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Concurrent headspace single-drop microextraction/solid-phase microextraction has been conducted on the same sample and vial and sample preparation was completed in the time duration of a single experiment.

Strategies have been used in this work for rapid and precise extraction of polycyclic aromatic hydrocarbons (PAHs) from grilled meat. Samples were pre-extracted with acetonitrile/potassium hydroxide under microwave irradiation, and after dilution with water subjected to two alternative pre-concentration and clean-up methods. In the first method, the extract was treated with hydrophilic deep eutectic solvent (DES) of choline chloride:phenol (1:2, molar ratio), and the extract phase separated by salt-assisted liquid–liquid extraction (SALLE) with acetonitrile. This method was found better than the conventionally used emulsification with tetrahydrofuran. In the other method, a methanolic solution of 1,4-dichlorobenzene (DCB) was injected into the extract when a cloudy solution was obtained due to dispersion of DCB particles. The sorbent with extracted PAHs was collected on bare Fe3O4 nanoparticles; a modification which was faster than the usually opted centrifugation in dispersive solid phase extraction. Matrix polar compounds and proteins were excluded due to low polarity of DES-SALLE combination and non-polar surface of DCB. Linear calibration graphs are obtained in HPLC–DAD in the range 0.1–1000 µg kg−1 of PAHs in both extraction methods (using 10 mL of standard extract). The limits of detection (S/N = 3) of PAHs (determined on tenfold diluted standard extract) were in the range 11–25 ng kg−1 by the DES method and 14–30 ng kg−1 by the DCB method, which were better than obtained by many of currently used extraction methods. The enrichment factors ranged 75–115 in DES extraction method, 60–95 in DCB method. The methods have been applied to the real samples of grilled meat, and the results found by the present methods agreed together and with those found by the standard methods. DES method in combination with SALLE was found more convenient to operate.

After the realization of extraction in a microdrop and development of single-drop microextraction as a technique potentially carried out under diverse modes in accordance with the nature of analytes, and the possibility of final analysis by a range of instrumental methods, the whole concept has received wide acceptance. A consolidation of efforts has enhanced the capability of this technique by advancements in configurational flexibilities of devices and control over solvent drop dislodgement. Integration of safe and efficient materials, such as ionic liquids and nanomaterials, automation and miniaturization, and applications to challenging real-world samples, has increased the importance of this microextraction technique. Many such topics are discussed in this chapter illustrating the significant developments that occurred in the field.

A novel method based on diffused reflectance Fourier-transform infrared spectroscopy (DRS-FTIR) was employed for iodate determination in food grade salt and food products. The method attained sensitivity that was comparable to or better than that in most of the contemporary spectrophotometric methods. This was realized through a combination of azo dye formation and dispersive liquid–liquid microextraction of dye when a 37-fold enrichment was obtained. FT-IR enabled integrating alternative target peak, and freedom in sample solvent composition relative to UV–visible spectrophotometry where the solvent polarity, pH, and presence of ions may affect the spectral properties of the measurable coloured species. Food samples containing iodide or covalently bonded iodine were oxidized with alkaline permanganate for mineralization and iodate formation. Optimization of both reaction conditions was carried out by means of response surface methodology. The method had a linear range 0.04–10 mg kg−1 iodate and limit of detection of 4.4 µg kg−1.

Covering the literature from 2011 until recently, this review highlights the analytical strategies that have been adopted for the extraction and analysis by high performance liquid chromatography comprising without or with derivatization of biogenic amines in real samples of food and beverages. The alternative ways of detection by tandem mass spectrometry, potential of multiple reaction monitoring and extracted ion chromatograms have been utilized when analyses performed without any derivatization. The reagents employed for derivatization differ widely in their structures, involve a variety of reaction mechanism, and allow detection by UV-absorption, fluorescence or mass spectrometry. The development of such a large number of reagents for a single class of analytes demonstrates the continued endeavours to overcome the implicit difficulties associated with low molar mass and polar analytes in complex sample matrices, and the inherent importance of the analysis of biogenic amines. The discussion presented will allow the alternative techniques to be adopted for particular biogenic amines samples, and have better control over selectivity and sensitivity of the method.

Relative to many other areas in chemistry, analytical chemistry appears singularly lagging behind in India despite the commendable growth it had shown in the past both in teaching and research. Certain presumptions in policy making and current educational practices are believed to be the crux of the problem.

Combined SDME and SPME worked as an elegant strategy to inject a large sampled mass of analytes into a GC. After headspace SDME of methyl derivatives of phenol, chlorophenols, methylphenols and other substituted phenols into 10 μL of solvent drop (1-butanol), the extract was subjected to headspace SPME (DVB/CAR/PDMS, 30/50 μm, fiber) for convenient transfer of analytes to the fiber and then into the GC. This combination resulted in achieving a high sensitivity of detection for a small volume (0.5–2 mL) of sample. The chromatographic separation of thirteen model phenols (as their methyl ethers) was complete within 10 min. A rectilinear calibration graph was obtained using combined headspace SDME/SPME and GC-MS in the range of 0.001–5 mg L−1, with a correlation coefficient of 0.990–0.999 and an average limit of detection of 20 ng L−1 (range 8–45 ng L−1), which was far better than that obtained by headspace SDME, 90 ng L−1 (range 50–138 ng L−1), or headspace SPME, 55 ng L−1 (range 36–70 ng L−1), when used alone. In spiking experiments on environmental water samples, the RSD of the results was in the range of 4.6–9.4%.

