Migration levels of PVC plasticisers: Effect of ionising radiation treatment.

Migration levels of commercial plasticisers [di-(2-ethylhexyl) adipate (DEHA) and acetyl tributyl citrate (ATBC)] from polyvinyl chloride (PVC) film into the EU specified aqueous food simulants (distilled water, 3% w/v acetic acid and 10% v/v ethanol) were monitored as a function of time. Migration testing was carried out at 40°C for 10days (EEC, 1993). Determination of the analytes was performed by applying the analytical methodology based on surfactant (Triton X-114) mediated extraction prior to gas chromatographic-flame ionisation detection (GC-FID) recently proposed by our group. The study focuses on the determination of the effect of gamma radiation on plasticiser migration into the selected simulants. PVC cling film used was subjected to ionising treatment with a [(60)Co] source at doses equal to 5, 15 and 25kGy. DEHA and ATBC migration into the EU aqueous simulating solvents was limited, yielding final concentrations in the respective ranges 10-100µg/l and 171-422µg/l; hence, ATBC demonstrated a stronger interaction with all three simulants compared to DEHA. Migration data, with respect to ATBC, showed that the most aggressive simulant seemed to be the 10% ethanol, while in the case of DEHA the 3% aqueous acetic acid exhibited the highest extraction efficiency; distilled water demonstrated the lowest migration in both cases. With regard to PVC treatment with gamma rays, high radiation doses up to 25kGy produced a statistically significant (p<0.05) effect on the migration of both plasticisers.

Determination of okadaic acid, dinophysistoxin-1 and related esters in Greek mussels using HPLC with fluorometric detection, LC-MS/MS and mouse bioassay.

An approach involving both chemical and biological methods was undertaken for the detection and quantification of the marine toxins okadaic acid (OA), dinophysistoxin-1 (DTX-1) and their respective esters in mussels from different sampling sites in Greece during the period 2006-2007. Samples were analyzed by means of a) high performance liquid chromatography with fluorometric detection (HPLC-FLD), using 9-athryldiazomethane (ADAM), as a pre-column derivatization reagent, b) liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and c) the mouse bioassay. Free OA and DTX-1 were determined by both HPLC-FLD and LC-MS/MS, while their respective esters were determined only by LC-MS/MS after alkaline hydrolysis of the samples. The detection limit (L.O.D.) and quantification limit (L.O.Q.) of the HPLC-FLD method were 0.015 microg/g HP and 0.050 microg/g HP, respectively, for OA. The detection limit (L.O.D.) and quantification limit (L.O.Q.) of the LC-MS/MS method were 0.045 microg/g HP and 0.135 microg/g HP, respectively, for OA. Comparison of results between the two analytical methods showed excellent agreement (100%), while both HPLC-FLD and LC-MS/MS methods showed an agreement of 97.1% compared to the mouse bioassay.

Formation of biogenic amines and relation to microbial flora and sensory changes in smoked turkey breast fillets stored under various packaging conditions at 4 degrees C.

The present study evaluated: (1) the formation of biogenic amines (BAs) in smoked turkey fillets during storage under aerobic and modified atmosphere packaging (MAP) conditions at 4 degrees C, (2) the relation of BAs to microbial and sensory changes in turkey meat and (3) the possible role of BAs as indicators of poultry meat spoilage. Smoked sliced turkey fillets were stored in air and under vacuum, skin and two modified atmospheres (MAP), M1 (30% CO(2)/70% N(2)) and M2 (50% CO(2)/50% N(2)), at 4+/-0.5 degrees C, for a period of 30 days. The BAs determined were: tryptamine, tyramine, histamine, putrescine, cadaverine, spermidine and spermine. Low levels of BAs were observed throughout the entire storage period, with the exception of histamine, tyramine and tryptamine, for which higher concentrations were recorded. Values for these three BAs were the highest for air-packaged samples (32.9, 25.0 and 4.1mg/kg, respectively) and the lowest for skin-packaged samples (11.9, 4.3 and 2.8 mg/kg, respectively) after 30 days of storage. All microorganism populations increased throughout the storage period, except for Pseudomonas spp. and Enterobacteriaceae, in skin-packaged fillets and modified atmosphere M2, which remained under the method detection limit (<1logCFU/g) until day 30 of storage. Pseudomonas spp. and Enterobacteriaceae for the rest of the packaging treatments remained below 5logCFU/g throughout storage. On the other hand, lactic acid bacteria were dominant throughout the storage period, regardless of the packaging conditions reaching 8.9logCFU/g on day 30 of storage. Mesophiles reached 7logCFU/g after ca. 19-20 days for the air and skin packed samples, 22-23 days for the M2 and vacuum packed samples and 25-26 days for the M1 packed samples. BA values for tryptamine, histamine and tyramine correlated well with both microbiological and sensory analyses data. Tryptamine, histamine and tyramine may be used as chemical indicators of turkey meat spoilage.

