Flow injection spectrophotometry coupled with a crushed barium sulfate reactor column for the determination of sulfate ion in water samples

A new type of a reactor column, a crushed BaSO4 reactor column used for the flow injection spectrophotometric determination of sulfate ion using the exchange reaction of sulfate ion and barium-dimethylsulfonazo III is proposed. The column is very simple and economical. It can be continuously used for 8 h before washing with water for repeated usage of at least 1 month. The procedure is sensitive. Application to various water samples was demonstrated. </p

On-site analysis for nitrogen oxides using a newly developed portable flow injection analyzer

A new portable flow injection system was developed for on-site chemical analysis, which allows the rapid analysis of aqueous samples at sampling sites. The system comprises a newly designed double-plunger micro pump, a six-way sample injector, a reaction coil in a thermostated compartment and a detector. All of these units are connected with 0.5 mmi.d. PTFE tubing. A visible detector is assembled using a maximum wavelength of 525 nm of a light-emitting diode (LED) and 540 nm of an interference filter. The system is of the one-box type, whose dimensions are 160(W) x 160(H) x 320(D) mm, and is easy to carry to the analysis site; the weight is 8 kg. A thermostated compartment is incorporated into the proposed system in order to be used outdoors, where temperatures are changeable. The system can workwith DC 12Vas well as AC 100V; therefore, a car battery or a portable battery can be used as the power source. The analytical data can be memorized in IC cards or a note-book personal computer connected with a RS232C cable. Furthermore, software on the market can be easily used. By using the proposed system, the on-site determination of nitrogen oxides, such as nitrate and nitrite, could be carried out. Calibration graphs for nitrate and nitrite ions were linear over ranges of 0 to 1.0ppm and 0 to 100ppb ofN-NOs and N-NO2 with good precision; the sampling rate was 40~50 samples per hour. The detection limit for N-NO3 and N-NO2 was 0.5 ppb. By using the proposed system, the on-site determination of nitrate and nitrite in river water samples was carried out. The relative standard deviations of ten injections were 0.65% for nitrate and 0.15% for nitrite. Furthermore, nitrate and nitrite in biological samples as a metabolic products of nitric oxide, which have attracted a lot of attension as a messenger of diverse physiological processes, were also determined on-site with high sensitivity. By using a car battery as a power source, the proposed system worked continuously. In addition, it worked for about 5 hours continuously with a portable battery.試料採取現場での迅速な分析，すなわちオンサイト分析のための新しいポータブルフローインジェクション分析計の開発を行った・このFIA装置では，160×160誉320（mm）の箱の中にダブルプランジ ャーマイクロポンプ，試料注入語検出器及び反応恒温槽を組み入れ，重量8kgと小型・軽量化を達成し，持ち運び容易な分析計とした．特に，525nmの発光ダイオード（LED）を光源とする新規検出 器を開発することにより，小型，省電力化が可能となった．温度変化の大きな屋外での測定に耐えられるように，反応恒温槽も装備した．本FIA装置は交流100Vでのほか，直流12Vでも稼働し，カーバ ッテリーや市販のポータブルバッテリーを電源とするオンサイト分析に対応できるよう設計した．カーバッテリーを電源とした場合は長時間の連続運転が可能である．測定データはメモリーカードや RS232Cによりノート型パーソナルコンピュータへの通信も可能で，更に市販の表計算ソフトを利用してデータ処理が可能である．本装置を窒素酸化物のオンサイト分析に応用した．硝酸，亜硝酸イオン標準液による検量線は，0～1・Oppm，0～100ppbの範囲で直線性，再現性共に良好で，1時間当たり40～50試料の分析が可能であった・検出限界（5／Ⅳ＝3）は硝酸，亜硝酸態窒素として0．5ppbと通常のFIAシステムを用いる場合と全く変わらない優れた性能を有することが分かった．河川水中の硝酸，亜硝酸イオンのオンサイト分析では10回の繰り返し測定における相対標準偏差は0．65％及び0．15％と良好な結果が得られた．また，血清中の一酸化窒素（NO）の酸化代謝物としての硝酸，亜硝酸イオン濃度のオンサイト分析を行い，良好な結果を得た．本研究で検討したポータブルバッテリーでは1回の充電で5時間の連続運転が可能であった

