M. Callejón Mochón

Heavy metal extractable forms in sludge from wastewater treatment plants

The analysis of heavy metals is a very important task to assess the potential environmental and health risk associated with the sludge coming from wastewater treatment plants (WWTPs). However, it is widely accepted that the determination of total elements does not give an accurate estimation of the potential environmental impact. So, it is necessary to apply sequential extraction techniques to obtain a suitable information about their bioavailability or toxicity. In this paper, a sequential extraction scheme according to the BCRs guidelines was applied to sludge samples collected from each sludge treatment step of five municipal activated sludge plants. Al. Cd, Co, Cu, Cr, Fe, Mn, Hg, Mo, Ni, Pb, Ti and Zn were determined in the sludge extracts by inductively coupled plasma atomic emission spectrometry. In relation to current international legislation for the use of sludge for agricultural purposes none of metal concentrations exceeded maximum permitted levels. In most of the metal elements under considerations, results showed a clear rise along the sludge treatment in the proportion of two less-available fractions (oxidizable metal and residual metal).

Simultaneous determination of 11 antibiotics and their main metabolites from four different groups by reversed-phase high-performance liquid chromatography-diode array-fluorescence (HPLC-DAD-FLD) in human urine samples.

A new, accurate and sensitive reversed-phase high-performance liquid chromatography (RP-HPLC) as analytical method for the quantitative determination of 11 antibiotics (drugs) and the main metabolites of five of them present in human urine has been worked out, optimized and validated. The analytes belong to four different groups of antibiotics (sulfonamides, tetracyclines, penicillins and anphenicols). The analyzed compounds were sulfadiazine (SDI) and its N(4)-acetylsulfadiazine (NDI) metabolite, sulfamethazine (SMZ) and its N(4)-acetylsulfamethazine (NMZ), sulfamerazine (SMR) and its N(4)-acetylsulfamerazine (NMR), sulfamethoxazole (SMX), trimetroprim (TMP), amoxicillin (AMX) and its main metabolite amoxicilloic acid (AMA), ampicillin (AMP) and its main metabolite ampicilloic acid (APA), chloramphenicol (CLF), thiamphenicol (TIF), oxytetracycline (OXT) and chlortetracycline (CLT). For HPLC analysis, diode array (DAD) and fluorescence (FLD) detectors were used. The separation of the analyzed compounds was conducted by means of a Phenomenex Gemini C(18) (150mm x 4.6mm I.D., particle size 5microm) analytical column with LiChroCART LiChrospher C(18) (4mm x 4mm, particle size 5microm) guard column. Analyzed drugs were determined within 34min using formic acid 0.1% in water and acetonitrile in gradient elution mode as mobile phase. A linear response was observed for all compounds in the range of concentration studied. Two procedures were optimized for sample preparation: a direct treatment with methanol and acetonitrile and a solid phase extraction procedure using Bond Elut Plexa columns. The method was applied to the determination of the analytes in human urine from volunteers under treatment with different pharmaceutical formulations. This method can be successfully applied to routine determination of all these drugs in human urine samples.

Enzymatic-microwave assisted extraction and high-performance liquid chromatography–mass spectrometry for the determination of selected veterinary antibiotics in fish and mussel samples

A new method based on enzymatic-microwave assisted extraction prior to high performance liquid chromatography (HPLC) has been developed for the determination of 11 antibiotics (drugs) and the main metabolites of five of them in fish tissue and mussel samples. The analysed compounds were sulfadiazine (SDI), N(4)-acetylsulfadiazine (NDI), sulfamethazine (SMZ), N(4)-acetylsulfamethazine (NMZ), sulfamerazine (SMR), N(4)-acetylsulfamerazine (NMR), sulfamethoxazole (SMX), trimetroprim (TMP), amoxicillin (AMX), amoxicilloic acid (AMA), ampicillin (AMP), ampicilloic acid (APA), chloramphenicol (CLF), thiamphenicol (TIF), oxytetracycline (OXT) and chlortetracycline (CLT). The main factors affecting the extraction efficiency were optimized in tissue of hake (Merluccius merluccius), anchovy (Engraulis encrasicolus), mussel (Mytilus sp.) and wedge sole (Solea solea). The microwave extraction was carried out using an extraction time of 5 min with 5 mL of water at 50W and posterior clean up with dichloromethane. High-performance liquid chromatography (HPLC)-mass spectrometry was used for the determination of the antibiotics. The separation of the analysed compounds was conducted by means of a Phenomenex® Gemini C(18) (150 mm × 4.6mm I.D., particle size 5 μm) analytical column with LiChroCART® LiChrospher® C(18) (4 mm × 4 mm, particle size 5 μm) guard-column. Analysed drugs were determined using formic acid 0.1% in water and acetonitrile in gradient elution mode as mobile phase. Under the optimal conditions, the average recoveries of all the analysed drugs were in the range 70-100%. The proposed method was applied to samples obtained from Mediterranean sea and also evaluated by a laboratory assay consisting in the determination of the targeted analytes in samples of Cyprinus carpio that had been previously administered the antibiotics.

