María T. Martín

High-performance liquid chromatographic determination of methyl anthranilate, hydroxymethylfurfural and related compounds in honey☆

A high-performance liquid chromatographic method for determining 5-hydroxymethyl-2-furaldehyde (hydroxymethylfurfural), 2-furaldehyde (furfural), furan-2-carboxylic acid (2-furoic acid), furan-3-carboxylic acid (3-furoic acid), furan-3-carboxaldehyde (3-furaldehyde) and 2-aminobenzoic acid methyl ester (methyl anthranilate) in honey and honeydew samples is described. To prevent matrix interference and to isolate the compounds, a clean-up step which implies a solid-phase extraction on polymeric cartridges and an elution with 0.5 ml methanol is recommended. The compounds are separated on a reversed-phase column with a gradient of (A) 1% aqueous acetic acid-acetonitrile (97:3, v/v) and (B) acetonitrile-water (50:50, v/v), with UV detection at 250 nm. The method is applied to the analysis of samples from different botanical origin.

Supercritical fluid chromatography in food analysis

In the last years, supercritical fluid chromatography (SFC) has increased its acceptance between scientists. The unique selectivity, short analysis times, low consumption of organic solvents as well as the improvements in instrumentation have contributed to expand its use. These characteristics make SFC a powerful tool when food analysis requires individualized evaluation of several compounds in very complex samples. In this work, the advantages and main applications of SFC in food analysis are reviewed, focusing special attention onto analytical and preparative separations.

Determination of seven neonicotinoid insecticides in beeswax by liquid chromatography coupled to electrospray-mass spectrometry using a fused-core column.

A new method has been developed to measure seven neonicotinoid insecticides (acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram, thiacloprid and thiamethoxam) in beeswax using liquid chromatography (LC) coupled to electrospray ionization mass spectrometry (ESI-MS) detection. Beeswax was melted and diluted in an n-hexane/isopropanol (8:2, v/v) mixture. After this, liquid extraction with water was performed followed by a clean-up on diatomaceous material based cartridges. The compounds were eluted with acetone, and the resulting solution was evaporated until dry and reconstituted with a mixture of water and acetonitrile 50:50 (v/v). The separation of all compounds was achieved in less than 15 min using a C18 reverse-phase fused-core column (Kinetex C18, 150 mm × 4.6 mm i.d.) and a mobile phase composed of a mixture of 0.1% formic acid in water and acetonitrile in gradient elution mode at 0.5 mL/min. This method was fully validated in terms of selectivity, linearity, precision and recovery. Low limits of detection and quantification could be achieved for all analytes ranging from 0.4 to 2.3 μg/kg, and from 1.5 to 7.0 μg/kg, respectively. Finally, the proposed method was applied to an analysis of neonicotinoid residues in beeswax samples from apiaries located close to fruit orchards.

Development and validation of an LC assay for sumatriptan succinate residues on surfaces in the manufacture of pharmaceuticals

A high performance liquid chromatographic (HPLC) method for the assay of sumatriptan succinate residues in swabs collected from manufacturing equipment surfaces was developed and validated in order to control a cleaning procedure. The swabbing procedure using two cotton swabs moistened with water was validated applying a wipe-test and a HPLC method developed to determine low quantities of the drug. The HPLC method involves a C18 column at 25 degrees C, a mixture of ammonium phosphate monobasic (0.05 M)-acetonitrile (84:16, v/v) as a mobile phase and UV detection at 228 nm. Using the proposed method, the average recoveries obtained are of 88.5% for vinyl, 94.2% for glass and 95.2% for stainless steel plates with RSD of 5.5 (n=36), 2.3 (n=36), 2.2% (n=36), respectively. The method was successfully applied to the assay of real swab samples collected from the equipment surfaces.

A new and simple method to determine trace levels of sulfonamides in honey by high performance liquid chromatography with fluorescence detection.

A novel method for the simultaneous analysis at trace level of sulfonamides (sulfaguanidine, sulfanilamide, sulfacetamide, sulfathiazole, sulfapyridine, sulfachloropyridazine, sulfamerazine, sulfameter, sulfamethazine, sulfadoxine, sulfadiazine, sulfamonomethoxine, sulfadimethoxine) in honey is described. Methanol has been used in the sample treatment step to avoid the emulsion formation and to break the N-glycosidic bond between sugars and sulfonamides. The determination is carried out by liquid chromatography in gradient elution mode, with fluorescence detection after the on-line pre-column derivatization with fluorescamine. The influence of parameters such as the mobile phase composition, column temperature, pH or injection volume, on the separation has been taken into account and the derivatization step has also been optimized. Recoveries of the compounds on spiked honey samples ranged from 56% for sulfadoxine to 96% for sulfacetamide, with relative standard deviations below 10%. The quantitation limits are between 4 and 15 ng g(-1).

