Tartrate reagent, alkaline copper

The earlier alkaline copper tartrate reagents required the addition of potassium iodide to prevent their slow autoreduction. However, if the constituents are of analytical quality, tartrate-biuret reagents are stable indefinitely, and potassium iodide can safely be omitted. 

Contrasting with the aforementioned assessments, the SC can be studied after staining the harvested SACD. Many dyes are available and their choice depends on the goal of the study. As an example, a mixture of rhodamine B and methylene blue conveniently decorates the corneocytes for microscopic examination. Another quantitative assay is based on the Lowry s reaction of proteins with an alkaline copper tartrate solution and Folin reagent followed by spectrophotometric measurement of the reaction product with maximum absorbance at 750 nm 59... 

Protein, total s Spectrophotometry Biuret reagent (alkaline copper tartrate) forms complex with proteins measure absorbance at 550 inn after 30 min... 

Separately prepare 100 ml of fresh alkaline copper reagent by mixing, in order, 1 ml of 1% CuSC>4 5H20 and 1 ml of 2% sodium tartrate into 98 ml of 2% Na2C03 in 1 N NaOH. 

Procedure The alkaline copper reagent was prepared just prior to use by mixing 1 vol. of copper sulphate solution with 1 vol. of sodium potassium tartrate solution followed by 98 vol. of the sodium carbon-ate/sodium hydroxide solution. Alkaline copper solution (5 ml) is added to 100 pA of sample, containing between 20-100 pig of protein, diluted with 900 pil of water. After 10 min 0.5 ml of diluted Folin and Ciocalteus reagent is added. The absorbance at 750 nm is read after 30 min and within 90 min from the final addition. 

FEHLING S SOLUTION. Test reagent consisting of two solutions, one of copper sulfate, the other of alkaline tartrate, which are mixed just before use. 

Fehling s solution. A reagent used as a test for sugars, aldehydes, etc. It consists of two solutions, copper sulfate and alkaline tartrate, which are mixed just before use. Benedict s modification is a one-solution preparation. Additional details are available in the Book of Methods, Association of Official Analytical Chemists. 

The Lowry assay [16] uses the reaction of cupric sulfate at alkaline pH in the presence of tartrate, producing a blue chromogen formed from four peptide bonds and one atom of copper. Addition of folin phenol reagent further enhances the color, with a maximum absorbance at 750 nm. The Lowry assay demonstrates the greatest sensitivity of the common protein concentration determination methods and varies only slightly when using the two common calibrators, BS A and BGG. Not surprisingly, this remains a very commonly used method. 

Aldehydes reduce an alkaline solution of a cupric salt to cuprous oxide. The reagent used is called Fehling s solution (311). It is prepared by adding copper sulphate to a solution which contains sodium hydroxide and Rochelle salt, sodium potassium tartrate (CHOH.COO)2KNa. In the presence of the tartrate copper hydroxide is not precipitated, and a clear, dark blue solution is obtained. When an aldehyde is warmed with Fehling s solution, cuprous oxide is formed as a precipitate, which is usually red. As certain substitution-products of ketones (357) reduce Fehling s solution, the test does not serve to identify aldehydes positively. It is, however, of service, and is much used in the study of carbohydrates, many of which contain aldehyde groups. 

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