scholarly journals A surface-based calibration approach to enable dynamic and accurate quantification of colorimetric assay systems

2021 ◽  
Author(s):  
Lin Tong ◽  
Joshua D. Hutcheson
Keyword(s):  
Dynamic Range ◽  
Colorimetric Assay ◽  
Mesh Surface ◽  
Color Saturation ◽  
Assay Time ◽  
Accurate Quantification ◽  
Calibration Approach

A mesh surface that incorporates color saturation, assay time, and standard concentration improves colorimetric assay dynamic range and accuracy.

Inter-Laboratory Validation of 4-(Dimethylamino) Cinnamaldehyde (DMAC) Assay Using Cranberry Proanthocyanidin Standard for Quantification of Soluble Proanthocyanidins in Cranberry Foods and Dietary Supplements, First Action Official MethodSM: 2019.06

2020 ◽  
Author(s):  
Andrew D Birmingham ◽  
Daniel Esquivel-Alvarado ◽  
Michael Maranan ◽  
Christian G Krueger ◽  
Jess D Reed
Keyword(s):  
Dietary Supplements ◽  
Colorimetric Assay ◽  
Reference Standard ◽  
Limit Of Quantification ◽  
Method Performance ◽  
Performance Requirements ◽  
Relative Standard ◽  
Plate Reader ◽  
Acceptance Range ◽  
Accurate Quantification

Abstract Background Proanthocyanidins (PAC) are oligomers and polymers of flavan-3-ols with putative health benefits. PAC are prevalent in a wide variety of natural products and dietary supplements. Objective An inter-laboratory study was conducted to validate the 4-(dimethylamino)cinnamaldehyde (DMAC) colorimetric assay using a 96-well plate spectrophotometer for the accurate quantification of PAC in cranberry products and to evaluate the comparison of the procyanidin A2 (ProA2) dimer and cranberry PAC (c-PAC) reference standards. Methods Four test materials analyzed in this study included cranberry fiber powder, cranberry extract powder, concentrated cranberry juice, and a solution of cranberry PAC (30%, w/v). The samples were homogenized, extracted, sonicated, centrifuged, and analyzed using a 96-well plate spectrophotometer. Results Linearity for both the ProA2 and c-PAC standards was determined from 4.053 to 50.666 µg/mL and from 13.520 to 135.95 µg/mL, respectively. The relative standard deviation of repeatability (RSDr) values for the four materials analyzed, using both ProA2 and c-PAC standards, met the Standard Method Performance Requirements (SMPR®). Inter-laboratory precision using Horwitz ratio (HorRat) values for the four materials analyzed, using both ProA2 and c-PAC standards, satisfies the acceptance range in Appendix K of the Official Methods of Analysis (2003): Guidelines for Dietary Supplements and Botanicals. The limit of quantification (LOQ) was estimated to be 3.16 µg/mL. Conclusions The results produced from this study demonstrate the utility of the c-PAC standard over the ProA2 standard and the advantages of using a 96-well plate spectrophotometer for the accurate quantification of PAC. Highlights The use of a 96-well plate reader and c-PAC reference standard in the DMAC method improves accuracy and percision for quantification of soluble proanthocyanidins in cranberry foods and dietary supplements.

A kinetic colorimetric assay of gamma-glutamyltransferase.

1986 ◽  
Vol 32 (8) ◽  
pp. 1581-1584 ◽  
Author(s):  
P Fossati ◽  
G V Melzi d'Eril ◽  
G Tarenghi ◽  
L Prencipe ◽  
G Berti
Keyword(s):  
Dynamic Range ◽  
Colorimetric Assay ◽  
Colorimetric Method ◽  
Volume Ratio ◽  
Ascorbate Oxidase ◽  
Good Precision ◽  
Gamma Glutamyltransferase ◽  
Gamma Glutamyl ◽  
Donor Substrate ◽  
Donor And Acceptor

