Extraction and determination of the potato glycoalkaloid α -solanine in soil

The toxic glycoalkaloids α-solanine and α-chaconine are produced in all parts of the potato plant, and post-harvest potato tubers may represent a source of soil and water contamination. A new method was developed for extraction and purification of α-solanine in soil samples. Soil samples were extracted with THF?:?H₂O?:?ACN?:?CH₃COOH (50?:?30?:?20?:?1) and the extract purified by SPE before HPLC determination of α-solanine. The limit of detection was 2.4?mg of α-solanine?kg^?1 soil. The new procedure was used for determination of α-solanine in spiked soils with varying content of organic matter and texture. Recovery for soil samples spiked with α-solanine 1?h before extraction was 61–68% for soils low in organic carbon (<2.2% C), and to 47% for soil high in organic carbon. Similar recoveries were obtained for α-chaconine. The reproducibility of the method shown by the relative standard deviation varied from 1.7 to 10.1%, depending on the soil type. No decrease in extractable α-solanine was observed until day 17 for soil samples spiked with pure α-solanine kept at 5°C, while the content in samples spiked with potato materials showed a faster decline. This indicates that the degradation and/or ageing processes proceed relatively slowly for glycoalkaloids in soil matrices. This is the first method reported for determination of potato glycoalkaloids in soil.     

Simultaneous determination of eight adulterants in weight management supplements and herbs by HPLC–DAD and LC–MS/MS

An efficient HPLC–DAD method was developed for simultaneous determination of eight adulterants in weight management supplements and herbs. The eight adulterants were phenolphthalein, sibutramine, nuciferine, and five anthraquinone compounds including aloe-emodin, rhein, emodin, chrysophanol, and physcion. The analytes were ultrasonically extracted with 70% (v/v) methanol aqueous solution followed by centrifugation. The supernatant was subjected to HPLC analysis. A Phenomenex Luna C18 column was applied for chromatographic separation. The mobile phase was consisted of methanol and aqueous solution of 0.05% (v/v) phosphoric acid–0.025% (m/v) sodium dodecyl sulfonate. The flow rate of mobile phase was 0.8?ml?min^?1 with gradient elution. Clenbuterol and ibuprofen were used as internal standards. The retention times and the characteristic UV spectrograms were used for qualitative analysis. Quantifications were based on the internal standard curves. Good linearities (r?>?0.9996) for all analytes were obtained with the intra- and inter-day precision (n?=?6) ranging from 0.76 to 5.9% and 0.90 to 8.1%, respectively. The average recoveries from the spiked samples with different matrices varied from 73.4 to 114%. Validations were subsequently performed using LC–MS/MS. The proposed method successfully determined the target adulterants in eight commercial weight management supplements and five weight reducing herbs with satisfactory results.     

Experimental strategy of the spectrophotometric approach using freeze-drying for PO43− determination in frozen and chilled chickens in the Saudi Arabia market

Herein, an efficient analytical method based on an extraction protocol was developed and validated for the spectrophotometric detection of phosphate (PO₄^3?) in chilled and frozen chicken samples. The preparation was a very simple sample that included freeze-drying, extraction with acidified amino acids and filtration of the final extract prior to spectrophotometric analysis. FT-IR spectrum of CS1 was confirmed that the selected solvent has successfully extracted PO₄^3? from the chilled chicken sample. Analytical performances were assessed in chilled of one of the merchant species and showed good recoveries with relative standard deviations (RSD) below 2%. The analytical validation parameters of the method in terms of limit of quantification (LOQ) and detection (LOD) were calculated and found to be 0.10 and 0.032 mg/L, respectively. This protocol has been effectively applied to PO₄^3? determination in chicken samples collected from Saudi supermarkets (Northern KSA), and PO₄^3? in all frozen samples was detected at high mg/kg levels ranging from 2.11 × 10⁴ to 2.90 × 10⁴ mg/kg, while in limit levels of PO₄^3? concentration were detected in the chilled samples except chilled sample 1 (CS1), which was 2.22 × 10⁴ mg/kg. The extraction and determination protocol suggested that this developed method could be validated for routine monitoring of PO₄^3? in food quality control laboratories and safety monitoring.     

