Simplified Plate Diffusion System for Microbial Assays of Antibiotics

1987 ◽  
Vol 70 (4) ◽  
pp. 641-646
Author(s):  
Marietta Sue Brady ◽  
Stanley E Katz
Keyword(s):  
Diffusion System ◽  
Standard Curve ◽  
Single Plate ◽  
Accuracy And Precision ◽  
Coefficients Of Variation

Abstract A protocol for microbial assays of antibiotics, using the plate diffusion system, is presented. The system is based on the concept that a complete standard curve and assay unknowns can be placed on an issay plate and that 2 plates can be a complete assay with an accuracy and precision essentially equivalent to the official AOAC diffusion procedure. Four antibiotics, bacitracin, chlortetracycline, oxytetracycline, and streptomycin, were used in the design and comparison studies with the AOAC protocol. The coefficients of variation (CVs) for the AOAC design, using 10 replicates, ranged from 1.4 to 10.3% with a mean of 4.5%. The CVs for the single-plate option of the simplified design ranged from 4.3 to 9.6% with a mean of 6.6%; the CVs for the 2-plate option ranged from 2.5 to 6.8% with a mean of 43%; the CVs for the 3-plate option ranged from 1.2 to 5.0% with a mean of 3.0%.

Multiresidue Gas Chromatographic Method for Determining Organochlorine Pesticides in Poultry Fat: Collaborative Study

1984 ◽  
Vol 67 (2) ◽  
pp. 284-289 ◽  
Author(s):  
James A Ault ◽  
Tim E Spurgeon ◽  
◽  
M M Anderson ◽  
R Bowers ◽  
...  
Keyword(s):  
Chromatographic Method ◽  
Collaborative Study ◽  
Gel Permeation Chromatography ◽  
Accuracy And Precision ◽  
Coefficients Of Variation ◽  
Poultry Fat ◽  
Gel Permeation ◽  
Detector Method ◽  
Gas Chromatographic Method

Abstract A gas chromatographic electron capture detector method is described for the quantitative determination of organochlorine pesticide residues in poultry fat. The samples are rendered and cleaned up using automated gel permeation chromatography. The collaborative samples consisted of 10 fortified samples and one incurred residue sample, all in duplicate. Fortification levels ranged from 0.15 to 1.0 ppm for a-BHC, lindane, cis- and frans-chlordane, octachlor epoxide, o,p' and p,p'-DDT, p,p'-DDE, p,p'-TDE, hexachlorobenzene, heptachlor epoxide, dieldrin, endrin, methoxychlor, mirex, and toxaphene. The average recovery was 91.9% with a range of 81-102%. The ranges of coefficients of variation were: CVo = 3.39-14.79%; CVL = 0-16.6%; and CVx = 5.82-19.0%. The results indicate accuracy and precision comparable to other official methodology. The method has been adopted official first action.

Immunoradiometric assay with use of magnetizable particles: measurement of thyrotropin in blood spots, to screen for neonatal hypothyroidism.

1986 ◽  
Vol 32 (10) ◽  
pp. 1966-1968 ◽  
Author(s):  
K V Waite ◽  
G F Maberly ◽  
G Ma ◽  
C J Eastman
Keyword(s):  
Incubation Time ◽  
Separation Procedure ◽  
Immunoradiometric Assay ◽  
Assay Sensitivity ◽  
Neonatal Hypothyroidism ◽  
Blood Spots ◽  
Standard Curve ◽  
Coefficients Of Variation ◽  
Specialized Equipment ◽  
Short Incubation Time

Abstract We adapted a commercial immunoradiometric assay (IRMA) to measure thyrotropin in filter-paper blood spots. Two 3-mm blood spots are used for each standard and sample. These are incubated for 2 h with radiolabeled antibody and for 30 min with magnetic antibody, followed by a 10-min separation procedure. Assay sensitivity is 6 milli-int. units/L. Coefficients of variation (precision profile of the standard curve) ranged from 4.3 to 9.6%. The coefficient of correlation (r) between thyrotropin concentrations in the blood spots and in serum was 0.93. Pre-elution of the blood spots is necessary for short incubation time. Short incubation time, little need for specialized equipment, the high precision and sensitivity characteristic of IRMA, and ease of collection, transport, and storage of the blood-spot samples make this assay suitable for neonatal hypothyroid screening.

