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An ecofriendly and efficient ultrasound-assisted deep eutectic solvents dispersive liquid-phase microextraction by solidifying the deep eutectic solvents-rich phase was developed to determine azoxystrobin, fludioxonil, epoxiconazole, cyprodinil, and prochloraz in fruit juices and tea drinks by high-performance liquid chromatography. A varieties of environmental hydrophobic deep eutectic solvents serving as extraction agents were prepared using L-menthol and decanoic acid as hydrogen-bond acceptor and hydrogen-bond donor, respectively. The deep eutectic solvents were ultrasonically dispersed in sample solutions, solidified in a freezer and easily harvested. The main variables were optimized by one-factor-at-a-time and response surface test. The new method performs well with relative recovery of 71.75-109.40%, linear range of 2.5-5000 μg/L (r ≥ 0.9968), detection limit of 0.75-8.45 μg/L, quantification limit of 2.5-25 μg/L,, and inter- and intraday relative standard deviations below 13.53 and 14.84%, respectively. As for the extraction mechanism, deep eutectic solvents were disposed into many fine particles in the solution and captured the analytes based on the changes of particle size and quantity in deep eutectic solvents droplets after extraction. The environmental method can successfully detect fungicide residues in real fruit juices and tea drinks.

An eco-benign effective in-situ decomposed nanofluid dispersive liquid-phase microextraction was developed to determine myclobutanil, flusilazole, hexaconazole, penconazole, epoxiconazole, paclobutrazol and diniconazole in tea drinks and fruit juices by HPLC. Various new nanofluids were prepared using multi-walled carbon nanotubes (MWCNTs) and hydrophilic deep eutectic solvents (DESs), with acetic acid/ DL-lactic acid/glycerol/propylene glycol/ethylene glycol/urea and choline chloride used as hydrogen-bond provider and receiver respectively. The nanofluids was decomposed in-situ in sample solutions, while MWCNTs and DESs served as adsorbent and carrier/stabilizer/dispersing agent, respectively. The optimal parameters influencing the extracting performance were identified by one-factor-at-a-time. The new approach was excellent with relative recovery, linear range, detection limit, quantification limit, and inter- and intra-day RSDs of 70.03-107.14%, 10-10000 μg/L, 3.34-8.30 μg/L, 10-25 μg/L

This article demonstrates 5,7-dimethyl-1,8-naphthyridine-2-amine based organic salts formation of crystalline solids 1 – 9 , in which the acidic units have been integrated via a variety of non-covalent bonds. Addition of equivalents of the acidic units to the solution of 5,7-dimethyl-1,8-naphthyridine-2-amine generates the single protonated species which direct the anions. The nine compounds crystallize as their salts with the acidic H transferred to the aromatic N of the 5,7-dimethyl-1,8-naphthyridine-2-amine. In 2 , 3 , 4 , and 7 the methyl substituted N-rings were protonated, while others were protonated at the NH 2 substituted N-ring. All salts have been characterized via IR, mp, EA and XRD technique. The major driving force for the salt formation is attributed to the classical H-bonds from 5,7-dimethyl-1,8-naphthyridine-2-amine and the acids. Other extensive intermolecular interactions also play great functions in space association of the molecular assemblies in the relevant crystals. The common R 2 2 (8) graph set has been observed in all salts due to the H-bonds and other intermolecular interactions, except 2 , 4 , and 6 . For the synergistic interactions of the various non-covalent bonds, all salts displayed 3D structures.

