Occurrence and exposure of 3-monochloropropanediol diesters in edible oils and oil-based foodstuffs from the Spanish market.

During the industrial refining process of edible oils and the manufacture of oil-based foodstuff, contaminants such as 3-monochloropropanediol (3-MCPD) fatty acid diesters can be produced. One hundred samples of different edible oils and related fatty food purchased from local Spanish markets were analyzed to evaluate the occurrence of these contaminants. Data of seven 3-MCPD diesters together with corresponding total 3-MCPD equivalents are presented. The procedure is based on a modified QuEChERS protocol followed by LC-MS/MS analysis. Extra virgin olive oil (EVOO) and unrefined oils did not contain detectable levels of the target analytes. The highest levels of 3-MCPD diesters were found in palm oils, for 1,2-Dilinoleoyl-3-chloropropanediol (LILI) and 1-2-Bispalmitoyl-3-chloropropanediol (PAPA) with concentrations close to 10 mg kg-1 and in the lipid fraction of margarines (8.09, 3.77 and 3.72 mg kg-1 for LILI, PAPA and 1-Oleoyl-2-linoleoyl-3-chloropropanediol (OLLI), respectively).

Comparison of methods for analysis of resveratrol in dietary vegetable supplements.

Resveratrol is a stilbene, which is one of a group of polyphenols in many plant foods. Interest in this substance lies in its potential health benefits. This study aimed to compare two different methods, chromatographic and constant-wavelength synchronous spectrofluorimetry, an alternative technique to determine the amount of resveratrol dietary supplements, as a model for more complex foods. High-performance liquid chromatography-photodyode array detector-mass spectrometry/mass spectrometry was used to confirm the results. The results obtained showed that both methods were valid for the determination of resveratrol in dietary supplements. HPLC with fluorescence and variable wavelength detectors offered better linearity and sensitivity, and would be more suitable for the determination of several stilbenes in complex samples. On the other hand, constant-wavelength synchronous spectrofluorimetry is a sensitive, rapid and inexpensive method that could be used for quick and precise determination when samples are expected to contain only one stilbene.

HPLC analysis of organic acids using a novel stationary phase.

In the present work, a high performance liquid chromatographic method with UV detection for the separation of six organic acids including, tartaric, malic, acetic, lactic, citric and succinic is described. The separation was performed on a novel stationary phase TEKNOKROMA, Tr-010065 Mediterranea sea(18) (15 cm x 0.4 cm, i.d. 3 microm) and using water with a 0.1% (v/v) of formic acid as mobile phase. The advantages of this packing over a conventional octadecylsilane (ODS2) column are reported. The method was validated with respect to linearity, limits of detection and repeatabilities within day and between days and satisfactory results were obtained. The proposed method was applied for the determination of these compounds in commercially available white wines. The samples were injected directly without previous treatment. LC-MS was used as a confirmatory technique.

Supercritical fluid extraction of polycyclic aromatic hydrocarbons from seaweed samples before and after the prestige oil spill.

Samples of seaweed which are used for human consumption were collected along the Galician coast (NW Spain), in order to determine the level of contamination from polycyclic aromatic hydrocarbons, by supercritical fluid extraction and liquid chromatographic analysis. No detection was made of benzo[a]pyrene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[ghi]perylene and dibenzo[ah]anthracene. PAHs were found and quantified in only two samples. The PAHs found were the following: anthracene, chrysene, fluoranthene, fluorene and pyrene. The levels found were below maximum limits established by the Spanish Food Safety authority (<200 mg/kg dry weight). Here we show that no relevant effects were detected in terms of PAHs contamination in seaweed.

Comparison of two stationary phases for the separation of five selected polyphenols.

