Comparison of slurry mixing and dry milling in laboratory sample preparation for determination of ochratoxin A and deoxynivalenol in wheat

The significance of laboratory sample preparation for the determination of two important mycotoxins, ochratoxin A (OTA) and deoxynivalenol (DON), in wheat was investigated by comparing water-slurry mixing and dry-milling procedures. The distribution of OTA and DON in 10 kg samples of naturally contaminated wheat was established by analyzing one hundred 100 g subsamples of each sample. A normal distribution and a good repeatability of DON measurements was observed for both water-slurry mixing (mean 2290 microg/kg, CV 4.6%, median 2290 microg/kg) and dry milling (mean 2310 microg/kg, CV 6.4%, median 2290 microg/kg) procedures. For OTA determinations, reliable results could be obtained only by slurry mixing sample preparation (mean 2.62 microg/kg, CV 4.0%, median 2.62 microg/kg), whereas dry-milling comminution resulted in an inhomogeneous distribution with a high variability (mean 0.83 microg/kg, CV 75.2%, median 0.60 microg/kg) and a positive skewness (2.12). Ad hoc experiments were performed on different size portions of the same sample (10 kg) to assess accuracy and precision of the comminution/homogenization procedures (slurry mixing and dry milling). Very good results were obtained for DON determination with both procedures in terms of accuracy (>98.7% of the "weighted value") and precision (CV <3%). For OTA determination good results were only obtained by slurry mixing (99.4% of the "weighted value," CV 10%), whereas dry milling provided results with low accuracy (43.2% of the "weighted value") and high variability (CV 110%). This study clearly demonstrated that sample preparation by slurry mixing is strictly necessary to obtain reliable laboratory samples for OTA determination in wheat to minimize misclassification of acceptable/rejectable lots, mainly within official control.     

Bromination of 3-substituted benzo[b]thiophenes: access to Raloxifen intermediate

A practical route to prepare halogeno-derivatives is described, starting from easily available 3-cyano-benzo[b]thiophene. Main efforts have been devoted to the optimization of the experimental procedures (solvent, bromination) to promote selectivity. Synthetic studies investigate the potential access to an advanced intermediate of Raloxifen.     

π-Extended and six-coordinate iron(II) complexes: structures, magnetic properties, and the electrochemical synthesis of a conducting iron(II) metallopolymer

Herein, we describe the preparation of three new bidentate π-extended derivatives of the ligand N-phenyl-2-pyridinalimine (ppi) containing a 3-thienyl (4) substituent at position 4 of the aniline ring or 2-thienyl (6) or phenyl (2) substituents at each of the 2,5 positions of the aniline rings. Three iron(2+) complexes (7-9) containing these ligands were prepared by combining two equivalents each of 2, 4, or 6 with Fe(NCS)(2), and the resulting neutral, six-coordinate complexes were fully characterized, including with single crystal X-ray diffraction experiments in the case of complexes 7 and 9. Variable temperature magnetic susceptibility and Mo?ssbauer experiments confirm the presence of spin-crossover in complexes 7 and 8, and the unusual solid state variable temperature magnetic properties of complex 9 likely result from crystal packing forces. Electropolymerization of the 2,5-dithienyl-substituted complex (9) produces a conducting and electrochromic metallopolymer film (poly-9).     

Determination of T-2 toxin in cereal grains by liquid chromatography with fluorescence detection after immunoaffinity column clean-up and derivatization with 1-anthroylnitrile

1-Anthroylnitrile (1-AN) has been shown to be an efficient labelling reagent for the determination of T-2 toxin (T-2) by high-performance liquid chromatography (HPLC)-fluorescence detection. This reaction has been used to develop a sensitive, reproducible and accurate method for the determination of T-2 in wheat, corn, barley, oats, rice and sorghum. The method uses immunoaffinity columns containing antibodies specific for T-2 for extract clean-up, pre-column derivatization with 1-AN and HPLC with fluorescence detection for toxin determination. Ground cereal samples were extracted with methanol-water (80:20, v/v), the extracts were purified by immunoaffinity columns and the toxin was quantified by reversed-phase HPLC with fluorometric detection (excitation wavelength 381 nm, emission wavelength 470 nm) after derivatization with 1-AN. Recoveries from the different cereals spiked with T-2 at levels ranging from 0.05 to 1.5 microg/g were from 80 to 99%, with relative standard deviations of less than 6%. The limit of detection was 0.005 microg/g, based on a signal-to-noise ratio of 3:1.     

Ruthenium(II) and ruthenium(IV) complexes containing kappa1-P-, kappa2-P,O-, and kappa3-P,N,O-iminophosphorane-phosphine ligands Ph2PCH2P[=NP(=O)(OR)2]Ph2 (R = Et,Ph): synthesis,reactivity, theoretical studies,and catalytic activity in transfer hydrogenation of cyclohexanone

