Automated Photometric Microbiological Assay for Monensin in Poultry Rations

1972 ◽  
Vol 55 (1) ◽  
pp. 114-118 ◽  
Author(s):  
F W Kavanagh ◽  
Mary Willis
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Aqueous Acetone ◽  
Microbiological Assay ◽  
Maximum Sensitivity ◽  
Automated System ◽  
Polysorbate 80 ◽  
Standard Curve ◽  
Relative Standard ◽  
Feed Samples

Abstract A new photometric microbiological assay is described for the coccidiostat monensin in poultry feeds and premixes. The crucial steps in the assay are performed by an automated system. Samples are extracted with acetone and diluted in 50% aqueous acetone to appropriate levels for assay by Streptococcus faecalis ATCC 8043. A special pH 5.2 medium, low in potassium, and polysorbate 80 are used to obtain maximum sensitivity without interference. The range of applicability of the standard curve is 0.10–0.4 μg monensin/ml sample. The assay is free from bias. A relative standard deviation of 1.7% was obtained when 10 feed samples were extracted and assayed 5 times each.

Comparison of Automatic and Manual Turbidimetric Analyses of Tylosin in Feeds with the Plate Method

1973 ◽  
Vol 56 (2) ◽  
pp. 363-366
Author(s):  
Hussein S Ragheb ◽  
H Latham Breunig ◽  
Robert E Scroggs
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Plate Method ◽  
Relative Standard ◽  
Significant Difference ◽  
Aoac Method ◽  
Turbidimetric Assay ◽  
The Mean ◽  
The Difference ◽  
Feed Samples

Abstract Two laboratories participated in a comparison of a manual turbidimetric assay with the AUTOTURB® System and the AOAC method of analysis of tylosin in 4 feed samples. Results showed no significant difference between the 2 turbidimetric assays. When the AOAC method was considered, the difference between laboratories was significant. On an overall basis the turbidimetric methods were significantly higher than the plate method. The relative standard deviation was higher (6.72%) for the plate assay versus turbidimetric assay (4.5%). The mean recovery in both laboratories was significantly less than the labeled amount of tylosin by all 3 methods.

Hydroxylamine Hydrochloride in Automated and Manual Methods for Riboflavin Determination

1977 ◽  
Vol 60 (1) ◽  
pp. 147-150
Author(s):  
Barabara S Jacobson
Keyword(s):  
Hydrogen Peroxide ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Flow System ◽  
Hydroxylamine Hydrochloride ◽  
Automated System ◽  
Relative Standard ◽  
Aoac Method ◽  
Manual Methods ◽  
Oxygen Gas

Abstract The AOAC method for riboflavin determination has been modified to improve the precision of the manual method and greatly simplify its automation. In the AOAC method, permanganate oxidation is used for sample cleanup, and hydrogen peroxide is used to reduce excess permanganate. By substituting hydroxylamine. HCl for the hydrogen peroxide, the generation of oxygen gas, which can be troublesome, is eliminated without otherwise changing the assay. The resulting manual assay has a relative standard deviation of 1% as opposed to 2.5% for the same assay with hydrogen peroxide. This method is simple to automate, using a continuous flow system. The automated system performs 40 determinations per hour with a 1% relative standard deviation and results agree with those from the AOAC method at the 98% confidence level.

scholarly journals Microbiological Assay for Lomefloxacin in Coated Tablets

2006 ◽  
Vol 89 (4) ◽  
pp. 1077-1079 ◽  
Author(s):  
Greici Cristiani Gomes ◽  
Hérida Regina Nunes Salgado
Keyword(s):  
Bacillus Subtilis ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Method Validation ◽  
Test Organism ◽  
Microbiological Assay ◽  
Plate Method ◽  
Relative Standard ◽  
Bacillus Subtilis Atcc

