Comparison of GLC and Colorimetric Methods for Determination of Methanol in Alcoholic Beverages

1971 ◽  
Vol 54 (4) ◽  
pp. 785-786
Author(s):  
R H Dyer
Keyword(s):  
Colorimetric Method ◽  
Alcoholic Beverages ◽  
Methanol Content ◽  
Comparison Of Results ◽  
Colorimetric Methods

Abstract A comparison of results by a proposed GLC method and the present AOAC colorimetric method (9.071-9.074) for methanol in alcoholic beverages is presented. The GLC method utilizes a Carbowax 1500 on Chromosorb W column (similar to 9.063) for determination of methanol content at concentrations as low as 0.003% methanol. In the lower methanol concentrations the GLC results were higher, possibly due to a loss of methanol during the distillation required for the colorimetric method. A total of 20 samples of various alcoholic beverages were analyzed for methanol and the concentration of methanol ranged from 0.004 to 0.37%.

Determination of Cobalt in Fertilizers

1965 ◽  
Vol 48 (2) ◽  
pp. 412-415
Author(s):  
J F Hodgson ◽  
Victor A Lazar
Keyword(s):  
Colorimetric Method ◽  
Isoamyl Acetate ◽  
Acid Mixture ◽  
Acid And Base ◽  
Colorimetric Methods

Abstract Cobalt in fertilizers was determined by a colorimetric method using 2-nitroso-l-naphthol. With this method the fertilizer is digested with a ternary acid mixture; cobalt is then extracted from a suitable aliquot into isoamyl acetate at pH 8.5 with an excess of 2-nitroso-l-naphthol. Excess dye and interferences are removed by successive washes with acid and base. A limited number of collaborator analyses indicate that agreement of results is not as satisfactory as might be expected with the major fertilizer constituents. However, collaborator agreement compares favorably with other methods of analyses accepted by the AOAC for Co. While the procedure is considered tedious by some collaborators, it is believed to be less tedious and less subject to interferences than other colorimetric methods available.

Colorimetric Method for Ester Content of Alcoholic Beverages

1971 ◽  
Vol 54 (5) ◽  
pp. 1225-1230
Author(s):  
G R Coe ◽  
S Baldwin ◽  
A A Andreasen
Keyword(s):  
Alkaline Solution ◽  
Hydroxamic Acid ◽  
Colorimetric Method ◽  
Small Sample ◽  
Alcoholic Beverages ◽  
Colored Complex ◽  
Ester Content

Abstract A colorimetric method for determination of esters in alcoholic products was studied for the effect of procedural variables. It is based on the quantitative reaction of esters with hydroxylamine in alkaline solution to form a hydroxamic acid which, upon acidification, forms a colored complex in the presence of Fe(III) ions. Mathematical data are presented to demonstrate that the colorimetric method is superior to the AOAC saponification method, 9.051-9.052, for comparing samples which contain widely differing ester compositions. The colorimetric method is rapid and requires a small sample.

Aluminum and Iron in Plants

1964 ◽  
Vol 47 (4) ◽  
pp. 785-787
Author(s):  
Elizabeth I Lixden
Keyword(s):  
Colorimetric Method ◽  
Chelating Agent ◽  
Review Of Literature ◽  
Comparison Of Results ◽  
Methods Of Analysis ◽  
Official Methods Of Analysis

Abstract A review of literature discloses nun erous methods applicable to determination of Al and Fe in plants. A comparison of results for Fe by a colorimetric method using 2,2’-bipyridine as chelating agent with those by the colorimetric o-phenanthroline and the TiCl3 titrimetric methods in Official Methods of Analysis showed that the 2,2’-bipyridine was simpler, less time-consuming, and equally as accurate as the o-phenanthroline procedure, and free of the Cu interference encountered in the TiCl3 method. Further study is recommended for accurate and efficient methods for Al and Fe.

Determination of Iron in Alcoholic Beverages

1970 ◽  
Vol 53 (1) ◽  
pp. 12-16
Author(s):  
M K Meredith ◽  
Sidney Baldwin ◽  
A A Andreasen
Keyword(s):  
Atomic Absorption ◽  
Collaborative Study ◽  
Colorimetric Method ◽  
Atomic Absorption Spectrophotometry ◽  
Alcoholic Beverages ◽  
Wet Oxidation ◽  
Special Equipment ◽  
Oxidation Method ◽  
Trained Personnel

Abstract Results are presented for a collaborative study on the determination of ppm iron in alcoholic beverages, except beer, by the following methods: atomic absorption spectrophotometry, direct colorimetry using 2,4,6-tripyridyl-s-triazine (TPTZ) for alcoholic beverages other than brandy, and wet oxidation using sodium hypochlorite and hydrogen peroxide followed by color development with TPTZ for brandy only. When available, atomic absorption is the method of choice because of its speed and accuracy. The colorimetric method eliminates ashing, is relatively rapid, and does not require special equipment or highly trained personnel; however, it does not give accurate results for brandy. The wet oxidation method is satisfactory for brandy but requires more time, proper ventilation, and trained personnel. Results by these methods are accurate for routine determinations and it is recommended that the first two methods be adopted as official first action for the alcoholic products specified. Study on the wet oxidation method for products containing chelating agents and/or “complexed iron” should be continued.