Cocrystallization of the bis(imidazole)/bis(benzimidazole) with a series of organic acids gave a total of eight molecular adducts with the compositions: (3,6-bis(imidazole-1-yl)pyridazine): (trichloroacetic acid)2 (1) [(H2L1)2+ · (tca−)2, L1 = 3,6-bis(imidazole-1-yl)pyridazine, tca− = trichloroacetate], (bis(N-imidazolyl)methane): (suberic acid) (2) [(L2) · (H2suba), L2 = bis(N-imidazolyl)methane, H2suba = suberic acid], bis(N-imidazolyl)methane: (3-nitrophthalic acid): 3H2O (3) [(H2L2)2+ · (3-Hnpa-)2 · 3H2O, 3-Hnpa- = 3-nitro hydrogenphthalate], (bis(N-imidazolyl)butane)0.5: (4-nitrophthalic acid): H2O (4) [(H2L3)0.5+ · (4-Hnpa-)- · H2O, L3 = bis(N-imidazolyl)butane, 4-Hnpa- = 4-nitro hydrogenphthalate], (1-(3-(1H-benzimidazol-1-yl)propyl)-1H-benzimidazole): (3,5-dinitrosalicylic acid) (5) [(HL4) · (3,5-dns-), L4 = 1-(3-(1H-benzimidazol-1-yl)propyl)-1H-benzimidazole, 3,5-dns- = 3,5-dinitrosalicylate], (1-(3-(1H-benzimidazol-1-yl)propyl)-1H-benzimidazole): (3-nitrophthalic acid) (6) [(H2L4) · (3-npa2-), L4 = 1-(3-(1H-benzimidazol-1-yl)propyl)-1H-benzimidazole, 3-npa2-=3-nitrogenphthalate], (bis(N-imidazolyl)butane): (pamoic acid) (7) [(H2L3) · (pam), pam = pamoate], and (3,6-bis(imidazole-1-yl)pyridazine): (1,5-naphthalenedisulfonic acid) [(H2L1)2+ · (npda)2- = 1,5-naphthalenedisulfonate] (8). The eight adducts have been characterized by X-ray diffraction technique, infrared spectrum, and elemental analysis, and the melting points of all adducts were also reported. And their structural and supramolecular aspects are fully analyzed. The result reveals that among the eight investigated crystals both the end ring N in the bis(imidazole) moieties are protonated when the organic acids are deprotonated except 2, and 5, and the crystal packing is interpreted in terms of the strong ionic N H⋯O H-bond between the imidazolium and the deprotonated acidic groups. Except the N H⋯O H-bond, the O H⋯O H-bonds were also found at the salts 3, 4, 5, and 7, salt 5 has the additional N H⋯N H-bond, the N H⋯S H-bond was established at 8. Further analysis of the crystal packing of the adducts indicated that a different set of additional CH O/CH2 O, CH Cl, CH-π/CH2-π, Cl C, Cl N, O O, O-π, OH-π, and π-π associations contribute to the stabilization and expansion of the total 3D frameworks. For the coexistence of the various weak interactions these structures had homo or hetero supramolecular synthons or both. Some supramolecular synthons, such as R12(4), R22(7), and R22(8) usually found in crystals of organic acids with imidazole unit, were again shown to be appeared in constructing most of these H-bond networks.

Cocrystallization of the widely available 4-dimethylaminopyridine, with a series of carboxylic acids gave nine molecular adducts 4-dimethylaminopyridinium trifluoroacetate (1), 4-dimethylaminopyridinium glycolate glycolic acid (2), 4-dimethylaminopyridinium 2-furoate dihydrate (3), tri(4-dimethylaminopyridinium) tri(o-chlorobenzoate) tetrahydrate (4), 4-dimethylaminopyridinium 4-bromobenzoate 4-bromobenzoic acid (5), 4-dimethylaminopyridinium 4-formylbenzoate 4-formylbenzoic acid (6), 4-dimethylaminopyridinium 2,4-dichlorobenzoate (7), 4-dimethylaminopyridinium 2-aminobenzoate 2-aminobenzoic acid (8) and bis(4-dimethylaminopyridinium) 5-nitroisophthalate 5-nitroisophthalic acid methanol solvate (9). The nine adducts have been characterised by X-ray diffraction, IR and elemental analysis, the melting points were also reported. Their structural and supramolecular aspects are fully analyzed. The result reveals that among the nine investigated crystals only the ring Ns in the 4-dimethylaminopyridine moieties are protonated when the carboxylic acids are deprotonated. The crystal packing is interpreted by the strong charge-assisted N-H⋯O hydrogen bond between the NH+ and the deprotonated acidic groups. Except the N-H⋯O hydrogen bonds, the charge assisted or neutral O-H···O hydrogen bonds were also found at 2-6, 8 and 9. The COOH···COO−synthon has been at 2, 5-6 and 8-9. Further analysis of the crystal packing indicated that a different family of additional CH-O/CH2-O/CH3-O, F-F, Br-Br, CH-Cl, CH3-Cl, CH-π/CH3-π, C-H···Cπ, C-π, Cl-O, O-C, O-π and π-π contacts contribute to the stabilization and expansion of the total high-dimensional (2D-3D) framework structures. For the synergism of the various nonbonding contacts there created homo/hetero supramolecular synthons or both.

