Stable Room Temperature Research Articles

A Promising CdSe@CdS-Quantum Dots-Cysteine for the Determination of Trace IgE by Solid Substrate Room Temperature Phosphorescence Immunoassay

The labelling reagent CdSe@CdS-QDs-Cys (QDs-Cys) with the grain diameter of 4.5nm was synthesized by modifying CdSe@CdS quantum dots (QDs) with cysteine (Cys). At the same time, QDs-Cys-Ab(IgE), a phosphorescent quantum dot probe, was developed based on the labelling reaction between -COOH of QDs-Cys and -NH(2) of goat anti human IgE antibody (Ab(IgE)). This probe with excellent biocompatibility and high specificity could not only emit strong and stable room temperature phosphorescence (RTP), but also could carry out specific immunoassay (IA) with immunoglobulin E (IgE), causing the RTP of the system to sharply enhance. Thus, a new solid substrate room temperature phosphorescence immunoassay (SSRTPIA) for the determination of IgE was established. The limit of quantification (LOQ) of the method was 0.12fg spot(-1), corresponding concentration was 3.0 × 10(-13)gmL(-1) and sampling quantity was 0.40μL spot(-1). This highly selective, sensitive and accurate SSRTPIA has been applied to determine IgE in biological samples and diagnose diseases, and the results agreed well with those obtained by enzyme-link immunoassay (ELISA). Meanwhile, the mechanisms of QDs-Cys labelling Ab(IgE) and the determination of IgE by SSRTPIA were also discussed.

Determination of trace gastrin and diagnosis of human diseases using CdTe quantum dots labelled gastrin antibodies as phosphorescence sensors

CdTe quantum dots (CdTe-QDs) can emit strong and stable room temperature phosphorescence (RTP) via the perturbation effect of a Pb(2+) ion on the surface of a nitrocellulose membrane (NCM). CdTe-QDs-Ab(GAS), the product of CdTe-QDs labelled gastrin antibodies (Ab(GAS)), can not only maintain good RTP characteristics, but can also be used as a RTP sensor and carry out highly specific immunoreactions with gastrin (GAS) to form GAS-Ab(GAS)-CdTe-QDs causing the ΔI(p) of the system to sharply enhance. Thus, a new solid substrate room temperature phosphorescence immunoassay (SSRTPIA) for the determination of GAS was established based on the linear relativity between the ΔI(p) of the system and the content of GAS. The limit of quantification (LOQ) of this method was 0.43 fg spot(-1) with the corresponding concentration being 1.1 × 10(-12) g mL(-1) and sampling quantity being 0.40 per spot(-1). This highly specific, accurate, selective and sensitive RTP sensor has been applied to the determination of GAS in biological samples and the diagnosis of diseases, and the results agreed well with those obtained by radioimmunometric assay (RIA). Meanwhile, the mechanism of SSRTPIA for the determination of GAS using CdTe-QDs-Ab(GAS) as the RTP sensor was discussed.

Determination of Trace Deoxyribonucleic Acid by Using Fluorescein Isothiocyanate-Phenosafranine as a Double-Luminescent Phosphorescence Probe

Using Pb2+ as ion perturber, phenosafranine (PF) and fluorescein isothiocyanate (FITC) could emit strong and stable room temperature phosphorescence (RTP) signal on the filter paper, respectively. When they were mixed, the phenomenon that the RTP signal of PF and FITC enhanced significantly was found. And 1.12 ag DNA spot−1 (sample volume was 0.40 μL, corresponding concentration was 2.8 × 10–15 g mL–1) could cause the RTP signal of both PF and FITC to enhance sharply. The content of DNA was proportional to the ΔI p of PF and FITC in the system at 634 and 659 nm. Thus, a new solid substrate room temperature phosphorimetry (SSRTP) for the determination of trace DNA was established by using FITC-PF as double-luminescent phosphorescence probe. The detection limit (LD) of this method calculated by 3Sb/k was 14 zg DNA spot–1 for PF and 18 zg DNA spot–1 for FITC, respectively, showing high sensitivity. It has been applied to the determination of trace DNA in practical samples and the analysis results were in accordance with those of fluorescence probe. The reaction mechanism of SSRTP for the determination of trace DNA was also discussed.

