Determination of proteins with Fast Red VR by a corrected resonance light-scattering technique

Study on the interaction between quinine sulfate and DNA by multiple spectral methods and their analytical applications

The interaction of quinine sulfate (QS) and DNA has been investigated by spectra methods including fluorescence spectroscopy and resonance light scattering (RLS) technique in aqueous solutions. The QS showed an obvious decrease of fluorescence intensity upon the addition of trace amounts of DNA, and the quenching mechanism was suggested to be static quenching according to the Stern-Volmer equation. Under the acidic condition of pH 2.5, the quenched fluorescence intensity of the QS-DNA system was linearly dependent on the concentration of ctDNA ranging from 0.02 to 2.5 mg/L. The interaction between QS and DNA as well as the detection of DNA was further confirmed by RLS technique, and the results showed that enhanced RLS intensity was linearly related to the concentration of ctDNA from 0.01 to 3.5 mg/L. Therefore, two spectral methods for the detection of ctDNA have been established with the use of a QS small molecular probe.

Environmental analysis by inductively coupled plasma mass spectrometry

This article reviews the numerous ways in which inductively coupled plasma mass spectrometry has been used for the analysis of environmental samples since it was commercially introduced in 1983. Its multielemental isotopic capability, high sensitivity and wide linear dynamic range makes it ideally suited for environmental analysis. Provided that some care is taken during sample preparation and that appropriate calibration strategies are used to circumvent non-spectroscopic interferences, the technique is readily applicable to the analysis of a wide variety of environmental samples (natural waters, soils, rocks, sediments, vegetation, etc.), using quadrupole, time-of-flight or double-focusing sector-field mass spectrometers. In cases where spectroscopic interferences arising from the sample matrix cannot be resolved, then separation methods can be implemented either on- or off-line, which can simultaneously allow analyte preconcentration, thus further decreasing the already low detection limits that are achievable. In most cases, the blank, prepared by following the same steps as for the sample but without the sample, limits the ultimate detection limits that can be reached.

A resonance light-scattering (RLS) serving for various quantitative events since 1995: a comment proposed towards how to apprehend well the meaning of RLS and its corresponding guiding role

A resonance light-scattering (RLS), which was creatively suggested for the first time by Pasternack et al. in 1993 [R.F. Pasternack, C. Bustamante, P.J. Collings, A. Giannetto, E.J. Gibbs, J. Am. Chem. Soc. 115 (1993) 5393], have been enjoyably practiced by numerous investigators for various quantitative events since 1995, and hitherto many research papers and some review papers have got published on lots of international journals specialized in or related to analytical and/or bioanalytical sciences. As revealed from these published papers of interests, however, it is a pity that the meaning of RLS is often apprehended unsatisfactorily both in theory and in practice. In this comment, as a result, I would like to do my best to propose an apprehension of the meaning of RLS as full and exact as possible and simultaneously I would like to deliver the important guiding role of this proposed apprehension in the course of the applications of RLS for various quantitative purposes.

Spectroscopic study on the interaction of acridine yellow with adenosine disodium triphosphate and its analytical application

The interaction of adenosine disodium triphosphate (ATP) with acridine yellow and its analytical application have been studied. In an alkalescent medium, adenosine disodium triphosphate react with acridine yellow to form an ion-association by virtue of electrostatic attraction and hydrophobic interaction, resulting in a remarkable enhancement of resonance light scattering (RLS) intensity of acridine yellow. The maximum scattering wavelength is at 325 nm. The spectral characteristics of the ion-associates, the effective factors and the optimum conditions have been investigated. The enhanced RLS intensity is directly proportional to the concentration of ATP in the range of 0.80-20.0 microg ml(-1) with the detection limit 0.086 microg ml(-1). The method has been successfully applied to the quick determination of ATP in tablet and injection samples. The results of the present method are in agreement with those obtained by the method in the Chinese Pharmacopoeia.