Cocrystallization of the commonly available organic amine, diisopropylamine, with a series of carboxylic acids gave a total of sixteen molecular salts with the compositions: diisopropylaminium 2-methyl-2-phenoxypropanate [(Hdpa)+ · (mpa−), mpa− = 2-methyl-2-phenoxypropanoate] (1), diisopropylaminium 2-methyl-2-(naphthalen-2-yloxy)-propionate [(Hdpa)+ · (npa−), npa− = 2-methyl-2-(naphthalen-2-yloxy)-propionate] (2), diisopropylaminium indole-3-acetate [(Hdpa)+ · (iaa−), iaa− = indole-3-acetate] (3), diisopropylaminium 4-chlorophenoxyacetate [(Hdpa)+ · (cpa−), cpa− = 4-chlorophenoxyacetate] (4), diisopropylaminium 2,4-dichlorophenoxyacetate [(Hdpa)+ · (dcpa−), dcpa− = 2,4-dichlorophenoxyacetate] (5), diisopropylaminium 4-hydroxybenzoate [(Hdpa)+ · (hba−), hba− = 4-hydroxybenzoate] (6), diisopropylaminium 4-aminobenzoate [(Hdpa)+ · (aba−), aba− = 4-aminobenzoate] (7), tetra(diisopropylaminium) tetra(1-hydroxy-2-naphthoate) trihydrate [(Hdpa)44+ · (2-hnpa)44− · 3H2O, 2-hnpa = 1-hydroxy-2-naphthoate] (8), diisopropylaminium 2-hydroxy-3-naphthoate [(Hdpa)+ · (3-hnpa-), 3-hnpa- = 2-hydroxy-3-naphthoate] (9), diisopropylaminium 5-bromosalicylate [(Hdpa)+ · (bsa−), bsa− = 5-bromosalicylate] (10), diisopropylaminium 3,5-dinitrobenzoate [(Hdpa)+ · (dna−), dna− = 3,5-dinitrobenzoate] (11), diisopropylaminium 3,5-dinitrosalicylate [(Hdpa)+ · (3,5-dns-), 3,5-dns- = 3,5-dinitrosalicylate] (12), tetra(diisopropylaminium) bis(m-phthalate) monohydrate [(Hdpa+)4 · (mpta2−)2 · H2O, mpta2− = m-phthalate] (13), bis(diisopropylaminium) dihydrogen 1,2,3,4-butane tetracarboxylate [(Hdpa+)2 · (H2Bta2−), H2Bta2− = dihydrogen 1,2,3,4-butane tetracarboxylate] (14), bis(diisopropylaminium) mucate [(Hdpa+)2 · (muc2−), muc2− = mucate] (15), and diisopropylaminium hydrogen 1,2-phenylenediacetate [(Hdpa) · (Hpda−), Hpda− = hydrogen 1,2-phenylenediacetate] (16). The sixteen salts have been characterised by XRD technique, IR, and elemental analysis, and the melting points of all the salts were also reported. And their structural and supramolecular aspects are fully analyzed. The result reveals that among the sixteen investigated crystals the NH groups in the diisopropylamine are protonated when the carboxylic acids are deprotonated, and the crystal packing is interpreted in terms of the strong charge-assisted N H⋯O hydrogen bond formation between the ammonium and the deprotonated COOH groups. Except the N H⋯O hydrogen bond, the O H⋯O hydrogen bonds (charge assisted or neutral) were also found at the salts 6, 8, 9, 10, 12, 13, 14, 15, and 16. Further analysis of the crystal packing of the salts indicated that a different family of additional CH O/CH2 O/CH3 O, CH-π/CH3-π, CH3-Cπ, N-π, and π-π associations contribute to the stabilization and expansion of the total structures. For the coexistence of the various weak interactions these structures adopted homo or hetero supramolecular synthons or both.