Simultaneous measurement of plasma apolipoproteins A-I and B by electroimmunoassay.

1982 ◽  
Vol 28 (1) ◽  
pp. 59-62 ◽  
Author(s):  
J C Fruchart ◽  
I Kora ◽  
C Cachera ◽  
V Clavey ◽  
P Duthilleul ◽  
...  
Keyword(s):  
Simultaneous Measurement ◽  
Apolipoprotein B ◽  
Secondary Standard ◽  
Plastic Film ◽  
Standard Curve ◽  
Atherosclerotic Lesions ◽  
Apolipoprotein A ◽  
Coefficients Of Variation

Abstract We describe a simplified electroimmunoassay for quantification of human apolipoproteins A-I and B on prepared plates. A solution of agarose at 55 degrees C, containing hydroxyethylcellulose and antibodies, is poured onto a plastic film and allowed to gel. Wells are punched in the gels and the plates are dried for storage. Before use, they are rehydrated and buffered. We use succinylated Sudan Black to prestain lipoprotein fractions of plasma. After electrophoresing samples of plasma or standards for 3 h at 4 degrees C at 12.5 V/cm, we measure the peak heights and read the results from a standard curve prepared by using calibrated sera of known apolipoprotein B and A-I content as secondary standard. The within- and between-assay coefficients of variation were less than 4% in all cases. Results correlated well with those obtained by classic electroimmunodiffusion. Subjects with confirmed atherosclerotic lesions had significantly (p less than 10(-9)) lower ratios of apolipoprotein A-I to apolipoprotein B, compared with ratios in controls.

Determination of nifedipine in serum or plasma by reversed-phase liquid chromatography.

1983 ◽  
Vol 29 (7) ◽  
pp. 1344-1348 ◽  
Author(s):  
P R Bach
Keyword(s):  
Liquid Chromatography ◽  
Reversed Phase ◽  
Extraction Column ◽  
Phase Extraction ◽  
Reversed Phase Liquid Chromatography ◽  
Ultraviolet Absorbance ◽  
Standard Curve ◽  
Coefficients Of Variation ◽  
Phase Liquid

Abstract Therapeutic concentrations of nifedipine in serum or plasma were measured by reversed-phase liquid chromatography, with detection by ultraviolet absorbance at 235 nm. In the procedure a disposable reversed-phase extraction column is used. A 1-mL sample is required. The method is sensitive to 3 micrograms of nifedipine per liter and the standard curve is linear to at least 400 micrograms/L. Coefficients of variation at 100 micrograms/L were 2.2% within-run, 2.8% between-run. The method has been used to determine nifedipine in patients involved in a test of its efficacy in treating muscular dystrophy.

scholarly journals A simple method for the analysis of urinary sucralose for use in tests of intestinal permeability

2005 ◽  
Vol 42 (3) ◽  
pp. 224-226 ◽  
Author(s):  
A D G Anderson ◽  
P Poon ◽  
G M Greenway ◽  
J MacFie
Keyword(s):  
Refractive Index ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Simple Method ◽  
Standard Curve ◽  
Additional Information ◽  
Accuracy And Precision ◽  
Analytical Recovery ◽  
Peak Areas ◽  
Syringe Filter

Background: Sucralose is a unique disaccharide probe which is stable in the colon and can be used to assess permeability over the whole gut. Additional information can be gained when sucralose is administered in combination with lactulose and a monosaccharide such as L-rhamnose in the form of a 'triple sugar test.' We describe a simple assay for urinary sucralose by HPLC with refractive index detection (HPLC-RI). Methods: Phenyl-β-D-glucopyranoside (internal standard) was added to 10 mL of urine, which was then passed through a 0.45 μm syringe filter. Elution was with 30% methanol (1 mL/min) on a reverse-phase C18 column. Detection was by refractive index, and integration based upon peak areas. Sixty standards of sucralose in human urine were analysed in order to quantify analytical variation. Results: The standard curve for urinary sucralose was linear from 25 to 500 mg/L ( r>0.99). The limit of detection was 11 mg/L. Analytical recovery of sucralose at concentrations of 25, 50 and 100 mg/L was 101.5% (CV 7.59%), 102.9% (CV 5.82%) and 105.0% (CV 4.26%), respectively Conclusions: The technique described represents a simple assay for urinary sucralose which performed with acceptable accuracy and precision and should facilitate the use of the triple sugar test in clinical research.