Validation of the removal of acetylsalicylic acid recovery and determination of residues on various surfaces by high performance liquid chromatographic

The validation of a procedure to clean glass, vinyl and stainless steel surfaces that have been exposed to acetylsalicylic acid during its manufacture is described. The cleaning procedure using two cotton swabs moistened with the mobile phase was validated using a wipe-test and a high-performance liquid chromatography (HPLC) method developed to determine low quantities of the acid. The HPLC method involves an octadecylsilane column at 55 degrees C, a mixture of water-acetonitrile-orthophosphoric acid (779:220:1, v/v) as mobile phase and detection at 226 nm. Recoveries of 86%, 90% and 94% were obtained from vinyl, glass and stainless steel plates respectively. The validation gave acceptable levels of sensitivity, recovery, precision and linearity.

Development and application of a liquid chromatography-mass spectrometry method to evaluate the glyphosate and aminomethylphosphonic acid dissipation in maize plants after foliar treatment.

A simple and fast method has been developed and validated to measure glyphosate (GLYP) and aminomethylphosphonic acid (AMPA), which were previously derivatized with 9-fluorenylmethylchloroformate (FMOC-Cl), in maize plants using liquid chromatography (LC) coupled to fluorescence (FLD) and electrospray ionization mass spectrometry (ESI-MS) detection. The method has shown to be consistent, reliable, precise, and efficient. Moreover, the limits of detection (LOD) and quantification (LOQ) reached with the proposed method for GLYP and AMPA are lower than the established maximum residue levels (MRLs). The validated method was applied to quantify GLYP and AMPA in genetically modified (GM) maize foliar treated with the herbicide. It has been found that the GLYP dissipation was mainly due to the progressive dilution effect after herbicide treatment. Finally, it was also observed that the GLYP residue dissipation trend in maize shoot (leaves and stem) tissue determined by LC-ESI-MS matched that determined by liquid scintillation.

Validation of a liquid chromatographic method for the determination of ranitidine hydrochloride residues on surfaces in the manufacture of pharmaceuticals

A liquid chromatographic method for determination of the residues of ranitidine hydrochloride on various surfaces employed in drug manufacture is described. Cotton swabs, moistened with a methanol-water (1:1, v/v) mixture were used to remove any residues of drugs from glass, vinyl, and stainless steel surfaces, and gave recoveries of 85%, 78% and 90%, respectively. Residues were determined by high-performance liquid chromatography on a C18 column at 25 degrees C with methanol-ammonium acetate (40:60 v/v) pH 6.7 as the mobile phase and detection at 320 nm. The method was validated over a concentration range of 20-10 000 ng/ml and had a detection limit of 2 ng/ml.

Residues of neonicotinoids and their metabolites in honey and pollen from sunflower and maize seed dressing crops.

A study was carried out to evaluate the possible presence of thiamethoxam, clothianidin and imidacloprid, as well as the metabolic breakdown products of these three neonicotinoids in pollen and honey obtained from brood chamber combs of honeybee colonies located next to sunflower and maize crops from coated seeds. Samples were analyzed by liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry detector, in combination with accurate mass tools such as diagnostic ions by exact mass, chlorine mass filters, and MS/MS experiments. The presence of thiamethoxam and clothianidin was confirmed in some of the pollen samples analyzed. Moreover, different metabolites of neonicotinoids were tentatively detected in the pollen and honey samples collected. The results suggested that four metabolites were found in the honey samples, while for pollen samples eleven metabolites were identified; among these, five were considered for the first time as metabolic breakdown products in sunflower and maize plants.

Capillary electrophoresis–mass spectrometry as a new approach to analyze neonicotinoid insecticides

This paper represents the first report of a capillary electrophoresis (CE) method compatible with mass spectrometry (MS) detection for simultaneously analyzing seven neonicotinoid insecticides (acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram, thiacloprid and thiamethoxam). Different variables affecting CE separation (buffer concentration, pH, applied voltage and injection time) and MS detection (electrospray parameters) were studied. Low limits of detection (LOD) and quantification (LOQ) were achieved for all analytes, ranging from 1.0 to 2.3μg/L, and from 3.5 to 7.2μg/L, respectively. In addition, the proposed method showed itself to be linear in the range from LOQ to 1000μg/L and to be precise, as the relative standard deviations of the migration times were lower than 4% in all cases. Finally, the proposed CE-MS method was applied to assess the efficacy of a beeswax cleaning treatment with oxalic acid to remove residues of three of the most commonly used neonicotinoids (clothianidin, imidacloprid and thiamethoxam), use of which has recently been restricted by the European Union.