Nianqin Jie

Determination of chromium in waste-water and cast iron samples by fluorescence quenching of rhodamine 6G.

A new simple, selective and sensitive fluorescence quenching method was developed to determine chromium with rhodamine 6G. The method is based on the oxidation of rhodamine 6G by chromium(VI) in sulfuric acid solution. The linear calibration graph was obtained in the range 8-80 ng ml(-1) chromium(VI). The detection limit is 0.8 ng ml(-1). The method was applied successfully to the determination of chromium in waste water and cast iron samples.

Study on the co-luminescence system of Tb-Gd-BPMPHD-CTMAB and its analytical application

Abstract The study indicates that the Tb-BPMPHD-CTMAB ion association system has strong fluorescence intensity. In this system, it is found that the fluorescence can be increased by Sm3+, Eu3+, Dy3+, Tm3+ and Yb3+, as well as well as Y3+, Lu3+, Gd3+ and La3+. This is a newly found co-luminescence system. The Tb-Gd-BPMPHD-CTMAB system is studied in detail on the formation conditions; and the affecting factors of the co-luminescence effect and the system is applied to determine the trace amount of Tb3+. The experiments indicate that in the optimum determining conditions, a linear relationship is obtained between the fluorescence intensity and the Tb3+ concentration in the range 2.0 × 10−11 − 8.0 × 10−6 mol 1−1. The detection limit of Tb3+ is 2.0 × 10−12 mol 1−1. The determination of samples give satisfactory results.

Study of the fluorescence system thulium–bis(1′-phenyl-3′-methyl-5′-pyrazol-4′-one) hexanedione–cetyltrimethylammonium bromide and its analytical application

The fluorescence system thulium–bis(1′-phenyl-3′-methyl-5′-pyrazol-4′-one)hexanedione–cetyltrimethylammonium bromide (Tm–BPMPHD–CTMAB) was studied. It was found that in aqueous solution Tm3+ could form an ion association complex with BPMPHD and CTMAB that could emit the intrinsic fluorescence of Tm3+. CTMAB could enhance the fluorescence intensity 25-fold. Based on the ion association system, a rapid, simple and sensitive method was developed for the determination of trace amounts of Tm3+ in samples containing rare earth elements. The composition of the ion association complex was determined to be 1:2:1 (Tm:BPMPHD:CTMAB).

Study on the co-luminescence system Sm-Gd-BPMPHD-CTMAB and its analytical application

It has been found that the Sm-BPMPHD-CTMAB ion association system shows a strong fluorescence intensity. In this system some rare earth ions, such as Lu3+, Y3+, Gd3+ and Tb3+, exert an evident fluorescence enhancement effect. The formation conditions of the system and the factors affecting the columinescence effect were studied in detail in order to determine trace amounts of Sm3+. Under optimum conditions a linear relationship was obtained between the fluorescence intensity and the Sm3+ concentration in the range of 5.0×10−8–8.0×10−6 mol·L−1. The detection limit of Sm3+ was 2.0×10−8 mol·L−1. The determination gave satisfactory results.

Fluorimetric determination of hydrogen peroxide in water using acetaminophen

A fluorimetric procedure for the determination of hydrogen peroxide, based on the oxidation of acetaminophen with hydrogen peroxide in acidic medium, is described. The calibration graph was linear in the range 5.0 x 10(-8) - 2.4 x 10(-5) M hydrogen peroxide at an emission wavelength of 333 nm with excitation at 298 nm. The method has been applied to the determination of hydrogen peroxide in rain water, and the recoveries in milk samples were good.

Fluorimetric determination of cerium with paracetamol.

A simple, sensitive and selective method for determination of cerium(IV), based on the oxidative reaction between cerium(IV) and paracetamol, has been developed. The fluorescent species is an oxidation product of paracetamol and has excitation and emission maxima at 265 and 360 nm, respectively. The fluorescent intensity of the system is linear over the range 2.0 x 10(-7)-8.0 x 10(-6)M Ce(IV). The method has been applied in the determination of Ce(IV) in synthetic mixtures and ores with good accuracy being achieved.

A Fluorescence Quenching Method for the Determination of Chromium(VI) with L-Tyrosine

Abstract A fluorescence quenching method for the determination of Cr(VI) in aqueous solution is described. The fluorescence intensity of the system is linear ever the range 5×10−6 - 1.0×10−4 M Cr(VI). The method has been applied to the determination of Cr(VI) In cast iron and waste water.

Fluorescent reaction between ascorbic acid and DAN and its analytical application

Fluorescent reaction between ascorbic acid (AA) and 2,3-diamino-naphthalene (DAN) was studied. The experimental results showed that AA could react with DAN at pH = 10.2-10.5, and form the fluorescent heterocyclic condensation products which emitted strong fluorescence. The fluorescence intensity was measured in a 1 cm quartz cell with excitation and emission wavelengths of 400 and 520 nm, respectively. The relationship was obtained between the fluorescence intensity and AA concentration in the range of 2-300 mug ml(-1), the regression coefficient is 0.9993. The detection limit (signal-to-noise = 2) is 0.4 mug ml(-1).

Study on the spectrophotometric determination of micro amounts of selenium(IV) with 2,3-diaminonaphthalene in the presence of sodium dodecylsulphate

Abstract. A method for the spectrophotometric determination of micro amounts of selenium(IV) in aqueous phase has been developed. A time-consuming extraction process is not required due to the use of sodium dodecylsulphate (SDS). Over the range of 0–40 μg/10 ml the calibration curve is linear with Sandells sensitivity being 0.0029 μg.cm–2. As compared with the toluene-extraction spectrophotometry, the present method is simple, rapid and sensitive. It has satisfactorily been used for the determination of Se(IV) in human hair.

Study on the fluorescence system Be-rutin-SDS-Triton X-100 and the determination of rutin

SummaryIt was found that rutin forms a fluorescent complex with Be2+, the fluorescence intensity of which can be increased thirty-one times in a mixed medium of sodium dodecyl sulfonate (SDS) and Triton X-100. A linear relationship is obtained between the fluorescence intensity and the rutin concentration in the range of 1.2×10−6 to 4.8×10−5 mol·l−1. The detection limit is 5.9×10−7 mol·l−1. Rutin traces were determined in drugs using the standard addition method. The luminescence mechanism of the system is discussed.