276. The technical and biological validation of an LH assay for use with the Western Grey Kangaroo (Macropus fuliginosis) and Black-flanked Rock Wallaby (Petrogale lateralis lateralis)

2008 ◽  
Vol 20 (9) ◽  
pp. 76
Author(s):  
P. Matson ◽  
C. Mayberry ◽  
N. Willers ◽  
M. A. Blackberry ◽  
G. B. Martin
Keyword(s):  
Plasma Concentrations ◽  
Standard Curve ◽  
Biological Validation ◽  
Grey Kangaroo ◽  
Coefficients Of Variation ◽  
Western Grey Kangaroo ◽  
Technical Validation ◽  
Zoo Biology ◽  
Smithsonian Institute ◽  
And Control

Methods for the measurement of marsupial LH invariably rely upon the similarity of the LH molecule between different species and usually use anti-ovine or anti-bovine LH antibody and an ovine or bovine labelled LH preparation. Initial attempts to measure plasma LH in the Western Grey Kangaroo with assays using antibodies to 4 different isoforms of ovine LH raised in 7 different rabbits were unsuccessful. An enzymeimmunoassay (EIA) developed for the Asian elephant (Zoo Biology 23:45–63) was then applied to the Western Grey Kangaroo and the Black-flanked Rock Wallaby. This EIA has an anti-bovine-LH monoclonal antibody (518B7 provided by Dr Jan Roser, University of California, Davis, USA), biotinylated ovine LH label and bovine LH standard (NIADDK-oLH-26 and NIH-bLH-B10, both provided by Dr Janine Brown and Nicole Abbondanza, Smithsonian Institute, Front Royal, Virginia USA). Technical validation showed that serial dilution down to 1:8 of plasma from 7 individuals of each species showed parallelism to the assay standard curve, and control samples (1.24–5.30 ng/mL) had between-assay coefficients of variation <9%. Biological validation was achieved by challenging animals with intramuscular GnRH (Fertagyl®, 2.5 µg/kg) and measuring LH before and 25 min after the injection. Significant increases in plasma concentrations of LH (mean ± sem; all P > 0.0005) were seen after GnRH for both the Western Grey Kangaroo (from 5.0 ± 0.8 ng/mL to 9.4 ± 1.2 ng/mL; n = 19) and the Black-flanked Rock Wallaby (from 6.0 ± 0.7 ng/mL to 10.6 ± 0.6 ng/mL; n = 28). In conclusion, this assay can be successfully used to measure LH in these two species.

Spectrophotometric Determination of Phosphorus in Certifiable Straight Color Additives: Collaborative Study

1981 ◽  
Vol 64 (4) ◽  
pp. 808-813
Author(s):  
Wallace S Brammell ◽  
◽  
C Arozarena ◽  
J Hunter ◽  
H G Kiernan ◽  
...  
Keyword(s):  
Total Phosphorus ◽  
Phosphorus Content ◽  
Collaborative Study ◽  
Mean Values ◽  
Total Phosphorus Content ◽  
Standard Curve ◽  
Coefficients Of Variation ◽  
Molybdovanadophosphoric Acid ◽  
Acid Reagent

Abstract A simple and rapid spectrophotometric method was developed for determining the total phosphorus content of certifiable straight color additives. The dye sample is mixed with a cellulose powder and MgO mixture, and ashed at 500°C in a small Pyrex beaker in a muffle furnace. The ash is dissolved in vanadomolybdic acid reagent and filtered through glass wool, and the absorbance of the resulting yellow molybdovanadophosphoric acid solution is measured at 400 nm. The total phosphorus content of the sample, expressed as percent Na3PO4, is determined from a standard curve. Recovery of phosphorus added as KH2PO4 to 39 different dyes in amounts equivalent to 0.300% Na3PO4 ranged from 95.3 to 106.8%, averaging 100.6%. In the collaborative study, 7 laboratories successfully performed duplicate analyses of 6 different dyes (D&C Orange No. 5, D&C Yellow No. 8, FD&C Blue No. 2, FD&C Red No. 3, FD&C Red No. 40, and FD&C Green No. 3). The mean values found ranged from 0.325 to 6.86% Na3PO4. In general, the accuracy and reproducibility of the method were satisfactory, with single determination coefficients of variation ranging from 3.76 to 9.60%. The method was adopted official first action.

