Measurement of Color and Turbidity in Solutions of White Granulated Sugars

Abstract

Results obtained by the modified Parr method were all well within A. S. T. M. tolerances for duplicates in the same laboratory. With the exception of results on one sample (5), the checks between the two laboratories were within A. S. T. M. tolerances.The determination of ash by Method D gives duplicates checking within the 0.3 per cent tolerance for all samples.The adequate removal of sulfur trioxide from the furnace during ashing is important.As compared to results obtained by the modified Parr procedure, Methods A and E gave results within the A. S. T. M.0.3 per cent tolerance for samples containing up to 0.6 per cent of carbon dioxide; Method B for coals up to 3.6 per cent of carbon dioxide; Method F for coals up to 4.2 per cent of carbon dioxide (with one exception); and Method D for coals containing up to 3.6 per cent of carbon dioxide.Sulfur trioxide-free ash values were similar for all methods.The slow heating method starting with a cold furnace appears to be satisfactory for determining ash in commercial samples of coal containing unusually large amounts of calcite and pyrite. ConclusionsMethods A and E are not recommended for determining ash in coals high in calcite and pyrite, because too much sulfur is retained in the ashes.Methods B, D, and F give most consistent results, with Method D apparently giving the best results of the three.Methods C and G appear to give good results, especially for coals high in calcite and pyrite where other procedures studied are not so satisfactory. This procedure requires more

Recent Developments in White Sugar Colorimetry

“…To overcome these difficulties, turbidity compensation has been advocated by several investigators (3,6,8,9) as a substitite for filtration. Turbidity compensation usually requires measurements at two points in the spectrum and the application of an empirically determined corrective factor, based on the relationship between the two readings.…”

“…In general, the method outlined is considered suitable for its intended use. Experience with a similar method (8) has shown it to correlate well with visual colors and to be simple, fast, and reproducible. The general adoption of this procedure will permit uniform reporting of white sugar color results and eliminate much confusion.…”

Grading of Soft Sugars - Photoelectric Reflectance Measurements

“…Since the development of this instrument, other photoelectric means of measuring the transmittancy or reflectance of sugar products have been described-i. e., Keane and Brice (6), Nees (18), and Morse and McGinnis (10), although these have been mainly for use on white refined sugars, primarily in solution.…”