Ultrasound-assisted emulsification–microextraction for the sensitive determination of ethyl carbamate in alcoholic beverages

A method based on ultrasound-assisted emulsification–microextraction (USAEME) was proposed in this contribution for the determination of ethyl carbamate (EC) in alcoholic beverages using gas chromatography coupled to triple quadrupole mass spectrometry. To achieve the determination of EC in alcoholic beverages, the influences on the extraction efficiency of type and volume of extraction solvent, temperature, ionic strength, alcohol content, and extraction time were studied, once the extraction solvent had been selected. The optimized conditions were 200.0 μL of chloroform at 30 °C during 5 min with 15 % (m/v) sodium chloride addition. The detection limit, relative standard deviations, linear range, and recoveries under the optimized conditions were 0.03 μg L^?1, 4.2–6.1 %, 0.1–50.0 μg L^?1, and 80.5–87.9 %, respectively. Moreover, the feasibility of the present method was also validated by real samples. To the best of our knowledge, this is the first time that USAEME has been applied to determine a strongly hydrophilic compound in alcoholic beverages.

Comparison of HPLC–DAD and LC–MS Techniques for the Determination of Tetracyclines in Medicated Feeds Using One Extraction Protocol

Chromatographia - Four antibiotics, oxytetracycline, tetracycline, doxycycline, and chlortetracycline were separated and quantified in medicated feed. Tetracyclines from feed samples were extracted...     

High-Throughput Screening of Drugs of Abuse in Urine by Supported Liquid–Liquid Extraction and UHPLC Coupled to Tandem MS

A qualitative method, involving supported liquid–liquid extraction (SLE) and ultra high pressure liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS–MS), was developed for the rapid tentative identification of various drugs of abuse in urine. In this study, 28 drugs and metabolites were covered by the screening procedure. Before analysis, urine samples were extracted by SLE and good extraction recoveries were obtained for most investigated compounds. The UHPLC strategy was then selected for the rapid separation of amphetamines, cocaine, opiates and related compounds in urine. Using columns packed with sub-2 µm particles, analysis time was reduced down to 2 min, while maintaining acceptable performance. Finally, the detection was by tandem MS operating in the single reaction monitoring (SRM) mode. The most intense transition was selected for the different drugs and SRM dwell times set at 5 ms, to maintain sufficient data points across the narrow UHPLC peaks. The tentative identification of the drugs of interest, including amphetamines, opiates and cocaine, was based on both, retention times and mass spectrometry information. With the proposed method, limits of detection were estimated at about 1 ng mL^?1 and the applicability was assessed by successfully analyzing several samples of drug abusers. Finally, this study demonstrates the potential of UHPLC coupled to tandem MS for the rapid screening of drugs of abuse in urine.     

Microwave-Assisted Extraction of Melamine Residues from Pet Food and Analysis by Ion-Exchange LC–DAD

Melamine is attracting much attention because of its toxicity. In the work discussed in this paper, microwave-assisted extraction in combination with ion-exchange high-performance liquid chromatography with diode-array detection was used for analysis of melamine in pet food. Trichloroacetic acid–N,N-dimethylformamide 10:1 was the best extractant, because of the strong polarity of melamine. Separation was performed on a 250 mm × 4.6 mm i.d., 5-μm particle, cation-exchange column; isocratic elution with a mixture of ammonium formate solution (pH 3.0) and acetonitrile was complete within 10 min. UV absorbance DAD detection was performed at 240 nm. Response was a linear function of melamine concentrations from 0.1 to 50 μg mL^?1, with a detection limit of 1.0 mg kg^?1. Intra-day and inter-day precision, as RSD, was <3% and the recovery of the assay was in the range 95.4–106.8%. In analysis of spiked pet food, the new method yielded satisfactory results. Because of its simplicity and accuracy this straightforward method is particularly suitable for routine melamine analysis.     

