Serum Propylthiouracil: Determination by a Direct Colorimetric Procedure

1972 ◽  
Vol 18 (11) ◽  
pp. 1373-1375 ◽  
Author(s):  
Charles R Ratliff ◽  
Paul F Gilliland ◽  
Frank F Hall
Keyword(s):  
Filter Paper ◽  
Colorimetric Method ◽  
Control Sample ◽  
Chloroform Solution ◽  
Soluble Compound ◽  
Aqueous Layer ◽  
Free Serum ◽  
Drug Free ◽  
Colorimetric Procedure

Abstract A direct colorimetric method is described for the determination of propylthiouracil in serum, which is based on reaction of the drug at pH 8.0 with 2,6-dichloroquinone-chloroimide to produce a colored chloroform-soluble compound. After isolation from the aqueous layer with phase-separating filter paper, the chloroform solution is read against a chloroform blank at 435 nm. Propylthiouracil added to drug-free serum serves as a control sample. The method obeys Beer's law up to a concentration of at least 10 mg/liter.

Fluorometric micromethod for determination of arginase activity in dried blood spots on filter paper.

1980 ◽  
Vol 26 (8) ◽  
pp. 1198-1200 ◽  
Author(s):  
A P Orfanos ◽  
E W Naylor ◽  
R Guthrie
Keyword(s):  
Filter Paper ◽  
Colorimetric Method ◽  
Dried Blood Spots ◽  
Arginase Activity ◽  
Kinetic Reaction ◽  
Hematological Disorders ◽  
Blood Spots ◽  
Blood Specimens ◽  
The Stability

Abstract We describe a microfluorometric method for determination of arginase activity in dried blood spots on filter paper. The arginase in discs punched from such dried blood specimens is activated by preincubation with Mn2+ at 37 degrees C. After incubation with substrate at the same temperature, urea is determined fluorometrically by oxidation of NADH to NAD+ in a coupled kinetic reaction. We compare the results of this method with those of a colorimetric method involving liquid blood samples, and assess the stability of the enzyme in dried blood on filter paper. The presence of serum has no effect on the activity. This method may be useful in the early detection of arginase deficiency and certain hematological disorders.

Determination of Trimethylamine Nitrogen in Extracts and in Volatile Fractions of Fish

1965 ◽  
Vol 48 (4) ◽  
pp. 731-735
Author(s):  
Sammie Bethea ◽  
Fred Hillig
Keyword(s):  
Colorimetric Method ◽  
Accurate Estimate ◽  
Colorimetric Procedure

Abstract Dyer’s colorimetric procedure was applied to the determination of trimethylamine nitrogen (TMA-N) in distillates from frozen cod and frozen haddock. Studies show that a more accurate estimate of the TMA-N contained in fish is obtained when this colorimetric method is applied to the distillates rather than to the extract. The method is also shortened by the elimination of one distillation, two oxidations, and two titrations.

Colorimetric Assay for N-Acetyl-β-D-glucosaminidase (NAG) in Pathological Urine Using the ω-Nitrostyryl Substrate: The Development of a Kit and the Comparison of Manual Procedure with the Automated Fluorimetric Method

1984 ◽  
Vol 21 (4) ◽  
pp. 295-300 ◽  
Author(s):  
C T Yuen ◽  
Patricia R N Kind ◽  
R G Price ◽  
P F G Praill ◽  
A C Richardson
Keyword(s):  
Renal Transplant ◽  
Colorimetric Assay ◽  
Clinical Chemistry ◽  
Colorimetric Method ◽  
Blood Contamination ◽  
Fluorimetric Method ◽  
Transplant Patients ◽  
Routine Monitoring ◽  
Colorimetric Procedure

This paper describes a comparison of the recently developed substrate 2-methoxy-4-(2′-nitrovinyl)-phenyl-2-acetamido-2-deoxy-β-d-glucopyranoside (MNP-GlcNAc) and the corresponding 4-methylumbelliferyl substrate (4-MU-GlcNAc) for the determination of urinary NAG. A good correlation ( r = 0·977) was found between NAG activities in 366 urine samples from renal transplant patients determined by either the fluorimetric method or the colorimetric procedure. The colorimetric method may be used with confidence as an alternative to the fluorimetric assay and does have the advantage that colorimetry is widely used in clinical chemistry laboratories. Sample blanks are not normally required unless there is blood contamination in the urine which can easily be identified visually. The incorporation of the MNP-GlcNAc substrate into a kit suitable for the assay of urinary NAG using a simple battery-operated miniphotometer is also described. The presence of elevated NAG levels in urine can be detected rapidly and this procedure is suitable for routine monitoring of renal patients in the laboratory and may prove to be suitable for use by non-laboratory personnel in clinics or on the ward.

