False-positive results of the determination of bacterial endotoxins in drugs: the use of a β-glucan blocker

2020 ◽  
Vol 69 (1) ◽  
Author(s):  
O.V. Shapovalova ◽  
N.P. Neugodova ◽  
G.A. Sapozhnikova
Keyword(s):  
False Positive ◽  
Bacterial Endotoxins ◽  
Positive Results

Interference by Tin in AOAC Dry-Ash Voltammetric Method for Determination of Lead and Cadmium in Canned Foods

1988 ◽  
Vol 71 (4) ◽  
pp. 857-859
Author(s):  
Walter Holak ◽  
John J Specchio
Keyword(s):  
Tartaric Acid ◽  
False Positive ◽  
Supporting Electrolyte ◽  
Canned Food ◽  
Voltammetric Method ◽  
Lead And Cadmium ◽  
Anodic Stripping ◽  
Canned Foods ◽  
Positive Results

Abstract When lead and cadmium were determined in samples of canned food by the AOAC anodic stripping voltammetric method, an interference was observed which was believed to be tin(IV). This interference could cause false positive results for lead and cadmium. The electroactivity of tin(IV) was suppressed by increasing the concentration of tartaric acid in the supporting electrolyte from 0.005M to 0.1M after mixing with an equal volume of sample solution.

Can cadaverous pollution from environmental lead misguide to false positive results in the histochemical determination of gunshot residues? Study on cadaveric skin samples

2017 ◽  
Vol 277 ◽  
pp. 16-20 ◽  
Author(s):  
Michele Boracchi ◽  
Salvatore Andreola ◽  
Federica Collini ◽  
Guendalina Gentile ◽  
Francesca Maciocco ◽  
...  
Keyword(s):  
False Positive ◽  
Gunshot Residues ◽  
Environmental Lead ◽  
Positive Results ◽  
Skin Samples

Four rapid serum-urine combination assays of choriogonadotropin (hCG) compared and assessed for their utility in quantitative determinations of hCG

1994 ◽  
Vol 40 (10) ◽  
pp. 1944-1949 ◽  
Author(s):  
S H Mishalani ◽  
J Seliktar ◽  
G D Braunstein
Keyword(s):  
False Positive ◽  
The Other ◽  
Urine Samples ◽  
Serum Samples ◽  
Positive Urine ◽  
Sample Application ◽  
Positive Results ◽  
Hcg Test ◽  
In Pregnancy

Abstract We evaluated the performance of four visually read pregnancy tests (TestPack Plus hCG Combo, ICON II hCG, SureCell hCG-Serum/Urine and PregnaGen 1-Step) designed to detect increased concentrations of choriogonadotropin (hCG) in either serum or urine samples. The biochemical sensitivities and specificity in both serum and urine samples were similar for each kit. All kits correctly identified pregnancy serum samples: The TestPack Plus hCG Combo and SureCell hCG-Serum/Urine were 100% specific; the other two kits exhibited a few false-positive results. For urine samples the ICON II hCG test was 100% sensitive, and the other three were 99.5% sensitive, with false-positive urine results occasionally reported by the PregnaGen 1-Step and ICON II hCG tests. Quantitative hCG concentrations could be estimated in pregnancy serum samples, but not urine samples, through determination of the time elapsed from the sample application or addition of the final reagent to the first appearance of a positive result.

Thyroid screening of neonates without use of radioactivity: evaluation of time-resolved fluoroimmunoassay of thyrotropin.

1986 ◽  
Vol 32 (6) ◽  
pp. 1013-1016 ◽  
Author(s):  
T E Torresani ◽  
R Scherz
Keyword(s):  
Early Diagnosis ◽  
Congenital Hypothyroidism ◽  
False Positive ◽  
Dried Blood Spots ◽  
Screening Assay ◽  
Time Resolved ◽  
Blood Samples ◽  
Thyroid Screening ◽  
Positive Results

Abstract We evaluated the usefulness, in routine newborn screening for congenital hypothyroidism, of a time-resolved fluoroimmunoassay kit (DELFIA Neonatal TSH) for the determination of thyrotropin (TSH) in dried blood spots. A total of 11 531 dried blood samples from newborns were tested in parallel in each of two Swiss screening laboratories, by RIA and DELFIA. Six cases of confirmed congenital hypothyroidism were detected during the study period. The rate of false-positive results, after single TSH determination in the DELFIA assay, was 0.16%. Correlation of RIA and DELFIA results for TSH was very good in both laboratories (0.959 and 0.97, respectively). The new method fulfills the criteria for precision and sensitivity of a screening assay. Screening results are usually available the day after the sample arrives in the laboratory, thus favoring early diagnosis and allowing treatment to begin by the seventh or eighth postnatal day.

