Method for raising the particle concentration detection limit for photoelectric sensors

1997 ◽  
Vol 40 (10) ◽  
pp. 1017-1020
Author(s):  
I. A. Kudryavtsev ◽  
L. M. Logvinov ◽  
E. I. Pominov ◽  
V. V. Fadeev
Keyword(s):  
Detection Limit ◽  
Particle Concentration ◽  
Concentration Detection Limit

Homogeneous immunofluorometric assays of alpha-fetoprotein with macroporous, monosized particles and flow cytometry

1993 ◽  
Vol 39 (10) ◽  
pp. 2174-2181 ◽  
Author(s):  
J Frengen ◽  
R Schmid ◽  
B Kierulf ◽  
K Nustad ◽  
E Paus ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Detection Limit ◽  
Correlation Coefficient ◽  
High Precision ◽  
Particle Concentration ◽  
Regression Line ◽  
Alpha Fetoprotein ◽  
Immunoradiometric Assay ◽  
Nonspecific Binding ◽  
Separate Particle

Abstract We evaluated two homogeneous immunofluorometric assays (IFMAs) of alpha-fetoprotein (AFP) based on new macroporous acrylate particles combined with flow cytometry. The standard IFMA, requiring 1 h of incubation, provided a working range from 1.8 to > 900 kIU/L (CV < 10%) and a detection limit of 0.6 kIU/L. Use of overnight incubation and a lower particle concentration extended the working range by 1 decade in the lower end. Analytical recoveries for the standard IFMA varied between 97% and 108%. The slope and y-intercept of the regression line correlating measurements by the standard IFMA and a routine immunoradiometric assay were not significantly different from 1 and 0, respectively (P > 0.5), and the correlation coefficient was 0.996. High precision and warning of spuriously high measurements were obtained by including in each sample separate particle types for detecting instrument instability and measuring nonspecific binding only.

scholarly journals Concentration Sensitivity of Nucleic Acid and Protein Molecule Detection Using Nanowire Biosensors

Biophysica ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 328-333
Author(s):  
Yuri D. Ivanov ◽  
Vadim Yu. Tatur ◽  
Alexander V. Glukhov ◽  
Vadim S. Ziborov
Keyword(s):  
Detection Limit ◽  
Nucleic Acid ◽  
Infectious Diseases ◽  
Early Stage ◽  
Protein Molecule ◽  
Cooperative Effect ◽  
Topical Issue ◽  
Low Concentration ◽  
Concentration Sensitivity ◽  
Concentration Detection Limit

The concentration detection limit (DL) of biomacromolecules attainable using a nanowire detector has become a topical issue. A DL of 10−15 M is required to reveal oncological and infectious diseases at an early stage. This study discusses the DL experimentally attainable in the subfemtomolar concentration range, and possible mechanisms explaining such a low-concentration DL through the cooperative effect of biomacromolecular complexes formed on the surface of the nanowire (NW) chip near the nanowire.

scholarly journals Spectrophotometric determination of arsenic in soil samples using 2-(5-bromo-2-pyridylazo)-5-di-ethylaminophenol (Br-PADAP)

2008 ◽  
Vol 33 (3) ◽  
pp. 23-28 ◽  
Author(s):  
S. F. P. Pereira ◽  
S. L. C. Ferreira ◽  
G. R. Oliveira ◽  
D. C. Palheta ◽  
B. C. Barros
Keyword(s):  
Detection Limit ◽  
Sample Volume ◽  
Molar Absorptivity ◽  
Soil Samples ◽  
Complexation Reaction ◽  
Precision And Accuracy ◽  
Concentration Detection Limit ◽  
Arsenic Determination ◽  
Sensitive Method