Raman spectroscopy and inelastic neutron scattering study of crystalline L-valine

Information about the strength of the hydrogen bond interactions in crystalline L-valinewas obtained by Raman and inelastic neutron scattering spectroscopies. Ramanstudies were carried out from room temperature up to 423 K in order to examineboth the external and the internal vibrations in L-valine. The structure seems tobe stable above room temperature since no indication of a phase transition orclear indication of reorientation of L-valine molecules was observed. From theinelastic neutron scattering measurements, made between 270 and 320 K, for fullyhydrogenated and partially deuterated L-valine, a better description of the lowfrequency modes was possible. Moreover it was possible to establish that the phasetransition at low temperatures is related to the activation of an infrared modein the Raman spectra. Additionally the low temperature phase of L-valine wasfurther characterized by means of specific heat measurements between 5 and 350 K.

First-principles study on ferromagnetism in nitrogen-doped In2O3

We report stable room temperature ferromagnetism in nitrogen doped In2O3 (N–In2O3) based on density functional theory. Our investigation on the electronic and magnetic properties of N–In2O3 suggests that N dopant introduces spin-polarized hole states in the band gap generating a total magnetic moment of 1.0μB per N, which is mainly localized on the doped N atoms. The ferromagnetic interaction in N–In2O3 system is mainly driven by the occurrence of coupling chains between a first N (N1)-2p to a second N (N2)-2p via a bridging In 5p and 4d orbitals.

Solid substrate-room temperature phosphorimetry for the determination of trace protein using ion association complex [Cu(BPY) 2] 2+·[(Fin) 2] 2− as a phosphorescent probe

Fluorescein (HFin) emitted strong and stable room temperature phosphorescence (RTP) on filter paper after set at 50 °C for 10 min using Li + as the ion perturber. HFin existed as Fin − when the pH value was in the range of 5.45–7.36. Fin − could react with [Cu(BPY) 2] 2+ (BPY: α,α-bipyridyl) to produce ion association complex [Cu(BPY) 2] 2+·[(Fin) 2] 2−, which could enhance the RTP signal of Hfin. In the presence of bovine serum albumin (BSA), the –COOH group of Fin − in the [Cu(BPY) 2] 2+·[(Fin) 2] 2− could react with the –NH 2 group of BSA to form the ion association complex [Cu(BPY) 2] 2+·[(Fin-BSA) 2] 2−, which contained –CO–NH– bond. This complex could sharply enhance the RTP signal of Hfin and the Δ I p was directly proportional to the content of BSA. According to the facts above, a new solid substrate-room temperature phosphorimetry (SS-RTP) for the determination of trace protein had been established using the ion association complex [Cu(BPY) 2] 2+·[(Fin) 2] 2−as a phosphorescent probe. This method had wide linear range (0.40 × 10 −9–280 × 10 −9 mg l −1), high sensitivity (the detection limit (LD) was 1.4 × 10 −10 mg l −1), good precision (RSD: 3.4–4.9%) and high selectivity (the allowed concentration of coexistent ions or coexistent materials was high). It had been applied to the determination of the content of protein in 10 kinds of real samples, and the result agreed well with pyrocatechol violet-Mo (VI) method (P.V.M.M.), which indicated it had high accuracy. Meanwhile, reaction mechanism for the determination of trace protein with [Cu(BPY) 2] 2+·[(Fin) 2] 2− phosphorescent probe was also discussed. The academic thought of this research could not only be used to develop many kinds of ion association complex phosphorescent probes, but also provided a new way to promote the sensitivity of SS-RTP.

Blue luminescent silicon nanocrystals prepared by short pulsed laser ablation in liquid media

The pulsed laser processing in liquid media is an attractive alternative to produce room temperature luminescent silicon nanocrystals (Si-ncs). We report on a blue luminescent Si-ncs preparation by using nanosecond pulsed laser (Nd:YAG, KrF excimer) processing in transparent polymer and water. The Si-ncs fabrication is assured by ablation of crystalline silicon target immersed in liquids. During the processing and following aging in liquids, oxide based liquid media, induce shell formation around fresh nanocrystals that provides a natural and stable form of surface passivation. The stable room temperature blue-photoluminescent Si-ncs are prepared with maxima located around ∼440 nm with corresponding optical band gap around ∼2.8 eV (∼430 nm). Due to the reduction of surface defects, the Si-ncs preparation in water, leads to a narrowing of full-width–half-maxima of the photoluminescence spectra.

Organic–Inorganic Sol–Gel Composites Incorporating Semiconductor Nanocrystals for Optical Gain Applications

Organic-inorganic sol-gel composite incorporating highly emitting CdSe/ZnS quantum dots and CdSe/CdS/ZnS quantum rods is reported. Optical gain measurements conducted on a quantum rod/sol-gel composite film show stable room temperature amplified spontaneous emission under ambient conditions.