Relation of biogenic amines' formation with microbiological and sensory attributes in Lactobacillus-inoculated vacuum-packed rainbow trout (Oncorhynchus mykiss) fillets.

The biogenic amine (BA) content of vacuum-packed filleted rainbow trout (Oncorhynchus mykiss) inoculated or not with two different Lactobacillus strains, individually or in combination, was monitored during refrigerated storage for 20 days and related to respective bacteriological and sensory changes occurring during the same period. Eight amines, namely putrescine, cadaverine, tyramine, tryptamine, beta-phenylethylamine, histamine, spermine, and spermidine, were determined, whereas agmatine was not detected in any of the samples. In all cases, BA concentration was higher (P < or = 0.05) in the controls compared to all inoculated treatments, whereas the trend with regard to the bacterial populations (Enterobacteriaceae, pseudomonads, and H2S-producing bacteria) and the off-odor scores was similar. Inoculation with Lactobacillus sakei CECT 4808 showed the best preservative effect among inoculated treatments. Concentrations of putrescine and cadaverine, the main BAs formed, correlated well with both spoilage bacterial counts and off-odor scores and can be useful indicators of shelf life. Spermine and spermidine contents decreased during storage, while levels of the other determined BAs remained below 10 mg/kg even after sensory rejection.

Determination of diethylhexyladipate and acetyltributylcitrate in aqueous extracts after cloud point extraction coupled with microwave assisted back extraction and gas chromatographic separation.

The determination of commercial plasticizers (di-(2-ethylhexyl)adipate (DEHA) and acetyl tributyl citrate (ATBC)) in aqueous solutions is described. The newly proposed technique of applying microwaves to cloud point extracts in order to enable combination with gas chromatographic analysis has been used for this purpose. Both plasticizers were entrapped in the micelles of the non-ionic surfactant Triton X-114 and removed from the bulk phase by centrifugation. Micellization was enhanced by increasing the ionic strength of the solution with concentrated NaCl. Extraction recoveries of the proposed method were over 95% for water and 3% (w/v) aqueous acetic acid and over 85% for 10% (v/v) aqueous ethanol, respectively. The calibration curves obtained, following the proposed methodology have a linear range between 50 and 2000 microg/L for each analyte while the detection limits were as low as 15 and 19 microg/L for DEHA and ATBC, respectively, with an RSD below 5% even for low concentrations. As an analytical demonstration the proposed methodology was applied for the determination of the migration levels of the selected plasticizers from a PVC food packaging film into aqueous simulants.

Cloud point extraction coupled with microwave or ultrasonic assisted back extraction as a preconcentration step prior to gas chromatography.

Cloud point extraction of nonionic and anionic surfactants was applied as a preconcentration step prior to gas chromatography. No cleanup step preceded chromatographic analysis. The obtained surfactant-rich phase was treated with water-immiscible solvents, and the target analytes were back extracted by short-term microwave application or ultrasonication. A mixture of six PAHs (naphthalene, acenaphthene, fluorene, anthracene, fluoranthene, pyrene) was used as test compounds. The obtained detection limits were in the microgram per liter area. Recoveries of spiked water and soil samples ranged between 92 and 105% while analysis of certified reference materials gave results in good agreement with the certified values. Under the optimum experimental conditions, there was no interference or blocking of the column. According to our results, this approach presents a convenient solution to the up-to-date problem of combining gas chromatography with micellar cloud point extraction.

Cationic surfactant-based polyfluorate salts: phase separation and analytical applications in the extraction and preconcentration of ionic species prior to liquid chromatography.