Cocrystallization of the aromatic bronsted bases with a series of mineral acids gave a total of ten hybrid salts with the compositions: (2-methylquinoline)2: (hydrochloride acid): 3H2O [(HL1)+. (L1)·· (Cl-) · (H2O)3] (1), (6-bromobenzo[d]thiazol-2-amine): (hydrochloride acid) [(HL2)+. (Cl-)] (2), (6-bromobenzo[d]thiazol-2-amine): (nitric acid) [(HL2)+. (NO3-)] (3), (6-bromobenzo[d]thiazol-2-amine): (sulfuric acid) [(HL2)+ · (HSO4)-] (4), (6-bromobenzo[d]thiazol-2-amine): (phosphoric acid) [(HL2)+ · (H2PO4)-] (5), (5,7-dimethyl-1,8-naphthyridine-2-amine): (hydrochloride acid): 3H2O [(HL3)+ · (Cl-) (H2O)3] (6), (5,7-dimethyl-1,8-naphthyridine-2-amine): (hydrobromic acid): CH3OH [(HL3)+ · (Br)- · CH3OH] (7), (5,7-dimethyl-1,8-naphthyridine-2-amine): (sulfuric acid): H2O [(HL3)+ · (HSO4)- · H2O] (8), (2-aminophenol): (phosphoric acid) [(HL4)+ · (H2PO4)-] (9), and (2-amino-4-chlorophenol): (phosphoric acid) [(HL5)+ · (H2PO4)-] (10). The ten salts have been characterized by X-ray diffraction analysis, IR, and elemental analysis, and the melting points of all the salts were also reported. And their structural and supramolecular aspects are fully analyzed. The result reveals that among the ten investigated crystals the ring N of the heterocycle or the NH2 in the aminophenol are protonated when the acids are deprotonated, and the crystal packing is interpreted in terms of the strong charge-assisted classical hydrogen bonds between the NH+/NH3+ and deprotonated acidic groups. Further analysis of the crystal packing of the salts indicated that a different family of additional CH O, CH Cl, CH3 N, CH3 O, CH Br, CH3 Br, Br Cl, Cl S, O S, O O, Br S, H H, and π-π associations contribute to the stabilization and expansion of the total high-dimensional frameworks. For the coexistence of the various weak nonbonding interactions these structures adopted homo or hetero supramolecular synthons or both. Some classical supramolecular synthons, such as R22(8), R42(8), R43(10) and R44(12), usually observed in the organic solids, were again shown to be involved in constructing most of these H-bonding networks.