Determination of Esters in Alcoholic Beverages

1972 ◽  
Vol 55 (3) ◽  
pp. 559-563
Author(s):  
G R Coe ◽  
S Baldwin ◽  
A A Andreasen
Keyword(s):  
Statistical Evaluation ◽  
Collaborative Study ◽  
Colorimetric Method ◽  
Alcoholic Beverages ◽  
Accuracy And Precision

Abstract Results are presented on a collaborative study comparing 2 methods for the determination of esters in distilled alcoholic beverages. A previously described colorimetric method was compared with the present official AOAC saponification method, 9.050–9.052. Statistical evaluation of the data shows that the 2 methods are comparable in accuracy and precision. The colorimetric method has been adopted as official first action as an alternative to 9.050–9.052 for the determination of esters in distilled alcoholic beverages.

Colorimetric Determination of Methyl Parathion and Oxygen Analog

1980 ◽  
Vol 63 (3) ◽  
pp. 536-538
Author(s):  
Nanguneri V Nanda Kumar ◽  
Mattipalli Ramasundari
Keyword(s):  
Methyl Parathion ◽  
Colorimetric Method ◽  
Acetone Powder ◽  
Colorimetric Determination ◽  
Pig Liver ◽  
Oxygen Analog ◽  
Nitrophenyl Phosphate ◽  
Colorimetric Methods ◽  
Nonenzymatic Reactions

Abstract A simple, sensitive, and rapid colorimetric method is described (or determining methyl parathion (0,0-dimethyl-O-ρ-nitrophenyl phosphorothioate) and methyl paraoxon (O,O-dimethyl-O-ρ-nitrophenyl phosphate), using ρ-nitrobenzene diazonium fluoroborate as the chromogenic salt. This colorimetric method is more sensitive than are other colorimetric methods based on nonenzymatic reactions. Pig liver acetone powder cholinesterase was found to be sensitive to methyl parathion. Inhibition can be detected at picogram levels, and 50–80 ng methyl paraoxon and 1–9 μg methyl parathion can be estimated.

The Need for Using An Enzymatic Colorimetric Assay in Creatinine Determination of Peritoneal Dialysis Solutions

1990 ◽  
Vol 10 (1) ◽  
pp. 89-92 ◽  
Author(s):  
Liliane Larpent ◽  
Christian Verger
Keyword(s):  
Peritoneal Dialysis ◽  
Reliable Method ◽  
Colorimetric Assay ◽  
Colorimetric Method ◽  
Peritoneal Membrane ◽  
Creatinine Kinetics ◽  
Dialysis Solutions ◽  
Peritoneal Dialysis Solutions ◽  
Enzymatic Test

The fate of the peritoneal membrane on continuous ambulatory peritoneal dialysis (CAPD) is usually evaluated through the modification of its permeability to various solutes as glucose, creatinine, and urea. Therefore, the accuracy of the methods used for measurements of creatinine is of great importance. A particular problem does exist for creatinine determination as it may be influenced by the presence of glucose. We studied a new enzymatic colorimetric method for creatinine determination in peritoneal dialysis solutions which contain high dextrose concentrations. Creatinine was measured in plasma, urine, and dialysate from 18 patients on CAPD and in pure dextrose solutions, with an enzymatic test (Boehringer Mannheim) and with Jaffe's reaction on two different analyzers: Astra (Beckman) and Eris (Merck). Creatinine results were similar with both assays (Jaffe's reaction and enzymatic test) when measured in blood and urine. However the Jaffe's reaction gave higher creatinine results than the enzymatic test (p < 0.001), when assays were performed in peritoneal dialysis solutions and in pure glucose solutions. In addition, it appeared that other components of dialysis solutions, mainly calcium chloride, influenced unpredictably the results of creatinine with the Jaffe's reaction. We conclude that specific enzymatic test is a more accurate and reliable method to evaluate creatinine kinetics through the peritoneal membrane when determined in CAPD solutions.

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