Simultaneous determination of six major ergot alkaloids and their epimers in cereals and foodstuffs by LC–MS–MS

This paper describes a new and rapid method for accurate quantification of the six ergot alkaloids, ergometrine, ergotamine, ergosine, ergocristine, ergocryptine, and ergocornine, by liquid chromatography–tandem mass spectrometry (LC–MS–MS). The six ergot alkaloids studied have been defined by the European Food Safety Authority (EFSA) as among the most common and physiologically active ones. In addition, the method enables the quantification of the corresponding six epimers (ergo-inines) of these ergot alkaloids. This is of considerable importance in terms of the differences in toxicity of the isomeric forms. The method involves extraction under alkaline conditions using a mixture of acetonitrile and ammonium carbonate buffer followed by a rapid clean-up using dispersive solid-phase extraction with PSA (primary secondary amine) and a short chromatographic LC-run (21 min) with subsequent MS–MS detection. The method was developed and validated using ten different cereal and food samples. The major strength of the new method compared with previously published techniques is the simplicity of the clean-up procedure and the short analysis time. The limits of quantification were 0.17 to 2.78 μg kg⁻¹ depending on the analyte and matrix. Recovery values for the 12 ergot alkaloids spiked into ten different matrices at levels of 5, 50, and 100 μg kg⁻¹ were between 69 and 105% for 85 of 90 recovery measurements made over six days. Measurement uncertainty values were highly satisfactory. At a concentration level of 5 μg kg⁻¹ the expanded measurement uncertainty ranged from ±0.56 to ±1.49 μg kg⁻¹, at a concentration level of 100 μg kg⁻¹ the expanded measurement uncertainty ranged from ±8.9 to ±20 μg kg⁻¹. Both LOQs and measurement uncertainties were dependent on the analyte but almost independent of the matrix. The method performance was satisfactory when tested in a mini-intercomparison study between three laboratories from three different countries. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Co-isolation of deoxynivalenol and zearalenone with sol–gel immunoaffinity columns for their determination in wheat and wheat products

The paper describes a sample clean-up method for the co-isolation of deoxynivalenol (DON) and zearalenone (ZON), two mycotoxins naturally co-occurring in wheat. The method is based on immunoaffinity columns prepared by co-immobilising anti-DON and anti-ZON antibodies in a porous sol–gel glass. The main task in developing the method consisted in finding a loading medium allowing retention of both analytes as well as a common elution medium for the dissociation of both antigen–antibody complexes formed. This can be achieved by co-extracting DON and ZON with ACN–water (60:40, v/v), reducing the acetonitril concentration to 2.5% before loading an aliquot of the diluted sample extract onto the DON/ZON column. The columns are washed with 5 ml of MeOH–water (10:90, v/v) before DON and ZON are co-eluted with 4 ml of ACN–water (50:50, v/v). Concentrations of DON and ZON are determined with HPLC-UV and HPLC-fluorescence detection, respectively. The sample clean-up method was shown to be applicable to wheat and wheat products, e.g., cornflakes, milk wheat mash and rusk. Spiking experiments (spike level 500 μg DON/kg and 50 μg ZON/kg) resulted in recovery rates from 82% to 111%.     

Application of ACC method to synchronous luminiscence: determination of α-tocopherol and α-tocopheryl acetate in beverages

A new method based on the Q parameter, that permits the determination of the C_{compound A} /C_{compound B} ratio without preparing calibration graphs of the two compounds, is proposed. This method has been applied to signals obtained by synchronous luminiscence. Simultaneous determination of α-tocopherol and α-tocopheryl acetate in beverages using synchronous fluorescence has been carried out. To isolate the compounds from samples, liquid extraction with n-hexane as the organic phase was employed. The presence of interferences was tested using the apparent content curves (ACC) method and the C_{α-tocopherol}/¶C_{α-tocopheryl acetate} ratio was calculated using the Q parameter. The reproducibility and detection limit for the determination of α-tocopherol and α-tocopheryl acetate were 6.6% and 0.016 mg/L and 1.8% and 0.017 mg/L, respectively.     