Abstract We have explored a kinetic colorimetric method for measuring gamma-glutamyltransferase (EC 2.3.2.2) activity in serum, using L-gamma-glutamyl-3,5-dibromo-4-hydroxyanilide and glycylglycine as donor and acceptor substrates. The released product, 3,5-dibromo-4-hydroxyaniline, reacts with 2,5-dimethylphenol to produce a blue quinone monoimine in the presence of ascorbate oxidase (EC 1.10.3.3). This dye has peak absorption at 610 nm, whereas the donor substrate shows negligible absorption throughout the visible spectrum. The reaction can be run with all the reagents in a single working solution with serum as starter, or with the substrate solution as starting reagent. The sample/reagent volume ratio is 1:24. Adaptation of the method to several automated instruments gave good precision in all cases. Comparison with a method in which L-gamma-glutamyl-3-carboxy-4-nitroanilide is the donor substrate showed good correlation of results (r greater than or equal to 0.987). The dynamic range of the method exceeds the upper limits of the reference intervals for men (9-33 U/L) and women (8-25 U/L) by at least 18-fold.

Rapid Single-Step Kinetic Colorimetric Assay for Lactate Dehydrogenase in Serum

1973 ◽  
Vol 19 (2) ◽  
pp. 223-227 ◽  
Author(s):  
Charles C Allain ◽  
Carl P Henson ◽  
M Keith Nadel ◽  
Adam J Knoblesdorff
Keyword(s):  
Lactate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Dynamic Range ◽  
Colorimetric Assay ◽  
Single Step ◽  
Tetrazolium Salt ◽  
Lactate Dehydrogenase Activity ◽  
Tetrazolium Chloride ◽  
System A ◽  
Reducing Substances

Abstract We report an improved kinetic colorimetric system for measuring lactate dehydrogenase activity in serum. In the system a tetrazolium salt, 2-p-iodophenyl-3-p-nitrophenyl-5-phenyl tetrazolium chloride, is used as the chromogenic indicator of dehydrogenase activity, with diaphorase serving as the electron transfer agent. All ingredients required for an assay are combined in a single dry reagent that is stable at room temperature. The method is 2.5 times as sensitive as the ultraviolet method of Wacker and has a dynamic range three times that of the ultraviolet method. Reducing substances in serum do not affect the results. Precision, range of linearity, and stability of reagent after reconstitution are excellent. Results for fresh sera correlated well with those obtained by the "A-Gent" ultraviolet method (Wacker method at 37°C) and with the SMA 12/60.

A gold nanoparticles-based colorimetric assay for alkaline phosphatase detection with tunable dynamic range

2013 ◽  
Vol 43 ◽  
pp. 366-371 ◽  
Author(s):  
Chun Mei Li ◽  
Shu Jun Zhen ◽  
Jian Wang ◽  
Yuan Fang Li ◽  
Cheng Zhi Huang
Keyword(s):  
Gold Nanoparticles ◽  
Alkaline Phosphatase ◽  
Dynamic Range ◽  
Colorimetric Assay

Comparison of digital PCR with real-time PCR calibrated to the International Scale for BCR-ABL monitoring.

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e18545-e18545
Author(s):  
Parth Shah ◽  
Furha Iram Cossor ◽  
Shiva Murarka ◽  
Hemangi Dixit
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Dynamic Range ◽  
Residual Disease ◽  
Pearson Correlation ◽  
Cost Effective ◽  
Digital Pcr ◽  
Absolute Quantitation ◽  
International Scale ◽  
Accurate Quantification

e18545 Background: Monitoring BCR-ABL1 fusion transcripts is the cornerstone of management in chronic myeloid leukemia (CML). Real Time PCR(RTPCR) has been the tool of choice for its sensitivity and dynamic range. The International Scale was recently introduced to allow for standardization across laboratories. Chip based Digital PCR(dPCR) which allows for absolute quantitation may obliviate the need for such standardization by giving absolute results.It has the potential to increase sensitivity for detection of minimal residual disease. This assumes great significance as we move into the era of treatment free remission. Methods: A total of 31 EDTA-blood samples of CML patients with known values ranging from 0.003-0.5 IS were processed via an accredited RTPCR protocol calibrated to the IS scale and a parallel dPCR workflow without any specific calibration . The analysis of digital PCR samples was performed on the Thermofisher Cloud Platform. Results: Both RTPCR and dPCR yielded extremely concordant results. The Pearson correlation between the two methods was r = 0.6043 (95%CI: 0.318 to 0.789; p = 0.0003). The calculated BCR-ABL/ABL ratios were comparable with a median of 0.098 for RT-PCR calibrated to the IS (range 0.003-0.55; n = 26) and 0.11 for dPCR (range 0.003-0.37; n = 29). The mean difference for the ratios between the two methods used for the detection was around 0.08. Conclusions: We demonstrate here the capability of dPCR to provide a parallel result to an IS scale calibrated protocol without any standardization. This approach required no specific calibrators or standards and resulted in extremely cost effective testing. This freedom from routine calibration provides for a significantly more robust workflow and greatly increased reliability. Limitations do persist in dPCR on account of limited chip densities which are the main parameter for the Poisson statistics. This has limited the dynamic range on dPCR to a maximum of Log 4 for accurate quantification. However as chip densities and emulsion concentrations increase in these technologies, they are poised to introduce a new era in the quest of accurate quantification.