scholarly journals Effects of Basal Area Factor and Plot Size on Precision and Accuracy of Forest Inventory Estimates

2011 ◽  
Vol 28 (3) ◽  
pp. 152-156 ◽  
Author(s):  
Peter Becker ◽  
Tom Nichols
Keyword(s):  
Forest Inventory ◽  
Basal Area ◽  
Cost Effective ◽  
Sampling Errors ◽  
Plot Size ◽  
Accuracy And Precision ◽  
Coefficients Of Variation ◽  
Fixed Radius ◽  
Tree Number ◽  
Biased Estimates

Abstract We tested the effects of plot size (0.05-0.30 ac) and basal area factor (BAF) (5-30) on the accuracy and precision of per-acre estimates of tree number, basal area, biomass (all for trees ≥4.5 in. dbh), and sawtimber volume (for trees ≥11.6 in. dbh). Field sampling errors, such as missing in-trees, did not affect our tests. Virtual variable- and fixed-radius plots were randomly located within an artificial matrix of 130 real plots in well-stocked upland hardwood forests of sawtimber-sized trees in the Missouri Ozarks. Inventory parameters were essentially independent of plot size and BAF, whereas their coefficients of variation decreased with plot size and increased with BAF. Thus, our results for random plots agreed with sampling theory, unlike a previous study using concentric virtual plots in West Virginia forests. A very concentrated zone of high tree density around some plot centers apparently caused the biased estimates by concentric plots. Compared with the entire composite forest, inventory means were accurately estimated (to within 5%) and size class distributions were well represented for plots ≥0.1 ac or ≤15 BAF. Our procedures provide a basis for selecting an efficient and cost-effective sampling design suited to forest characteristics and the inventory's purpose.

Microbiological Assay of Oleandomycin in Feed: Collaborative Study

1974 ◽  
Vol 57 (4) ◽  
pp. 823-827
Author(s):  
Hans J Mayerhofer ◽  
Sherrill J Thompson
Keyword(s):  
Confidence Level ◽  
Collaborative Study ◽  
Microbiological Assay ◽  
Standard Curve ◽  
Coefficients Of Variation ◽  
Aoac Method

Abstract The present official final action AOAC method of analysis for oleandomycin in feeds, 38.204–38.207, was modified and collaboratively studied. The modifications consist of elimination of the compensating standard curve, changes in the curve point concentrations, and a change in the plating medium. Ten collaborators assayed 4 feed types each at 3 levels of fortification ranging from 1.8 to 18.2 g/ton. All feeds were tested for 2 days, 2 weights per day. The average mean recovery for all feeds at all levels was 92.3% (ranging from 90.11% at the 1.82 g/ton level to 93.51% for the 18.17 g/ton level). The coefficients of variation ranged from 18.2 at the 1.82 g/ton level to 9.3 at the 18.2 g/ton level. The assay variation for all collaborators was 12.5%. No statistically significant differences were found between feed types, levels, and collaborators at the 95% confidence level. This method has been adopted as official first action for the assay of oleandomycin at levels ≤2 g/ton.

Use of a Laser-equipped Centrifugal Analyzer for Kinetic Measurement of Serum IgG

1974 ◽  
Vol 20 (10) ◽  
pp. 1320-1323 ◽  
Author(s):  
Gregory J Buffone ◽  
John Savory ◽  
R E Cross
Keyword(s):  
Protein Concentration ◽  
Scattered Light ◽  
Fixed Time ◽  
Time Interval ◽  
Kinetic Measurement ◽  
Standard Curve ◽  
Fixed Time Interval ◽  
Coefficients Of Variation ◽  
Visible Laser ◽  
Replicate Measurements

Abstract Use of a visible laser in an Aminco "Rotochem" centrifugal analyzer enables light-scattering measurements to be made with this instrument. The modification is technically simple, inexpensive, and requires no fundamental changes in basic instrument design. The laser-modified analyzer has been applied to the measurement of IgG in serum. A two-point kinetic analysis is used to quantitate IgG from a standard curve: protein concentration vs. change in intensity of the scattered light during a fixed time interval. Fourteen 20-µl samples can be simultaneously determined in 1.9 min. No sample blank corrections are required. Within-run precision studies, based in each case on 56 replicate measurements, yielded coefficients of variation of 3.8% and 4.8% for normal and abnormal pools, respectively.

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