Development and application of an ultratrace method for speciation of organotin compounds in cryogenically archived and homogenized biological materials

An accurate, ultra-sensitive and robust method for speciation of mono, di, and tributyltin (MBT, DBT, and TBT) by speciated isotope-dilution gas chromatography-inductively coupled plasma-mass spectrometry (SID-GC-ICPMS) has been developed for quantification of butyltin concentrations in cryogenic biological materials maintained in an uninterrupted cryo-chain from storage conditions through homogenization and bottling. The method significantly reduces the detection limits, to the low pg g(-1) level (as Sn), and was validated by using the European reference material (ERM) CE477, mussel tissue, produced by the Institute for Reference Materials and Measurements. It was applied to three different cryogenic biological materials-a fresh-frozen mussel tissue (SRM 1974b) together with complex materials, a protein-rich material (whale liver control material, QC03LH03), and a lipid-rich material (whale blubber, SRM 1945) containing up to 72% lipids. The commutability between frozen and freeze-dried materials with regard to spike equilibration/interaction, extraction efficiency, and the absence of detectable transformations was carefully investigated by applying complementary methods and by varying extraction conditions and spiking strategies. The inter-method results enabled assignment of reference concentrations of butyltins in cryogenic SRMs and control materials for the first time. The reference concentrations of MBT, DBT, and TBT in SRM 1974b were 0.92 +/- 0.06, 2.7 +/- 0.4, and 6.58 +/- 0.19 ng g(-1) as Sn (wet-mass), respectively; in SRM 1945 they were 0.38 +/- 0.06, 1.19 +/- 0.26, and 3.55 +/- 0.44 ng g(-1), respectively, as Sn (wet-mass). In QC03LH03, DBT and TBT concentrations were 30.0 +/- 2.7 and 2.26 +/- 0.38 ng g(-1) as Sn (wet-mass). The concentration range of butyltins in these materials is one to three orders of magnitude lower than in ERM CE477. This study demonstrated that cryogenically processed and stored biological materials are a promising alternative to conventional freeze-dried materials for organotin speciation analysis, because these are, at present, the best conditions for minimizing degradation of thermolabile species and for long-term archival. Finally, the potential of the analytical method was illustrated by analysis of polar bear (Ursus maritimus) and beluga whale (Delphinapterus leuca) liver samples that had been collected in the Arctic and archived at the Marine Environmental Specimen Bank. Significant concentrations of butyltin compounds were found in the samples and provide the first evidence of the presence of this class of contaminant in the Arctic marine ecosystem. Figure Eye catch image.

Artificial neural networks for qualitative and quantitative analysis of target proteins with polymerized liposome vesicles

We investigate the feasibility of using the luminescence response of polymerized liposomes incorporating ethylenediaminetetraacetate europium(III) (EDTA-Eu(3+)) for monitoring protein concentrations in aqueous media. Quantitative analysis is based on the linear relationship between the luminescence enhancement of the lanthanide ion and protein concentration. Analytical figures of merit are presented for carbonic anhydrase, human serum albumin, gamma-globulins, and thermolysin. Qualitative analysis is based on the luminescence lifetime of the liposome sensor. This parameter, which follows well-behaved single exponential decays and provides characteristic values for each of the four studied proteins, demonstrates the selective potential for protein identification. Then partial least squares-1 and artificial neural networks are compared toward the quantitative and qualitative analysis of human serum albumin and carbonic anhydrase in binary mixtures without previous separation at the concentration levels found in aqueous humor.

Interpretation of butyltin mass spectra using isotope pattern reconstruction for the accurate measurement of isotope ratios from molecular clusters

The fragmentation patterns of butyltin compounds (mono-, di-, and tributyltin) in an electron impact ion source were studied using an isotope pattern reconstruction algorithm with emphasis on isotope ratio measurements from molecular clusters. For this purpose, standards of natural tin isotope abundance and a (119)Sn-enriched mixture of the three compounds were both ethylated and propylated using sodium tetraalkylborates. The corresponding mass spectra of the various tetraalkyltin compounds prepared were obtained by GC/MS after their extraction with hexane. The results showed that pure interference-free molecular clusters were obtained only for certain R(3)Sn(+) ions where no isobaric overlap with R(2)SnH(+) ions occurred (e.g. BuEt(2)Sn(+) overlaps with Bu(2)SnH(+)). These ions are ideal candidates for accurate Sn isotope ratio measurements, while isotope pattern perturbing interferences are observed for other molecular fragments down to Sn(.)(+). Isotope pattern reconstruction algorithm thus can be used as an analytical tool to ensure the absence of molecular interferences--a requirement for accurate isotope ratio measurements from molecular clusters. The relevance of these studies for the determination of butyltin compounds in environmental samples by isotope dilution GC/MS is also discussed.

