John A. Stratis

Assessment of the surface water quality in Northern Greece

The application of different multivariate statistical approaches for the interpretation of a large and complex data matrix obtained during a monitoring program of surface waters in Northern Greece is presented in this study. The dataset consists of analytical results from a 3-yr survey conducted in the major river systems (Aliakmon, Axios, Gallikos, Loudias and Strymon) as well as streams, tributaries and ditches. Twenty-seven parameters have been monitored on 25 key sampling sites on monthly basis (total of 22,350 observations). The dataset was treated using cluster analysis (CA), principal component analysis and multiple regression analysis on principal components. CA showed four different groups of similarity between the sampling sites reflecting the different physicochemical characteristics and pollution levels of the studied water systems. Six latent factors were identified as responsible for the data structure explaining 90% of the total variance of the dataset and are conditionally named organic, nutrient, physicochemical, weathering, soil-leaching and toxic-anthropogenic factors. A multivariate receptor model was also applied for source apportionment estimating the contribution of identified sources to the concentration of the physicochemical parameters. This study presents the necessity and usefulness of multivariate statistical assessment of large and complex databases in order to get better information about the quality of surface water, the design of sampling and analytical protocols and the effective pollution control/management of the surface waters.

Direct determination of toxic trace metals in honey and sugars using inductively coupled plasma atomic emission spectrometry

A rapid method for the determination of Pb, Cd, Cu, Cr, Co, Ni, Mn and Zn in honey and sugars without prior digestion or ashing of the sample was developed, using inductively coupled plasma atomic emission spectrometry (ICP-AES). The critical instrumental parameters such as sample flow rate and radio frequency incident power were thoroughly optimized. The effect of matrix type and its concentration was also examined for glucose/fructose, sucrose and honey matrices. The sensitivity was investigated using calibration curves obtained in presence of the above matrices. The obtained recoveries for Cd, Cu, Cr, Co, Ni and Mn at the mugl(-1) level were satisfactory and practically independent of the matrix used for the calibration standards. The recoveries of Pb and Zn were less sufficient. Various commercial samples of honey, sugar, glucose and fructose were analyzed with respect to their toxic metal content. The method can be applied for routine analysis, quality and environmental pollution control purposes at the mugl(-1) level of concentration, after suitable dilution of the samples.

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. The system offered improved flexibility, low backpressure and applicability to all the studied metals. At a sample frequency of 36 h(-1) and a 60 s preconcentration time, the enhancement factor was 170, 131 and 28, the detection limit was 0.2, 1.8 and 2.0 mug l(-1), and the precision, expressed as relative standard deviation (s(r)), was 2.8 (at 10 mug l(-1)), 3.4 (at 50 mug l(-1)) and 3.6% (at 50 mug l(-1)) for Cu(II), Pb(II) and Cr(VI), respectively. The accuracy of the developed method was sufficient and evaluated by the analysis of certified reference materials and spiked water samples. Finally, the method was applied to the analysis of environmental samples.

A study of air pollution with heavy metals in Thessaloniki city (Greece) using trees as biological indicators

The air pollution of the city of Thessaloniki was studied, using park trees as biomonitors. The species analyzed were Ligustrum japonicum, Nerium oleander, Olea europea, Pinus brutia, Platanus orientalis, Populus alba, Populus nigra, and Robinia pseudoacacia. Acid digestion of leaf tissues and subsequent use of atomic absorption spectrometry was the analytical methodology used for the determination of heavy metals (Cu, Zn, and Pb). The concentration of heavy metals in the tree leaves depended on the metal species as well as on the position of the tree in the city. The mean concentrations of Cu ranged between 5 and 10 mg kg−1 dry weight, of Zn between 19 and 85 mg kg−1 DW and of Pb between <1.5 and 4.5 mg kg−1 DW. In some cases, the effect of road junctions proved more significant than the traffic load for the contamination of leaves. Some differentiation was also observed between tree species. Old leaves collected during the fall were more contaminated than young leaves collected during the spring. The roughness of the outer surface leaves contributed to the trapping and retention of air particles. The results were compared with corresponding results from lichens and mosses which were also collected for a similar study.

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). The organic phase was effectively separated from a large volume of aqueous phase and is led into a 100mul loop of an injection valve before its introduction into the nebulizer. The system was optimized and offered good performance characteristics with unlimited life time of phase separator, greater flow rate ratios and improved flexibility, as compared with other solvent extraction preconcentration systems. With a sampling frequency of 33h(-1), the enhancement factor was 155, the detection limit was 0.02mugl(-1), the relative standard deviation was 3.2% at 2.0mugl(-1) Cd concentration level and the calibration curve was linear over the concentration range 0.06-6.0mugl(-1). The accuracy of the proposed method was evaluated by analyzing a certified reference material of water and by recovery measurements on spiked samples. Finally, it was successfully applied to the analysis of tapwater, river and seawater samples.