Cocrystallization of the commonly available organic primary amine, 4-chlorobenzylamine, with a series of organic acids gave a total of nine molecular salts with the compositions: (4-chlorobenzylamine): (p-toluenesulfonic acid) (1) [(HL+) · (ptsa−)], (4-chlorobenzylamine): (m-chlorobenzoic acid) (2) [(HL+) · (mcba−)], (4-chlorobenzylamine): (m-nitrobenzoic acid) (3) [(HL+) · (mba−)], (4-chlorobenzylamine)2: (3-nitrophthalic acid): H2O (4) [(HL+)2 · (3-npa2-) · H2O], (4-chlorobenzylamine)2: (1,5-naphthalenedisulfonic acid) (5) [(HL+)2 · (nds2−)], (4-chlorobenzylamine): (dichloroethanoic acid) (6) [(HL+) · (dca−)], (4-chlorobenzylamine)2: (oxalic acid)2: H2O (7) [(HL+)2 · (Hoxa−)2 · H2O], (4-chlorobenzylamine): (fumaric acid): H2O (8) [(HL+) · (Hfum−) · H2O] and (4-chlorobenzylamine)2: (1,2,3,4-butane tetracarboxylic acid) (9) [(HL+)2 · (H2bta2−)]. The nine salts have been characterized by single crystal X-ray diffraction (SCRD) technique, IR and elemental analysis (EA), the melting points of all salts were also reported, and their structural and supramolecular aspects are analyzed in some detail. The result tells that among the nine investigated crystals the NH2 units in the 4-chlorobenzylamine moieties are protonated when the organic acids are deprotonated, and the crystal packing is interpreted in terms of the strong charge-assisted N-H⋯O H-bond formation from the NH3+ and the deprotonated acidic groups. Except the N-H⋯O H-bond, the O-H⋯O H-bonds were also existed at the salts 4 and 7–9. Further analysis of the crystal packing of the salts unveiled that a distinct set of additional CH-C, CH-O/CH2-O, CH-Cl, CH2-Cl, CH-π/CH2-π, O-O, C-C, O-Cπ and Cl-Cl associations also contribute to the stabilization and extension of the total 2D-3D frameworks. For the concurrence of the manifold weak nonbonding interactions these structures adopted the homo or hetero supramolecular synthons or both. Some classical supramolecular synthons, such as R21(7), R42(8) and R44(12), usually appeared in organic solids of organic acids with amine, were again shown to be involved in constructing some of these H-bonding networks.

The use of online FT-IR is described for investigating the degradation kinetics of the solid amorphous pharmaceutical compound, fosaprepitant dimeglumine (FD), under stress storage conditions (i.e., high temperature, T, and humidity, % RH). It is found that under conditions of elevated T and % RH, the kinetics are denucleation rate limited for the deliquescence of the amorphous FD solid, based on the high quality fits obtained to the authors' dispersive kinetic model for that mechanism. At elevated T and low % RH, it is found that a classical, first-order hydrolysis mechanism for the degradation of FD (which forms crystalline aprepitant, AP) significantly contributes to the overall conversion rate. That mechanism is similar to the one observed previously for the solution-phase hydrolysis of FD. Appropriate kinetic models are proposed for the FD-to-AP conversion under all of the experimental conditions investigated in this work. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 42: 25–36, 2010

Optical pure (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid, a chiral crown ether, was successfully used as a chiral selector for the stereoisomeric separation of numerous real pharmaceutical compounds. Both practical and mechanistic aspects were described. Effects of chiral selector concentration under different pH values of BGE were discussed. Chiral recognition for the enantiomeric compounds with (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid was investigated through model compounds using CE and infrared spectroscopic techniques. Relations between the enantioselectivity of the chiral crown ether and the structural features of the studied compounds were also investigated. Unusual resolutions of compound-p and its enantiomer as well as compound-o and its 2b epimer were described. These compounds contained only tertiary amine, believed to be nonbinding with crown ethers in general. The possible mechanisms for the interaction between compound-o and the chiral crown ether were investigated using CE, electrospray MS (ESI-MS), and proton ((1)H) NMR spectroscopy. All experiments provided clear evidence that binding between compound-o and the chiral crown ether had occurred. ESI-MS spectra indicated that the complexes had a 1:1 stoichiometric ratio. The advantages and disadvantages of using chiral crown ether for stereoisomeric separations were compared with those using sulfated CDs.