Evaluation of two lanthanide complexes for qualitative and quantitative analysis of target proteins via partial least squares analysis

Two lanthanide complexes, namely 5-aminosalicylic acid ethylenediaminetetraacetate europium(III) (5As-EDTA-Eu3+) and 4-aminosalicylic acid ethylenediaminetetraacetate terbium(III), were evaluated for the analysis of carbonic anhydrase, human serum albumin (HSA), and gamma-globulin. Quantitative analysis is based on their luminescence enhancement upon protein binding and qualitative analysis on their lifetime capability to recognize the binding protein. Analytical figures of merit are presented for the three proteins. The limits of detection with 5As-EDTA-Eu3+ are at the parts per billion level. Partial least square regression analysis is used to determine HSA and gamma-globulin in binary mixtures without previous separation at the concentration ranges typically found in clinical tests of human blood serum.

Determination of proteins with fullerol by a resonance light scattering technique

Fullerol has been synthesized through the reaction of fullerene C60 with NaOH in aqueous solution by means of ultrasonic agitation and characterized by infrared and 1H-nuclear magnetic resonance spectroscopy. The fullerol obtained shows good solubility and excellent stability in water. A weak resonance light scattering (RLS) spectrum of fullerol was observed in aqueous solution. However, the intensity of the RLS signal could be enhanced in the presence of proteins, including bovine serum albumin (BSA), human serum albumin (HSA), pepsin (Pep), and lysozyme (Lys). Based on the enhancement of the RLS, a sensitive method for the determination of proteins has been established. The quantitative conditions were considered with regard to the effects of the pH, the ion strength, and the concentration of the fullerol. Under the optimum conditions, the intensity of the RLS was proportional to the concentration of proteins with the limits of detection of 9.7, 10.9, 57.4, and 8.5 ng mL(-1) for BSA, HSA, Pep, and Lys, respectively. Almost no interference can be observed from some amino acids, nucleic acids, and most of the metal ions. The model samples and human serum samples were determined satisfactorily with the proposed method.

Protein analysis with tetra-substituted sulfonated cobalt phthalocyanine by the technique of Rayleigh light scattering

This is the first report of cobalt-tetrasulfonatophthalocyanine (CoTSPc) as a probe of Rayleigh light scattering (RLS) to determine proteins at nanogram levels. A highly sensitive method has been developed for the determination of proteins by the light scattering technique on a common spectrofluorimeter, based on the fact that the weak RLS of CoTSPc can be greatly enhanced in the presence of proteins. Under optimum conditions, the linear ranges of the calibration curves were 0.10-34.3 microg x mL(-1) for both human serum albumin and bovine serum albumin, with detection limits of 15.5 and 13.9 ng x mL(-1), respectively. Moreover, there is almost no interference of any amino acids and metal ions. The method has been applied to the direct determination of total proteins in human serum samples, and the results were satisfactory with clinical data provided.

Time-resolved Chemiluminescence Technique for the Microdetermination of Proteins Based on Their Complexation with Copper(II)

Based on the complexation between proteins and Cu(II) coupled with the time-resolved chemiluminescence (CL) technique, a highly sensitive and quantitative assay for measuring proteins in solution is described. The complexes of proteins with Cu(II) have a strongly catalytic effect on the luminol-H2O2 CL reaction. Because the CL emission produced by the complexes is much more long-lived than that by Cu(II), the CL signals originating from proteins can be easily identified and measured with a time-resolved technique. On this basis, bovine albumin fraction V (BAF V) can be quantitatively determined in the range of 0.01 - 5.0 microg/ml with a detection limit of 5.8 ng/ml. The results show that the proposed assay exhibits a small variation in the response values for the same amount of different proteins, as compared to the Lowry as well as Bradford assays. The CL assay has also been studied for the detection of immobilized proteins.