A Modified Ninhydrin Colorimetric Method for the Determination of Plasma Alpha-Amino Nitrogen

1963 ◽  
Vol 9 (5) ◽  
pp. 573-581 ◽  
Author(s):  
Lillian J Fisher ◽  
Sylvia L Bunting ◽  
Leon E Rosenberg
Keyword(s):  
Amino Acid ◽  
Present Report ◽  
Colorimetric Method ◽  
Amino Nitrogen ◽  
Amino Acid Content ◽  
Human Blood Plasma ◽  
Nitrogen Concentrations ◽  
Amino Acid Solutions ◽  
Colorimetric Procedure

Abstract The present report describes the development of and results with a modified ninhydrin colorimetric method for the determination of free plasma -amino nitrogen. Precipitation of the plasma proteins with a hydrochloric acid-sodium tungstate reagent, filtration of the deproteinized filtrate through glass wool plugs, and reduction of the pH of the reaction resulted in improved reproducibility, lower water blank readings, and lower plasma -amino nitrogen concentrations which agreed closely with values obtained using other standard technics. The stoichiometry of the modified reaction and recovery of standard amino acid solutions were investigated and found to be satisfactory. A comparative study with the ninhydringasometric technic showed that the modified colorimetric procedure described herein yielded values in very close agreement with the more laborious manometric determination. Fasting venous plasma samples obtained from 21 normal volunteers yielded a mean plasma concentration of 3.85 mg./100 ml. The report concludes from these observations that the modified colorimetric procedure provides an accurate, simple, and rapid estimation of the total free amino acid content of human blood plasma.

Nonaqueous Copper Colorimetric Method for Determination of Malathion in Technical Grade Malathion and in Malathion Formulations

1972 ◽  
Vol 55 (5) ◽  
pp. 926-938
Author(s):  
R S Wayne ◽  
W C Ghoth ◽  
James W Miles ◽  
Gordon O Guerrant
Keyword(s):  
Colorimetric Method ◽  
Technical Grade ◽  
Nonpolar Solvents ◽  
Ion Activity ◽  
Aoac Method ◽  
Assay Methods ◽  
The Stability ◽  
Critical Timing ◽  
Colorimetric Procedure

Abstract A nonaqueous copper colorimetric procedure has been developed for the assay of technical and formulated products of malathion. The stability of the copper O,O-dimethyl phosphorodithioate complex has been substantially improved by the use of nonpolar solvents and by lowering the hydrogen ion activity of the system. This has permitted the elimination of the partitioning step and has relaxed the critical timing requirements specified in the offi cial first action AOAC method. The new method has a precision of ±1.6% at a 95% confidence level. The accuracy of the technique is discussed in terms of various minor interferences and by contrasting the results obtained with alternative assay methods.

Fluorometric and colorimetric enzymic determination of triglycerides (triacylglycerols) in serum.

1980 ◽  
Vol 26 (5) ◽  
pp. 613-617
Author(s):  
H Winartasaputra ◽  
V N Mallet ◽  
S S Kuan ◽  
G G Guilbault
Keyword(s):  
Colorimetric Method ◽  
Glycerol Dehydrogenase ◽  
Tetrazolium Salt ◽  
Fluorometric Method ◽  
Serum Samples ◽  
Fluorescent Compound ◽  
Microbial Lipase ◽  
Colored Compound ◽  
Colorimetric Procedure

Abstract We describe two fully enzymic methods, fluorometric and colorimetric, for determination of triglycerides (triacylglycerols) in serum. Samples are incubated with microbial lipase for 10 min, and the glycerol released from the triglycerides is oxidized by NAD+ in the presence of glycerol dehydrogenase. In the fluorometric method, the resulting NADH is in turn oxidized by resazurin as catalyzed by diaphorase to form resorufin, a highly fluorescent compound. In the colorimetric method, the NADH is oxidized by coupling with a tetrazolium salt/diaphorase system to form formazan, a highly colored compound. Calibration curves, constructed by plotting change in fluorescence or absorbance vs concentration of triglycerides, were linear up to 6 and 5 g of triglycerides per liter of serum for the fluorometric and colorimetric methods, respectively. The assays require only 5 and 15 microL of serum for fluorometry and colorimetry, respectively. The CV was 0.59% for the fluorometric method, 0.91% for the colorimetric procedure. The time for analysis for either method is less than 15 min. The results correlate well with those obtained by the Dow Diagnostic Kit method, a colorimetric method in which glycerol kinase and glycerol-1-phosphate dehydrogenase form NADH from ATP and NAD+ in the presence of glycerol and glycerol 1-phosphate.