Fast SPE and HPLC–DAD determination of brucine in human urine using multi-walled carbon nanotubes modified with magnetic nanoparticles

A nanomaterial comprising Fe₃O₄-modified hydroxylated multi-walled carbon nanotubes (Fe₃O₄–MWCNTs–OH) was prepared by a co-precipitation method. Combined with HPLC-photodiode array detector (DAD), Fe₃O₄–MWCNTs–OH was used to determine brucine in human urine. Some important parameters that could influence extraction efficiency of brucine were optimized, including the extraction time, amounts of Fe₃O₄–MWCNTs–OH, pH of sample solutions, desorption solvent and desorption time. Under the optimal conditions, the recoveries of brucine from spiked urine samples were between 93.1 and 104.1%, and the relative standard deviations (RSDs) ranged from 3.1 to 5.7%. The correlation coefficient was 0.9997. The limits of detection and quantification were 6 and 21 ng/mL at a signal-to-noise ratio of 3 and 10, respectively. The results indicated that Fe₃O₄–MWCNTs–OH combined with HPLC–DAD is a promising solid-phase extraction material for the sample pretreatment in the determination of brucine.     

Simultaneous determination of amodiaquine and pioglitazone on dried blood spots (DBS) by HPLC–DAD and its usefulness in pharmacokinetic studies

A simple and rapid method for simultaneous determination of amodiaquine and pioglitazone in dried blood spots (DBS) was developed and validated. Blood samples were spotted on protein saver cards and dried and a 4-mm punch was extracted with methanol first and later with 1% acetic acid and dichloromethane. The separation was achieved on a C8 Zorbax Eclipse XDB analytical column (4?µm, 150?×?4.6?mm² i.d.) at 27°C with a mobile phase of methanol/0.2% acetic acid (60:40) at a flow rate of 0.8?mL/min and detected at 230?nm. The method was linear over the range 2–80?ng/mL for amodiaquine and 10–1500?ng/mL for pioglitazone with correlation coefficients greater than 0.9995. The limits of detection were 1.12 and 10.93?µg/L and the limits of quantification were 3.39 and 33.11?µg/L for amodiaquine and pioglitazone, respectively. The inter- and intra-day precision were <6.7 and <7% for amodiaquine and <6.3 and <3% for pioglitazone. The method was applied to estimate the pharmacokinetic (PK) parameters in four healthy volunteers and it was found to yield identical PK profiles with other earlier methods supporting the use of DBS as an alternative for PK study.     

Preparation of β-caryophyllene oxidation products and their determination in ambient aerosol samples

Oxidation of β-caryophyllene with ozone followed by reduction was carried out in dichloromethane. Reaction led to the formation of β-caryophyllene aldehyde (11%, purity 90.8%) and β-nocaryophyllone aldehyde (79%, purity 99%). Compounds were purified and separated by liquid–liquid extraction and flash chromatography. Identifications were achieved by electron-impact and electrospray ionization mass spectrometry, and precise structures were confirmed by one and two-dimensional nuclear magnetic resonance spectroscopy. The prepared compounds were used in the analysis of ambient aerosol samples collected during spring 2003 at Hyytiälä, Finland. β-Nocaryophyllone aldehyde was positively identified and quantified in ambient aerosol samples for the first time. The amount of quantified β-nocaryophyllone aldehyde of aerosol origin was 17.4?±?1.0 ng m^?3 of sampled air. Comparison with previous findings led to the conclusion that oxidation products of β-caryophyllene participate in biogenic aerosol formation over boreal forest during late spring.     