The liquid-solid phase separation originating from the formation of cationic surfactant-based polyfluorate salts (CSBPS) has been explored for extracting and preconcentrating ionic species. Two cationic surfactants were tested; one with aliphatic hydrocarbon tail [Cetyltrimethylammonium bromide (CTAB)]and the other containing a heterocyclic ring [Hexadecylpyridinium bromide (HPyBr)]. Phase separation possibility was investigated with the use of hexafluorophosphates (PF6-) and tetrafluoroborates (BF4-). The effect of added acid, base and salt on the phase separation and analyte extraction was also investigated. In all cases the obtained phase diagrams consisted of two regions: a homogeneous liquid region and a solid-liquid region. Analytes of hydrophilic and hydrophobic nature such as amines, amino acids and organic chromophores were used as test compounds in both their anionic and cationic forms. The respective recoveries ranged from over 90% for anionic species and in the proximity of 50% for cationic species, remaining below 20% for neutral species. Extracts from alkaline aqueous and plasma samples spiked with tyrosine and phenylalanine were also subjected to HPLC separation with UV detection with satisfactory results. On line application was also enabled using a flow through-solid phase extraction-HPLC hyphenated apparatus, thus adding the element of automatization and increased reproducibility.

The use of surfactant-based separation techniques for monitoring of orthophosphate in natural waters and wastewater.

In an effort to monitor orthophosphate in natural waters and wastewater in the Ipirous region (Greece), an analytical methodology was established owing to the need for interference-free determination at the low mg/l levels. The method applied for the determination of orthophosphate is based on its reaction with molybdate towards a yellow heteropoly acid complex, which is electrically balanced with a cationic surfactant (cetylatrimethylammonium bromide) towards a complex non-polar derivative. This derivative is conveniently solubilized in the micelles of a non-ionic surfactant under mild conditions and measured spectrophotometrically at 370 nm after its uptake with a sulfuric acid-methanol solution. By simply preconcentrating 10 ml of sample volume a detection limit of 2.6 microM was obtained. Due to the required dilution step and signal enhancement caused by the presence of surfactant, interference from the presence of anionic species (mostly silicate and arsenate) was minor and could be conveniently alleviated by the use of tartaric acid and Na(2)SO(3), respectively. The method was successfully applied to real samples obtained for the natural sites subject to the monitoring survey ranging in their matrix complexity from clean river water to wastewater.

Copper fractionation with dissolved organic matter in natural waters and wastewater--a mixed micelle mediated methodology (cloud point extraction) employing flame atomic absorption spectrometry.

A cloud point extraction-preconcentration methodology for the speciation analysis of free and organically complexed metal species in natural waters is presented. The method is based on the neutralization of the electrostatic charge of the humate-metal complexes with a positively charged surfactant in a high ionic strength solution environment. The resulting complexes are conveniently solubilized in the micelles of a non-ionic surfactant medium and are thus separated from the bulk aqueous phase. Free metal species are also determined by complexation with a conventional chelating agent under mild conditions. The overall procedure is easy, rapid and allows for a high sample throughput in terms of massive analysis of many samples in the same time period. The method offers substantially low detection limits of 8.5 and 0.9 micrograms l-1 for bound and labile species respectively, with a calibration curve rectilinear in the wide range 40-150 micrograms l-1 for the humate associated and 4-40 micrograms l-1 for the free metal species. The method is free from interferences yielding recoveries in the range 97-102% for various samples of different matrixes.

Speciation of Fe(II) and Fe(III) by the modified ferrozine method, FIA-spectrophotometry, and flame AAS after cloud-point extraction.

A method has been developed for the simultaneous determination of traces of Fe(III) and Fe(II) in water by on-line coupling of spectrophotometry with flame atomic absorption spectrometry (FAAS). The method involves cloud-point extraction (CPE) of both species with ammonium pyrrolidinecarbodithioate (APDC) under standard conditions, which facilitates the in situ complexation and extraction of both species. Differentiation of the oxidation states of iron is achieved by using mathematical equations to overcome the interference of Fe(III) in the spectrophotometric determination of Fe(II) when they are both present in the same solution. In this manner the time-consuming and labor-intensive steps of preoxidation of Fe(II) or reduction of Fe(III) are eliminated. By preconcentrating a 10-mL sample solution detection limits as low as 7 microg L(-1), were obtained after a single-step extraction procedure. The relative standard deviation (n=4, 30 microg L(-1)) was 2.6 % and 1.8 % for spectrophotometry and FAAS, respectively. Recoveries in the range of 96-105 % were obtained by analysis of spiked real samples. The method was further verified by analyzing a certified reference material (IMEP-9); for this the recovery was 98.5 %.

