Monitoring of five sulfonamide antibacterial residues in milk by in-tube solid-phase microextraction coupled to high-performance liquid chromatography

A simple, rapid, and sensitive method for the quantitative monitoring of five sulfonamide antibacterial residues in milk was developed by coupling in-tube solid-phase microextraction (SPME) to high-performance liquid chromatography with an ultraviolet detector. A poly(methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary column was selected as the extraction medium for this on-line technique. To obtain optimum extraction efficiency, several parameters relating to in-tube SPME were investigated. By simple extraction with ethanol, dilution with phosphate buffer solution, and centrifugation, the sample solution then could be directly injected into the device for extraction. The calculated detection limits for sulfadiazine, sulfamethazine, sulfamethoxazole, sulfamonomethoxine sodium, and sulfacetamide sodium were 2.0, 2.8, 1.7, 2.5, and 22 ng/mL, respectively. The method was linear over the range of 20-5000 ng/mL (100-5000 ng/mL for sulfacetamide sodium) with a correlation coefficient R (2) value >0.9980. Excellent method reproducibility was found by intra- and interbatch precisions, yielding the relative standard deviations of <10.0 and <9.94%, respectively. The proposed method was proved to be robust in monitoring sulfadiazine, sulfamethazine, sulfamethoxazole, sulfamonomethoxine sodium, and sulfacetamide sodium residues in milk.     

Quantitative determination of short-chain free fatty acids in milk using solid-phase microextraction and gas chromatography

The objective was to establish a rapid, precise, and accurate methodology for the quantification of short-chain free fatty acids (FFA) (C(4)-C(12)) in milk by solid-phase microextraction and gas chromatography. Sampling conditions such as fiber type, pH, salt addition, temperature, volume, and time were investigated. FFA extraction consisted of placing 40 mL of milk containing 28% NaCl at pH 1.5 in a sealed vial and equilibrating for 30 min at 70 degrees C. A polyacrylate fiber was exposed to the sample headspace for 60 min and desorbed for 5 min into the gas chromatograph. Calibration curves for FFA followed linear relationships with highly significant (p < 0.001) correlation coefficients (R(2) = 0.99). Coefficients of variation of less than 7.7% for FFA concentrations indicated that the technique was reproducible. The limits of quantification for C(4)-C(10) were in the low parts per million level, which were below the concentration range found in fresh pasteurized milk (0.48-2.52 ppm) or rancid milk (4.73-32.31 ppm).     

Ochratoxin a determination in beer by solid-phase microextraction coupled to liquid chromatography with fluorescence detection: a fast and sensitive method for assessment of noncompliance to legal limits

A solid-phase microextraction-liquid chromatography-fluorescence detection (SPME-LC-FD) method for the determination of ochratoxin A (OTA) in commercial beer samples was developed for the first time using a 60 microm thick poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB) fiber. The procedure required a very simple sample pretreatment, an isocratic elution, and provides a selective extraction. All of the factors influencing fiber adsorption (extraction time, temperature, pH, and salt addition) and desorption of the analyte (desorption and injection time and desorption solvent mixture composition) have been investigated. The linear range investigated in beer was 0.03-2 ng/mL; within-day and between-days relative standard deviation in beer were 4.3 and 5.9%, respectively. The limit of quantification in spiked beer was 53 pg mL(-)(1), well below all European regulatory levels.     

A simple and economic method for simultaneous determination of 11 antibiotics in manure by solid-phase extraction and high-performance liquid chromatography

Purpose

A simple and highly efficient economic method for the analysis of 11 antibacterial drugs including two tetracyclines, three quinolones, four sulfonamides, chloramphenicol and tylosin, in livestock manure, was developed using solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC).

Materials and methods

The analytes were successively extracted by EDTA-McIlvaine solution and organic solvent mixture. The extracts were degreased with n-hexane and cleaned through SPE on a hydrophile-lipophile balance (HLB) cartridge. All compounds were determined on a C18 reverse phase column with gradient elution.