Optical sensing of heavy metal ions in anionic micellar solution using a Pd porphyrin phosphorescent probe

Using sodium sulfite as an oxygen scavenger, meso-tetra (4-N,N,N-trimethylanilinium) porphyrin-Pd (Pd-TAPP) emits strong and stable room temperature phosphorescence (RTP) in sodium dodecyl sulfate (SDS) micellar solution. Heavy metal ions, including Fe 2+, Co 2+, Ni 2+ and Cu 2+, can efficiently quench the phosphorescence of Pd-TAPP. The Stern–Volmer constants increased in the order Fe 2+ < Co 2+ < Cu 2+ < Ni 2+, directly reflecting the relative sensitivity of the method for these ions. The detection limits calculated following the 3σ IUPAC criteria are: 2.3 × 10 −7 mol/L for Cu 2+, 3.4 × 10 −7 mol/L for Co 2+, 1.2 × 10 −7 mol/L for Ni 2+ and 2.1 × 10 −6 mol/L for Fe 2+. The addition of these ions also resulted in reduction of the lifetime ( τ) of Pd-TAPP. The linear relationship between the concentration of Fe 2+, Co 2+, Ni 2+ or Cu 2+ ions and τ 0/ τ indicated the dynamic quenching mechanism.

Electrodeposition of Ni-Cu Alloys in an Air and Water Stable Room Temperature Ionic Liquid

Due to the ligand property of the DCA anion, both CuCl and NiCl2 are soluble in 1-ethyl-3-methylimidazolium dicyanamide (EMI-DCA) ionic liquid. Cyclic voltammograms of Ni(II), Cu(I), and Ni(II)+Cu(I), respectively, in EMI-DCA were recorded on the glassy carbon electrode at 30°C. It is interesting to note that the thermodynamic deposition potentials of Ni and Cu are very close to each other. This is especially favorable for the electrodeposition of Ni-Cu alloys without any additive. The Ni-Cu alloys were electrodeposited using bulk controlled-potential electrolysis experiments. Energy-dispersive spectroscopy (EDS) data indicates that the composition of the Ni-Cu alloys not only depends on the deposition potential, but also on the Cu(I) and Ni(II) concentrations in the melt.

Effect of Applied Load and Surface Roughness on the Tribological Properties of Ni-Based Superalloys Versus Ta2AlC/Ag or Cr2AlC/Ag Composites

The novel Ta2AlC–20 vol.% Ag (TaAg) and Cr2AlC–20 vol.% Ag (CrAg) composites were tribologically tested versus a Ni-based superalloy Inc718 (SA) by dry sliding at a sliding speed of 1 m/s at room temperature in air at loads from 3 N to 18 N. The TaAg composites were also tested at 8 and 18 N at 550 °C, and at a 3 N load against the SA with different surface roughnesses at 26 °C and 550 °C. At room temperatures, the coefficients of friction, μ’s, decreased from ~0.8–0.9 to ~0.3–0.4 for both the TaAg and CrAg composites as the applied normal force increased from 3 N to 8 N. Further increases in load to 18 N did not change the μ’s. The specific wear rates, sWR, increased with increased loads for the TaAg composite; they remained almost unchanged for the CrAg composite. This behavior was attributed to the formation of glaze tribofilms—similar to ones observed previously in these tribocouples at elevated temperatures and 3 N—promoted by the increased loads. Preconditioning of the SA surface by sliding against the TaAg composite at 550 °C and 8 N resulted in μ’s of <0.2 and sWR < 10−6 mm3/N-m in subsequent room temperature sliding at 3 N. Somewhat higher, but stable room temperature μ’s of ~0.3 and sWR of ~3 × 10−5 mm3/N-m were observed when the TaAg composites were slid versus a sandblasted SA surface at 500 °C and 3 N. It follows that in situ preconditioning of the tribo-surfaces is a powerful tool for improving the properties of the MAX/Ag-SA tribocouples. The relationship between sliding conditions, chemistries of tribofilms, and their properties are discussed.

