Inductively coupled plasma-mass spectrometry for the determination of elements and elemental species in food: a review

Inductively coupled plasma-mass spectrometry (ICP-MS) has definitely emerged as a powerful technique for total element determination and as a sensitive and selective detector in hyphenated methods for speciation analyses of elements in foods. In this review, the analytical challenges of elemental analysis of food and agricultural matrixes are discussed and several applications are examined. Selected examples illustrate the analytical approaches being used so far to address specific issues in various areas of food and nutrition research. The applications discussed include studies on dietary intake, element metabolism in man, transfer of elements through the food chain, effects of food processing and domestic preparation, and authenticity and origin assessment. The use of ICP-MS in the field of analytical quality assurance, food control, evaluation of food contact materials, and radionuclide contamination is also examined. Finally, the hyphenated techniques with ICP-MS detection used for elemental speciation in food are reviewed, and an overview of the main applications currently in the literature is presented. Throughout, recent trends and analytical developments likely to have a major impact on food-related areas are highlighted.     

Preparation and characterization of bolaform surfactant vesicles

Vesicular formulations (liposomes and niosomes) play an increasingly important role since they can be used as drug delivery and targeting systems. We described the formation of two niosomal systems based on synthetic bolaform surfactants (4,7,10,13-pentaoxa-16-aza-cyclooctadecane)-hexadecanedioc acid diamide (BD-16) and alpha,omega-(4,7,10,13-pentaoxa-16-aza-cyclooctadecane)-hexadecane (BC-16). Systems containing BD-16 or BC-16 and different amount of cholesterol (CH) were prepared by aqueous dispersion of films, followed by examination of methylene blue (MB) entrapment, particle size and morphology. Indeed, we also studied the hydration in the distilled water and physiological solution, in order to investigate the complexing ability on vesicle formation. The results obtained in this study show a high encapsulation capacity and this ability and the size depends on cholesterol content.     

2-Methylisoxazolin-5-ones III. Curboxylic. Acids and their Derivatives

Carbethoxy-substituted 12-methylisoxazolin-5-ones and several functional derivatives have been prepared. Spectral properties of the corresponding carboxylic acids are discussed. These acids ant stronger when the carboxy group is in position 3 than when in position 4 of the heterocycle.     

On the origin of quasi-racemic aplysinopsin cycloadducts, (bis)indole alkaloids isolated from scleractinian corals of the family Dendrophylliidae. Involvement of enantiodefective Diels-Alderases or asymmetric induction in artifact processes involving adventitious catalysts?

Reported here are two novel quasi-racemic (bis)indole alkaloids, cycloaplysinopsin A (5) and cycloaplysinopsin B (6), isolated from tropical Indo-Pacific (Comoros, Philippines) scleractinian corals of the family Dendrophylliidae. Although their structures suggest a Diels-Alder cycloaddition origin from aplysinopsin-type precursors, neither experiments, nor theory allowed us to clearly distinguish an enzymatic process with scarce enantioselection from the intrusion of an adventitious catalyst in the coral extracts, where the chiral environment caused a slight asymmetric induction.     

Activity coefficients of electrolytes from the E.M.F. of liquid membrane cells. II - multicharged electrolyte solutions

The activity coefficients of Co(en)₃Cl₃ and K₂SO₄ were measured by means of a cell with ion-exchange liquid membranes following the method described in paper I. The results prove that this method is even more valuable with multicharged salts than with 1-1 electrolytes. The values obtained are precise and reliable down to dilution limits never before accessible, e.g., 4×10^–5 mol-kg^–1 in Co(en)₃Cl₃. High dilution levels are of particular importance when dealing with highly charged electrolytes since the trend at higher concentrations often leads to errors both in extrapolation to infinite dilution and in the absolute activity coefficients. As an application, the activity coefficients of [Co(en)₃]₂(SO₄)₃-suspected to be wrongly evaluated in past literature-were measured, and their values at low concentrations were actually lower than those quoted before.     