In this study, a conventional TEKNOKROMA, Tr-015605 TRACER EXTRASIL ODS2 (25 cm x 0.4 cm, i.d. 5 microm) column and a new stationary phase TEKNOKROMA, Tr-010065 Mediterranea sea(18) (15 cm x 0.4 cm, i.d. 3 microm) were compared for the separation of five phenolic compounds. Sensitivity, performance characteristics, analysis time and method validation were reported for both columns. A better sensitivity and performance were achieved with the novel chromatographic support. In addition the total analysis time was significantly reduced. The method was applied to the determination of the selected polyphenols in commercial available white wines. LC-MS was used as a confirmatory technique.

High-performance liquid chromatographic determination of chitin in the snow crab, Chionoecetes opilio.

A HPLC method was developed for the determination of glucosamine in crab shells. The amount of glucosamine residue can be used to estimate the amount of chitin in analyzed material. Crab samples were hydrolysed with 6M HCl at 100 degrees C for 13 h and the released glucosamine was determined by HPLC using refractive index (RI) detection. Separations were performed using an ODS-2 column with an isocratic mobile phase consisting of 10% methanol, 90% hexanesulfonate, pH 2.1. Glucosamine identification was carried out not only on basis of retention time, but also with respect to mass spectra, which were acquired by HPLC-MS.

Comparison of supercritical fluid extraction and Soxhlet extraction for the determination of aliphatic hydrocarbons in seaweed samples.

Supercritical fluid extraction (SFE) and Soxhlet extraction methods were compared in a study of the aliphatic hydrocarbon profiles of seaweed samples. Method precision for Soxhlet extraction (< or = 7.58%) was slightly better than that for SFE (< or = 9.28%) except for C28. The SFE method is a good alternative for the routine determination of alkanes in seaweed samples; however, for a complete study of shorter-chain n-alkanes, the Soxhlet extraction is a more suitable method. To evaluate the SFE and Soxhlet methods developed, three diverse Undaria pinnatifida samples collected at different dates and areas of the Galician coast were analyzed. n-Alkanes C18, C20, C22, C24, and C28 were found in all samples, with values lower than 7.9 microg g(-1) d.w. The total hydrocarbon content was within the range of 13.6-21.7 microg g(-1) d.w. C18 was found to be the most abundant.

Extraction of hydrocarbons from seaweed samples using sonication and microwave-assisted extraction: a comparative study.

A sonication method is compared with a microwave-assisted extraction method for recovering polycyclic aromatic hydrocarbons and aliphatic hydrocarbons from seaweed and acid humic samples. Different extracting solvents and adsorbents for the purification step are tested. For the sonication extraction, 10 g of the sample are extracted in an ultrasonic bath (60 degrees C for 15 min with 20 mL of hexane). For the microwave-assisted extraction two steps are carried out, each step at 90 degrees C under pressure in closed vessels with 20 mL of hexane for 10 min at 950 W. A clean-up step is performed for both extraction techniques. The results indicate that the recovery of hydrocarbons is dependent on both the extraction technique and the type of matrix. The most suitable technique appears to be sonication employing hexane as the extraction solvent. The recoveries obtained for aliphatic hydrocarbons are higher than those achieved for the polycyclic aromatic hydrocarbons, with values ranging within 81-109% and 40-76%, respectively.

Comparison of supercritical fluid extraction and Soxhlet extraction for the determination of PCBs in seaweed samples.

The efficiency of supercritical fluid extraction for the determination of 12 polychlorinated biphenyls from algae samples is compared to Soxhlet extraction. Analytical detection limits for the individual congeners ranged from 0.62 microgl(-1) to 19 microgl(-1). Recovery was tested for both methods using standard addition procedure. At maximum spike level of concentration, the mean recoveries were not significantly different (P>0.05) of all PCBs studied, with the exception of PCBs 28, 52, 77 and 169. Method precision for Soxhlet extraction (< or =3.9%) was slightly better than for SFE (< or =9.2%). Although both methods yield comparable results, SFE offers the advantage of detecting all PCBs studied at lower concentrations, reducing extraction time, and reducing the amount of solvents needed. The optimized methods were applied to the analysis of three real seaweed samples, except for PCB101 the concentrations of all PCBs were low or below the detection limits. The levels of PCB101 found in sample 1 were 6.6+/-0.54 ng g(-1) d.w., in sample 2 the levels were 8.2+/-0.86 ng g(-1) d.w. and in sample 3 they were 7.7+/-0.08 ng g(-1) d.w.

