Turbidimetric immunoassay of serum C-reactive protein.

Abstract This rapid, reliable equilibrium turbidimetric immunoassay for serum C-reactive protein involves a potent monospecific antibody. Polyethylene glycol-6000 to accelerate and enhance the immunoprecipitation reaction, and Tween-20 surfactant to lower and stabilize the sample blank values. Grossly lipemic, icteric, or hemolyzed sera can be assayed. Values up to about 220 mg/L, for which the standard curve is linear, can be measured without sample dilution. Results by the proposed method and by radial immunodiffusion (r 0.989) or laser nephelometry (r = 0.957) correlated well. Analytical recovery averaged 101.3%. Within-, between-, and day-to-day CVs ranged from 0.9% to 3.5%, 0.8% to 5.5%, and 1.9% to 4.8%, respectively. The method is demonstrably superior to radial immunodiffusion or nephelometry. Any spectrophotometer that can measure turbidimetrically at 340 nm can be used.

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A new automated turbidimetric immunoassay for quantifying alpha 1-antitrypsin in serum.

Clinical Chemistry ◽

10.1093/clinchem/32.6.1020 ◽

1986 ◽

Vol 32 (6) ◽

pp. 1020-1022 ◽

Cited By ~ 2

Author(s):

J A Viedma ◽

A de la Iglesia ◽

M Parera ◽

M T López

Keyword(s):

Polyethylene Glycol ◽

Parametric Estimation ◽

Tween 20 ◽

Upper Limit ◽

Analytical Recovery ◽

The Mean ◽

Alpha 1 Antitrypsin ◽

Polyethylene Glycol 6000 ◽

Immunoprecipitation Reaction ◽

Turbidimetric Immunoassay

Abstract This rapid, sensitive equilibrium turbidimetric immunoassay for quantification of alpha 1-antitrypsin involves a monospecific antibody, polyethylene glycol 6000 to accelerate and enhance the immunoprecipitation reaction, and Tween 20 surfactant to decrease and stabilize the sample-blank values. Turbidity at 334 nm is measured by an automated discrete analyzer. Grossly lipemic, icteric, or hemolyzed samples can be assayed. Correlation with results by radial immunodiffusion (RID) was excellent (r = 0.97, n = 84). Analytical recovery averaged 97.7 (SD 2.9)%. Within-run CVs ranged from 1.6 to 1.9%, between-day CVs from 2.0 to 3.5%. Reference values for healthy adults (n = 147) were determined by parametric estimation (for an assumed normal distribution of untransformed data). The lower limit (g/L) with its 0.90 confidence interval is 1.23 (range 1.18-1.28), the upper limit is 2.15 (2.10-2.20), and the mean is 1.69 g/L.

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Immunoturbidimetry of Serum C-Reactive Protein in Low Concentration of Polyethylene Glycol

Annals of Clinical Biochemistry International Journal of Laboratory Medicine ◽

10.1177/000456328502200309 ◽

1985 ◽

Vol 22 (3) ◽

pp. 269-272 ◽

Cited By ~ 8

Author(s):

I Byrjalsen ◽

S H Ingwersen

Keyword(s):

Polyethylene Glycol ◽

Radial Immunodiffusion ◽

C Reactive Protein ◽

Low Concentration ◽

Reactive Protein ◽

Polyethylene Glycol 6000

A simple, rapid immunoturbidimetric assay for determination of serum C-reactive protein is presented. In order to obtain constant sample blank values within a few minutes we found it necessary to use a low concentration (10 g/L) of polyethylene glycol 6000 in contrast to the commonly used 40 g/L PEG solution. The sensitivity of the assay presented is 7 mg/L; within-run and between-run CVs ranged respectively from 1·4% to 2·4% and from 2·1% to 5·5%. Results obtained with the proposed method correlate well with radial immunodiffusion.

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Rapid quantification of C-reactive protein by centrifugal analysis.

Clinical Chemistry ◽

10.1093/clinchem/29.4.696 ◽

1983 ◽

Vol 29 (4) ◽

pp. 696-697 ◽

Cited By ~ 8

Author(s):

L Melamies

Keyword(s):

Reaction Time ◽

Normal Values ◽

Regression Equation ◽

Radial Immunodiffusion ◽

C Reactive Protein ◽

Reactive Protein ◽

Coefficients Of Variation ◽

Quantitative Results ◽

Rapid Quantification

Abstract I describe a rapid, simple immunoturbidimetric method for determining C-reactive protein in serum. With the Instrumentation Laboratory Multistat III microcentrifugal analyzer, quantitative results are obtained automatically after a few minutes of reaction time. Within-run and between-run coefficients of variation ranged from 2.5 to 12.7% at C-reactive protein concentrations of 55 to 69 and 14 to 25 mg/L, respectively, normal values being less than 10 mg/L. Comparison with the commercially available radial immunodiffusion method (y) yields the regression equation y = 1.011x - 2.112 (r = 0.979, n = 100).