Micelle mediated extraction of magnesium from water samples with trizma-chloranilate and determination by flame atomic absorption spectrometry.

This article describes an analytical method for the determination of magnesium taking advantage of the cloud point phenomenon employing a suitable chelating agent (chloranilate) for Mg analysis. The method encompasses pre-concentration of the metal chelate followed by flame atomic absorption spectrometry (FAAS) analysis. The chelating agent chosen for this task is a newly synthesised salt of chloranilic acid, trizma-chloranilate, which reacts with Mg but at the same time has a very low affinity for other metallic cations like silicon, aluminium and sodium, which interfere with the determination of Mg in FAAS. The condensed surfactant phase with the metal chelate(s) is introduced into the flame of an atomic absorption spectrometer after its treatment with an acidified methanolic solution. In this way, complex and time-consuming steps for sample treatment are avoided while increased sensitivity is achieved by the presence of both methanol and surfactant in the aspirated sample. The analytical curve was rectilinear in the range of 5-220 mugl(-1) and the limit of detection was as low as 0.75 mugl(-1) with a standard deviation of 5.2%. The method was applied for the determination of Mg in natural and mineral waters with satisfactory results and recoveries in the range of 97-102%.

Development of 1-(2-pyridylazo)-2-naphthol-modified polymeric membranes for the effective batch pre-concentration and determination of zinc traces with flame atomic absorption spectrometry.

The development of 1-(2-pyridylazo)-2-naphthol (PAN)-modified polymeric membranes for the effective batch pre-concentration and determination of zinc traces with flame atomic absorption spectrometry (FAAS) is described. The method is based on the chemical bonding of the metal species with a suitable ligand, which has been immobilized into a water-insoluble cellulose acetate (CA) membrane followed by simple rinsing of the chelating agent-metal complex with an acidified methanolic solution. The latter is directly aspirated to the nebulizer of a FAA spectrophotometer without any other treatment. As an analytical demonstration, trace concentrations of Zn(II) were successfully detected in real samples, such as seawater, river and lake water, wastewater as well as in a reference material, without any laborious and time-consuming treatment. Several working parameters were investigated. A pre-concentration factor of 100 was achieved by simple immersing of a circular piece of the CA-PAN membrane (0.6 cm diameter) in the tested samples for 30 min at room temperature. The analytical curve was rectilinear up to 30 mug l(-1) zinc with detection limit of 0.7 mug l(-1), a quantitation limit of 2.0 mug l(-1) and a relative standard deviation lower than 2%.

Monitoring of time variation and effect of some meteorological parameters in polynuclear aromatic hydrocarbons in Ioannina, Greece with the aid of HPLC-fluorescence analysis.

This paper describes the monitoring of 16 polynuclear aromatic hydrocarbons (PAH) in the suspended particulate matter in the area of Ioannina. A total of 244 samples were collected from five locations throughout the city. These samples were analyzed in order to acquire a complete picture of the PAH abundance and distribution above the city of Ioannina. The sampling sites covered the center of the city as well as the suburban territory. The monitoring lasted for one year starting in November 1996. Higher values of PAH were found at the sites surrounding the city center, while at the rest of the area the concentration of PAH was substantially lower. The effect of ambient temperature and humidity on PAH abundance and distribution was also evaluated. As a result it was revealed that higher concentrations of PAH are favored by low temperatures and high values of humidity. Regarding the seasonal variation of PAH it was found that their concentrations are elevated during the winter months where heating systems are operating. On a daily basis it appears that the highest abundances of PAH occur on Wednesdays while the lowest on Sundays. The mean yearly concentration values of benzo[a]pyrene varied between 0.32+/-0.02 and 2.63+/-0.08 ng m(-3) for the various sites. Compared with the reported values the PAH levels in the area of Ioannina can be characterized as medium to low.