Synthesis and structure of [(Ph3P)2Cu(µ-SeCH2Ph)2In(SeCH2Ph)2] as a single-source precursor for the preparation of CuInSe2 nano-materials.

The reaction of freshly prepared Na[In(SeCH2C6H5)4] with the mixture of CuCl and triphenylphosphine in methanol yielded [(PPh3)2CuIn(SeCH2C6H5)4]. The X-ray structure of the complex revealed the monomeric form of [(Ph3P)2Cu(µ-SeCH2Ph)2In(SeCH2Ph)2] consisting of tetrahedral Cu(i) and In(iii) centers, bridged by two benzyl selenolate ligands. The complex on pyrolysis in a furnace or in oleylamine/HDA yielded tetragonal CuInSe2. The morphology and composition of nanostructures were investigated by pXRD, SEM, TEM and EDX analysis. The band gap of the CuInSe2 nanostructures, obtained from pyrolysis in HDA and OA has been deduced from DRS as 1.85 and 1.86 eV, respectively.

Development of X-ray CCD camera based X-ray micro-CT system.

Availability of microfocus X-ray sources and high resolution X-ray area detectors has made it possible for high resolution microtomography studies to be performed outside the purview of synchrotron. In this paper, we present the work towards the use of an external shutter on a high resolution microtomography system using X-ray CCD camera as a detector. During micro computed tomography experiments, the X-ray source is continuously ON and owing to the readout mechanism of the CCD detector electronics, the detector registers photons reaching it during the read-out period too. This introduces a shadow like pattern in the image known as smear whose direction is defined by the vertical shift register. To resolve this issue, the developed system has been incorporated with a synchronized shutter just in front of the X-ray source. This is positioned in the X-ray beam path during the image readout period and out of the beam path during the image acquisition period. This technique has resulted in improved data quality and hence the same is reflected in the reconstructed images.

Multiplexed magnetic nanoparticle-antibody conjugates (MNPs-ABS) based prognostic detection of ovarian cancer biomarkers, CA-125, ß-2M and ApoA1 using fluorescence spectroscopy with comparison of surface plasmon resonance (SPR) analysis.

A multiplexed MNPs-Abs based fluorescence spectroscopic system in analysis of serum biomarkers; CA-125, ß2-M and ApoA1 for the early detection of ovarian cancer was first time proposed. The lowest detection limits measured in multiplexed setup were 0.26 U/mL, 0.55 ng/mL and 7.7 ng/mL respectively for CA-125, ß2-M and ApoA1. A comparative real sample analysis of healthy normal (Control), benign and ovarian cancer patients with SPR has also been done to validate the process. Moreover CA-125 detection only confirms 50-60% of early stage disease. This multiplexed system achieved sensitivity and specificity up to 94% and 98% respectively to distinguish early stage ovarian cancer patients from healthy individuals.

A comparative study on PVC based sensors in determination of.

The proposed work described the synthesis of neutral ionophores; 4,8-diaza-3,3,10,10-tetramethyl-1,2-dithiacyclodecane (S1), 5,8-diaza-3,3,10,10-tetramethyl-1,2 dithiacyclodecane-N,N''-diacetic acid (S2) and N,N''-bis(2,2-dimethyl-2-mercaptoethyl)ethylenediamine-N,N-diacetic acid (S3) used for comparative analysis in determination of molybdenum(v) as PVC-based membrane sensors. The best result was obtained with sensor no. 7 based on S3 ionophore with membrane composition (w/w, mg%); 5.0(S) : 30.0(PVC) : 5.0(KTpClPB) : 60.0(o-NPOE) showing a working range of 2.3 × 10-7-1.0 × 10-2 M with a detection limit of 1.2 × 10-7 M and a toleration of non-aqueous media up to 15% with slope of 11.7 mV/decade of activity. The sensor no. 7 can also be used to assess the Mo(v) concentration in different natural samples (water bodies, soils, root nodules and urine samples) with comparative analysis of ETAAS and spectrophotometric methods. The proposed sensor no. 7 can be used 2.5 months without any distortion in results after that leaching of ionophore was observed from the membrane phase in aqueous solutions of Mo(v). The proposed sensor has shown a good dynamic response time of 11 s.

Comparative study on 2-amino-1,4-naphthoquinone derived ligands as indium (III) selective PVC-based sensors.

The three different ligands (Q(2) to Q(4)) based on 2-amino-1,4-naphthoquinone (Q(1)), have been synthesized and explored as neutral ionophores for preparing polyvinyl chloride-based membrane sensors selective to indium (III). The addition of potassium tetrakis(4-chlorophenyl) borate and various plasticizers, viz., o-NPOE, DBP, DBBP, DOP and CN has been found to substantially improve the performance of the sensors. The best performance was obtained with the sensor no. 16 having membrane of ligand (Q(2)) with composition (%, w/w) ionophore Q(2) (3.0%):PVC (30.0%):o-NPOE (63.0%):KTpClPB (4.0%). This sensor exhibits Nernstian response with slope 19.8 mV/decade of activity in the concentration range 2.5 x 10(-7) to 1.0 x 10(-2) M indium (III), performs satisfactorily over wide pH range of (2.5-7.5) with a fast response time (10 s). The sensor was also found to work satisfactorily in partially non-aqueous media up to 20% (v/v) content of acetonitrile, ethanol and methanol. The proposed sensor can be used over a period of 3.5 months without significant drift in potentials. The quantitative application of sensor was also evaluated by comparative analysis of artificially made sea water with AAS.