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Internal quality control of a turbidimetric immunoassay for canine serum C-reactive protein based on pooled patient samples

Veterinary Clinical Pathology ◽

10.1111/j.1939-165x.2004.tb00363.x ◽

2004 ◽

Vol 33 (3) ◽

pp. 139-144 ◽

Cited By ~ 19

Author(s):

Mads Kjelgaard-Hansen ◽

Asger Lundorff Jensen ◽

Annemarie T. Kristensen

Keyword(s):

Quality Control ◽

Internal Quality Control ◽

Internal Quality ◽

C Reactive Protein ◽

Reactive Protein ◽

Canine Serum ◽

Turbidimetric Immunoassay

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Development and performance of a fully automated method for assay of C-reactive protein in the aca discrete clinical analyzer.

Clinical Chemistry ◽

10.1093/clinchem/34.8.1646 ◽

1988 ◽

Vol 34 (8) ◽

pp. 1646-1649 ◽

Cited By ~ 6

Author(s):

M W Schwartz ◽

R S Schifreen ◽

E Gorman ◽

P M Tuhy ◽

J Bienvenu ◽

...

Keyword(s):

Emergency Room ◽

Rheumatoid Factor ◽

Total Bilirubin ◽

Reference Interval ◽

C Reactive Protein ◽

Reactive Protein ◽

Automated Method ◽

Quantitative Immunoassay ◽

And Performance ◽

Turbidimetric Immunoassay

Abstract A quantitative immunoassay for C-reactive protein (CRP) has been developed for use in the Du Pont aca discrete clinical analyzer. Particle-enhanced turbidimetric immunoassay (PE-TIA) technology is used. The method has a CV of less than 10% in the range 2 to 120 mg/L. Neither hemolyzed samples (Hb less than 5 g/L), icteric samples (total bilirubin less than 300 mg/L), lipemic samples (triglyceride less than 15 g/L), nor some commonly used drugs interfere. Dithioerythritol is used to eliminate interference from rheumatoid factor. Good correlation was seen when the Du Pont CRP method was compared with the Beckman ICS, Syva EMIT, TDx, and Behring methods for CRP. The normal reference interval is 0 to 9 mg/L. The method, which is fully automated, is fast, requires only a few microliters of serum, and is well suited to emergency-room requirements.

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Evaluation of a high-sensitivity turbidimetric immunoassay for serum C-reactive protein: application to the study of longitudinal changes throughout normal pregnancy

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm.2005.053 ◽

2005 ◽

Vol 43 (3) ◽

Cited By ~ 9

Author(s):

Núria Bertran ◽

Jordi Camps ◽

Joan Fernández-Ballart ◽

Michelle M. Murphy ◽

Victoria Arija ◽

...

Keyword(s):

Protein Concentration ◽

Limit Of Detection ◽

High Sensitivity ◽

Normal Pregnancy ◽

Mean Value ◽

C Reactive Protein ◽

Reactive Protein ◽

Weight Gain During Pregnancy ◽

Turbidimetric Immunoassay ◽

Good Agreement

AbstractC-Reactive protein has been associated with several complications of pregnancy. The aims of the present study were: (1) to evaluate a turbidimetric immunoassay for the measurement of C-reactive protein; and (2) to investigate the chronological changes of the levels of this protein from preconception throughout normal pregnancy and its relationship with variables associated with preconception and pregnancy outcome. Inter-assay imprecision was <5% for C-reactive protein >1mg/L and 18% at a mean value of 0.33mg/L. The limit of detection was 0.10mg/L. The method was linear between 0.10 and 30mg/L. There were no observed interferences from jaundice, hemolysis, lipemia or paraproteinemia at the levels studied. There was good agreement with the nephelometric method. A total of 39 women were studied at preconception, at 8, 20 and 32weeks of pregnancy, and in labor. Preconception C-reactive protein concentration was 1.17±0.18mg/L and increased (p<0.001) throughout pregnancy up to 5.69±0.82mg/L. Body mass index at preconception and weight gain during pregnancy were the main factors associated with this increase in C-reactive protein.