Simultaneous Determination of Selected Veterinary Antibiotics and their Main Metabolites in Fish and Mussel Samples by High-Performance Liquid Chromatography with Diode Array-Fluorescence (HPLC-DAD-FLD) Detection

A reversed-phase high-performance liquid chromatography (RP-HPLC) method for the quantitative determination of 11 antibiotics (drugs) and the main metabolites of five of them in fish tissue and mussel samples were developed, optimized, and validated. The analytes belong to four different classes of antibiotics (sulfonamides, tetracyclines, penicillin, and amphenicols). The analyzed compounds were sulfadiazine and its N4-acetylsulfadiazine metabolite; sulfamethazine and its N4-acetylsulfamethazine; sulfamerazine and its N4-acetylsulfamerazine; sulfamethoxazole; trimetroprim; amoxicillin and its main metabolite amoxicilloic acid; ampicillin and its main metabolite ampicilloic acid; chloramphenicol; thiamphenicol; oxytetracycline; and chlortetracycline. For HPLC analysis, diode array and fluorescence detectors were used. The separation of the analyzed compounds was conducted by means of a C18 (150 mm × 4.6 mm I.D., particle size 5 µm) analytical column with LiChrospher® C18 (4 mm × 4 mm, particle size 5 µm) guard-column. Analyzed drugs were determined within 35 minutes using formic acid 0.1% in water and acetonitrile in gradient elution mode as the mobile phase. The method was applied to the determination of the analytes in tissue of hake (Merluccius merluccius), anchovy (Engraulis encrasicolus), mussel (Mytltus sp.), and wedge sole (Solea solea). The proposed method was also evaluated by a laboratory assay consisting of the determination of the targeted analytes in samples of Cyprinus carpio that were previously administered controlled doses of the antibiotics.

Application of enzymatic probe sonication extraction for the determination of selected veterinary antibiotics and their main metabolites in fish and mussel samples.

A new method based on enzymatic probe sonication extraction prior to high-performance liquid chromatography (HPLC) has been developed for the determination of 11 antibiotics (drugs) and the main metabolites of five of them in fish tissue and mussel samples. The analytes belong to four different classes of antibiotics (sulfonamides, tetracyclines, penicillins and amphenicols). The analysed compounds were sulfadiazine (SDI) and N(4)-acetylsulfadiazine (NDI) metabolite, sulfamethazine (SMZ) and N(4)-acetylsulfamethazine (NMZ), sulfamerazine (SMR) and N(4)-acetylsulfamerazine (NMR), sulfamethoxazole (SMX), trimetroprim (TMP), amoxicillin (AMX) and its main metabolite amoxicilloic acid (AMA), ampicillin (AMP) and its main metabolite ampicilloic acid (APA), chloramphenicol (CLF), thiamphenicol (TIF), oxytetracycline (OXT) and chlortetracycline (CLT). The main factors affecting the extraction efficiency (type of enzyme, type and volume of extractant, ultrasounds power and extraction time) were optimised in tissue of hake (Merluccius merluccius), anchovy (Engraulis encrasicolus), mussel (Mytilus sp.) and wedge sole (Solea solea). The extraction was carried out using an extraction time of 5 min with 5 mL of water and subsequent clean-up with dichloromethane. High-performance liquid chromatography (HPLC) with diode array (DAD) and fluorescence (FLD) detectors was used for the determination of the antibiotics. The separation of the analysed compounds was conducted by means of a Phenomenex Gemini C(18) (150 mm x 4.6 mm I.D., particle size 5 microm) analytical column with LiChroCART LiChrospher C(18) (4 mm x 4 mm, particle size 5 microm) guard-column. Analysed drugs were determined using formic acid 0.1% (v/v) in water and acetonitrile in gradient elution mode as mobile phase. The proposed method was also evaluated by a laboratory assay consisting of the determination of the targeted analytes in samples of Cyprinus carpio which had previously administered the antibiotics.