An application of Fourier transform infrared (FT-IR) spectroscopy equipped with an attenuated total reflectance (ATR) probe for in-line monitoring of a hydrochloride (HCl) salt formation process of 4-{1-methyl-2-piperidin-4-yl-4-[3-(trifluorometryl)phenyl]-1H-imidazol-5-yl}-N-[(1S)-1-phenylethyl]pyridine-2-amine (freebase), an active pharmaceutical ingredient as a P38 MAP kinase inhibitor, is described. The freebase forms both mono- and bis-HCl salts due to its structural features. The mono-HCl salt is the desired product but the bis-salt is an impurity. The key to maximizing the product yield and minimizing the impurity level is to monitor the salt-forming reaction and to terminate it at the correct HCl charge amount. The process analytical technology (PAT) provided real-time data for process control and overcame the limitations that had been previously encountered by other analytical instrumentations, such as high-performance liquid chromatography and titration. Two qualitative approaches for reaction endpoint determination were employed. In the first approach, changes in the concentration of the freebase and bis-salt were monitored via the first derivative concentration profiles. The flat point in the freebase profile and the rise in the bis-salt profile were used as a detection bracket for the endpoint of HCl charging. In the second approach, principal component analysis (PCA) was used to classify the status of the process based on a spectral library consisting of spectra collected around the endpoint. Results indicated that both methods provided adequate accuracy for endpoint control in a small window between 1.0 and 1.05 HCl to freebase mole ratio. Both methods were used to support a scaled up process. Three batches of MAP mono-HCl salt formation were successfully controlled and prepared.

A novel approach for the potential on-line determination of the enantiomeric excess (ee) of an M3 antagonist drug substance combining attenuated total reflectance infrared (ATR-IR) spectroscopy, guest-host complexes, and chemometric data analysis is described. Chiral recognition through a formation of diastereomeric complexes was measured by ATR-IR. Small changes on the IR spectra reflect the interaction between the guest (M3) and host (chiral selector). These changes are measured as a function of M3 enantiomer excess. The standard error of prediction is 1.3 ee%. The prediction results based on the IR method were in good agreement with the gravimetric method. The robustness of the calibration model was evaluated by varying the concentration of the chiral selector, the pH of the solution, and the organic solvents. The stability of the calibration model was also demonstrated through measuring different sets of samples on different days. Chirality, 2006. © 2006 Wiley-Liss, Inc.

Thermodynamic analysis of the reversed-phase retention behavior of a doxorubicin–peptide conjugate demonstrated that the degree of non-linearity observed in Van’t Hoff plots was impacted by mobile phase acetonitrile content over the 25–38% acetonitrile (v/v) range tested. Small decreases in the non-polar surface area of the doxorubicin–peptide conjugate as a function of temperature were estimated from these data using linear solvent strength relationships, suggesting that the retention behavior may be the result of minor analyte conformational changes during the chromatographic experiment. This hypothesis was supported via circular dichroism (CD), Raman and 1 H NMR spectroscopic studies of the doxorubicin–peptide conjugate in selected chromatographic mobile phase compositions. The CD and Raman data indicated small changes to the apparent analyte microenvironment as a function of temperature and bulk solvent environment, while 1 H NMR studies specifically demonstrated the environmental sensitivity of protons on three non-polar peptide residues and the proximal aromatic region of the analyte. Together, these data suggest that minor changes to the conformational order of the essentially random structure of the doxorubicin–peptide conjugate are sufficient to impact chromatographic performance.

The FlowProb TM is a new type of chemical sensor that integrates traditional reagent-based chemical analysis techniques, fiber-optic spectroscopic detection, and membrane sampling in a compact rugged system. The FlowProbe is novel relative to other immobilized-reagent fiber-optic sensors in that the reagent in the FlowProbe sensor is replenished between each analysis. In a typical application the probe is inserted in the sample matrix and fresh reagent is pumped into the probe head. The analytes then diffuse across the sampling membrane where they react with the reagent to form a colored product. Fiber optics guide light to the probe tip where the differential optical absorption resulting from the product formation is measured spectroscopically. The analyzer monitors multiple wavelengths during the reaction, and advanced mathematical calibration techniques (i.e., chemometrics) are employed to provide a robust calibration model, and probe diagnostics to the user. Two field-portable FlowProbe prototype designs have been constructed. The first design is an insertion, or dip sensor consisting of a 1/2 inch OD stainless-steel probe attached to a case containing the fluid-delivery system. The optical components, spectrometer, and computer are located in a second case. The second design also separates the fluid delivery and optical systems, however the sensor head and fluid-delivery system are engineered into a 2 inch OD unit that can be deployed up to 250 feet down a well casing for in situ groundwater monitoring. This work describes the FlowProbe instrumentation and focuses on the development of the chemistries and membranes for the analysis of copper in a simulated cooling-tower rig using the insertion FlowProbe prototype.