The Berthelot reaction for ammonia is revisited with the aim of miniaturization and addressing interferences as encountered with food and water samples. Headspace single drop microextraction of ammonia in phosphoric acid served to attain selectivity in complex matrices, and liquid-liquid microextraction of red or blue indophenol species into 1-octanol-isooctane (60:40, v/v) resulted into high sensitivity. Fiber-optics-based cuvetteless micro-spectrophotometry has been used for colorimetric determination on microliter volumes of extract. The linear dynamic range, limit of detection and enrichment factor have been found to be 0.2–3 mg kg−1, 0.14 mg kg−1 and 38, respectively, measuring red species for milk, cheese and beer (4.9–5.5% error; 4.8–6.3% RSD; n = 5); and 5–400 µg L−1, 0.4 µg L−1 and 137, respectively, measuring blue species for water samples (3.3–5.7% error; 3.6–6.8% RSD; n = 5). A plausible reaction scheme has been proposed for nitroprusside catalysis in indophenol reaction.

Today we are living in a digital era. In this era E-governance is now playing a vital role for providing various services to citizen, business, employee and other government sectors through information server (cyber hub or web hub). It ensures government to be transparent in its dealings, accountability for its activity and response for its service delivery. In this paper we will focus on uniform growth and development of e-services in each sector & state of country. We will also analyze various parameters that are directly related to e-services and e-governance. Some data mining applications and its implementation is discussed for effective decision making.

To deal the stubborn problem arising from oily matrix of cosmetics in the chromatography of parabens, an efficient, rapid, and economic sample preparation method is proposed involving separation of matrix material by extraction with 1 mL of isooctane/1-octanol (50:50, v/v) in the presence of 1 mL of 1 mol/L sodium hydroxide, and centrifugation. Then, parabens in the alkaline solution were preconcentrated, after acidification, by liquid–liquid–liquid microextraction using 200 µL of isooctane/1-octanol (50:50, v/v) as organic solvent and 5 µL of 0.1 mol/L of sodium hydroxide as the acceptor drop. Using the optimized procedure, the method provided a rectilinear graph for 0.01–8 mg/kg of parabens with correlation coefficient (r) in the range 0.9982–0.9990, limit of detection in the range 1.7–4.3 µg/kg, and enrichment factor in the range 79–118. Intra-day (and inter-day) RSD at 0.01 and 5 mg/kg spiked levels of parabens were found as 7.7% (9.2%) and 4.7% (5.6%), respectively. Average recovery of spiked amounts...

The genusTimarchaseems unique among Chrysomelidae: Chrysomelinae by having plesiomorphic characters such as genitalia with a ring-like tegmen, covered with a setose parameral cap, together with apomorphic characters, including apterism and fused elytra. The distribution of this genus is also very peculiar: circum Mediterranean and northwestern American. Food selection also seems rather stict, comprising 8 families and 20 genera of plants. Two of the subgenera (MetallotimarchaandAmericanotimarcha) share one plant family, the Ericaceae. The plant family Rubiaceae is also shared between three subgenera:Timarcha,Timarchostoma andMetallotimarcha. Reflex bleeding among diurnal species, aposematism, thanatosis, stomatic regurgitation are means of defense against predators, but not against parasites and commensals. A very archaic genus, probably originating in early Mesozoic, with around 100 taxa, and 50 subspecies. Mutations remain very common in the group and new species are possibly still emerging.

A novel and highly selective method has been developed for the determination of aromatic primary amines by their conversion to dithiocarbamates by reaction with carbon disulphide, and then to isothiocyanates, which are volatile, by heating in the presence of a heavy metal ion. Zinc(II) was selected owing to its low toxicity and optimum yield of isothiocyanates. The latter were sampled by headspace-solid phase microextraction (HS-SPME) on divinylbenzene-carboxen-polydimethylsiloxane fibre, 50/30 μm. The HS-SPME procedure was optimized to provide adequate limits of detection in the analysis of aromatic amines in their real samples by gas chromatography with mass spectrometry (GC–MS) or flame ionization detection (GC–FID). The method gave rectilinear calibration graph, correlation coefficient and limit of detection, respectively, over the range 0.08–100 μg L −1 , 0.9950–0.9990 and 25–240 ng L −1 in gas chromatography–mass spectrometry, and 0.01–10 mg L −1 , 0.9910–0.9991 and 0.8–3.0 μg L −1 in gas chromatography–flame ionization detection. At two different levels, 10 and 40 μg L −1 , the range of intra-day RSD was 3.7–8.5% (GC–MS) and 3.3–9.2% (GC–FID), respectively. The proposed method is simple and rapid, and has been applied to determine aromatic primary amines in the environmental waters, food samples of ice cream powder and soft drinks concentrate, and food colours. The intra-day RSD in the analysis of real samples by GC–MS was in the range 3.6–6.2%. The food/colour samples were found to contain elevated levels of aniline and 2-toluidine.

Aggregations of conspecifics are ubiquitous in the biological world. In arthropods, such aggregations are generated and regulated through complex interactions of chemical and mechanical as well as abiotic and biotic factors. Aggregations are often functionally associated with facilitation of defense, thermomodulation, feeding, and reproduction, amongst others. Although the iconic aggregations of locusts, fireflies, and monarch butterflies come to mind, many other groups of arthropods also aggregate. Cycloalexy is a form of circular or quasicircular aggregation found in many animals. In terrestrial arthropods, cycloalexy appears to be a form of defensive aggregation although we cannot rule out other functions, particularly thermomodulation. In insects, cycloalexic-associated behaviors may include coordinated movements, such as the adoption of seemingly threatening postures, regurgitation of presumably toxic compounds, as well as biting movements. These behaviors appear to be associated with attempts to repel objects perceived to be threatening, such as potential predators or parasitoids. Cycloalexy has been reported in some adult Hymenoptera as well as immature insects. Nymphs of the orders Hemiptera (including Homoptera) as well as larvae of the orders Neuroptera, Coleoptera, Diptera, Hymenoptera, and, in a less circular fashion, the Lepidoptera, cycloalex. There are remarkable convergences in body form, life habit, and tendencies to defend themselves in the social larval Coleoptera, particularly chrysomelids, social larval Lepidoptera, and social larval Hymenoptera. In immature insects, the cycloalexing organisms can be arranged with either heads or abdominal apices juxtaposed peripherally and other conspecifics may fill in the center of the array. In the Chrysomelidae, the systematic focus of this review, species in the generaLema,Lilioceris(Criocerinae),Agrosteomela,Chrysophtharta,Eugonycha,Gonioctena,Labidomera,Paropsis,Paropsisterna,Phratora,Phyllocharis,Plagiodera,Platyphora,Proseicela,Pterodunga(Chrysomelinae),Coelomera(Galerucinae), andAcromis,Aspidomorpha,Chelymorpha,Conchyloctenia,Ogdoecosta,OmaspidesandStolas(Cassidinae) are reported to cycloalex although cycloalexy in other taxa remains to be discovered. Other types of aggregations in insects include stigmergy, or the induction of additional labor, and epialexy, or the positioning of conspecifics organisms over the midvein or an elongated aspect of a leaf.