Determination of Glucose by Affinity Adsorption Solid Substrate‐room Temperature Phosphorimetry Based on Triticum Vulgare Lectin Labeled with Silicon Dioxide Nanoparticle Containing Fluorescein Isothiocyanate

Abstract In the presence of heavy atom perturber Pb2+, silicon dioxide nanoparticle containing fluorescein isothiocyanate (FITC‐SiO2) could emit a strong and stable room temperature phosphorescence (RTP) signal on the surface of acetyl cellulose membrane (ACM). It was found in the research that a quantitative specific affinity adsorption (AA) reaction between triticum vulgare lectin (WGA) labeled with luminescent nanoparticle and glucose (G) could be carried on the surface of ACM. The product (WGA‐G‐WGA‐FITC‐SiO2) of the reaction could emit a stronger RTP signal, and the ΔIp had linear correlation to the content of G. According to the facts above, a new method to determine G by affinity adsorption solid substrate room temperature phosphorimetry (AA‐SS‐RTP) was established, based on WGA labeled with FITC‐SiO2. The detection limit (LD) of this method calculated by 3Sb/k was 0.47 pg·spot−1 (corresponding to a concentration value 1.2×10−9 g·mL−1, namely 5.3×10−9 mol·L−1), the sensitivity was high. Meanwhile, the mechanism for the determination of G by AA‐SS‐RTP was discussed.

Catalytic solid substrate-room temperature phosphorimetry for the determination of trace As(V) based on oxidising reaction between hydrogen peroxide and fullerenol using tween-80 as sensitizer

A new catalytic solid substrate-room temperature phosphorimetry (SS-RTP) for the determination of trace arsenic(V) has been established. It is based on the fact that fullerenol (F-ol) emitted strong and stable room temperature phosphorescence (RTP) on nitric acid cellulose membrane (NCM) substrate. H2O2 could oxidise F-ol to cause the quenching of RTP. As(V) could catalyse H2O2 to oxidise F-ol and decrease the RTP signal of F-ol sharply. After adding tween-80 in the system, its ΔI p enhanced 7.7 times compared with the without-tween-80 levels. Under the optimum conditions, the linear dynamic range of this method was 0.016−11.2 ag spot−1 with a detection limit (LD) of 9.3 zg spot−1 (corresponding concentration: 2.3 × 10−17 g mL−1). This sensitive, simple and selective method has been successfully applied to the determination of trace As(V) in human hair and tea samples. The reaction mechanism for SS-RTP is also discussed.

Determination of Bioactive Matter by Affinity Adsorption Solid Substrate–Room Temperature Phosphorimetry Based on Lectin Labeled with Self-ordered Ring of Eosin Y

A new phosphorescent labeling reagent named self-ordered ring (ESOR) of eosin Y (E) was developed. And the application of the determination of bioactive matter by affinity adsorption solid substrate-room temperature phosphorimetry (AA-SS-RTP) based on ESOR labeling lectin was studied. Results showed that pink and homogeneous ESOR could be formed by E on polyamide membrane (PAM) in the presence of cetyltrimethylammonium bromide (CTAB) and ammonia water. ESOR could emit strong and stable room temperature phosphorescence (RTP) signal of E in the presence of heavy atom perturber. Specific affinity adsorption (AA) reactions could be carried out between the products of concanavalin agglutinin (Con A), triticum vulgaris lectin (WGA) labeled with ESOR and alpha-fetoprotein variant (AFP-V), alkaline phosphatase (ALP), glucose (G), respectively. Not only did the products of the affinity adsorption reactions preserve good RTP characteristic of E, but also the DeltaIp (DeltaIp=Ip2-Ip1, Ip1 is the RTP intensity of blank reagent, Ip2 is the RTP intensity of sample) of these products was proportional to the content of AFP-V, ALP and G, respectively. According to the facts above, a new method of AA-SS-RTP for the determination of AFP-V, ALP and G was established, based on ESOR labeling lectin. Detection limits (LD) of this method were 0.040 fg spot(-1) for AFP-V, 0.045 fg spot(-1) for ALP and 0.090 fg spot(-1) for G. And it has been successfully applied to the determination of AFP-V in human serum as well as the survey and forecast of human diseases. This method had high sensitivity, good repeatability, long RTP lifetime and little background interference with lamdamaxem at the long wavelength area. Meanwhile, the mechanism for the determination of trace AFP-V by AA-SS-RTP based on Con A labeled with ESOR was also discussed.