[(Ru(eta(6)-p-cymene)(mu-Cl)Cl)(2)] and [(Ru(eta(3):eta(3)-C(10)H(16))(mu-Cl)Cl)(2)] react with Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2) (R = Et (1a), Ph (1b)) affording complexes [Ru(eta(6)-p-cymene)Cl(2)(kappa(1)-P-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))] (R = Et (2a), Ph (2b)) and [Ru(eta(3):eta(3)-C(10)H(16))Cl(2)(kappa(1)-P-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))] (R = Et (6a), Ph (6b)). While treatment of 2a with 1 equiv of AgSbF(6) yields a mixture of [Ru(eta(6)-p-cymene)Cl(kappa(2)-P,O-Ph(2)PCH(2)P[=NP(=O)(OEt)(2)]Ph(2))][SbF(6)] (3a) and [Ru(eta(6)-p-cymene)Cl(kappa(2)-P,N-Ph(2)PCH(2)P[=NP(=O)(OEt)(2)]Ph(2))][SbF(6)] (4a), [Ru(eta(6)-p-cymene)Cl(kappa(2)-P,O-Ph(2)PCH(2)P[=NP(=O)(OPh)(2)]Ph(2))][SbF(6)] (3b) and [Ru(eta(3):eta(3)-C(10)H(16))Cl(kappa(2)-P,O-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))][SbF(6)] (R = Et (7a), Ph (7b)) are selectively formed from 2b and 6a,b. Complexes [Ru(eta(6)-p-cymene)(kappa(3)-P,N,O-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))][SbF(6)](2) (R = Et (5a), Ph (5b)) and [Ru(eta(3):eta(3)-C(10)H(16))(kappa(3)-P,N,O-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))][SbF(6)](2) (R = Et (8a), Ph (8b)) have been prepared using 2 equiv of AgSbF(6). The reactivity of 3-5a,b has been explored allowing the synthesis of [Ru(eta(6)-p-cymene)X(2)(kappa(1)-P-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))] (R = Et, Ph; X = Br, I, N(3), NCO (9-12a,b)). The catalytic activity of 2-8a,b in transfer hydrogenation of cyclohexanone, as well as theoretical calculations on the models [Ru(eta(6)-C(6)H(6))Cl(kappa(2)-P,N-H(2)PCH(2)P[=NP(=O)(OH)(2)]H(2))]+ and [Ru(eta(6)-C(6)H(6))Cl(kappa(2)-P,O-H(2)PCH(2)P[=NP(=O)(OH)(2)]H(2))]+, has been also studied.     

Synthesis and α‐Mannosidase Inhibitory Evaluation of (2R,3R,4S)‐ and (2S,3R,4S)‐2‐(Aminomethyl)pyrrolidine‐3,4‐diol Derivatives

The synthesis of 46 derivatives of (2R,3R,4S)‐2‐(aminomethyl)pyrrolidine‐3,4‐diol is reported (Scheme 1 and Fig. 3), and their inhibitory activities toward α‐mannosidases from jack bean (B) and almonds (A) are evaluated (Table). The most‐potent inhibitors are (2R,3R,4S)‐2‐{[([1,1′‐biphenyl]‐4‐ylmethyl)amino]methyl}pyrrolidine‐3,4‐diol ( 3fs ; IC₅₀(B)=5 μM , K_i=2.5 μM ) and (2R,3R,4S)‐2‐{[(1R)‐2,3‐dihydro‐1H‐inden‐1‐ylamino]methyl}pyrrolidine‐3,4‐diol ( 3fu ; IC₅₀(B)=17 μM , K_i=2.3 μM ). (2S,3R,4S)‐2‐(Aminomethyl)pyrrolidine‐3,4‐diol ( 6 , R?H) and the three 2‐(N‐alkylamino)methyl derivatives 6fh, 6fs , and 6f are prepared (Scheme 2) and found to inhibit also α‐mannosidases from jack bean and almonds (Table). The best inhibitor of these series is (2S,3R,4S)‐2‐{[(2‐thienylmethyl)amino]methyl}pyrrolidine‐3,4‐diol ( 6o ; IC₅₀(B)=105 μM , K_i=40 μM ). As expected (see Fig. 4), diamines 3 with the configuration of α‐D ‐mannosides are better inhibitors of α‐mannosidases than their stereoisomers 6 with the configuration of β‐D ‐mannosides. The results show that an aromatic ring (benzyl, [1,1′‐biphenyl]‐4‐yl, 2‐thienyl) is essential for good inhibitory activity. If the C‐chain that separates the aromatic system from the 2‐(aminomethyl) substituent is longer than a methano group, the inhibitory activity decreases significantly (see Fig. 7). This study shows also that α‐mannosidases from jack bean and from almonds do not recognize substrate mimics that are bulky around the O‐glycosidic bond of the corresponding α‐D ‐mannopyranosides. These observations should be very useful in the design of better α‐mannosidase inhibitors.     

Validation of a new HPLC‐UV method for determination of the antibiotic linezolid in human plasma and in bronchoalveolar lavage

A rapid and selective HPLC‐UV method was developed for the quantification of linezolid (LNZ) in human plasma and bronchoalveolar lavage (BAL) at the concentrations associated with therapy. Plasma samples were extracted by solid‐phase extraction followed by evaporation to dryness and reconstitution in mobile phase solution. The chromatographic separation was carried out on a C₁₈ column with an isocratic mobile phase consisting of dihydrogen phosphate buffer 50 mm (pH 3.5) and acetonitrile (60:40 v/v). The detection was performed using a photodiode array. Under these conditions, a single chromatographic run could be completed within 12 min. The method was validated by estimating the precision and the accuracy for inter‐ and intra‐day analysis in the concentration range of 25–25600 ng/mL. The method was linear over the investigated range with all the correlation coefficients R > 0.999. The intra‐ and inter‐day precision was within 8.90% and the accuracy ranged from ?4.76 to +5.20%. This rapid and sensitive method was fully validated and could be applied to pharmacokinetic study for the determination of LNZ levels in human plasma and BAL samples. Copyright © 2013 John Wiley & Sons, Ltd.