2-Iodosobenzoate and N,N -dimethylaniline have been used at pH 6.4 for selective conversion of iodide to 4-iodo- N,N -dimethylaniline which was extracted with ethanol, when the phase separation occurred by addition of ammonium sulphate, a process called salt-assisted liquid–liquid microextraction (SALLME), and analysed by high-performance liquid chromatography-diode array detection. Iodate was reduced to iodide before derivatisation. The method has been optimised for extracting solvent, salt for phase separation, and reaction time. A linear calibration was obtained for 10 μg-10 mg L −1 of iodide with correlation coefficient of 0.9989 and limit of detection of 3.7 μg L −1 . The SALLME produced 280-fold enrichment of the derivative. The commercial iodised table salt samples have been found highly inhomogeneous; the RSD in analysis of different aliquots of the same sample ranged 18.0-78.1%. The average recovery of spiked iodide to real samples was 98.4% with an average RSD of 7.9% (range 5.2-12.4%).

A new, selective and sensitive method has been developed for the determination of tricyclic antidepressant drugs, amoxapine and nortriptyline, in human blood plasma and serum, involving their reaction with allyl isothiocyanate and extraction of thiourea derivatives with water-miscible organic solvent acetonitrile. The phase separation was effected by addition of ammonium sulphate, a process called salt-assisted liquid-liquid microextraction. The extract was analyzed by HPLC with UV detection at 254 nm. The method has been optimized for derivatization reaction time and temperature, solvent for extraction, and salt for solvent phase separation. Under the optimal conditions, a linear calibration graph was obtained between the amount of drug and the peak area of thiourea derivatives in the range of 0.002-20 mg/L drugs. The correlation coefficient and limit of detection values for amoxapine and nortriptyline in serum/plasma samples were in the range of 0.9953-0.9999 and 0.46-0.58 μg/L, respectively. The recovery in spiking experiments ranged, respectively, 75-88% (RSD 3.4-7.2%) and 79-97% (RSD 3.7-7.9%) for the two drugs.

Headspace single-drop microextraction has been used for the determination of cyanide with ninhydrin in combination with fibre-optic-based cuvetteless microspectrophotometry which accommodates sample volume of 1 microL placed between the two ends of optical fibres, and has been found to avoid salient drawbacks of batch methods. This method involved hydrocyanic acid formation in a closed vial, and simultaneous extraction and reaction with 2 microL drop of ninhydrin in carbonate medium suspended at the tip of a microsyringe needle held in the headspace of the acidified sample solution. The method was linear in range 0.025-0.5 mg L(-1) of cyanide. The headspace reaction was free from the interference of substances, e.g., thiocyanate, hydrazine sulphate, hydroxylammonium chloride and ascorbic acid. Sulphide was masked by cadmium sulphate, nitrite by sulphamic acid, sulphite by N-ethylmaleimide, and halogens by ascorbic acid. The limit of detection was found to be 4.3 microg L(-1) of cyanide which was comparable to existing most sensitive methods for cyanide. However, the present method is far more simple. The method was applied to acid-labile and metal cyanides complexes by treatment with sulphide when metal sulphides were precipitated setting cyanide ion free, and to iron(II) and (III) cyanide complexes by their decomposition with mercury(II), the mercury(II) cyanide formed was then determined. These pre-treatment methods avoided cumbersome pre-separation of cyanide by methods such as distillation or gas diffusion. The overall recovery of cyanide in diverse samples was 97% with RSD of 3.9%.

Summary Vicariance and dispersion both must be considered as possibilities for the fauna and flora of New Zealand and New Caledonia. Oligocene submersion, promoted by the geologists and several biologists, does not seem to have been total. Refuge stations must have existed in mountains and even in plains in some surrounding areas. From there the relicts must have radiated after the partial submersion. Certain “primitive” Chrysomelidae Eumolpinae (Bohumiljania spp.) are closely related to Patagonian genera. Their case is not unique among the terrestrial organisms of New Caledonia. How to explain the occurrence of Amborella in New Caledonia and of the tuataras in New Zealand, already very probably extinct elsewhere during the Paleogene?

A simple and rapid method has been reported for the determination of carbonyl compounds involving reaction with 2,4-dinitrophenylhydrazine and extraction of hydrazones with water-miscible organic solvent acetonitrile when the phase separation occurs by addition of ammonium sulphate, a process called salt-assisted liquid-liquid microextraction. The extract was analyzed by high-performance liquid chromatography with UV detection at 360 nm. The procedure has been optimized with respect to solvent suitable for extraction, salt for phase separation between water and organic solvent, reaction temperature and reaction time. The method has been validated when a linear dynamic range was obtained between the amount of analyte and peak area of hydrazones in the range 7 microg-15 mg L(-1), the correlation coefficient over 0.9964-0.9991, and the limit of detection in the range 0.58-3.2 microg L(-1). Spiked water samples have been analyzed with adequate accuracy, and application of the method has been demonstrated in the analysis of benzaldehyde formed as oxidation product in pharmaceutical preparation where benzyl alcohol is used as preservative, and for a keto drug dexketoprofen.