Results and discussion

Recoveries calculated from spiked samples of animal manures ranged from 62.65 to 99.16 % for 11 antibiotics with relative standard deviations of less than 10.0 %. Limits of detection ranged from 0.1 to 1.9 μg kg^?1, and limits of quantification ranged from 0.3 to 5.9 μg kg^?1.

Conclusions

The results show that SPE-HPLC is an inexpensive and practical method for rapid detection of multiple antibiotics in animal manure.

     

Analysis of phenolic acids in barley by high-performance liquid chromatography

Phenolic acids from 30 barley varieties (combination of hulled/hulless/two-row/six-row/regular/waxy) were investigated by HPLC following four different sample treatments: (a) simple hot water extraction, (b) extraction after acid hydrolysis, (c) acid plus alpha-amylase hydrolysis, and (d) acid plus alpha-amylase plus cellulase hydrolysis treatments. The benzoic acid (p-hydroxybenzoic, vanillic, and protocatechuic acids) and cinnamic acid derivatives (coumaric, caffeic, ferulic, and chlorogenic acids) were identified, and some of the phenolic acids were quantified after each above-mentioned treatment. The data indicated that a combination of sequential acid, alpha-amylase, and cellulase hydrolysis treatments might be applicable for release of more phenolic acids from barley.     

Simultaneous determination of oxytetracycline, tetracycline, and chlortetracycline in milk by liquid chromatography

A simple, rapid procedure is described for the simultaneous quantification of 3 tetracycline drugs in bovine milk. Samples are prepared by dilution with an EDTA/phosphate buffer solution and filtration through a molecular weight cutoff filter. Analytes are concentrated on-column using a reverse-phase gradient elution system of oxalic acid, acetonitrile, and methanol. The limits of quantitation are approximately 15-50 ng/mL and the limits of detection are 10-20 ng/mL, depending on the compound. For oxytetracycline, over the range 50-1200 ng/mL, the average recovery and intralaboratory coefficient of variation were 97% and 4.1%, respectively. Over the same range, these parameters were, respectively, 97% and 5.0% for tetracycline, and 89% and 6.4% for chlortetracycline. The applicability of this procedure is demonstrated by separation and detection of incurred tetracycline residues in milk from treated animals.     

Simultaneous determination of four biogenic and three volatile amines in anchovy by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry

A new method has been developed and validated for the simultaneous determination of four biogenic (putrescine, cadaverine, histamine, and tyramine) and three volatile amines (trimethylamine, triethylamine, and tripropylamine) in anchovy. Separation and determination of the selected compounds were carried out by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS), using an electrospray ionization source (ESI) in positive ion mode. Chromatographic separation was carried out using an aqueous solution of formic acid (0.1%) and methanol as mobile phase in gradient mode. The method was validated, and mean recoveries were evaluated at three concentration levels (75, 150, and 250 μg/kg), ranging from 70 to 110% at the three levels assayed. Intra- and interday precision, expressed as relative standard deviation (RSD), were lower than 15% and 20%, respectively. Limits of quantitation (LOQs) were 25 μg/kg for all cases, except for that of TMA, which was set at 60 μg/kg. The developed procedure was applied to determine the target compounds in anchovy samples stored during 7 days at 4 °C, observing the increasing in the concentration of these compounds at longer storage time.     

Simultaneous determination of neonicotinoid insecticides in agricultural samples by solid-phase extraction cleanup and liquid chromatography equipped with diode-array detection

Effective sample pretreatment procedures based on solid-phase extraction (SPE) for multiresidue determination of seven neonicotinoid insecticides in agricultural products were investigated. After extraction with acetone and concentration, the insecticides in aqueous sample extracts were transferred into organic solvent phases with a Chem Elut SPE cartridge. Finally, the eluate from the cartridge was cleaned up with a SPE cartridge packed with graphitized carbon black and aminopropyl silica gel, which showed a higher cleanup efficiency than the classical silica gel SPE cartridge. Seven insecticides were separated on a reversed-phase C18 column and a gradient system of methanol and phosphate solution based on high-performance liquid chromatography. The established multiresidue determination has been applied to several artificially spiked agricultural samples, with the result that the average recoveries were excellent, with the exception of nitenpyram. The limit of detection of the method ranged from 0.01 to 0.03 mg/kg for the insecticides.     