Determination of Menthol in Cigarette Tobacco Filler

1968 ◽  
Vol 51 (3) ◽  
pp. 650-653
Author(s):  
Charles L Tucker
Keyword(s):  
Chromatographic Method ◽  
Colorimetric Method ◽  
Cigarette Tobacco ◽  
Mean Values ◽  
Gas Chromatographic Method ◽  
Colorimetric Procedure

Abstract A gas chromatographic method and two variations of a colorimetric method for determining menthol in cigarette tobacco filler were studied collaboratively by 13 laboratories. No statistically significant differences were found in the precisions within or between laboratories. There were no significant differences between means for any two of the three methods for any sample. A trend toward higher mean values was noted for both colorimetric procedures. The colorimetric procedure that uses a nonmentholated tobacco blank gave mean values nearest to those obtained by the gas chromatographic method. It is recommended that both the gas chromatographic method and the colorimetric method that uses the nonmentholated tobacco blank be adopted as official, first action

Colorimetric Microdetermination of Free Fatty Acids

1973 ◽  
Vol 19 (4) ◽  
pp. 419-424 ◽  
Author(s):  
Felix G Soloni ◽  
Laura C Sardina
Keyword(s):  
Fatty Acids ◽  
Oxalic Acid ◽  
Free Fatty Acids ◽  
Filter Paper ◽  
Normal Values ◽  
Colorimetric Method ◽  
Reference Method ◽  
Chloroform Extract ◽  
Related Difference

Abstract A colorimetric method for determination of free fatty acids has been developed, based on the estimation of copper in a chloroform extract of their cupric salts with oxalic acid bis-(cyclohexylidenehydrazide). Contamination with inorganic copper during extraction is practically eliminated by using filter-paper pads. Specificity and interferences are discussed. Recoveries average 101.1%. Normal values are 10.0 ± 8.2 mg/dl (0.390 ± 0.320 mmol/liter), with no statistically significant sex-related difference. Correlation with the reference method of Dole and Meinertz [J. Biol. Chem. 235, 2595 (1960)] is 0.954. Ten samples can be measured in about 45 min.

Fluorometric and colorimetric enzymic determination of triglycerides (triacylglycerols) in serum.

1980 ◽  
Vol 26 (5) ◽  
pp. 613-617 ◽  
Author(s):  
H Winartasaputra ◽  
V N Mallet ◽  
S S Kuan ◽  
G G Guilbault
Keyword(s):  
Colorimetric Method ◽  
Glycerol Dehydrogenase ◽  
Tetrazolium Salt ◽  
Fluorometric Method ◽  
Serum Samples ◽  
Fluorescent Compound ◽  
Microbial Lipase ◽  
Colored Compound ◽  
Colorimetric Procedure

Abstract We describe two fully enzymic methods, fluorometric and colorimetric, for determination of triglycerides (triacylglycerols) in serum. Samples are incubated with microbial lipase for 10 min, and the glycerol released from the triglycerides is oxidized by NAD+ in the presence of glycerol dehydrogenase. In the fluorometric method, the resulting NADH is in turn oxidized by resazurin as catalyzed by diaphorase to form resorufin, a highly fluorescent compound. In the colorimetric method, the NADH is oxidized by coupling with a tetrazolium salt/diaphorase system to form formazan, a highly colored compound. Calibration curves, constructed by plotting change in fluorescence or absorbance vs concentration of triglycerides, were linear up to 6 and 5 g of triglycerides per liter of serum for the fluorometric and colorimetric methods, respectively. The assays require only 5 and 15 microL of serum for fluorometry and colorimetry, respectively. The CV was 0.59% for the fluorometric method, 0.91% for the colorimetric procedure. The time for analysis for either method is less than 15 min. The results correlate well with those obtained by the Dow Diagnostic Kit method, a colorimetric method in which glycerol kinase and glycerol-1-phosphate dehydrogenase form NADH from ATP and NAD+ in the presence of glycerol and glycerol 1-phosphate.

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