Liquid-phase microextraction (LPME) has been investigated for trace analysis in the present work in conjunction with fibre-optic-based micro-spectrophotometry which accommodates sample volume of 1 microL placed between the two ends of optical fibres. Methods have been evolved for the determination of (i) 1-100 microM and 0.5-20 microM of thiols by single drop microextraction (SDME) and LPME in 25 microL of the organic solvent, respectively, involving their reaction with the Ellman reagent and ion pair microextraction of thiolate ion formed; (ii) 70 microg to 7 mg L(-1) of chlorine/chlorine dioxide by headspace in-drop reaction with alternative reagents, viz., mixed phenylhydrazine-4-sulphonic acid and N-(1-naphthyl)ethylenediamine dihydrochloride, o-dianisidine, o-tolidine, and N,N-diethyl-p-phenylenediamine; (iii) 0.2-4 mg L(-1) of ammonia by reaction with 2,4-dinitro-1-fluorobenzene to give 2,4-dinitroaniline which was diazotized and coupled with 1-naphthylamine, the resulting dye was subjected to preconcentration by solid-phase extraction and LPME; and (iv) 25-750 microg L(-1) of iodide/total iodine by oxidation of iodide by 2-iodosobenzoate, microextraction of iodine in organic solvent, and re-extraction into aqueous starch-iodide reagent drop held in the organic phase. LPME using 25-30 microL of organic solvent was found to produce more sensitive results than SDME. The cuvetteless spectrophotometry as used in combination with sample handling techniques produced limits of detection of analytes which were better than obtained by previously reported spectrophotometry.

A simple and rapid method has been reported for the determination of carbonyl compounds involving sample preparation by headspace single drop microextraction using 1-butanol as extraction solvent containing 2,4-dinitrophenylhydrazine for hydrazone formation, and direct transfer of the drop into the injector for high-performance liquid chromatography with diode array detection. An angle-cut polytetrafluoroethylene sleeve, 3 mm × 0.5 mm, was fixed at the tip of the syringe needle and this allowed the use of 7 μL drop of solvent drop for extraction and derivatization. The procedure has been optimized with respect to suitable solvent for headspace drop formation, drop volume, concentration of reagent, sample temperature, reaction time, and headspace-to-sample volume ratio. The method has been validated when rectilinear relationship was obtained between the amount of analyte and peak area ratio of hydrazones in the range 0.01–15 mg L −1 , the correlation coefficient over 0.996–0.999, and the limit of detection in the range 1.7–24.1 μg L −1 . Spiked real samples have been analyzed with adequate accuracy, and application has been demonstrated of the method for analysis of carbonyl compounds formed as oxidation products.

This communication is a general review of Eumolpinae, a subfamily of Chrysomelidae. The subfamily includes more than 7000 species. It is specially numerous and much diversified in the tropics, with both the attributes declining northward. It has several distinctive features, and is clearly related to Clytrinae, Cryptocephalinae, Chlamisinae, Lamprosomatinae, Hispinae, and Cassidinae. Megascelidines, though generally treated as a subfamily, they should be taken as a part of Eumolpinae. Through some larval features, Eumolpinae seem related also to Galerucinae-Chrysomelinae. Separation from Eumolpinae of the primitive eumolpines, the Tribe Spilopyrini, and inclusion of Syneta among Eumolpinae have been contradicted.

Presence of iodine in aromatic amines, introduced by their reaction with iodine, and other electron withdrawing substituents such as chlorine and nitro, has been found to afford excellent liquid-phase microextraction (LPME) in toluene and separation by gas chromatography in the determination of primary, secondary and tertiary aromatic amines. The effect is due to decreased basic nature of amines when electronegative substituents are present. Single drop microextraction (SDME) of the amines in 2 μl of toluene and injection of the whole extract into GC, or LPME into 50 μl of toluene and injection of 2 μl of extract, were used. LPME has been found more robust and to give better extraction in shorter period than SDME. In SDME–GC–FID, the average correlation coefficient was 0.9939 and average limit of detection 25 μg l−1 (range 12–61 μg l−1) whereas the corresponding values in LPME–GC–MS were, respectively, 0.9953 and 33 ng l−1 (range 18–60 ng l−1). The method has been applied to determine aromatic amines in river water, dye factory effluents and food dye stuffs. The LPME was found as robust, rugged and simple extraction method.

In the determination of bromate and iodate, any free bromide and iodide present was quantitatively removed by anion exchange with silver chloride exploiting the differences in silver salts solubility product, being AgCl, 1.8 x 10(-10), AgBr, 5.0 x 10(-13), AgI, 8.3 x 10(-17), AgBrO(3), 5.5 x 10(-5) and AgIO(3), 3.1 x 10(-8). The oxyhalides were reduced with ascorbic acid to halides and converted to 4-bromo-2,6-dimethylaniline and 4-iodo-2,6-dimethylaniline by their reaction with 2-iodosobenzoate in the presence of 2,6-dimethylaniline at pH 6.4 and 2-3, respectively. Single drop microextraction (SDME) of the haloanilines in 2 microl of toluene and injection of the whole extract into GC-MS, or liquid-phase microextraction (LPME) into 50 microl of toluene and injection of 2 microl of extract, resulted in a sensitive method for bromate and iodate. The latter method of extraction has been found more robust, sensitive and to give better extraction in shorter period than SDME. Total bromine/iodine was determined without any treatment with silver chloride. High concentration of chloride in the matrix did not interfere. A rectilinear calibration graph was obtained for 0.05 microg-25 mg l(-1) of bromate/bromide and iodate/iodide, the limit of detection were 20 ng l(-1) of bromate, 15 ng l(-1) of iodate, 20 ng l(-1) of bromide and 10 ng l(-1) of iodide (by LPME in 50 microl of toluene). The method has been applied to seawater and table salt. From the pooled data, the average recovery of spiked oxyhalide/halide to real samples was in range 96.7-105.7% with RSD in range 1.6-6.5%.