Simultaneous determination of thiamin and riboflavin in mushrooms by liquid chromatography

A simple, fast, inexpensive, and reliable method useful for the simultaneous, routine determination of thiamin and riboflavin in mushrooms is examined. It uses the extraction procedure, with slight modifications, proposed by the AOAC for the extraction of thiamin and riboflavin, followed by a liquid chromatographic separation on a reversed-phase Spherisorb ODS column with methanol/water as mobile phase gradient. Fluorometric detection is used at the following excitation and emission wavelengths, respectively, 360 and 425 nm in the case of thiamin and 422 and 515 nm for riboflavin. The analytical parameters of linearity, the precision of the method (RSD = 2.45 and 2.51% for thiamin and riboflavin, respectively), and the results of the comparison with the corresponding AOAC fluorometric methods show that the studied method is useful for the measurement of thiamin and riboflavin in fresh mushrooms.     

Simultaneous determination of thiamine and riboflavin in foods by liquid chromatography

Recent methods for determination of thiamine (thiochrome) and riboflavin by liquid chromatography (LC) are outlined and discussed, and a new method allowing the simultaneous determination of these 2 vitamins by using a single fluorescence detector is described. This system involves an ODS 5 micron ultrasphere column and a pH 7.5 mobile phase composed of 0.005M tetrabutyl ammonium phosphate in methanol-water (20 + 80).     

Simultaneous determination of terbuthylazine and its major hydroxy and dealkylated metabolites in wetland water samples using solid-phase extraction and high-performance liquid chromatography with diode-array detection

A method based on high-performance liquid chromatography with diode-array detection was developed and validated aiming at the simultaneous determination of terbuthylazine (TER) and its five major metabolites, desisopropyl-hydroxy-atrazine, desethyl-hydroxy-terbuthylazine, desisopropyl-atrazine, hydroxy-terbuthylazine, and desethyl-terbuthylazine. Although s-triazines are used worldwide as herbicides for agricultural and nonagricultural purposes, there is limited information on the environmental impact of TER degradation products. The proposed method includes a solid-phase extraction procedure (using MCX cartridges) with adequate recovery efficiency (70-80%). The statistical evaluation of the method reveals good linearity, accuracy, and precision for the compounds determined, with RSD values less than 14.6%, while the detection limit was found to be 0.05 microg L(-1) for DIHA and 0.01 microg L(-1) for the other substances. This method can be employed in biodegradation studies of TER and its metabolites in water samples from constructed wetlands, thus assisting the evaluation of their environmental impact.     

Analysis of tea catechins in human plasma by high-performance liquid chromatography with solid-phase extraction

Accurate monitoring of tea catechins in biological samples might provide a means of better evaluation of their benefits. The aim of the present study was to develop a rapid method for extracting tea catechins from human plasma samples with a solid-phase extraction technique and to subsequently measure their concentrations using an HPLC system. A human plasma sample spiked with known concentrations of the analyte standards was passed through a Waters Oasis HLB cartridge. After repeated washing, tea catechins were eluted with 70% dimethylformamide containing 0.1% phosphoric acid, and the resulting eluate was injected into an HPLC system. Analytes were separated on a reverse-phase C18 column using an isocratic mobile phase and detected electrochemically. The coefficient of variation for inter- and intraday reproducibility was less than 5.0% and 6.4%, respectively. Linearity was established for the concentration range of 0.01-1.0 microM. The method was successfully applied to measure tea catechin concentrations in the plasma of two healthy subjects who received a single ingestion of a green tea beverage. The proposed method enables the rapid and accurate quantitation of plasma tea catechins and might prove useful for the evaluation of beneficial health effects of tea consumption.     