In this paper, a new, simple and sensitive method for arsenic determination in soil is proposed. This is based on the reduction of silver (I) and iron (III) ions by arsine followed by a complexation reaction of iron (II) with the spectrophotometric reagent Br-PADAP 2-(5-bromo-2-pyridylazo)-5-di-ethylaminophenol. Arsenic determination with a Sandell's sensitivity of 3.1 10-4 cm-2, linear range from 0.1 µg ml-1 to 2.0 µg ml-1 (r560 = 0.9995), molar absorptivity of 2.45 10(5) l mol-1 cm-1 and a concentration detection limit of 1.4 ng ml-1 (3s) were obtained using a 10 ml sample volume. Selectivity was increased with the use of EDTA as a masking agent. The proposed method was applied for arsenic determination in the presence of several ions amounts in digested soil samples. The results revealed that antimony (III), mercury (II), germanium (IV), platinum (IV) interferes at all analyzed proportions. The interferences can be easily removed by the use of EDTA. Precision and accuracy obtained were satisfactory with a R.S.D. < 5 %. Recovery of arsenic in soil samples varied from 95.55 to 102.70 % with a mean of 99.63 %. These results demonstrated that the proposed method is applicable for arsenic analysis in different soil samples.

Colorimetric Determination of Fluoride in Drinking Groundwater using a Polymeric Zirconium Complex of 5-(2-Carboxyphenylazo)-8-Hydroxyquinoline

2013 ◽  
Vol 12 (7) ◽  
pp. 460-465
Author(s):  
Sameer Amereih ◽  
Zaher Barghouthi ◽  
Lamees Majjiad
Keyword(s):  
Drinking Water ◽  
Detection Limit ◽  
Complex Formation ◽  
Molar Absorptivity ◽  
Colorimetric Determination ◽  
Zirconium Complex ◽  
Reliable Determination ◽  
Percentage Recovery ◽  
Quantitation Limit

A sensitive colorimetric determination of fluoride in drinking water has been developed using a polymeric zirconium complex of 5-(2-Carboxyphenylazo)-8-Hydroxyquinoline as fluoride reagents. The method allowed a reliable determination of fluoride in range of (0.0-1.5) mg L-1. The molar absorptivity of the complex formation is 7695 ± 27 L mol-1 cm-1 at 460 nm. The sensitivity, detection limit, quantitation limit, and percentage recovery for 1.0 mg L-1 fluoride for the proposed method were found to be 0.353 ± 0.013 μg mL-1, 0.1 mg L-1, 0.3 mg L-1, and 101.7 ± 4.1, respectively.

Insecticide Residues on 1972 U.S. Auction-Market Tobacco

1975 ◽  
Vol 8 (1) ◽  
Author(s):  
J. J. Domanski ◽  
P. L. Haire ◽  
T.J. Sheets
Keyword(s):  
Detection Limit ◽  
Auction Market ◽  
Insecticide Residues ◽  
Low Detection Limit ◽  
Average Residue ◽  
The Individual ◽  
In Fire

AbstractAverage residue Ievels of DDT + TDE in flue-cured tobacco decreased from 6.1 ppm in 1970 to 0.85 ppm in 1972. DDT + TDE residues in Burley also dropped sharply from previous levels. In 1972 one sample from Kentucky contained 8.17 ppm; all other Burley samples were less than 0.25 ppm. DDT + TDE residues also declined in fire-cured and air-cured types; of these samples Tennessee dark air-cured tobacco contained the highest average residue (3.5 ppm of DDT + TDE). In 1972 over 90 % of the flue-cured samples were positive for toxaphene. Since each of our samples was a composite of tobacco from 10 farmers, we cannot conclude from this result that 90 % of the individual piles contained toxaphene. Significant amounts of toxaphene were found in other types also; for example, 50 % of the 1972 Burley samples had toxaphene concentrations greater than 0.5 ppm. Average endosulfan levels decreased between 1970 and 1972 in flue-cured and Burley tobaccos. However, in all of the dark air and dark fire-cured samples from Tennessee endosulfan residues exceeded 5 ppm. Average endrin residues were at or near the low detection limit in alI samples except fire-cured and dark air-cured tobacco from Tennessee; these averaged 0.26 and 0.17 ppm, respectively.

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