Gd 5Ni 0.96Sb 2.04 and Gd 5Ni 0.71Bi 2.29: Crystal structure, magnetic properties and magnetocaloric effect. Structural transformation and magnetic properties of hexagonal Gd 5Bi 3

Nickel was successfully introduced into the Gd 5Sb 3 and Gd 5Bi 3 binaries to yield the Gd 5Ni 0.96(1)Sb 2.04(1) and Gd 5Ni 0.71(1)Bi 2.29(1) phases. Both Ni-substituted compounds adopt the orthorhombic Yb 5Sb 3-type structure. While the Gd 5Ni 0.71Bi 2.29 phase is thermodynamically stable at 800 °C and decomposes at lower temperatures upon annealing, it can be easily quenched to room temperature by rapid cooling from 800 °C. The Gd 5Ni 0.96Sb 2.04 phase is found to be thermodynamically stable till room temperature. Through annealing at different temperatures, Gd 5Bi 3 was proven to undergo the Mn 5Si 3-type (LT)↔Yb 5Sb 3-type (HT) transformation reversibly, whereas Gd 5Sb 3 was found to adopt only the hexagonal Mn 5Si 3-type structure. Orthorhombic Gd 5Ni 0.96Sb 2.04 and Gd 5Ni 0.71Bi 2.29 and low-temperature hexagonal Gd 5Bi 3 order ferromagnetically at 115, 162 and 112 K, respectively. In Gd 5Bi 3, the ferromagnetic ordering is followed by spin reorientation below 64 K. Magnetocaloric effect in terms of Δ S was evaluated from the magnetization data and found to reach the maximum values of −7.7 J/kgK for Gd 5Ni 0.96Sb 2.04 and −5.6 J/kgK for Gd 5Ni 0.71Bi 2.29 around their Curie temperatures.

Solid Substrate–Room Temperature Phosphorimetry for the Determination of Trace Terbutaline Sulfate Based on Its Inhibition Oxidation of Rhodamine 6G by Sodium Periodate

When 1.00 mol l(-1) I(-) is used as ion perturber, rhodamine 6G (Rh 6G) can emit strong and stable room temperature phosphorescence (RTP) on filter paper substrate in KHC(8)H(4)O(4)-HCl buffer solution (pH = 3.50), heated at 70 degrees C for 10 min. NaIO(4) can oxidize Rh 6G, which makes the RTP signal quench. Terbutaline sulfate (TBS) can inhibit NaIO(4) from oxidizing Rh 6G, which makes the RTP signal of Rh 6G enhance sharply. The content of TBS is linear correlation to DeltaIp of the system. Based on the facts above, a new inhibition solid substrate-room temperature phosphorimetry (SS-RTP) for the determination of trace TBS has been established. The linear range of this method is 0.0104-2.08 pg spot(-1) (corresponding concentration: 0.026-5.2 ng ml(-1), with a sample volume of 0.4 microl) with a detection limit (L.D.) of 2.6 fg spot(-1) (corresponding concentration: 6.5 x 10(-12) g ml(-1)), and the regression equation of working curve is DeltaIp = 2.040 + 54.54 m(TBS) (pg spot(-1)), n = 6, correlation coefficient is 0.9994. For the samples containing 0.0104 pg spot(-1) and 2.08 pg spot(-1) TBS, the relative standard deviation (RSD) are 3.8% and 2.3% (n = 8), respectively, indicating good precision. This method has been applied to determination of trace TBS in the practical samples with satisfactory results. The reaction mechanism of NaIO(4) oxidizing Rh 6G to inhibit SS-RTP for the determination of trace TBS is also discussed.

Optical properties and local structure of Eu 3+-doped synthetic analogue of the microporous titanosilicate mineral sitinakite

The synthetic analogue of the microporous titanosilicate mineral sitinakite has been hydrothermally synthesized and used as a host in the preparation of a new photoluminescent material. The inclusion of Eu 3+ in the pores of the sitinakite doubles the unit cell volume and changes the symmetry of the initial sodium phase. The Eu 3+-doped material displays a stable room temperature emission ascribed to the Eu 3+ intra-4f 6 5D 0→ 7F 0−4 transitions, with a maximum external quantum yield of 6%. The observation of two components for the non-degenerated 5D 0→ 7F 0 transition, the local field splitting of the 5D 0→ 7F 1−2 transitions, and the 5D 0 emission decay curves point out the presence of two optically active Eu 3+ sites. Possible structural distribution of the detected Eu 3+ cations is discussed.