scholarly journals Comparison of enzyme linked immunoassay and high performance liquid chromatography for determination of fumonisin in dried figs

2009 ◽  
pp. 37-43 ◽  
Author(s):  
Funda Karbancioglu-Guler ◽  
Dilek Heperkan
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
False Positive ◽  
High Performance ◽  
Screening Method ◽  
Fumonisin B1 ◽  
Aegean Region ◽  
Positive Results

The occurrence of fumonisin in dried figs was investigated by Enzyme Linked Immunoassay (ELISA) and High Performance Liquid Chromatography (HPLC). Total fumonisins (FB1, FB2, FB3) in dried figs were determined using ELISA, whereas only fumonisin B1 (FB1) was determined by HPLC. In the period 2003-2004, one hundred and fifty five dried fig samples were taken during their drying in 7 different districts in the Aegean Region. Among a total of 115 samples, the incidence of total fumonisin in the dried figs was 82% within the range of 0.16 - 108.34 mg/g when determined by ELISA. In comparison, FB1 was detected in 86 samples (74.8%) within the range between 0.046 and 3.649 mg/g by HPLC. Correlation between ELISA and HPLC methods was observed for all samples. However, no correlation between methods was recorded for the samples with less than 1 mg/g Fumonisin B1 level (obtained by HPLC). Although there was a correlation between methods for all the samples, fumonisin levels obtained by ELISA were much higher than those obtained by HPLC. False positive results were obtained by ELISA in 11 out of 115 dried fig samples. The results indicated that ELISA can be used as a screening method for determining the occurence of fumonisin in dried figs.

Influence of Distillation Temperature in the Determination of Added Sulfites in Dehydrated Garlic Powders Using the Modified Optimized Monier-Williams Method

2016 ◽  
Vol 99 (3) ◽  
pp. 721-724
Author(s):  
Ramya Addala ◽  
Leonard Fong ◽  
Mihir Vasavada ◽  
Siva Subramanian
Keyword(s):  
Positive Result ◽  
Sea Level ◽  
Coefficient Of Variation ◽  
False Positive ◽  
Boiling Temperature ◽  
Organosulfur Compounds ◽  
Distillation Temperature ◽  
Hydrolysis Of ◽  
Positive Results

Abstract Influence of distillation temperature on the determination of added sulfites in dehydrated garlic originating from China and California using the modified optimized Monier-Williams method was evaluated. In the study, the temperature of the distillation was monitored and maintained from 90° to 95°C instead of boiling temperature (>95°C). Samples from 38 unsulfited dehydrated garlic powders were analyzed at the 90° to 95°C temperature and at boiling temperature (>95°C) at 94 m above sea level. At the boiling distillation temperature, 25 of the 38 unsulfited garlic samples had a positive result for sulfite content ranging from 10.2 to 14.1 ppm using the modified optimized Monier-Williams procedure. Maintaining distillation temperature between 90° and 95°C eliminated false-positive results for added sulfite and had an average spiked sulfite recovery of 95.6% with a coefficient of variation of 3.79%. Lowering of the distillation temperature decreases the possible acid hydrolysis of organosulfur compounds that can lead to positive added sulfite results in unsulfited dehydrated garlic samples.

Critical Evaluation of Impedance Phlebography for the Diagnosis of Deep Vein Thrombosis

1974 ◽  
Vol 31 (02) ◽  
pp. 273-278
Author(s):  
Kenneth K Wu ◽  
John C Hoak ◽  
Robert W Barnes ◽  
Stuart L Frankel
Keyword(s):  
Deep Vein Thrombosis ◽  
False Positive ◽  
False Negative ◽  
Critical Evaluation ◽  
Original Method ◽  
Vein Thrombosis ◽  
Negative Results ◽  
False Negative Results ◽  
Deep Vein ◽  
Positive Results

SummaryIn order to evaluate its daily variability and reliability, impedance phlebography was performed daily or on alternate days on 61 patients with deep vein thrombosis, of whom 47 also had 125I-fibrinogen uptake tests and 22 had radiographic venography. The results showed that impedance phlebography was highly variable and poorly reliable. False positive results were noted in 8 limbs (18%) and false negative results in 3 limbs (7%). Despite its being simple, rapid and noninvasive, its clinical usefulness is doubtful when performed according to the original method.

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