Simultaneous determination of ginsenosides and polyacetylenes in American ginseng root (Panax quinquefolium L.) by high-performance liquid chromatography

A method for simultaneous determination of ginsenosides and polyacetylenes in Panax quinquefolium L. (American ginseng) roots was developed. The ginsenosides Rb1, Rb2, Rc, Rd, Re, Rg1, Ro, malonyl-Rb1, malonyl-Rc, and malonyl-Rd and the polyacetylenes falcarinol and panaxydol were extracted from fresh ginseng roots in a sequential extraction process with 100% methanol followed by 80% aqueous methanol and quantified simultaneously in extracts by high-performance liquid chromatography using diode array detection. Separations were achieved with a phosphate buffer-acetonitrile gradient system using an RP-C18 column. Except for Rd, the present extraction method resulted in similar or significantly higher concentrations of both ginsenosides and polyacetylenes in comparison to commonly used extraction methods for these compounds. The contents of polyacetylenes and ginsenosides were determined in the root hairs, lateral roots, and main roots of 6 year old ginseng plants. The total mean concentrations of ginsenosides and polyacetylenes in root hairs were 31.0 g/kg fresh weight (FW) and 2.6 g/kg FW, respectively, whereas the concentrations of these bioactive compounds in the main roots were significantly lower with total mean concentrations of 17.8 g/kg FW for ginsenosides and 0.6 g/kg FW for polyacetylenes. The concentration of individual and total ginsenosides and polyacetylenes did not differ significantly between main roots of different sizes. Consequently, it is possible to do quantitative screening for ginsenosides and polyacetylenes to breed ginseng roots with higher levels of bioactive compounds.     

Determination of aflatoxins in high-pigment content samples by matrix solid-phase dispersion and high-performance liquid chromatography

A fast, efficient, and cost-effective method was developed for the analysis of aflatoxins in farm commodities with high-pigment content, such as chili powder, green bean, and black sesame. The proposed method involved matrix solid-phase dispersion (MSPD) and high-performance liquid chromatography (HPLC)-fluorescence detection (FLD) with postcolumn electrochemical derivatization in a Kobra cell. The MSPD procedure combined the extraction with neutral alumina and pigment cleanup with graphitic carbon black (GCB) in a single step. The recoveries of aflatoxins ranged from 88% to 95% with the relative standard deviations (RSD) less than 6% (n = 6). The limits of detection (LODs) were 0.25 ng/g aflatoxin B1, G1, and 0.10 ng/g aflatoxin B2, G2, respectively. The analytical results obtained by MSPD were compared to those of the immunoaffinity column (IAC) cleanup method. No significant differences were found between the two methods by t-test at the 95% confidence level.     

Simultaneous determination of free amino acid content in tea infusions by using high-performance liquid chromatography with fluorescence detection coupled with alternating penalty trilinear decomposition algorithm

In this paper, a novel application of alternating penalty trilinear decomposition (APTLD) for high-performance liquid chromatography with fluorescence detection (HPLC-FLD) has been developed to simultaneously determine the contents of free amino acids in tea. Although the spectra of amino acid derivatives were similar and a large number of water-soluble compounds are coextracted, APTLD could predict the accurate concentrations together with reasonable resolution of chromatographic and spectral profiles for the amino acids of interest owing to its "second-order advantage". An additional advantage of the proposed method is lower cost than traditional methods. The results indicate that it is an attractive alternative strategy for the routine resolution and quantification of amino acids in the presence of unknown interferences or when complete separation is not easily achieved.     

Simultaneous determination of beauvericin, enniatins, and fusaproliferin by high performance liquid chromatography

A rapid, sensitive and inexpensive HPLC method for routine screening of beauvericin, fusaproliferin, and enniatin B(1), A(1), and B has been optimized. Detection limits were determined, ranging between 0. 5 and 3.6 ng according to the compound obtained after spiking samples with each mycotoxin at 10-56 microg/mL concentration range; recoveries averaging from 56 to 74% were obtained. LC-MS conditions for enniatin analyses by API electrospray technique were set up, this allowing a unique identification of three different enniatins.     