Comparative studies on Tb (III)-selective PVC membrane sensors.

A new terbium selective sensor based on N-(2-hydroxyphenyl)-3-(2-hydroxyphenylhydroxyphenylimino)-N-phenylbutanamidine (L(1)) and N,N'-bis((1H-indole-3-yl)methylene)butane-1,4 diamine (L(2)) as a ionophore is reported. Effect of various plasticizers; 2-nitrophenyloctylether (o-NPOE), dibutyl butylphosphonate (DBBP), chloronaphthelene (CN), dioctylphthalate (DOP) and tri-(2-ethylhexyl)phosphate (TEHP) with anion excluder, potassium tetrakis (p-chloropheny1)borate (KTpClPB) have been studied. The membrane with a composition of ionophore (L(1)):KTpClPB:PVC:o-NPOE (w/w, %) in ratio of 3.0:5.0:30.0:62.0 exhibited enhanced selectivity towards terbium ions (III) in the concentration range of 3.5 x 10(-7) to 1.0x10(-2)M with a detection limit of 1.2 x 10(-7)M and a Nernstian slope (20.0+/-0.5mVdec(-1) activity). The sensors showed the working pH range to be 3.5-7.5 with response time of 11s. The sensor has been found to work satisfactorily in partially non-aqueous media up to 15% (v/v) content of methanol, ethanol or acetonitrile and could be used for a period of 3 months. The selectivity coefficients indicated high selectivity for terbium (III). The fast and stable response, good reproducibility and long-term stability of the sensors were observed. The application of the sensor has been demonstrated in determination of terbium (III) ions in spiked water samples.

Gallium(III) selective sensors based on 2-amino-3-(alpha-N-phenylmethyl-2'-amino-1',4'-naphthoquinonyl)-1,4 naphthoquinones in poly (vinyl chloride).

Synthesis and application of 2-amino-3-(alpha-N-phenylmethyl-2'-amino-1',4'-naphthoquinonyl)-1,4 naphthoquinone (S) as a neutral ionophore for the determination of gallium(III) in PVC-based membrane sensors has been described. The sensor based on membrane composition (w/w, mg%); 5.0 (S):30.0 (PVC):5.0 (KTpClPB):60.0 (o-NPOE) is the best and showed a working range of 2.3x10(-7) to 1.0x10(-2) M with detection limit of 1.2x10(-7) M. It can tolerate non-aqueous media up to 15% with a slope of 19.7 mV decade(-1) of activity. The sensor has been used to assess the Ga(III) concentration in different natural samples (peach and tomato leaves, coal-fly-ash and river sediments). It can be used for 2.5 months without any distortion in results, after which, leaching of ionophore was observed from the membrane phase. The proposed sensor has shown a good dynamic response time of 11 s.

Comparative studies of praseodymium(III) selective sensors based on newly synthesized Schiff's bases.

Praseodymium ion selective polyvinyl chloride (PVC) membrane sensors, based on two new Schiff's bases 1,3-diphenylpropane-1,3-diylidenebis(azan-1-ylidene)diphenol (M(1)) and N,N'-bis(pyridoxylideneiminato) ethylene (M(2)) have been developed and studied. The sensor having membrane composition of PVC: o-NPOE: ionophore (M(1)): NaTPB (w/w; mg) of 150: 300: 8: 5 showed best performances in comparison to M(2) based membranes. The sensor based on (M(1)) exhibits the working concentration range 1.0x10(-8) to 1.0x10(-2) M with a detection limit of 5.0x10(-9) M and a Nernstian slope 20.0+/-0.3 mV decade(-1) of activity. It exhibited a quick response time as <8 s and its potential responses were pH independent across the range of 3.5-8.5. The influence of the membrane composition and possible interfering ions have also been investigated on the response properties of the electrode. The sensor has been found to work satisfactorily in partially non-aqueous media up to 15% (v/v) content of methanol, ethanol or acetonitrile and could be used for a period of 3 months. The selectivity coefficients determined by using fixed interference method (FIM) indicate high selectivity for praseodymium(III) ions over wide variety of other cations. To asses its analytical applicability the prepared sensor was successfully applied for determination of praseodymium(III) in spiked water samples.

Comparative evaluation of Dy(III) selective poly(vinyl) chloride based membrane electrodes of macrocyclic tetraimine Schiff's bases.