Kinetic Colorimetric Assay of Lipase in Serum

1992 ◽  
Vol 38 (2) ◽  
pp. 211-215 ◽  
Author(s):  
Piero Fossati ◽  
Maurizio Ponti ◽  
Paolo Paris ◽  
Giovanni Berti ◽  
Giordano Tarenghi
Keyword(s):  
Dynamic Range ◽  
Colorimetric Assay ◽  
Colorimetric Method ◽  
Order Reaction ◽  
Glycerol Phosphate ◽  
Long Chain Fatty Acid ◽  
Peak Absorption ◽  
Monoglyceride Lipase ◽  
Zero Order Reaction ◽  
Extended Dynamic

Abstract We describe a kinetic colorimetric method for assaying lipase (EC 3.1.1.3) activity in serum by using a natural long-chain fatty acid 1,2-diglyceride. In the presence of colipase, deoxycholate, and calcium ions, pancreatic lipase hydrolyzes the clear substrate solution to produce a 2-monoglyceride, which in turn releases glycerol by the action of a 2-monoglyceride lipase. Glycerol is then assayed by a sequence of enzymatic actions (glycerol kinase, glycerol phosphate oxidase, and peroxidase) that produce a violet quinone monoimine dye with peak absorption at 550 nm. The method features zero-order reaction kinetics, provides a simple and rapid assay with an extended dynamic range, is specific and precise, gives results that correlate well (r greater than or equal to 0.99) with those of methods in which emulsified triolein is the substrate, and lends itself readily to automation. For all these reasons, the method seems highly suitable for routine use in clinical laboratories.

scholarly journals Data validation procedures in agricultural meteorology – a prerequisite for their use

2011 ◽  
Vol 6 (1) ◽  
pp. 141-146 ◽  
Author(s):  
J. Estévez ◽  
P. Gavilán ◽  
A. P. García-Marín
Keyword(s):  
Quality Control ◽  
Crop Production ◽  
Dynamic Range ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Irrigated Agriculture ◽  
Data Validation ◽  
Control Procedures ◽  
Weather Stations ◽  
Accurate Quantification

Abstract. Quality meteorological data sources are critical to scientists, engineers, climate assessments and to make climate related decisions. Accurate quantification of reference evapotranspiration (ET0) in irrigated agriculture is crucial for optimizing crop production, planning and managing irrigation, and for using water resources efficiently. Validation of data insures that the information needed is been properly generated, identifies incorrect values and detects problems that require immediate maintenance attention. The Agroclimatic Information Network of Andalusia at present provides daily estimations of ET0 using meteorological information collected by nearly of one hundred automatic weather stations. It is currently used for technicians and farmers to generate irrigation schedules. Data validation is essential in this context and then, diverse quality control procedures have been applied for each station. Daily average of several meteorological variables were analysed (air temperature, relative humidity and rainfall). The main objective of this study was to develop a quality control system for daily meteorological data which could be applied on any platform and using open source code. Each procedure will either accept the datum as being true or reject the datum and label it as an outlier. The number of outliers for each variable is related to a dynamic range used on each test. Finally, geographical distribution of the outliers was analysed. The study underscores the fact that it is necessary to use different ranges for each station, variable and test to keep the rate of error uniform across the region.

scholarly journals Colorimetric High-Throughput Screen for Detection of Heme Crystallization Inhibitors