The aim of present work was to optimize the experimental parameters in single drop microextraction under solution immersion (SDME) and headspace (HS-SDME) extraction modes for the determination of periodate using guaifenesine [3-(2′-methoxyphenoxy)-1,2-propane diol] and norephedrine (phenylpropanolamine) as new and alternative reagents for the Malaprade reaction. The reactions were complete within 5 min resulting in the formation of 2-(2′-methoxyphenoxy)-acetaldehyde and benzaldehyde, respectively. SDME/HS-SDME of oxidation products with 2 μl of anisole or 1 μl of toluene, respectively, has permitted the determination of periodate at μg l−1 concentration levels. The results indicated that HS-SDME (range 0.01–10 mg l−1, r2 = 0.9990; limit of detection 1.55 μg l−1) was more sensitive than SDME (range 0.05–50 mg l−1, r2 = 0.9984; limit of detection 3.42 μg l−1), and was inexpensive, rapid and convenient. Tolerance of excess of iodate has permitted the application of this method in the determination of ethylene glycol in motor oil; the average recovery on spiked sample was 98.6% with R.S.D. of 4.2%.

A new method for determining biogenic amines in fruit juices and alcoholic beverages is described involving reaction of biogenic amines with 1-naphthylisothiocyanate followed by extraction of 1-naphthylthiourea derivatives with water-miscible organic solvent acetonitrile when solvents phase separation occurred using ammonium sulphate, a process called salting-out assisted liquid-liquid extraction. The extract was analyzed by high-performance liquid chromatography with UV detection at 254nm. The new reagent avoided many of the inconveniences as observed with existing derivatizing agents, such as dansyl chloride and benzoyl chloride, in regard to their inselectivity, instability, adverse effect of excess reagent, and necessity to remove excess reagent. The procedure has been optimized with respect to reaction time and temperature, water-miscible extraction solvent, and salt for solvents phase separation. Use of reagent as dispersed phase in aqueous medium produced derivatives in high yield. A linear calibration was obtained between the amount of biogenic amines in range 1-1000μgL(-1) and peak areas of corresponding thioureas formed; the correlation coefficient was 0.9965, and the limit of detection and limit of quantification found were 1.1μgL(-1) and 3.2μgL(-1), respectively. The pre-concentration method gave an average enrichment factor of 94. The application of the method has been demonstrated in the determination of biogenic amines in commercial samples of fruit juices and alcoholic beverages. In spiking experiments to real samples, the average recovery found by the present method was 94.5% that agreed well with 95.8% obtained by established comparison methods.

Microbial products offer a non-chemical alternative to manage noxious weeds with the goal of reducing input into the environment of harmful chemicals that are otherwise used for the same purpose. During the present investigations cell-free culture filtrate (CFCF) of Phoma herbarum FGCC no. 75 was evaluated for its phytotoxic property against Parthenium hysterophorus L. The results of shoot cut, detached leaf and seedling bioassays revealed the presence of a toxic metabolite in the CFCF that was responsible for the toxicity against the target weed. Further, the toxic metabolite was characterized after the CFCF extraction with butanol, hexane, chloroform, acetone and ethyl acetate. The residues left after solvent evaporation were evaluated separately for their toxicity against the weed. Residue obtained from ethyl acetate fraction showed very distinct toxicity when compared with others. On the basis of analysis by gas chromatography- mass spectrometry, the tentative structure of the phytotoxic compound was deduced to be 3-nitro-1,2-benzenedicarboxylic acid (3-nitrophthalic acid). This is the first report confirming the potential of this particular toxin from Ph. herbarum as a biorational, which can be applied as a phytotoxin against Par. hysterophorus.

Conversion of nitrate into a nitro-phenol derivative by reaction with 2-methylphenol or 2,6-dimethylphenol allowed at least 100-fold enrichment of the derivative on Lichrolut EN polymeric cartridge, and it is stable for up to 1 month on the cartridge. The derivative could be eluted with ammonia–methanol mixture. This reaction for nitrate determination has permitted a choice of final measurement by UV-Vis spectrophotometry, liquid chromatography or gas chromatography–mass spectrometry when the limits of detection were 10, 6 and 3 μg l −1 , respectively, and the calibration range 20 μg to 10 mg l −1 nitrate. The method has been validated by spiking natural water samples, when the recovery of nitrate was 98.5–108.4% (relative standard deviation 2.5–6.1%).

Derivatization of aromatic primary amines to N-allyl-N′-arylthioureas by reaction with allyl isothiocyanate and GC–MS of the derivatives, when pyrolysis to aryl isothiocyanates occurs in the heated injector, has been used to determine aromatic amines in the range 0.5–50 μg l−1 with a correlation coefficient, r, in the range 0.9902–0.9992. The limit of detection ranged 8 to 30 ng l−1 when 60 ml of sample were preconcentrated, after derivatization, on a styrene–divinylbenzene copolymer sorbent. The pyrolytic cleavage of sym- and unsym-diaryl or alkyl-/arylthioureas has been rationalized. The chromatography of isothiocyanates is much superior to that of aryl amines and the specific mass fragmentation permits positive identification of amines. The method has been applied to spiked drinking water, groundwater and river water samples, when the recovery ranged from 84 to 109% with RSD of 5–9%, and to detect aromatic amines formed by reductive cleavage of azo dyes in effluents when the recovery of amine was in the range 81–95% with RSD 8–15%. The method is not applicable to nitroanilines.