Development of a green stability-indicating HPLC–DAD method for the determination of donepezil hydrochloride in the presence of its related substance and degradation products

A simple, eco-friendly, stability-indicating HPLC method was developed for the determination of donepezil hydrochloride (DH) in tablet dosage form in the presence of its pharmacopoeia-related compound (donepezil-related compound A) and its different degradation products. The chromatographic conditions were optimized to achieve the highest performance parameters using Zorbax Eclipse Plus C18 rapid resolution column (4.6?×?100?mm, 3.5?µm), with a mobile phase composed of 72.5% acetate buffer pH 5.5 and 27.5% ethanol, flowing at 1?mL?min^?1. The diode array detector (DAD) was set at 315?nm and the column oven was adjusted at 45°C. Linear response (r?=?0.9999) was observed over the range of 2–28?µg?mL^?1 of donepezil, with detection and quantitation limits of 0.031 and 0.103?µg?mL^?1, respectively. Forced degradation studies were performed on standard DH and test Demepezil® 5-mg tablets under various conditions and the method was found to be stability indicating. The purity of DH peak was confirmed using the DAD. In the developed method, two principles of green chromatography were adopted (reduce and replace) by reducing solvent consumption through the utilization of a short column (10?cm) with a smaller particle size (3.5?µm) instead of a normal 25?cm with a 5?µm particle size and by replacing hazardous solvents of the official United States Pharmacopoeia method as acetonitrile with ethanol. Furthermore, the greenness of the method was assessed using three assessment tools.     

UHPLC method for the simultaneous determination of β-blockers, isoflavones, and flavonoids in human urine

A simple method using solid-phase extraction (SPE) and ultra high-performance liquid chromatography (UHPLC) for the simultaneous determination of β-blockers, isoflavones, and flavonoids in human urine is developed. A statistical central composite design and response surface analysis is used to optimize the separation of the analytes. These multivariate procedures are efficient in determining the optimal separation condition using resolutions and retention time as responses. A gradient elution using a mobile phase consisting of 0.05% trifluoroacetic acid in water and acetonitrile is applied on a Hypersil GOLD column within a short analysis time of 4.5 min. UV detection was used to monitor the analytes. The suggested method was linear in a concentration range from 0.04-20.00 μg/mL, depending on the compound. The limits of detection ranged from 8.9 to 66.2 ng/mL. The precision was lower than 2.74%, and the accuracy was between 0.01-3.65%. The Oasis HLB column, with the highest recoveries, is selected for the pre-concentration step. This present paper reports, for the first time, a method for the simultaneous determination of β-blockers, isoflavones, and flavonoids in human urine samples. Furthermore, the developed method can also be applied to the routine determination of examined compounds concentrations in human urine.     

Simultaneous determination of deoxynivalenol,zearalenone, and their major masked metabolites in cereal-based food by LC–MS–MS

Cereals and cereal-based food have often been found to be contaminated with the mycotoxins deoxynivalenol (DON) and zearalenone (ZON), after infection of the grain with the pathogenic fungus Fusarium. Both the pathogen and the infected plants can chemically modify DON and ZON, including acetylation, glucosidation, and sulfation. Analytical strategies for detection and quantification of DON and ZON are well known and established but often fail to recognize the respective metabolites, which are, therefore, also referred to as “masked” mycotoxins. However, several masked forms are also known to be harmful to mammals. Failure to detect these could lead to significant underestimation of the toxic potential of a particular sample. To monitor the levels of DON and ZON metabolites in cereals and cereal-based food, we have developed a LC–MS–MS method capable of simultaneous determination of DON, ZON, and eight of their masked metabolites, namely deoxynivalenol-3-glucoside (D3G), 3-acetyl-deoxynivalenol (3ADON), zearalenone-4-glucoside (Z4G), α-zearalenol (α-ZOL), β-zearalenol (β-ZOL), α-zearalenol-4-glucoside (α-ZG), β-zearalenol-4-glucoside (β-ZG), and zearalenone-4-sulfate (Z4S). The suitability of several cleanup strategies including C₁₈-SPE, primary and secondary amines (PSA), MycoSep push-through columns, and immunoaffinity columns was evaluated. The final method used no sample cleanup and was successfully validated for four cereal-based food matrices, namely cornflour, porridge, beer, and pasta, showing good recoveries and precision for all analytes.