From Epiraikovenal,an Instrumental Niche-Exploitation Sesquiterpenoid of Some Strains of the Marine Ciliated Protist euplotes raikovi,to an unusual intramolecular tele-dienone-olefin [2+2] photocycloaddition

It is shown that strains of the marine ciliate Euplotes raikovi are subtly variable in their production of secondary metabolites. Strains GA8 and 39W from Mediterranean and SB8 from Californian coasts produce the sesquiterpenoid epiraikovenal ( 3 ), while strains GA8 and SB8 also produce secoepiraikovenal ( 4 ), which play an instrumental niche-exploitation role and have also taxonomic significance. Comparison of 3 and 4 with raikovenal ( 2 ) and its putative biogenetic precursor 1 , which have similar roles in the conspecific strain Morl from Casablanca coast in the Atlantic Ocean, inspired us the first case of intramolecular tele-dienone-olefin [2+2] photocycloaddition, exemplified here by the transformation of 1 into ent- 3 . This served also to unequivocally clarify the stereochemical relationship between 3 and 2 .     

Xenicane Diterpenes Revisited: Thermal (E)→(Z) isomerization and conformational motions. A unifying picture

Kinetic and equilibrium studies show that typical xenicanes such as dictyolactone ( 1 ) and 4-hydroxydictyolactone ( 3 ) undergo slow conformation medium-ring flipping between the predominant trans-( 1a or 3a ; Me(20) trans to H–C(3)) and the minor cis-conformers ( 1b or 3b ; Me(20) cis to H–C(3); see Scheme 1). The formation of the latter is inhibited in heterocyclic-ring-opened congeners such as 18-acetoxy-4-hydroxydictyo-19-al ( 7 ). Molecular-mechanics calculations suggest that typical-xenicane cis-conformers are disfavoured by mainly C(4)–C(5) torsional strain. This is confirmed by the observation of two sizably populated cis-and trans-conformers for the unnatural 4-oxoxenicanes 10–12 . Unusually facile thermal (E)→(Z) isomerization of xenicanes 1,3,10–12 , and 7 is also observed (→ 13–17 and 9 , resp.; Scheme 3), reflecting great strain relief in the transition state. Conflicting results in the literature now fit into this scheme which provides a basis for unravelling recognition phenomena with these biologically active systems.     

Bretonin A and Isobretonin A,Unique Glycerol Derivatives Isolated from a Demosponge of Brittany Waters

It is shown that an unidentified marine demosponge of Brittany contains two unique lipids consisting of glycerol etherified by a C₁₂ trienic linear alcohol and esterified by 4-hydroxybenzoic acid. The latter is attached to the secondary position of glycerol in bretonin A (= 3-[((4E, 6E, 8E)-dodeca-4,6,8-trienyl)oxy]-2-(4-hydroxy-benzoyl)propan-1-ol; 1a ), and to the other primary position of glycerol in isobretonin A ( = (+)-3-[((4E, 6E, 8E)-dodeca-4,6,8-trienyl)oxy]-1-(4-hydroxybenzoyl)propan-2-ol; (+) -2 ). The structures are based on NMR and MS data, including the ones of the acetylation product (?)- 1b of 1a .     

(η3‐Allyl‐2κ3C)(chloro‐1κCl)(μ‐N,N′‐diethyldithioxamidato‐1:2κ4S,S′:N,N′)[diphenyl(2‐pyridyl)phosphine‐1κP]palladium(II)platinum(II) chloroform solvate

The title compound, [PdPtCl(C₃H₅)(C₆H₁₀N₂S₂)(C₁₇H₁₄NP)]·CHCl₃, was obtained by deprotonation of the initial platinum(II) complex of the di­thio­xamide and subsequent reaction with [Pd(η³‐C₃H₅)(μ‐Cl)]₂. Both metal atoms exhibit a square‐planar coordination geometry, with the two planes forming a dihedral angle of 21.7 (2)°. The di­thio­xamide bis‐chelating bridge is flat.