S. Rubio-Barroso

A NEW METHOD FOR THE DETERMINATION OF SELECTED PAHs IN COFFEE BREW SAMPLES BY HPLC WITH FLUORIMETRIC DETECTION AND SOLID-PHASE EXTRACTION

A rapid analytical method is proposed for the determination of PAHs (fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[e]pyrene, benzo[a]pyrene, dibenzo[a,h]anthracene and benzo[g,h,i]perylene) in coffee brew samples. The method is based on solid phase extraction with Sep-Pak Vac tC-18 cartridges and elution with ethyl ether. The extracts were analyzed by RP-HPLC with a Green PAH column and fluorescence detection under an acetonitrile-water mobile phase gradient. Some PAHs were detected in the samples studied and their mean contents were 1.65–2.87 ng/L coffee brew. The relative standard deviations were in the range 2–13% for four replicates.

DETERMINATION OF SELECTED POLYCYCLIC AROMATIC HYDROCARBONS IN TOASTED BREAD BY SUPERCRITICAL FLUID EXTRACTION AND HPLC WITH FLUORIMETRIC DETECTION

A new method for PAHs determination in toasted bread samples is proposed. The method is based on supercritical-fluid extraction, using CO2 and acetonitrile as modifier. The extracted PAHs were collected in 1 mL acetonitrile. Quantitation was carried out by HPLC with fluorimetric detection. A Hypersil Green PAH column, acetonitrile-water gradient mobile phase, and a program of 11 excitation and emission wavelength pairs for fluorimetric detection were used. Recoveries at concentration levels in the range 0.15–3.56 μg/kg bread were close to 100% for all PAHs except fluoranthene, chrysene, and benzo[ghi]perylene. Some PAHs were detected in these samples within the range 0.323–9.40 μg/kg toasted bread; the relative standard deviations were in the range 2 – 12% (n=4).

Determination of PAHs in particulate air by micellar liquid chromatography

Abstract An acetonitrile/0.2OM SDS mobile phase was used to determine PAHs by HPLC with fluorimetric detection. Because the peak area is greater the method is more sensitive than using an acetonitrile/water mobile phase. The method was applied to determine PAHs in particulate air samples and the results are in good agreement with those found by GC.

Rapid determination of PAHs in drinking water samples using solid-phase extraction and HPLC with programmed fluorescence detection

Abstract A rapid, sensitive and selective method for determining 13 PAHs in drinking water samples using solid-phase extraction and HPLC with programmed fluorescence detection is developed. A solid-phase extraction method is described for preconcentrating the PAHs on Sep-Pak vac tC-18 cartridges. The volume of water analyzed was 1500 mL. The PAHs were eluted with ethyl ether, the eluates were evaporated to dryness and the residue was dissolved in methanol. The PAHs were analyzed on a Hypersil Green PAH column and a program of nine excitation and emission wavelength pairs were used. A mobile phase gradient of acetonitrile-water was used. It is possible to detect all the individual PAHs at very high sensitivity, at levels of ng/L. Recoveries were 60–96% for 12 PAHs at concentration levels of 2.33–48.7 ng/L with relative standard deviations in the range 0.4–10% (n=4). The method was applied to determine PAHs in tap-water and reservoir-water samples.

Determination of Benzo(a)pyrene in Total Particulate Matter of Virginia and Black Tobacco Smoke by HPLC with Fluorimetric Detection

Abstract A method for the determination of the benzo(a)pyrene by RP-HPLC with fluorimetric detection in total particulate matter of Virginia and blak tobacco smoke is developed. The total particulate matter was collected on glass fibre filters, which were ultrasonically extracted with cyclohexane. A fraction of the resulting extract was cleaned up on Sep-Pak Vac Si cartridges and the PAHs were eluted with mehylene chloride. The eluate was evaporated to drynees and the residue was dissolved in methanol. The mean recoveries in the extraction and clean-up steps were 100.1% and 49.2%, respectively, with relative standard deviations of 3.8% and 2.4%, respectively, in the concentration range 20–140 ng. The quantification is achieved by means of external standard method.

Separation Study of PAHs by HPLC Using A Micellar SDS Mobile Phase and Short Chain Columns

Abstract The possibility of using micellar sodium dodecyl sulfate mobile phase modified with n-propanol to separate six PAHs on apolar columns was examined. The large capacity factors found in large-chain stationary phases made the analysis impractical. The use of short-chain stationary phases and the presence of n-propanol in the mobile phase, as a modifier, significantly decreased the capacity factors but also decreased resolution, allowing separation of five PAHs in reasonable analysis times. Conditioning of the column was easy and reproducible but the effect of temperature was quite critical. The gradient technique decreased peak width significantly.

Free D-amino acids determination in ready-to-eat cooked ham irradiated with electron-beam by indirect chiral HPLC

Potential racemization of L-amino acids (AA) in ready-to-eat (RTE) cooked ham after hygienization by electron-beam irradiation between 1 and 8kGy was studied. An indirect chiral method based on the derivatization reaction of AA with o-phthaldialdehyde and N-acetyl-L-cysteine followed by reversed-phase HPLC and fluorimetric detection was applied to detect ten enantiomeric pairs of free AA (Asp, Ser, Thr, Ala, Tyr, Val, Trp, Phe and Leu). Five of the D-AA were not found in any of the samples analyzed; the other five remaining D-AA (D-Asp, D-Ser, D-Ala, D-Val and D-Leu) were detected both in irradiated and non-irradiated cooked ham samples, their content being in the range 1.25-13.79μg/g. Although significant differences appeared for a few of the samples and doses, no positive correlation between the D-AA content and the irradiation doses was observed. Therefore, the electron-beam irradiation technique could be useful for sanitation of packed RTE cooked ham at doses allowed by WHO and EU, since it remains chemically safe to eat.

Determination of D- and L-Amino Acids in Pharmaceutical Preparations by Indirect Chiral HPLC and Fluorimetric Detection

Abstract An indirect chiral HPLC method based on the derivatization reaction with o-phthaldialdehyde and N-acetyl-L-cysteine and fluorimetric detection is applied to determine the enantiomeric purity of amino acids in pharmaceutical preparations. Three samples, vanim™ 14, tebetane, and tulgrasum were analized and their enantiomeric contents were determined. Sample preparation did not require cleanup. The validity of the method was established. The D-AA content is not always specified in the labels of these pharmaceutical preparations.