Determination of folates in seaweeds by high-performance liquid chromatography.

A reversed-phase high-performance liquid chromatography (HPLC) method, with a combination of fluorescence and ultraviolet detectors, to determine the folate forms present in commercial macroalgae products form northwest Spain as part of nutritional studies in dehydrated and canned seaweeds is reported. The method includes extraction of folates from seaweed by heat treatment, deconjugation of folate polyglutamates by incubation with hog kidney conjugase and purification by solid-phase extraction (SPE) with strong anion-exchange (SAX) cartridges. Separation was achieved with a Tracer Extrasil ODS 5 microm 25 cm x 0.4 cm column using acetonitrile and potassium phosphate buffer (pH 2.21 as mobile phase. Good results were obtained with respect to repeatability (relative standard deviation (R.S.D.) < or = 4.12%) and recovery (> or = 90.80%). The amount of folate (as folic acid) in the six species ranged from 61.4 to 161.6 microg per 100 g dry mass. In all the seaweeds studied (Himanthalia elongata, Laminaria ochroleuca, Palmaria spp., Undaria pinnatifida and Porphyra spp. and Saccorhiza polychides) the single most abundant form is 5-CH3-H4-folate, except Porphyra and Himanthalia.

Determination of aliphatic hydrocarbons in the alga Himanthalia elongata.

The algae considered new foods according to Regulation CE 258/97 need a guarantee of their healthfulness before being in the European market. In this work ten samples of the brown alga Himanthalia elongata have been analyzed with the aim of verifying the absence of aliphatic hydrocarbons, due to the ability of the macroalgae to capture lipophilic organic compounds of the marine water coming from accidental or continuous leaks of raw oil and refined products, which happen each year with the growth of the industrialization and the demand of energy. The fat of the samples were Soxhlet extracted using hexane:dichloromethane (1:1) for 7h. The organic fractions were purified using silica microcolumns. The identification and quantification of the aliphatic hydrocarbons have been carried out using gas chromatography (GC) with flame ionization detector (FID). The total hydrocarbon content was between 14.8 and 40.2 microg g(-1) dry weight.

Aliphatic hydrocarbons in birds of prey from Galicia (NW Spain).

Eleven aliphatic hydrocarbons, unresolved over resolved ratio (U/R), carbon preference index (CPI), pristane/C17 ratio, and totals were determined in six classes of tissues (heart, liver, intestine, muscle, lung, and kidney) of 10 buzzards (Buteo buteo), 10 barn owls (Tyto alba), and five tawny owls (Strix aluco) from Galicia (NW Spain). Among individuals detected at quantifiable levels, in general, C18 was found to be the most abundant. Total aliphatic hydrocarbons were detected in 77% tissue samples. Phytane was detected in only three samples: intestine and muscle of two buzzards and lung of one barn owl. Pristane was found in 15% of total samples. Juveniles had higher concentrations than adults in the three species. Females had higher levels than males except for C32 and C36 in barn owl, C24 in tawny owls, and all hydrocarbons (except pristane) in buzzards. The highest concentrations of aliphatic hydrocarbons were detected in birds from La Coruña

Levels of seven PCBs used as markers of dioxin in commercial pork meat in Spain.

The levels of 7 PCBs used as markers of dioxin in 62 pork meat samples (head, loin, and dewlap) were determined by supercritical fluid extraction and gas chromatography with electron capture detection. Analytical limits of detection for the individual congeners ranged from 0.048 to 0.2 ng/g dry wt. PCB congeners 153 and 180 were detected in all samples. Among congeners in general, PCB 52, 101, and 153 were the most abundant. There was a linear relationship with a good correlation between PCB 101 and PCB 52.

Organochlorine pesticides in wolves from Galicia.