Application of chitosan functionalized with 3,4-dihydroxy benzoic acid moiety for on-line preconcentration and determination of trace elements in water samples

Chitosan resin functionalized with 3,4-dihydroxy benzoic acid (CCTS-DHBA resin) was used as a packing material for flow injection (FI) on-line mini-column preconcentration in combination with inductively coupled plasma-atomic emission spectrometry (ICP-AES) for the determination of trace elements such as silver, bismuth, copper, gallium, indium, molybdenum, nickel, uranium, and vanadium in environmental waters. A 5-mL aliquot of sample (pH 5.5) was introduced to the minicolumn for the adsorption/preconcentration of the metal ions, and the collected analytes on the mini-column were eluted with 2 M HNO3, and the eluates was subsequently transported via direct injection to the nebulizer of ICP-AES for quantification. The parameters affecting on the sensitivity, such as sample pH, sample flow rate, eluent concentration, and eluent flow rate, were carefully examined. Alkali and alkaline earth metal ions commonly existing in river water and seawater did not affect the analysis of metals. Under the optimum conditions, the method allowed the determination of metal ions with detection limits of 0.08 ng mL(-1) (Ag), 0.9 ng mL(-1) (Bi), 0.07 ng mL(-1) (Cu), 0.9 ng mL(-1) (Ga), 0.9 ng mL(-1) (In), 0.08 ng mL(-1) (Mo), 0.09 ng mL(-1) (Ni), 0.9 ng mL(-1) (U), and 0.08 ng mL(-1) (V). By using 5 mL of sample solution, the enrichment factor and collection efficiency were 8-12 fold and 96-102%, respectively, whereas the sample throughput was 7 samples/hour. The method was validated by determining metal ions in certified reference material of river water (SLRS-4) and nearshore seawater (CASS-4), and its applicability was further demonstrated to river water and seawater samples.</p

Aminophospholipids are signal-transducing TREM2 ligands on apoptotic cells

Variants of triggering receptor expressed on myeloid cells 2 (TREM2) are associated with an increased incidence of Alzheimer’s disease, as well as other neurodegenerative disorders. Using a newly developed,highly sensitive reporter cell model, consisting of Jurkat T cells stably overexpressing a reporter gene and a gene encoding TREM2DAP12 fusion protein, we show here that TREM2-dependent signal transduction in response to apoptotic Neuro2a cells is mediated by aminophospholipid ligands,phosphatidylserine and phosphatidylethanolamine, which are not exposed on the intact cell surface, but become exposed upon apoptosis. We also show that signal-transducing TREM2 ligands different from aminophospholipids, which appear to be derived from neurons, might be present in membrane fractions of mouse cerebral cortex. These results may suggest that TREM2 regulates microglial function by transducing intracellular signals from aminophospholipids on apoptotic cells, as well as unidentified ligands in the membranes of the cerebral cortex

On-Line Photo-Oxidative Decomposition of Phosphorus Compounds to Orthophosphate and Its Application to Flow Injection Spectrophotometric Determinations of Total Phosphorus in River and Waste Waters

A simple and mild on-line photo-oxidative decomposition method for the highly sensitive flow-injection spectrophotometric determination of total phosphorus in river and waste waters was developed for the first time by using low pressure mercury lamps. Organic and inorganic phosphorus compounds in sample solutions were injected into a carrier solution, which merged with the decomposition solution containing sulfuric acid and potassium peroxodisulfate. The solution components were decomposed oxidatively to orthophosphate while flowing in a photo-reactor. After the decomposition, orthophosphate was determined spectrophotometrically based on the formation of Molybdenum Blue. The photo-reactor consisted of two low pressure mercury lamps, a poly(terafluoroethylene) (PTFE) tubing and a reflection mirror. The PTFE tubing was wound directly around the mercury lamps, which were covered with reflection mirror. The detection limit for phosphorus was about 0.001 mg l(-1), and the sample throuphput was about 20 samples per hour for total phosphorus determination. By using the photo-reactor, most of the phosphorus compounds were decomposed completely, whereas some condensed phosphates were less susceptible to photo-oxidation. The analytical results for practical samples obtained by the proposed method showed a good correlation with those obtained by using a heat-oxidation method, which indicates that the content of the condensed phosphates difficult to be decomposed was very scarce in the practical samples

