The simultaneous determination of vitamins A, E and β-carotene in bovine milk by high performance liquid chromatography–ion trap mass spectrometry (HPLC–MSn)

Bovine milk is considered to be a good dietary source of vitamins A, E and β-carotene. This paper describes a robust method for the simultaneous determination of these compounds using high performance liquid chromatography–ion trap mass spectrometry (HPLC–MSn) as the determinative step. The compounds were separated with a 5 μm Polaris 2.1 × 150 mm C18-A column and an aqueous-methanol mobile phase and the levels determined using the MS2 fragments (vitamin A, m/z 213 and m/z 199, vitamin E m/z 165 and β-carotene m/z 413). The HPLC–MSn was operated in the positive ion APCI mode. The method was validated using repeatability studies, duplicate analyses, recovery experiments, proficiency study data and comparison with previously validated high performance liquid chromatographic ultraviolet/visible (HPLC–UV/Vis) and fluorescence (HPLC–Fl) procedures used in our laboratory. Expanded measurement uncertainties were similar for HPLC–MSn, HPLC–UV/Vis and HPLC–Fl, e.g. vitamin A 45 μg/100 ml, HPLC–MSn ±8%, HPLC–UV ±9%; vitamin E 150 μg/100 ml, HPLC–MSn ±11%, HPLC–Fl ±9%; β-carotene 12 μg/100 ml, HPLC–MSn ±18%, HPLC–Vis ±21%

Supercritical Fluid Extraction of Pesticide Residues from Strawberries

A supercritical fluid extraction (SFE) method for the determination in strawberries of a number of commonly used organochlorine insecticides, organophosphorus pesticides, and dichloroanilide fungicides is described. Gas chromatography was used to examine the extracts, with both electron-capture detection and either flame photometric or nitrogen phosphorus detection. Confirmation was performed by gas chromatography-mass spectrometry. The analytes were extracted with supercritical carbon dioxide at 4000 psi and 50 °C with a run time of 20 min, which corresponded to an extraction volume of 20−30 mL of carbon dioxide. In developing the method, the operating parameters of temperature, pressure, extraction time, collection solvent, and sample preparation were optimized. Recoveries ranged from 74 to 126% (with the exception of iprodione), and a method precision of ±3−18% was obtained for spiking levels of 0.08−3.7 mg/kg. The method was validated for the following organochlorine insecticides and organophosphorus pesticides:  aldrin, dichloran, dieldrin, p,p‘-DDE(TDE), p,p‘-DDD, p,p‘-DDT, α-endosulfan, β-endosulfan, endosulfan sulfate, diazinon, dichlorvos, ethion, malathion, methyl parathion, methyl pirimiphos, mevinphos E+Z, and parathion; and the following dichloroanilide fungicides:  iprodione, procymidone, and vinclozolin. The SFE procedure was quicker, more environmentally friendly, and more cost effective than the traditional solvent extraction methods. Keywords: Supercritical fluid extraction (SFE); residue analysis; organochlorine insecticides; organophosphorus pesticides; dichloroanilide fungicides; strawberrie

The determination of vitamin D3 in bovine milk by liquid chromatography mass spectrometry

Over the last few years there has been increased interest in using liquid chromatography mass spectrometry (LC–MS). The aim of this study was to develop a straight forward, robust liquid chromatography-2D ion trap mass spectrometry (LC–MSn) procedure for the determination of endogenous levels of vitamin D3 in fresh bovine milk, commercially available bovine milk and infant formula for use in consulting and research laboratories

The determination of glucoraphanin in broccoli seeds and florets by solid phase extraction and micellar electrokinetic capillary chromatography

A robust method for the determination of glucoraphanin in broccoli (brassica oleracea ssp. italica ‘Marathon’) seeds and florets has been developed using solid phase extraction (SPE) and micellar electrokinetic capillary chromatography (MECC) as the determinative step. Glucosinolates were extracted from the broccoli seeds and florets with hot water. Unwanted impurities were removed by passing the extracts through C18 and protonated amino propyl SPE cartridges connected in series. The glucosinolate fraction was removed from the protonated amino propyl cartridge with 2% v/v ammonia solution in methanol. The solvent was removed with a stream of nitrogen, the residue dissolved in water and the level of glucoraphanin determined by MECC using a 77 cm × 75-μm id bare fused silica capillary column (effective length 69.4 cm) and a buffer consisting of 18 mM sodium tetraborate, 30 mM sodium dihydrogen orthophosphate and 30 mM cetyltrimethylammonium bromide, pH 7. MECC parameters and capillary conditioning procedures were optimised with respect to reducing the analysis time without compromising peak integrity. The level of glucoraphanin in broccoli seeds and florets compared favorably with the levels determined by a validated high performance liquid chromatography (HPLC) literature procedure; broccoli seeds MECC 2.1 gm/100 g, HPLC 2.0 gm/100 g; broccoli florets, MECC 71 mg/100 g, HPLC 70 mg/100 g. The MECC instrument reproducibility data (n = 7) for glucoraphanin in broccoli seed and floret extracts for migration time (CV; seeds 1.2%, florets 2%) and area calculation (CV; seeds 3.7%, florets 7%) relative to the internal standard were suitable

The isolation and purification of glucoraphanin from broccoli seeds by solid phase extraction and preparative high performance liquid chromatography

Plant foods contain not only essential nutrients, e.g. This paper reports a rapid method for the isolation and purification of glucoraphan in from broccoli seeds using solid phase extraction (SPE) and preparative HPLC based on a method developed in our laboratories for the quantification of glucoraphanin in broccoli seeds and broccoli florets