Comparison of Kinetic Profile of Free and Immobilized Glucose Oxidase, Immobilized on Low‐Density Polyethylene Using UV Polymerization

Bioactive packaging is an important area of active packaging in which an active component is incorporated into the food contact surface of the package to interact with the food components without itself migrating into the food. Embedding bioactivity in a UV polymerizable resin is a novel and versatile technique for incorporating bioactive components into food packaging. In a previous article, glucose oxidase was immobilized in a packaging material using a UV curable resin. The relevance of this model system for deoxygenation of fruit juices was discussed. Though the technique efficiently immobilized enzymes in packaging material, during polymerization and immobilization the catalytic ability of the enzyme was not specifically explored. This article compares and contrasts the catalytic ability in terms of the kinetic profile of free and immobilized enzyme for the same model system: deoxygenation of juices. Kinetic behavior of immobilized and free glucose oxidase enzyme was evaluated at both shelf stable (room temperature) and refrigerated storage conditions to simulate the actual package life. It was observed that both the free enzyme and the immobilized enzymes follow the Michaelis-Menten kinetics model. There was no significant difference between the catalytic ability (k(cat)/K(m)) of free and immobilized enzymes at treatment temperatures (30, 25, and 10 degrees C); however, at refrigeration temperature (5 degrees C), the values for free enzyme were significantly higher than the immobilized enzyme.

Determination of glucose by affinity adsorption solid substrate-room temperature phosphorimetry based on concanavalin agglutinin labeled with fluorescein using 1.5-generation dendrimers as sensitizer

In the presence of the heavy atom perturber Pb(Ac)2, fluorescein (HFin) can emit strong and stable room temperature phosphorescence (RTP) on the surface of a nitrocellulose membrane (NCM) at λexmax/λemmax = 480/648 nm. It can be spiked with the 1.5-generation polyamidoamine dendrimers (abbreviated: D-1.5) to emit stronger RTP. It was found that a quantitative specific affinity adsorption (AA) reaction between concanavalin agglutinin (abbreviated: Con A) labeled with D-1.5-HFin and N-acetylglucosamine (G) could be carried out on the surface of NCM. The product of the reaction (D-1.5-HFin- Con A-G) could emit strong and stable RTP, and the ΔIp was proportional to the content of G. According to the above facts, a new method for determination of G by affinity adsorption solid substrate-room temperature phosphorimetry (AA-SS-RTP) was established, based on Con A labeled with fluorescein using D-1.5 dendrimers molecules as sensitizer. The linear range of the sandwich method was 0.040–60 pg G spot−1 (corresponding concentration range: 0.10–150 ng mL−1; sample volume: 0.40 µL spot−1). The regression equation of the working curve was ΔIp = 6.880 + 5.610 mG pg spot−1, r = 0.9987. The working solutions containing 0.10 and 150 ng mL−1 G were determined repeatedly 11 times, respectively. The corresponding RSDs were 2.9 and 3.8%. The detection limit of this method calculated by 3Sb/k was 0.021 pg spot−1 (5.2 × 10−11 g mL−1). Compared with the direct method (detection limit: 0.078 pg spot−1, linear range: 0.40–40 pg G spot−1), the sensitivity was obviously improved and the linear range was wider. This method has been successfully applied to the determination of G in human plasma, as well as to the supervision and forecast of human diseases, for it is of good sensitivity, accuracy and precision.

Determination of trace formaldehyde by solid substrate-room temperature phosphorescence quenching method based on the rose bengal–potassium bromate–Tween-80 system

A new method for the determination of trace formaldehyde by solid substrate-room temperature phosphorescence quenching method has been proposed. It is based on the facts that rose bengal (R) can emit intense and stable room temperature phosphorescence on the solid substrate of filter paper (SS-RTP). Potassium bromate (KBrO 3) can oxidize R, which causes the quenching of RTP. In the presence of HCHO, it can react with KBrO 3 to form Br 2 and Br 2 can oxidize R, which causes smart quenching of RTP. The phosphorescence intensity (Δ I p) is directly proportional to the concentration of HCHO. In the presence of Tween-80, the Δ I p will be increased to 9.1 times higher than that without it. The linear range of this method is 0.016–1.6 fg spot −1 (corresponding concentration: 0.040–4.0 pg ml −1, 0.40 μl spot −1) with the detection limit of 4.5 ag spot −1 (corresponding concentration: 1.1 × 10 −14 g ml −1). The regression equation for working curve is Δ I p = 136.6 + 28.28 m HCHO fg spot −1 ( r = 0.9935, n = 6). This method is sensitive, simple, rapid and has been applied to the determination of trace formaldehyde in real samples with satisfactory results. The mechanism of determination of trace formaldehyde by SS-RTP quenching method based on the rose bengal–KBrO 3–Tween-80 system is also discussed.