Abstract The validation of a microbiological assay, applying cylinder plate method for determination of the activity of lomefloxacin in coated tablets is described. Using a strain of Bacillus subtilis ATCC 9372 as the test organism, lomefloxacin was measured in concentrations ranging from 2.0 to 8.0 μg/mL. The method validation showed that it is linear (r = 0.9999), precise (relative standard deviation = 1.15%), and accurate (it measured the added quantities). The excipients did not interfere in the determination. It was concluded that the microbiological assay is satisfactory for quantitation of lomefloxacin in tablets.

scholarly journals Enumeration of Probiotic Bacilli Spores in Animal Feed: Interlaboratory Study

2003 ◽  
Vol 86 (3) ◽  
pp. 568-575 ◽  
Author(s):  
Renata G K Leuschner ◽  
Jan Bew ◽  
Armando Cruz ◽  
A Adler ◽  
E Auclair ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Animal Feed ◽  
Interlaboratory Study ◽  
Probiotic Bacteria ◽  
Precision Data ◽  
Official Control ◽  
Colony Forming Units ◽  
Relative Standard ◽  
Feed Samples

Abstract Fourteen out of 17 laboratories completed an interlaboratory study comparing 2 pretreatment protocols of feed samples containing authorized probiotic bacilli spores. Both methods used tryptone soy agar for enumeration. Pretreatment A involved preparation of a suspension of the feed sample in 50% ethanol. For pretreatment B, the sample was suspended in peptone salt solution and heated at 80°C for 10 min. Each laboratory analyzed 12 samples (6 per pretreatment), which represented duplicates of a high (109 colony-forming units [CFU]/g) and low (105 CFU/g) level of bacilli spores or a blank that contained vegetative probiotic bacteria only. For pretreatment A, the re-peatability relative standard deviation (RSDr) was 2.9% for the low level and 2.5% for the high. The reproducibility relative standard deviation (RSDR) values were 7.8 and 5.9%, respectively. Pretreatment B revealed RSDr values of 1.1 and 1.0%, and RSDR values of 5.8 and 3.4%, respectively. The heat treatment (pretreatment B) of feed samples had better precision data, resulted in higher viable bacilli counts, and was more effective in deactivating vegetative background flora. It is therefore recommended for adoption for official control purposes and for CEN and ISO standards.

An Automated Procedure for the Determination of Ammonia in Tobacco

1972 ◽  
Vol 6 (4) ◽  
Author(s):  
P.F. Collins ◽  
W.W. Lawrence ◽  
J.F. Williams
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Distillation Method ◽  
Relative Standard ◽  
Tobacco Sample ◽  
Automated Determination

AbstractA procedure for the automated determination of ammonia in tobacco has been developed. Ammonia is extracted from the ground tobacco sample with water and is determined with a Technicon Auto Analyser system which employs separation of the ammonia through volatilization followed by colourimetry using the phenate-hypochlorite reaction. The procedure has been applied to a variety of tobaccos containing from 0.02 to 0.5 % ammonia with an overall relative standard deviation of 2 %. The accuracy of the procedure as judged by recovery tests and by comparison to a manual distillation method is considered adequate

How Certain Are the Reported Ionic Conductivities of Thiophosphate-Based Solid Electrolytes? an Interlaboratory Study

2020 ◽  
Author(s):  
Saneyuki Ohno ◽  
Tim Bernges ◽  
Johannes Buchheim ◽  
Marc Duchardt ◽  
Anna-Katharina Hatz ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Ionic Conductivity ◽  
Relative Standard Deviation ◽  
Solid Electrolytes ◽  
Ionic Conductivities ◽  
Ionic Conductors ◽  
Energy Storage Devices ◽  
Activation Barriers ◽  
Storage Devices ◽  
Relative Standard