Interference by large chloride matrix and high acidity in the sample, which makes chromatographic determination of low (μg l−1) level of bromide difficult, can be avoided by pre-column reaction of bromide with 2-iodosobenzoic acid and 2,6-dimethylphenol or 2-tert-butyl-4-methylphenol to form within 1 min 4-bromo-2,6-dimethylphenol and 6-bromo-2-tert-butyl-4-methylphenol, respectively. The derivative was extracted into cyclohexane and injected into the GC. The aqueous sample could be subjected to clean-up using LiChrolut EN sorbent to remove organic matter before derivatization. The bromo derivative could be extracted from up to 250 ml of sample without any breakthrough. A rectilinear calibration graph was obtained for 0.02–100 μg l−1 bromide with a correlation coefficient of 0.9993 (10 calibration points) using 2-tert-butyl-4-methylphenol as reagent and the method has a limit of detection of 5 ng l−1 bromide. This method has also been applied to determine bromide in table salt and concentrated hydrochloric acid and to the spiked samples when the recovery was in the range 98–104% (R.S.D. 0.8–2.2%). The proposed method is simple and precise and high concentrations of ionic impurities including chloride, as found in sea water and table salt and acidity, as in concentrated hydrochloric acid, can be tolerated.

Low concentrations of phenols and amines in environmental waters and their low breakthrough volume during solid-phase extraction (SPE) hinder the detection of phenols and aromatic amines, whereas ammonia and aliphatic amines are not suitable for SPE. Pre-column derivatization to arylbenzoates and N-alkyl- or N-arylbenzamides and their GC-MS is proposed to separate and determine phenols and amines in aqueous samples in the range 0.1–100 μg l−1 with correlation coefficients in the range 0.9910–0.9992. The limit of detection ranged from 7 to 39 ng l−1 for most analytes (90 ng l−1 for 2,3,6-trichlorophenol and 20 μg l−1 for ammonia) when 80 ml of sample were preconcentrated, after derivatization, on a styrene–divinylbenzene copolymer sorbent. The developed method was applied to spiked drinking water, groundwater and river water samples, and was used to detect halo-phenols in paper mill effluents. The average recovery ranged from 96 to 110% with RSD of 4–12%. The described method is rapid and can be applied to control the water quality of environmental waters with respect to three important classes of organic pollutants and ammonia.

Hydrogen sulfide in water stabilized with or absorbed from air in an alkaline mixture of zinc acetate and EDTA was treated with 4-N,N-diethylaminoaniline and iron(III) in sulfuric acid medium and the absorbance of ethylene blue was measured at 670 nm after 5 min. The molar absorptivity was found to be 9.42 × 105 l mol−1 cm−1. The ethylene blue dye could be preconcentrated by solid-phase extraction on a CN sorbent and eluted by potassium bromide solution in water–methanol leading to an enrichment factor of at least 50. Coloured samples were subjected to clean-up by using Lichrolut EN and the colourless eluate was treated for colour development. Rectilinear calibration graphs were obtained over the range 10–800 μg l−1 sulfide (r = 0.9997) without solid-phase extraction, and 1–100 μg l−1 sulfide (r = 0.9989) after solid-phase extraction of the dye. The limits of detection were 5 μg l−1 and 0.2 μg l−1 sulfide without and after solid-phase extraction, respectively. The interference of up to 100 mg l−1 thiols, 50 mg l−1 sulfite and 10 mg l−1 thiosulfate could be avoided by their masking with N-ethylmaleimide. Up to 10 mg l−1 fluoride and 100 mg l−1 thiocyanate did not cause any interference. Interference of up to 100 mg l−1 fluoride was avoided by masking with zirconyl nitrate. The method has been validated by analysing spiked river water samples, when the average recovery was 99% (range 96–104%) with an RSD of 3% (range 2–4%). Sulfide has been detected in many river waters at low μg l−1 levels.

Pre-column conversion of ammonia and a number of aliphatic amines into phenylthiourea or its derivatives by reaction with phenyl isothiocyanate, followed by HPLC, has been used for their determination in environmental waters. Optimum conversion was found when the reaction was carried out in sodium hydrogencarbonate–carbonate medium at 40°C for 15 min. Well separated peaks were obtained on a C18 column with an acetonitrile–water gradient (1 ml min–1) of 30% acetonitrile for an initial 5 min which was increased linearly to 100% over 15 min and then maintained isocratic for 5 min, the acetonitrile ratio finally being returned to 30% in 5 min. The derivatized analytes were subjected to off-line solid phase extraction on C18 sorbent. A linear calibration graph was obtained for 0.01–10 mg l–1 analytes with a correlation coefficient of 0.9954 for ammonia and in the range 0.9982–0.9996 for amines. The limit of detection for ammonia was 0.2 µg l–1 and for amines in the range 0.3–0.6 µg l–1. The method was applied to tap, underground, river and aquarium waters, the recovery being in the range 97–106% (RSD 1.8–4.5%). Many of the samples were found to contain more than the permissible limit of ammonia. Phenyl isothiocyanate is stable for long periods in aqueous medium over wide ranges of pH and temperature, and the resulting phenylthioureas have adequate retention on C18 sorbent and strong UV absorption, making this reagent suitable for the determination of amines in water.

A new reaction for determining iodate in table salt is proposed. It is based on oxidation of phenylhy-drazine-4-sulfonic acid by iodate in acidic medium to the 4-diazobenzenesulfonic acid cation and its electrophilic coupling with N-(1-naphthyl)ethylene- diamine dihydrochloride to give an azo dye, which is measured spectrophotometrically at 545 nm. Maximum molar absorptivity was 8.41 ×104 L/mol cm. A rectilinear calibration graph was obtained for iodate in the range 0.25–5 mg/L. The azo dye could be preconcentrated at least 40-fold by solid-phase extraction on C18 sorbent. The limit of detection was 0.6 μg iodate/L. The method was used to determine iodate in laboratory-prepared and commercially available table salt samples. Up to 5 mg bromate/kg and 10 mg iron(lll)/kg in table salt did not interfere.