Three different derivatives of macrocyclic tetraimine Schiff's base have been synthesized and explored as a neutral ionophores for preparing poly(vinyl chloride) based membrane sensors selective to Dy(3+). The addition of sodium tetraphenyl borate and various plasticizers, viz., o-NPOE, DBP, DBBP, DOP and CN has been found to substantially improve the performance of the sensors. The best performance was obtained with the sensor no. 1 having membrane of Schiff's base (SL-1) with composition (w/w) SL-1 (4.5%): PVC (30.5%): o-NPOE (59.5%): NaTPB (5.5%). This sensor exhibits Nernstian response with slope 19.4 mV/decade of activity in the concentration range of 10(-8) to 1.0x10(-2)M Dy(3+), performs satisfactorily over wide pH range of (2.8-7.2) with a fast response time (10s). The sensor was also found to work satisfactorily in partially non-aqueous media up to 20% (v/v) content of acetonitrile, methanol or ethanol. The proposed sensor can be used over a period of 1.5 months without significant drift in potentials. The sensor has been also utilized for the determination of Dy(3+) level in different soil samples.

Nano level detection of Cd(II) using poly(vinyl chloride) based membranes of Schiff bases.

The construction and performance characteristics of polymeric membrane electrodes based on two neutral ionophores, 2,2'-(1Z,1'Z)-(1E,1'E)-(1,2-phenylenebis(methan-1-yl-1-ylidene))bis(azaan-1-yl-1-ylidene)bis(methylene)bis(azan-1-yl-1-ylidene)bis(methan-1-yl-ylidene)diphenol (L(1)) and 4,4'-(1E,1'E)-(butane-1,4-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)dinaphthalen-1-ol (L(2)) for quantification of cadmium ions, are described. The influences of membrane compositions on the potentiometric response of the electrodes have been found to substantially improve the performance characteristics. The best performance was obtained with the electrode having a membrane composition (w/w) of (L(1)) (2.6%):PVC (31.6%):DOP (63.2%):NaTPB (2.6%). The proposed electrode exhibits Nernstian response in the concentration range 5.0 x 10(-9) to 1.0 x 10(-1)M Cd(2+) with limit of detection 3.1 x 10(-9), performs satisfactorily over wide pH range (2.0-8.5) with a fast response time (11s). The electrode has been found to work satisfactorily in partially non-aqueous media up to 40% (v/v) content of methanol, ethanol and acetonitrile and could be used for a period of 2.5 months. The analytical usefulness of the proposed electrode has been evaluated by its application in the determination of cadmium in cigarette samples. The practical utility of the membrane electrode has also been observed in the presence of surfactants.

Comparative study of Ag(I) selective poly(vinyl chloride) membrane sensors based on newly developed Schiff-base lariat ethers derived from 4,13-diaza-18-crown-6.

The six Schiff-base lariat ether chelates based on 4,13-diaza-18-crown ether, have been synthesized and explored as a neutral ionophores for preparing poly(vinyl chloride) based membrane sensors selective to silver(I). The addition of potassium tetrakis(4-chlorophenyl) borate and various plasticizers, viz., o-NPOE, DBP, DBBP, DOP and CN has been found to substantially improve the performance of the sensors. The best performance was obtained with the sensor no. 5 having membrane of chelate (A(6)) with composition (w/w) chelate (2.8%):PVC (45.7%):o-NPOE (48.6%):KTpClPB (2.8%). This sensor exhibits Nernstian response with slope 59.3mV/decade of activity in the concentration range 5.6 x 10(-8)-1.0 x 10(-1)M Ag(I), performs satisfactorily over wide pH range of (3.0-8.0) with a fast response time (12s). The sensor was also found to work satisfactorily in partially non-aqueous media up to 25% (v/v) content of acetonitrile, methanol or ethanol and can tolerate the concentration 1.0 x 10(-2)M of ionic (SDS, TBC) and nonionic (Triton X-100) surfactants. The proposed sensor can be used over a period of 4 months without significant drift in potentials. The response of the sensor was highly selective to Ag(+) over a large number of cations and it could therefore be used for Ag(+) estimation in blood of occupationally exposed persons.

Ni(II) selective sensors based on Schiff bases membranes in poly(vinyl chloride).

The two nickel chelates of Schiff bases, 3-hydroxy-N-{2-[(3-hydroxy-N-phenylbutyrimidoyl)-amino]-phenyl}-N'-phenylbutyramidine (M(1)) and bis-4-(ethyliminomethyl)naphthalene-1-ol (M(2)), have been synthesized and explored as ionophores for preparing PVC-based membrane sensors selective to nickel ion. The influences of membrane compositions on the potentiometric response of the electrodes have been found to substantially improve the performance characteristics. The best performance was obtained with the electrode having a membrane composition (w/w; mg) of (M(1)): PVC:NaTPB:CN in the ratio 5:150:5:150. The sensor shows a linear potential response for Ni(2+) over a wide concentration range 1.6x10(-7) to 1.0x10(-2) M with Nernstian compliance (30.0+/-0.2 mV/decade of activity) within pH range 2.5-9.5 and a fast response time of 10 s. The sensor has been found to work satisfactorily in partially non-aqueous media up to 20% (v/v) content of methanol, ethanol, and acetonitrile and could be used for a period of 4 months. The analytical usefulness of the proposed electrode has been evaluated by its application in the determination of nickel in real samples. The practical utility of the membrane electrode has also been observed in the presence of surfactants.