<p>Owing to highly conductive solid ionic conductors, all-solid-state batteries attract significant attention as promising next-generation energy storage devices. A lot of research is invested in the search and optimization of solid electrolytes with higher ionic conductivity. However, a systematic study of an <i>interlaboratory reproducibility</i> of measured ionic conductivities and activation energies is missing, making the comparison of absolute values in literature challenging. In this study, we perform an uncertainty evaluation via a Round Robin approach using different Li-argyrodites exhibiting orders of magnitude different ionic conductivities as reference materials. Identical samples are distributed to different research laboratories and the conductivities and activation barriers are measured by impedance spectroscopy. The results show large ranges of up to 4.5 mScm<sup>-1</sup> in the measured total ionic conductivity (1.3 – 5.8 mScm<sup>-1</sup> for the highest conducting sample, relative standard deviation 35 – 50% across all samples) and up to 128 meV for the activation barriers (198 – 326 meV, relative standard deviation 5 – 15%, across all samples), presenting the necessity of a more rigorous methodology including further collaborations within the community and multiplicate measurements.</p>

scholarly journals Indirect and Direct Determination of the Casein Content of Milk by Kjeldahl Nitrogen Analysis: Collaborative Study

1998 ◽  
Vol 81 (4) ◽  
pp. 763-774 ◽  
Author(s):  
Joanna M Lynch ◽  
David M Barbano ◽  
J Richard Fleming
Keyword(s):  
Standard Deviation ◽  
Nitrogen Content ◽  
Relative Standard Deviation ◽  
Collaborative Study ◽  
Direct Determination ◽  
Raw Milk ◽  
Method Performance ◽  
Relative Standard ◽  
Milk Casein

Abstract The classic method for determination of milk casein is based on precipitation of casein at pH 4.6. Precipitated milk casein is removed by filtration and the nitrogen content of either the precipitate (direct casein method) or filtrate (noncasein nitrogen; NCN) is determined by Kjeldahl analysis. For the indirect casein method, milk total nitrogen (TN; Method 991.20) is also determined and casein is calculated as TN minus NCN. Ten laboratories tested 9 pairs of blind duplicate raw milk materials with a casein range of 2.42- 3.05℅ by both the direct and indirect casein methods. Statistical performance expressed in protein equivalents (nitrogen ⨯ 6.38) with invalid and outlier data removed was as follows: NCN method (wt%), mean = 0.762, sr = 0.010, SR = 0.016, repeatability relative standard deviation (RSDr) = 1.287℅, reproducibility relative standard deviation (RSDR) = 2.146%; indirect casein method (wt℅), mean = 2.585, repeatability = 0.015, reproducibility = 0.022, RSDr = 0.560℅, RSDR = 0.841; direct casein method (wt℅), mean = 2.575, sr = 0.015, sR = 0.025, RSDr = 0.597℅, RSDR = 0.988℅. Method performance was acceptable and comparable to similar Kjeldahl methods for determining nitrogen content of milk (Methods 991.20, 991.21,991.22, 991.23). The direct casein, indirect casein, and noncasein nitrogen methods have been adopted by AOAC INTERNATIONAL.

scholarly journals A computer-controlled potentiometric/spectrophotometric titrator

1988 ◽  
Vol 10 (2) ◽  
pp. 95-100
Author(s):  
John D. Stong
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Bromophenol Blue ◽  
System Control ◽  
Data Format ◽  
Relative Standard ◽  
Spectrophotometric Titrations ◽  
Computer Controlled ◽  
Major Attention ◽  
Diode Array Spectrophotometer

A laboratory computer controlled potentiometric titrator interfaced to a diode array spectrophotometer is described. The titrator consists of widely used, commercially available components; therefore, major attention is given to modes of interconnection and software implementation in data format and system control. Replicate potentiometric titrations of glycines gave a relative standard deviation in titre of 1.035% and a relative standard deviation in pH of 0.745%. Replicate spectrophotometric titrations of bromophenol blue were analysed at three wavelengths to yield pKa= 3.898 ± 0.075 (1.9% rsd).Methods of data presentation and manipulation are presented.

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