Determination of organic acids, sugars, diacetyl, and acetoin in cheese by high-performance liquid chromatography.

Sugars (lactose, glucose, and galactose), nonvolatile acids (citric, orotic, piruvic, lactic, ossalic, and hippuric), some free fatty acids (formic, acetic, propionic, butyric, isobutyric, valeric, and isovaleric), diacetyl, and acetoin were separated on an Aminex HPX-87H column using a simple isocratic HPLC method and identified by retention times with ultraviolet and refractive index detectors. With the proposed technique it is possible to evaluate the development of microbial fermentations and, at the same time, degree of cheese ripening.     

A new method for the determination of carbonyl compounds in wines by headspace solid-phase microextraction coupled to gas chromatography-ion trap mass spectrometry

A new analytical method for the determination of 18 carbonyl compounds [2,3-pentadione, hexanal, (E)-2-hexen-1-al, octanal, acetoin, (E)-2-octenal, furfural, decanal, (E)-2-nonenal, benzaldehyde, 5-methylfurfural, (E,E)-2-cis-6-nonadienal, β-damascenone, phenylacetaldehyde, acetophenone, (E,E)-2,4-decadienal, benzophenone, and vanillin] in wines using automated headspace solid-phase microextraction (HS/SPME) coupled to gas chromatography-ion trap mass spectrometry (GC-ITMS) was developed. Five fibers with different polarities were tested, and a study of the influence of various factors such as time and extraction temperature, desorption time and temperature, pH, and ionic strength and content in tannins, anthocyans, sucrose, SO(2), and alcoholic degree was conducted. These factors were optimized using a synthetic wine doped with the different analytes. The proposed method affords wide ranges of linearity, good linearity (r(2) > 0.998), values of repeatability and reproducibility lower than 5.5% of RSD, and detection limits ranging from 0.62 μg/L for β-damascenone to 129.2 μg/L for acetoin. Therefore, the optimized method was applied to the quantitative analysis of the aforementioned analytes in real samples of wines.     

Simultaneous assay for six alkaloids in opium, using high-performance liquid chromatography.

A method is described for the quantitative determination of morphine, codeine, cryptopine, thebaine, papaverine, and narcotine in opium by high-performance liquid chromatography. The alkaloids are isolated from a dilute acid extract by adsorption on an Amberlite XAD-2 resin column and eluted first with methanol and then with chloroform-methanol (3+1). After solvent removal by reduced pressure evaporation, the alkaloids are redissolved in chloroform-methanol (3+1). The sample solution, plus brucine as an internal standard, is injected onto a Corasil II column and eluted with hexane that is gradient programmed with a solution of chloroform-methanol-diethylamine (100+300+1). The absorbances of the separated alkaloids are continuously monitored at 254 nm, using a flow-through ultraviolet double-beam photometer.     

Quantitation of o- and p-sulfamoylbenzoic acids in commerical saccharin by high-performance liquid chromatography.

Quantitation of o- and p-sulfamoylbenzoic acid residues in saccharin and its sodium salt is achieved by a method comprising methanolic extraction and high-performance ion exchange chromatography. A commercially available anion exchange column was employed with an aqueous buffered (pH 9.2) mobile phase. As little as 80 ppm of the ortho-isomer and 25 ppm of the para-isomer can be accurately determined. The levels of detectability (2 times noise) are estimated as 8 ppm (0.16 mug on column) and 2.5 ppm (0.05 mug on column), respectively. Recoveries from saccharin ranged from 92.7 to 96.5% (ortho) and from 92.2 to 103.3% (para). Recoveries from the sodium salt ranged from 93.1 to 104.4% (ortho) and from 93.5 to 97.8% (para). Of 9 other potential saccharin impurities tested separately, only one was found to interfere slightly in the chromatographic part of the procedure.