On-line solid phase extraction system using PTFE packed column for the flame atomic absorption spectrometric determination of copper in water samples

A new flow injection on-line adsorption preconcentration system adapted to flame atomic absorption spectrometry (FAAS) for copper determination at the mug l(-1) level was developed. Polytetrafluoroethylene (PTFE) turnings packed in a mini-column were used as sorbent material. The copper ammonium pyrrolidine dithiocarbamate (APDC) complex was sorbed on the PTFE turnings, from which it could be eluted on-line instantly by isobutyl methyl ketone (IBMK) into the flame at a flow rate of 2.3 ml min(-1). The system was optimized and offered good performance characteristics with practically unlimited life time, greater flow rates and improved flexibility, as compared with other sorbent materials and the knotted reactor preconcentration systems. With 1 min preconcentration time, and a sample frequency of 40 h(-1), the enhancement factor was 340, which could be further improved by increasing the preconcentration time. The detection limit was c(L)=0.05 mug l(-1), and the precision was 1.5%, at the 2.0 mug l(-1) Cu level. The method has been applied successfully to the analysis of potable, river and seawater, and its accuracy was tested by the analysis of certified reference materials and by recovery measurements on spiked samples. No significant interferences exist from other substances usually occurring in natural water.

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 0.8-1.4. The complex is subsequently eluted with isobutyl methyl ketone (IBMK) and introduced directly into the nebulizer-burner system. The optimized system offered improved performance characteristics, with unlimited lifetime of the proposed column. The enhancement factor was 80, for a 3-min preconcentration time and the sample frequency was 18 h(-1). The calibration curve was linear over the concentration range 1-40 mug l(-1) with a detection limit of c(L)=0.8 mug l(-1) and a relative standard deviation of s(r)=3.2%, at the 20 mug l(-1) level. The proposed method was evaluated by analyzing samples of certified and spiked water, and it was applied to the analysis of natural water samples and sediments.

Electrothermal atomic absorption spectrometric determination of aluminium, cadmium, chromium, copper, iron, manganese, nickel and lead in olive oil

A simple and fast procedure for the direct ETAAS determination of Al, Cd, Cr, Cu, Fe, Mn, Ni and Pb in olive oil is proposed.N,N-Hexamethylenedithiocarbamic acid, hexamethyleneammonium salt (HMDC-HMA), was used as a universal modifier with two functions: isoformation of the chemical species of the investigated elements, present in olive oil and their thermal stabilisation during the pre-treatment step. Various organic solvents were studied and 1,4-dioxane was found to be the most suitable solvent for oil dilution prior to ETAAS analysis. 1,4-Dioxane improves the decomposition of triglycerides during the pre-treatment step and permits aqueous standard solutions to be used for calibration. Uncoated graphite tubes with platforms are proposed as atomisers for the ETAAS determination of Cd, Cu, Fe, Mn and Fe, and pyrolytic graphite coated graphite tubes with grooves are the most suitable atomisers for Al, Cr and Ni. Instrumental parameters optimised according to pre-treatment and atomisation curves, obtained in the presence of the olive oil matrix and with HMDC-HMA as modifier, are presented. The proposed method permits the determination of 0.1 µg g–1 Fe, 0.05 µg g–1 Ni, 0.02 µg g–1 Al, Cu, Cr and Pb, and 0.01 µg g–1 Cd and Mn with relative standard deviations of about 8–10% for all analytes in this concentration range.

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 1.4-3.2. The preconcentrated complex was effectively eluted with isobutyl methyl ketone (IBMK) and introduced into the nebulizer-burner system. A nested coil (NC) is proposed for parking the eluate temporarily, in order to enable different elution and nebulization flow rates. With 180 s preconcentration time the sample frequency was 15 h(-1), and the enhancement factor was 330 at 13.0 ml min(-1) sample flow rate. The detection limit was c(L)=0.8 mug l(-1), the relative standard deviation (R.S.D.) 2.6% at the 30 mug l(-1) level and the calibration curve was linear over the concentration range 1.6-100 mug l(-1). The proposed method was evaluated by analyzing certified reference materials of water, sediments and fish tissue. Finally, it was applied successfully to the analysis of various environmental samples.

Development and optimisation of a portable micro-XRF method for in situ multi-element analysis of ancient ceramics

Non-destructive analysis of cultural objects by micro-XRF spectrometry is an advantageous multi-element technique that has rapidly developed during the past few years. Portable instruments contribute significantly to the in situ analysis of valuable cultural objects, which cannot be transported to the laboratory. Ancient ceramics are the most common archaeological findings and they carry a significant historical content. Their analysis often presents certain particularities due to surface irregularities and heterogeneity problems. In the present work, the analytical characteristics (beam spot size, geometry effect and detection limits) of a compact and portable micro-XRF instrument with a monocapillary lens are presented in details. The standard reference materials SARM 69, SRM 620, NCS DC 73332 and the reference materials AWI-1 and PRI-1 were analysed for the determination of the detection limits (DLs) and the evaluation of the accuracy of the micro-XRF. Emphasis is given on the critical parameters, which should be monitored during measurements and influence the final results in the analysis of ancient ceramics. A quantitative analysis of ancient ceramic samples from Abdera (North Greece) is also presented.