Levels of seven organochlorine pesticides (heptachlorepoxide, dieldrin, endrin, p,p'-DDE, o-p'-DDT, p,p'-DDT, and methoxychlor) and DDE/DDT ratios were determined in spleen, liver, muscle, kidney and suprarenal from 12 wolves from three provinces of Galicia (eight male and four female). Analysis was carried out by GC-ECD. Heptachlorepoxide was in found only 25% of samples, while p,p'-DDE was the most dominant of the organochlorine compounds analyzed. DDE/DDT ratios higher than 1 were found in liver and muscle.

Supercritical fluid extraction of polycyclic aromatic hydrocarbons from liver samples and determination by HPLC-FL.

An extraction/clean-up procedure by SFE was developed for isolating PAHs from liver samples for subsequent HPLC-FL determination of ten PAHs in the enriched extract. Recoveries (90-115%) and RSD % (< or =7.7) were satisfactory. When applied to 11 samples of bird of prey (Tyto alba) protected species and classified of special interest, from the Galicia (Northwest to Spain), benzo[ghi]perylene and indeno[1,2,3-cd]pyrene were undetectable; chrysene and benzo[a]pyrene are only detected in one sample; benzo[a]anthracene and benzo[k]fluoranthene are only quantified in one sample and benzo[b]fluoranthene in two samples. The other PAHs, anthracene, fluoranthene and pyrene are present in almost all the samples.

Enrichment of benzo[a]pyrene in vegetable oils and determination by HPLC-FL.

We have developed a simple method for the determination of the carcinogen Benzo[a]pyrene (BP) in vegetable oils. The method consists of extraction of the vegetable oil in acetonitrile, concentration to dryness in rotary evaporator and redissolution of the residue in hexane. The purification of the hexane extract was on Sep-Pack Silica Plus cartridges, and the determination of the BP in the isolated extract was by HPLC-FL. Detection and quantification limits were 0.23 and 0.32 mug kg(-1) of olive oil, respectively. Recovery (>93%) and RSD (<4%) were satisfactory. When applied to 18 oil samples, BP levels varied from not detected to 1.99 mug kg(-1).

Determination of benzo[a]pyrene in some Spanish commercial smoked products by HPLC-FL.

In order to investigate the levels of the potently carcinogenic benzo[a]pyrene (BP), 31 samples of smoke foods were analysed. The samples tested included five samples of meal products, three samples of cheese and 22 samples of fish. A liquid chromatographic method was developed using a fluorescence detector. BP was found in 74% of the samples analysed. The levels varied from not detected to 2.46 microg/kg. Only one sample showed a BP level above 1 microg/kg, the maximum level that the EU intends to set for smoked foods.

A simple ultraviolet method for discriminating between polychlorobiphenyls and organochloride pesticides coeluting under gas chromatography with electron-capture detection.

Certain congeners of Aroclor 1260 coelute with o,p'-or p,p'-DDT under gas chromatography with electron-capture detection. We describe a simple ultraviolet irradiation method that allows qualitative and quantitative analyses of mixtures of these organochlorides in complex matrices. Detection limits are 0.20 and 0.22 microgram/kg dry mass for Aroclor 1260 and the two DDTs, respectively. The method is applied to six replicate pork liver samples, for which recoveries ranged from 72 to 90%.

Aliphatic hydrocarbons in wolf tissue samples from Galicia (N.W. Spain).

We have investigated the levels of aliphatic hydrocarbons, UCM and CPI in wolves from Galicia (Spain). The n-alkanes distribution was characterized by a predominance of even carbon n-alkanes. Suprarenal and muscle tissues contained more aliphatic hydrocarbons (AHs) than spleen, liver or kidney. The AHs which were detected were found most frequently in adults and males. The mean concentrations of C10, C33, C34, C35 and C36 were the lowest of all compounds quantified (< 1 mg/kg lipid weight) and C12, C14, C16 and C22 were the highest (> 14.2 mg/kg lipid weight). The presence of phytane and UCM (> 3) together to PR/C17 and PH/C18 ratios (both < 1) suggest a large contribution of crude oils.