Oxidation of phenylhydrazine-4-sulfonic acid to the 4-diazobenzenesulfonic acid cation and its electrophilic coupling with N-(1-naphthyl)ethylenediamine dihydrochloride to give an azo dye is a new reaction scheme that is proposed for the spectrophotometric determination (545 nm) of chlorine in air and free and combined chlorine residuals in environmental waters. Masking of free chlorine with acetone permitted the determination of combined chlorine residuals in water. The maximum molar absorptivity was found to be 1.46 × 106 l mol–1 cm–1. A rectilinear calibration graph was obtained for 2.5–100 µg l–1 Cl. The azo dye could also be preconcentrated by solid-phase extraction on a C18 sorbent, leading to an enrichment factor of at least 40-fold. The limit of detection (without enrichment) was 0.2 µg l–1 Cl. Up to 50 µg l–1 bromate, 10 mg l–1 chlorate, 40 µg l–1 copper(II) and 100 µg l–1 iron(III) did not interfere. Chlorine dioxide was removed by bubbling the water sample with nitrogen. A comparison of the proposed method with the standard 4-N,N-diethylaminoaniline procedure was made and advantages of the present method are noted.

Nitrite can be determined by its reaction with 2-aminobiphenyl in acidic medium to produce 2-phenylphenol which is quantified by gas chromatography with flame ionisation detection using biphenyl as an internal standard. The hydrolysis of the intermediate diazonium ion avoids many of the problems encountered in the conventional determination of nitrite by the diazotization of an aromatic amine (usually sulphanilamide) and coupling with N-(1-napthyl)ethylenediamine dihydrochloride to yield an azo dye followed by spectrophotometry. Unlike this method, the proposed reaction is rapid and does not suffer from interferences by copper(II), iron(III) and lead(II). The calibration graph was linear over the range 5–1000 μg/l NO 2 -N and the limit of detection found to be 0.5 μg/l NO 2 -N. A single analysis can be completed within 20 min. The method was not affected by coloured or turbid analyte solutions and has been used to determine nitrite in natural waters.

Bromide has been determined (i) in the presence of a large excess of chloride and other ions to evaluate its level in sea water, concentrated hydrochloric acid and salts, (ii) after selective mineralization of aliphatic bromo-compounds to measure total bromide residues of fumigants such as 1,2-dibromoethane in water and (iii) to assess bromate levels in water after removal of any free bromide, and reduction of bromate to bromide. The method involves a pre-column derivatization of bromide to 4-bromoacetanilide by reaction with 2-iodosobenzoic acid and acetanilide, sample clean-up by solid-phase extraction using C~ cartridges and high-performance liquid chromatography. The method is simple and precise and has a limit of detection of 1 /zg/1 bromide.

Ascorbic acid is frequently determined by titration with 2,6-dichlorophenolindophenol. The determination is rapid, but the method is neither specific for ascorbic acid nor very sensitive. The coloring matter in the assay solution interferes with the visual endpoint, and iron(ll), copper(l), sulfite, and sulfhydryl substances such as cysteine and glutathione interfere with the color reaction. Sample cleanup by solid-phase extraction with C18 bonded silica was developed to remove the coloring matter. Extraction sorbent impregnated with 2,2′-bipyridyl, 2,9-dimethyl-1,10-phenanthroline (neocuproine) and Jv-ethylmaleimide removes Fe(ll), Cu(l), and sulfhydryl compounds, respectively. The procedure was applied to highly colored multivitamin pharmaceuticals, soft drinks, and fruit and vegetable juices. In contrast to the results from the original method, which is not applicable to such samples, the results obtained by the method incorporating cleanup were accurate and selective for ascorbic acid. The sample cleanup also permitted determination of dehydroascorbic acid by reducing it to ascorbic acid with cysteine and titrating the ascorbic acid formed with indophenol. As little as 3 μg ascorbic acid was determined by the method incorporating cleanup.

Two flow injection systems for the spectrophotometric determination of ascorbic acid at 245 nm have been described. On treatment with sodium hydroxide a fraction of the ascorbic acid was decomposed into substances, which do not absorb in UV region, and the decrease in signal measured. This was directly related to the amount of ascorbic acid present. The calibration graph was linear over the range 1-25 and 1-50 microg/ml in the two methods with a correlation coefficient of 0.9981 and 0.9994, respectively. The detection limit (2sigma) was 0.5 and 0.2 microg/ml, respectively. The RSD for 1 microg/ml standard was 2.5 and 1.8% (n = 6) in the two methods, and the sampling throughput 30/hr. The methods permitted the use of 6 microg/ml of 2-mercaptoethanol as an anti-oxidant and stabilizer for ascorbic acid, which is difficult to handle at its microg/ml level. Upon matrix absorbance correction, spiked samples that are known to contain UV-absorbing substances produced an average recovery of 101% with a RSD of 1.2%. The methods were used for the rapid and simple determination of ascorbic acid in soft drinks, preserved fruit juices and pharmaceuticals and the results thus produced compared with those obtained by previously checked methods involving titration with iodine, chloranil 2,6-dichlorophenolindophenol, and HPLC. When there was a disagreement between the results, this was traced to the presence of substances which are known to interfere in comparison methods.

During the past fifteen years since its introduction, single-drop microextraction has witnessed incessant growth in the range of applications of samples preparation for trace organic and inorganic analysis. This was mainly due to the array of modes that are available to accomplish extraction in harmony with the nature of analytes, and to use the extract directly for analysis by diverse instrumental methods. Whilst engineering of novel sorbent materials has expanded the sample capabilities of rival method of solid-phase microextraction, the single-drop microextraction - irrespective of the mode of extraction - uses common equipment found in analytical laboratories sans any modification, and in a much economic way. The recent innovations made in the field, as highlighted in this review article in the backdrop of historical developments, are due to the freedom in operational conditions and practicability to exploit chemical principals for optimum extraction and sensitive determination of analytes. Literature published till July 2011 has been covered.