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Enzymic ethanol assay: a new colorimetric method based on measurement of hydrogen peroxide.

Clinical Chemistry ◽

10.1093/clinchem/33.4.486 ◽

1987 ◽

Vol 33 (4) ◽

pp. 486-489 ◽

Cited By ~ 20

Author(s):

L Prencipe ◽

E Iaccheri ◽

C Manzati

Keyword(s):

Hydrogen Peroxide ◽

Gas Chromatography ◽

Human Plasma ◽

Colorimetric Method ◽

Alcohol Oxidase ◽

Blue Dye ◽

Standard Curve ◽

Analytical Recovery ◽

Sample Dilution ◽

Coupled Assay

Abstract We describe a new colorimetric method for measuring ethanol in plasma by use of a peroxidase-coupled assay system and alcohol oxidase (EC 1.1.3.13) from Pichia species. Absorptivity is low enough to give useful results without sample dilution. The procedure is also applicable to saliva samples and utilizes only one working reagent. The absorbance of the blue dye that is formed is measured at 600 nm. The standard curve for the method is linear for ethanol concentrations up to 4 g/L. Average analytical recovery of ethanol in human plasma exceeded 99%. Within-run and between-run CVs were less than 2.45% and less than 1.92%, respectively. Results correlate very well with those by gas chromatography (r = 0.9977). The method is adaptable to automation.

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Four immunochemical methods for measuring C-reactive protein in plasma compared.

Clinical Chemistry ◽

10.1093/clinchem/35.3.461 ◽

1989 ◽

Vol 35 (3) ◽

pp. 461-463 ◽

Cited By ~ 7

Author(s):

S Grützmeier ◽

H von Schenck

Keyword(s):

Enzymatic Degradation ◽

Close Agreement ◽

Radial Immunodiffusion ◽

C Reactive Protein ◽

Reactive Protein ◽

Laser Nephelometry ◽

Immunochemical Methods ◽

Good Agreement

Abstract Four immunochemical methods for measuring C-reactive protein (CRP) in plasma were compared: radial immunodiffusion (RID), electroimmunoassay (EIA), immunoturbidimetry (IT), and laser nephelometry (LN). Close agreement was found between RID and EIA (EIA = 0.96 RID + 7.7 mg/L, r = 0.977, n = 100), IT and EIA (EIA = 1.11 IT - 15.8 mg/L, r = 0.951, n = 100), IT and RID (RID = 1.10 IT - 11.5 mg/L r = 0.959, n = 94). In initial studies in 1983, LN showed good agreement with RID (LN = 0.98 RID + 11.9 mg/L, r = 0.973, n = 60). Since then, normal CRP values measured by LN have tended to increase and, at the time of the present study (1986), LN agreed poorly with other methods. The reason for this change is obscure. Having excluded the possibility of enzymatic degradation of CRP, we conclude that instrumentation problems are involved, and therefore we no longer use this method.

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Automated particle-counting immunoassay of C-reactive protein and its application to serum, cord serum, and cerebrospinal fluid samples.

Clinical Chemistry ◽

10.1093/clinchem/29.6.1127 ◽

1983 ◽

Vol 29 (6) ◽

pp. 1127-1131 ◽

Cited By ~ 23

Author(s):

D Collet-Cassart ◽

J C Mareschal ◽

C J Sindic ◽

J P Tomasi ◽

P L Masson

Keyword(s):

Cerebrospinal Fluid ◽

Geometric Mean ◽

Reaction Medium ◽

C Reactive Protein ◽

Cord Serum ◽

Standard Curve ◽

Reactive Protein ◽

Minimal Sample ◽

Particle Counting ◽

High Concentrations

Abstract The assay for C-reactive protein has been fully automated as a particle-counting immunoassay. For cerebrospinal fluid, cord serum, and adults' serum its range of sensitivity extends from 1 microgram/L to 300 mg/L, with a minimal sample dilution of twofold and a maximal dilution of 50-fold being required. This range is so broad because free antibodies are added to the reaction medium. However, we have used Fab fragments rather than whole antibody to avoid too steep a standard curve and a decrease of agglutination at high concentrations of antigen. For 99 consecutive cord sera examined, the concentrations of C-reactive protein ranged from 7 micrograms/L to 1.750 mg/L. The geometric mean was 50 micrograms/L and the upper normal limit (geometric mean +/- 2 SD of the log values) was established at 525 micrograms/L.

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