2009 ◽  
Vol 53 (6) ◽  
pp. 2564-2568 ◽  
Author(s):  
Margaret A. Rush ◽  
Mary Lynn Baniecki ◽  
Ralph Mazitschek ◽  
Joseph F. Cortese ◽  
Roger Wiegand ◽  
...  
Keyword(s):  
Small Molecules ◽  
High Throughput ◽  
High Throughput Screening ◽  
Dynamic Range ◽  
Colorimetric Assay ◽  
Microtiter Plate ◽  
Viability Assay ◽  
Parasite Viability ◽  
Screening Platform ◽  
Intraerythrocytic Stage

ABSTRACT Malaria infects 500 million people annually, a number that is likely to rise as drug resistance to currently used antimalarials increases. During its intraerythrocytic stage, the causative parasite, Plasmodium falciparum, metabolizes hemoglobin and releases toxic heme, which is neutralized by a parasite-specific crystallization mechanism to form hemozoin. Evidence suggests that chloroquine, the most successful antimalarial agent in history, acts by disrupting the formation of hemozoin. Here we describe the development of a 384-well microtiter plate screen to detect small molecules that can also disrupt heme crystallization. This assay, which is based on a colorimetric assay developed by Ncokazi and Egan (K. K. Ncokazi and T. J. Egan, Anal. Biochem. 338:306-319, 2005), requires no parasites or parasite-derived reagents and no radioactive materials and is suitable for a high-throughput screening platform. The assay's reproducibility and large dynamic range are reflected by a Z factor of 0.74. A pilot screen of 16,000 small molecules belonging to diverse structural classes was conducted. The results of the target-based assay were compared with a whole-parasite viability assay of the same small molecules to identify small molecules active in both assays.

scholarly journals Correction of Color Saturation for Tone Mapping Operator

2019 ◽  
Author(s):  
Елисей Бирюков ◽  
Elisey Birukov ◽  
Михаил Копылов ◽  
Mikhail Kopylov ◽  
Анастасия Хлюпина ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Human Vision ◽  
Tone Mapping ◽  
Improved Method ◽  
Dynamic Range Compression ◽  
Color Saturation ◽  
Average Brightness ◽  
Order Of Magnitude ◽  
Pixel Brightness

This article reviews the problems of color saturation correction during dynamic range compression of images. Special attention is drawn to emulation of human vision and photo cameras effects during processing of the images which have very bright areas (with brightness more than an order of magnitude greater than average brightness of the rest of the image). A method of desaturation of the brightest parts of images is suggested. This method provides lowering of the color saturation of each pixel depending on the pixel brightness. The improved method lowers saturation only of the brightest parts of an image. The size of the desaturated part of the image should not exceed 25% of the size of an entire image.

scholarly journals MS Western, a Method of Multiplexed Absolute Protein Quantification is a Practical Alternative to Western Blotting

2017 ◽  
Author(s):  
Mukesh Kumar ◽  
Shai R. Joseph ◽  
Martina Augsburg ◽  
Aliona Bogdanova ◽  
David Drechsel ◽  
...  
Keyword(s):  
Western Blotting ◽  
Dynamic Range ◽  
Protein Detection ◽  
Absolute Quantification ◽  
Protein Quantification ◽  
Linear Dynamic Range ◽  
Reference Protein ◽  
Core Histones ◽  
Accurate Quantification

Absolute quantification of proteins elucidates the molecular composition, regulation and dynamics of multiprotein assemblies and networks. Here we report on a method termed MS Western that accurately determines the molar abundance of dozens of user-selected proteins at the sub-femtomole level in whole cell or tissue lysates without metabolic or chemical labelling and without using specific antibodies. MS Western relies upon GeLC-MS/MS and quantifies proteins by in-gel co-digestion with an isotopically labelled QconCAT protein chimera composed of concatenated proteotypic peptides. It requires no purification of the chimera and relates the molar abundance of all proteotypic peptides to a single reference protein. In comparative experiments, MS Western outperformed immunofluorescence Western blotting by the protein detection specificity, linear dynamic range and sensitivity of protein quantification. To validate MS Western in an in vivo experiment, we quantified the molar content of zebrafish core histones H2A, H2B, H3 and H4 during ten stages of early embryogenesis. Accurate quantification (CV<10%) corroborated the anticipated histones equimolar stoichiometry and revealed an unexpected trend in their total abundance.

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