Kinetic-spectrophotometric determination of traces of vanadium(V) by its catalytic effect on the oxidation of 1,4-dihydroxyphthalimide dioxime with bromate

Abstract A kinetic-spectrophotometric method for the determination of trace amounts of vanadium(V) is described. It is based on the catalytic action of this ion on the oxidation of 1,4-dihydroxyphthalimide dioxime by bromate, which yields a red-violet product in acidic medium. The reaction is followed spectrophotometrically by measuring the rate of change in absorbance at 500 nm and 30°C. Using several kinetic methods (tangent, fixed-time and fixed-absorbance), vanadium(V) in the range 10–400 ng ml−1 can be determined. The proposed methods are hardly subject to interferences. The tangent method was used for the determination of vanadium in atmospheric particulate matter, human serum and synthetic mixtures. The kinetic parameters of the catalysed and uncatalysed reactions are reported.

Spectrophotometric study of a ternary zirconium/fluoride/alizarin complex with application to the determination of zirconium

A ternary zirconium/fluoride/alizarin complex is extracted into methyl isobutyl ketone. The apparent molar absorptivity at 556 nm is 1.52 × 105 1 mol−1 cm−1. The r.s.d. is 1.3% for 10 μg Zr (n = 12). There are several interferences, some of which can be masked with EDTA.

Simultaneous Determination of Cefepime and the Quinolones Garenoxacin, Moxifloxacin and Levofloxacin in Human Urine by HPLC-UV

Abstract.A liquid chromatographic method with a C18 column and acetonitrile/0.1 M phosphoric acid/ sodium hydroxide buffer (pH 3.0)/0.01 M n-octylamine (pH 3.0) as mobile phase in gradient mode has been developed and optimised for the simultaneous determination of the cephalosporin cefepime and the quinolones garenoxacin, levofloxacin and moxifloxacin. Identification and quantification was carried out with a diode-array UV detector, with working wavelengths of 256 nm for cefepime, 292 nm for levofloxacin, 294 nm for moxifloxacin and 282 nm for garenoxacin. The mobile flow-rate and sample volume injected were 1 mL min−1 and 20 µL, respectively. The retention times and detection limits for each antibiotic were 4.9 min and 1.9 µg mL−1 for cefepime, 7.5 min and 2.2 µg mL−1 for levofloxacin, 8.9 min and 2.7 µg mL−1 for moxifloxacin and 10.7 min and 1.8 µg mL−1 for garenoxacin, respectively. The method was applied to the determination of the four molecules in spiked samples of human urine.

Spectrophotometric determination of periodate with the bisthiosemicarbazones of phthalimide and 1,3-indandione

Abstract Phthalimide bisthiosemicarbazone (FT) and 1,3-indandione bisthiosemicarbazone (IDTS) have been examined in order to evaluate their usefulness as Spectrophotometric reagents for periodate. FT forms a yellow oxidation product with periodate in acid medium, with maximum absorption at 410 nm; the molar absorptivity is 2.84 × 104 M−1 cm−1. IDTS gives a red color in acid medium; the molar absorptivity at 520 nm is 4.8 × 103 M−1 cm−1.

Determination of heavy metals in sewage sludge by microwave acid digestion and inductively coupled plasma atomic emission spectrometry

A description is given of a method for the determination of metals in sewage sludge samples using an acid mixture of HNO3, HClO4 and HF and a microwave oven in open vessel. The elements Al, Cd, Co, Cu, Cr, Fe, Mn, Mo, Hg, Ni, Pb, Ti and Zn were measured by inductively coupled plasma atomic emission spectrometry. The results for the analysis of three reference materials (sewage sludge CRM 145R, sewage sludge from domestic origin CRM 144R and sewage sludge from industrial origin CRM 146R) after microwave acid digestion showed close agreement with the state values for all the metals studied (except Hg). The proposed method was applied to the analysis of Al, Cd, Co, Cu, Cr, Fe, Mn, Mo, Ni, Pb, Ti and Zn in a conventional sewage treatment work to the east of Seville.