitive and low cost, flow injection time-based method was developed for on-line preconcentration and determination of copper, lead and chromium(VI) at sub mug l(-1) levels in natural waters and biological samples. At the optimum pH, the on-line formed metal-ammonium pyrrolidine dithiocarbamate (APDC) complexes were sorbed on the unloaded commercial polyurethane foam (PUF), and subsequent eluted quantitatively by isobutylmethylketone and determined by flame atomic absorption spectrometry (FAAS). All chemical, and flow injection variables were optimized for the quantitative preconcentration of each metal and a study of interference level of various ions was also carried out.

Determination of lead by on-line solid phase extraction using a PTFE micro-column and flame atomic absorption spectrometry.

A rapid and sensitive time-based flow injection (FI) method for on-line preconcentration and determination of lead by flame atomic absorption spectrometry (FAAS), using polytetrafluoroethylene (PTFE) turnings as packing material in a micro-column, has been developed. The sample was mixed on-line with ammonium pyrrolidine dithiocarbamate (APDC) and the non-charged Pb(II)-PDC complex was absorbed quantitatively on the hydrophobic PTFE material, at a pH range 1.4-3.

Flame atomic absorption spectrometric determination of chromium(VI) by on-line preconcentration system using a PTFE packed column.

A new, sensitive and robust time-based flow injection (FI) method for on-line preconcentration and determination of ultra trace amounts of chromium(VI) by flame atomic absorption spectrometry (FAAS) has been elaborated. The sample is initially mixed on-line with ammonium pyrrolidine dithiocarbamate (APDC) and the Cr(VI)-PDC chelate is absorbed quantitatively on a mini-column packed with polytetrafluoroethylene (PTFE) turnings at a pH range 0.8-1.

Use of fractional factorial design for optimization of digestion procedures followed by multi-element determination of essential and non-essential elements in nuts using ICP-OES technique.

Two digestion procedures have been tested on nut samples for application in the determination of essential (Cr, Cu, Fe, Mg, Mn, Zn) and non-essential (Al, Ba, Cd, Pb) elements by inductively coupled plasma-optical emission spectrometry (ICP-OES). These included wet digestions with HNO(3)/H(2)SO(4) and HNO(3)/H(2)SO(4)/H(2)O(2). The later one is recommended for better analytes recoveries (relative error<11%).

Development and validation of routine analysis methods for the determination of essential, nonessential, and toxic minor and trace elements in cereal and cereal flour samples by inductively coupled plasma-atomic emission spectrometry.

Various digestion procedures were carefully investigated and accurately evaluated with respect to their effect on the analysis of cereals and cereal flours. Multielement methods were selected and well developed for the determination of essential (Cr, Cu, Fe, Mg, Mn, and Zn), nonessential (Ag, Al, Ba, Bi, In, and Ga), and toxic (Cd and Pb) minor and trace elements by inductively coupled plasma-atomic emission spectrometry. Only Ag could be determined, either with aqueous standard or standard addition calibration methods, while the standard addition methods were more accurate for the determination of other elements.

Time-based on-line preconcentration cold vapour generation procedure for ultra-trace mercury determination with inductively coupled plasma atomic emission spectrometry.

A time-based sequential dispensing on-line column preconcentration procedure for mercury determination at trace levels by cold vapour generation inductively coupled plasma atomic emission spectrometry (CV-ICP-AES), by means of a unified module of a preconcentration column and a gas-liquid separator (PCGLS) is described. The complex of mercury formed on-line with ammonium pyrrolidine dithiocarbamate (APDC) is retained on the surface of the hydrophobic poly(tetrafluoroethylene) (PTFE) turnings, which are packed into the lower compartment of the PCGLS. Subsequently, mercury vapour is generated directly on the PTFE turnings by reductant SnCl(2) and separated from the liquid mixture via the PCGLS by argon purge gas.

Determination of mineral content of active dry yeast used in pharmaceutical formulations.

The efficiency of seven common methods of digestion of active dry yeast (ADY), which is used in anticariogenic dental formulations, was evaluated for the analytical determination of Fe, Zn, Ca, Mg, Na and K. Four wet-acid digestion and three dry ashing methods are compared in consideration of their estimated reproducibility and metal concentrations obtained. HNO(3), HNO(3)+HCl, HNO(3)+H(2)SO(4) and HNO(3)+HClO(4) were applied for wet digestion of the samples in medium temperatures, while dry ashing at higher temperature with Mg(NO(3))(2) or SrCl(2) as ashing aid agents, were the alternative methods.