In this work, a simple, rapid and sensitive analytical method for the determination of rhodamine B in chili-containing foodstuffs is described. The dye is extracted from samples with methanol and analysed without further cleanup procedure by high-performance liquid chromatography (HPLC) coupled to fluorescence detection (FLD). The influence of matrix fluorescent compounds (capsaicin and dihydrocapsaicin) on the analysis was overcome by the optimisation of mobile-phase composition. The limit of determination (LOD) and limit of quantification (LOQ) were 3.7 and 10 μg/kg, respectively. Validation data show a good repeatability and within-lab reproducibility with relative standard deviations10%. The overall recoveries are in the range of 98-103% in chili powder and in the range of 87-100% in chili oil depending on the concentration of rhodamine B in foodstuffs. This method is suitable for the routine analysis of rhodamine B due to its sensitivity, simplicity, reasonable time and cost.

Chemically facilitated Donnan dialysis (CFDD) of heavy metal ions in combination with continuous reagent flow has been studied. A simplified model to describe this process has been established. The model relates the diffusion behavior of metal ions through a Nafion cation-exchange membrane with the stability constant of complexation, the ionic strength of the receiving and sample solutions, the flow rate of the receiving solution, and the area-to-volume ratio of the membrane dialysis cell. A novel fiber optic heavy metal sensor has been fabricated by directly interfacing the dialysis device with a fiber optic colorimetric detection mechanism

A fully selective and versatile fiber optic heavy metal sensor based on the concept of second-order instrumentation has been fabricated and evaluated. This sensor uses chemically facilitated Donnan dialysis as the means of temporal species discrimination and reagent-assisted spectroscopy for spectral species discrimination. The signals in both orders (time and wavelength) are combined and analyzed with second-order tensorial analysis algorithms-generalized rank annihilation method (GRAM) and trilinear decomposition (TLD)-in order to extract the information of analytes form the sensor responses that are interfered by unknown interferents. Principal component analysis (PCA) is used to evaluate sensor characteristics

The trilinear decomposition algorithm (TLD) is a method for calibration of second-order instrumentation (e.g., LC-UV). This method, like the generalized rank annihilation method (GRAM), estimates the intrinsic profiles (e.g., spectra and chromatograms) of each component present in each sample by solving an eigenvector/eigenvalue problem. The relative concentration of each component between the samples is found by the least squares fitting of the intrinsic profiles to the instrument response of the samples. The advantage the TLD algorithm has over GRAM is the ability to analyze data from multiple samples simultaneously. The previously published algorithm provided unreliable calibration estimates when imaginary eigenvectors were included in the solution of the eigenproblem

The possible mechanisms for the chiral recognition of 2-(R)-N-[1-(6-aminopyridin-2-ylmethyl)piperidin-4-yl]-2-[(1R)-3,3-difluorocyclopentyl]-2-hydroxy-2-phenylacetamide (RR-M3), and its enantiomer (SS-M3) with octakis(2,3-di-O-acetyl-6-sulfo)-gamma-cyclodextrin (ODAS-gamma-CD) and octakis(6-sulfo)-gamma-cycopdextrom enantiomer; (OS-gamma-CD), were investigated using capillary electrophoresis (CE), proton ((1)H), fluorine ((19)F) and carbon ((13)C) nuclear magnetic resonance spectroscopy (NMR), and infrared (IR) spectroscopy. Clear evidence for the formation of diastereomeric complexes between the enantiomers and the two CDs was observed. NMR spectra suggest that the phenyl and difluorocyclopentyl rings are involved in the complexation. The phenyl ring on the guest molecule is deeply penetrated into the cavity of OS-gamma-CD, but it is not included into the cavity of ODAS-gamma-CD. The continuous variation plots built based on the (1)H NMR and IR spectra indicate a 1:1 complex stoichiometric ratio of the M3 enantiomers for both CDs. The affinity of the enantiomers for the two CDs is opposite.