Biomedical subjects

J J Thrasher

Publications and source records attributed to J J Thrasher.

At least 19 recordsLinked to original sources

PubMed1981

Chemical test for mammalian feces: collaborative study.

A chemical method was developed to determine the presence of mammalian feces in food. The method consisted of the colorimetric determination of alkaline phosphatase and involved the splitting of the phosphate radical and phenolphthalein diphosphate and the resultant color development of phenolphthalein in a basic medium. A collaborative study testing the feces of 22 animals resulted in a 95% correct identification of samples as mammalian feces. The method has been adopted official first action.

Alkaline Phosphatase↗

PubMed1980

Extraction and thin layer chromatographic confirmation of urine residues: new plate development.

AOAC method 44.146--44.148 (12th ed.) yielded incomplete separation of compounds recovered from urine residues. Problems with decomposition of standard compounds, loss of sample during extraction/concentration, and development of excessive background color during plate spraying were encountered. Modifications were made to deal with these problems as follows: Allantoin standard is now stored in 90% acetone, 30ml beakers are used instead of conical tubes during extraction, and smaller amounts of pDMAB are used during plate spraying. A collaborative study was conducted to compare sandwich chamber spot separation to larger tank separation. The study showed that total separation of all spots among all analysts was obtained with the sandwich chamber, whereas incomplete separation of spots was obtained with the tank. Also, standard deviation of spot Rf values was smaller with the sandwich chamber. The modified method has been adopted as official first action.

Animals↗

PubMed1979

Mineral oil extraction of light filth from rubbed sage: collaborative study.

The official methods for extracting light filth from rubbed sage, 44.D08--44.D10, specifies a hot isopropanol pretreatment and flotation from cooled dilute isopropanol with mineral oil to extract light filth. The method gives good recoveries, but occasionally excessive interfering plant material is extracted along with the filth elements. A new method has been developed in which chloroform is used for pretreatment instead of isopropanol, and Tween 80-EDTA is added twice rather than once. This method has given consistently cleaner filter papers and better recoveries for rodent hairs, 85 vs. 79%, and for elytral squares, 95 vs. 84%. The new method has been adopted as official first action.

Animals↗

PubMed1979

Extraction of light filth from ground nutmeg: collaborative study.

The official method for extracting light filth from ground nutmeg, 44.116, gives variable recoveries of filth elements and results in large amounts of interfering plant material in the light filth extraction. A new method has been developed using a chloroform pretreatment for heavy filth followed by a water-40% isopropanol-mineral oil flotation of light filth. A comparison of the methods in the collaborative study showed a higher recovery of insect fragments, 90.6 vs. 65.2%, and of rodent hairs, 86.5 vs. 66.5%, for the new method over the present official first action method, 44.116. Frothing, an additional problem with the official method, has been reduced by the new method. The new method has been adopted as official first action to replace the existing method.

Condiments↗

PubMed1978

Extraction of light filth from coconut: collaborative study.

The official method for filth in coconut, 44.029, frequently produces filter papers with excessive plant debris and low hair recoveries. To overcome these deficiencies, 3 changes in the method were made: (1) the defatting step was modified to use sodium lauryl sulfate in combination with borax for better defatting; (2) 40% isopropanol was substituted for 60% ethanol as the aqueous phase for cleaner papers; and (3) mineral oil was substituted for n-heptane to improve hair recoveries. These changes resulted in higher, more reproducible recoveries of rodent hairs and insect fragments and cleaner filter papers. The method has been adopted as official first action to replace 44.029.

Animals↗

PubMed1978

Oil flotation extraction of light filth from ground capsicums excluding paprika: collaborative study.

A collaborative study has been completed on an improved method for the isolation of light filth from ground capsicums other than paprika. The proposed method involves isopropanol pretreatment, wet-sieving, and extraction from cooled 60% ethanol with a mineral oil-heptane mixture. The collaborative tests by the proposed method showed an approximate 2-fold increase in recoveries of insect fragments and rodent hairs with acceptable coefficients of variation and clean filter papers. The proposed method has been adopted as official first action to replace 44.123.

Capsicum↗

PubMed1978

Thin layer chromatographic method for the detection of uric acid: collaborative study.

A collaborative study has been completed on an improved method for the detection and confirmation of uric acid from bird and insect excreta. The proposed method involves the lithium carbonate solubilization of the suspect excreta material, followed by butanol-methanol-water-acetic acid thin layer chromatography, and trisodium phosphate-phosphotungstic acid color development. The collaborative tests resulted in 100% detection of uric acid standard at the 50 ng level and 75% detection at the 20-25 ng level. No false positives were reported during tests of compounds similar to uric acid. The proposed method has been adopted official first action; the present official final action method, 44.161, will be retained for screening purposes.

Animals↗

PubMed1977

Collaborative study of a mineral oil method for the extraction of light filth from ground paprika.

An official first action method for the extraction of light filth from spices, 44.A03--44.A05, was modified for the analyses of ground paprika. The sample is extracted with isopropanol and light filth is isolated from 40% isopropanol with mineral oil. Eight collaborators analyzed 4 paprika samples, 2 by the official method and 2 by the proposed method. Average recoveries of added elytral squares were 97 and 66%, respectively, for the proposed and official methods. Recoveries of added rodent hairs were 94 and 61%, respectively. The method has been adopted as official first action for the extraction of light filth from ground paprika.

Condiments↗

PubMed1977

Method for the flotation oil extraction of light filth from ground capsicums.

The present official first action method for ground capsicums, 44.123, was adopted in 1945 and there have been great changes in processing and examination of spices since that time. The proposed method involves isopropanol pretreatment, followed by wet sieving and extraction of the light filth from 60% ethanol with flotation oil. The filter papers were clean and recoveries were good (95%) for 5 different lots of capsicums and annato spiked with insect fragments and rodent hairs.

Capsicum↗

PubMed1976

Collaborative study of a method for the extraction of light filth from ground mace and ground caraway seed.

A new method has been developed for the extraction of light filth from ground mace and ground caraway seed. The method uses a 2-step chloroform-isopropanol pretreatment followed by separation of the light filth from 40% isopropanol with mineral oil. The collaborative study resulted in clean filter papers with more reproducible recoveries of light filth elements than the official first action method, 44.116 (b). The method has been adopted as official first action.

Condiments↗

PubMed1975

Collaborative study of a method for the extraction of light filth from crushed red peppers.

A new method was developed for the extraction of light filth from crushed red peppers. The method utilizes an isoprapanol defatting of the product followed by separation of light filth elements with mineral oil and n-heptane (85+15) in a 2 L trap flask. Collaborative studies resulted in good recoveries of light filth spike elements and clean extration papers. The method has been adopted as official first action.

Animals↗

PubMed1974