The solution obtained by oxidizing some of the ascorbic acid to dehydroascorbic acid by reaction with potassium iodate is used as a reagent for the reduction of paraquat to a blue radical cation in the flow-injection spectrophotometric determination of paraquat. A rectilinear calibration graph was obtained over the range 0.1–100 μg ml−1 paraquat, and the limit of detection was 20 ng ml−1 paraquat (signal-to-noise ratio = 3). This reagent has been found superior to ascorbic acid alone or sodium dithionite because of the lower limit of detection, wide linear range of determination, rapid and high stability.

Chlorine has been be determined in air and water samples by a rapid and sensitive method entailing precolumn derivatization to 4-bromoacetanilide. A mixed potassium bromide-acetanilide reagent was used as a trapping agent for chlorine in air, and for its derivatization. The 4-bromoacetanilide formed was determined by reversed-phase HPLC on an ODS column, using methanol-water, 65∶35 (v/v) as mobile phase; detection was at 240 nm. A rectilinear calibration graph was obtained for the range 0.1–30 μg mL−1 chlorine; the limit of detection found to be 0.01 μg mL−1.

Solid-phase extraction (SPE) of phenol and chlorophenols, their derivatization to methyl ethers, headspace single-drop microextraction (HS-SDME) of methyl ethers using 1-butanol as extraction solvent, and direct transfer of the drop into the injector for high performance liquid chromatography with diode array detection (HPLC-DAD) have been reported. A flanged-end polytetrafluoroethylene sleeve, 3 mm × 0.5 mm, placed at the tip of the syringe needle, allowed the use of 10 μL solvent drop for extraction. The procedure has been optimized for variables involved in SPE and HS-SDME. A rectilinear relationship was obtained between the amount of chlorophenols and peak area ratio of their methyl ethers/internal standard (4-methoxyacetophenone) in the range 0.01–10 mg L−1, correlation coefficient in the range 0.9956–0.9996, and limit of detection in the range 1.5–3.9 μg L−1 when HS-SDME alone was used for sample preparation. When using coupled SPE and HS-SDME, the linear range obtained was 0.1–500 μg L−1, correlation coefficient in the range 0.9974–0.9998, and the limit of detection in the range 0.04–0.08 μg L−1. Spiked real samples have been analyzed with adequate accuracy, and application of the method has been demonstrated for the analysis of chlorophenols formed upon bamboo pulp bleaching.

Nitrite has been determined by reversed-phase high-performance liquid chromatography by its pre-column reaction with 2-aminobiphenyl to give a diazonium salt and with iodide to form 2-iodobiphenyl. Chromatographic analysis was done using a C18-column, a mobile phase of aceto-nitrile - 0.05M sulfuric acid, 60:40 (v/v), detection at 254 nm and using biphenyl as an internal standard. The pre-column derivatization required about 8 min and the chromatographic separation was complete in about 10 min. As low as 8 μg 1−1 of nitrite could be determined with a limit of detection of 2 μg 1−1 Application of the proposed method to river water and pharmaceutical tablets has been demonstrated.

Derivatization od iodide into 4-iodo-2,6-dimethylphenol and HPLC of iodophenol with UV detection has been found to be a suitable method for the sensitive detection of iodide. The precolumn derivatization involved oxidation of iodide with 2-iodosobenzoate at pH 6.4 in the presence of 2,6-dimethylphenol. The reaction mixture was chromatographed on an octadecylsilane column using a mobile phase of acetonitrile-water, 60:40 (v/v), and detection at 220 nm

A new reaction scheme for the determination of free residual chlorine in the presence of other chlorine species, viz. chlorite, chlorate, combined chlorine and chlorine dioxide, has been evaluated. It is based on the oxidation of 4-nitrophenylhydrazine by free chlorine to the 4-nitrophenyldiazo cation and its electrophilic coupling with N -(1-naphthyl)ethylenediamine dihydrochloride to give an azo dye which absorbs maximally at 532 nm. Flow-injection systems are proposed for the determination of 0.05–10 μg ml −1 free chlorine by the reagent-injection technique, and 1–40 μg ml −1 free chlorine by sample injection. The limits of detection of free chlorine and mean R.S.D. (range) were 0.03 μg ml −1 and 0.9% (0.6–1.2%), and 0.4 μg ml −1 and 0.6% (0.4–0.8%), respectively. Only chlorine dioxide interferes. The results were in good agreement with those obtained by flow-injection N , N -diethyl- p -phenylenediamine spectrophotometric and classical iodimetric titration methods. Since chloramines do not interfere in free chlorine determination, a method was developed for the determination of total chlorine (and hence of combined chlorine by difference after determination of free chlorine) utilizing a secondary reaction of both free and combined chlorine with bromide to yield bromine which then acts as oxidizing agent. The sample throughput was 110 h −1 in both methods.

Bromide has been determined by its oxidation with an excess of phenyl iodosoacetate in the presence of acetanilide to give bromine which subsequently reacts with acetanilide to form 4-bromoacetanilide. The residual amount of phenyl iodosoacetate was evaluated iodometrically. Thus, for every mol of bromide one mol of phenyl iodosoacetate was consumed. For the determination of bromine in organic compounds, the test substance was decomposed by fusion with alkali peroxide to liberate bromide which was then evaluated by the phenyl iodosoacetate method. For its determination, nitrite has been reacted with an excess of isoniazid in acid medium to form isonicotinyl azide (which does not react with phenyl iodosoacetate) and the residual amount of isoniazid was titrated with phenyl iodosoacetate in the presence of acidified bromide and methyl red indicator (when isoniazid and phenyl iodosoacetate react in a 1∶2 molar ratio). Each mol of nitrite is equivalent to 2 mol of phenyl iodosoacetate.