Development of a new gas-permeation system and its application to the spectrophotometric determination of ammonium ion by FIA

A new on-line gas-permeation system was developed to enhance the efficiency and stability of gas permeation for a long time, and was applied to the determination of ammonium ion in river-water samples by the flow- injection method. The proposed gas-permeation system consists of a newly designed gas-permeation unit, a sample injection valve, a reaction coil and two six-way rotary valves in a constant-temperature oven. The gas- permeation unit was assembled using an inner micro porous polytetrafluoroethylene (PTFE) membrane tubing and an outer glass tube, which could be easily connected with one another using connectors with ferrules and o-rings. A sample solution was injected into a carrier containing 0.02 M sodium hydroxide, in which ammonium ion was converted to gaseous ammonia. The gaseous ammonia generated in the carrier passed through the micro porous PTFE membrane, was absorbed in a reagent solution and changed the pH of the reagent solution, which resulted in a color change to cresol red. The absorbance change of cresol red at 550 nm was measured using a visible detector with a flow cell (8μl, 10mm path). After the measurement, two six-way rotary valves were switched over from the flowing state to the drain state of the gas-permeation unit, and the residual solutions in the gas-permeation unit were removed and the PTFE membrane tubing was dried. By keeping the temperature of the oven at 40℃, the sensitivity and the reproducibility for the determination of ammonium ion was improved. Furthermore, the efficiency of gas permeation through the inner tubing could be kept high and constant for a long period without any procedure for reactivating the porous PTFE membrane tubing. Calibration graphs for ammonium ion were liner over ranges of 0 to 10 ppm and 0 to 1.0 ppm of N-NH(4)(+), and the sampling rate was 30 samples per hour. The detection limit for N-NH(4)(+) was about 0.01 ppm when the effective length of the membrane tubing was 5 cm. By using the proposed FIA system, ammonium ion in river-water samples was determined. The analytical results obtained by the proposed method showed a good correlation with those obtained using the indophenol derivatization/FIA method. The relative standard deviations of ten injections were 0.51% and 0.83% with concentrations of 2.73 ppm and 4.11 ppm, respectively. The recoveries of ammonium ion were found to be 97～98%.ガス透過分離におけるガス透過の長期間の安定性と高効率化,更にガス透過効率の長期間の再現性を向上させた,新しいオンラインガス透過システムを構築した.このシステムでは新しく設計・製作したガス透過ユニットを組み込み,ユニット中を溶液が下方から上方に流れるようにし,気泡の発生を防ぐ工夫がほどこされ,更に測定後にガス透過ユニット内に滞留する溶液を排除するために2個の六方切り替えバルブを内蔵させている.ガスの安定的透過のために温度制御できる小型恒温槽を装着した.この装置中にガス透過ユニット,アンモニウムイオン定量用の反応コイルなどを組み入れ,精密測定の向上を目指した.ガス透過ユニットは,多孔質ポリテトラフルオロエチレン(PTFE)チューブとガラス管からなり,接続には樹脂製フェラル及びO-リングを用い,組み立てを容易にし,デッドボリュームも小さくした.ガス透過ユニット,反応コイル及び試料注入器などを恒温槽の中で一定温度に保つことにより,安定した再現性の良い測定が可能となった.ガス透過ユニット内に滞留する溶液を簡単かつ迅速に強制排除する機能も備えており,測定後はガス透過ユニット中の溶液を除いておくことにより,多孔質チューブの透過性能が長期間維持され,再活性化の操作をすることなく,高いガス透過効率を維持することができた.本システムを用いると,検量線は0～10,0～1.0ppmの範囲で良好な直線性を示し,1時間当たり30試料の分析が可能となった.実際に,河川水中のアンモニウムイオンの定量を行ったところ,インドフェノール誘導体/FIA/吸光光度法による定量値と良く一致し,試料に対する相対標準偏差は0.51,0.83%で,回収率は97～98%と良好であった