ALTANA LCS III - Manual (Page 48)

47
Standard Operations
For iodine color values of less than or approximately 1, the
determination of the Hazen value according to DIN-ISO 6271 is to
be preferred. Sampling and preparation are described in section
5.4
on page 36 .The Iodine value can be accurately determined using
an 11 mm round glass cuvette/sample cell.
5.5.5 Determine the Hazen color value (Pt-Co or APHA-method)
The Hazen color value (ISO 6271, also known as "AHPA-method "
or Platinum-Cobalt Scale) is defined as mg of platinum per 1 litre of
solution. The Hazen parent solution is composed of 1.246 g of
potassium hexachloroplatinate (IV) and 1.00 g of cobalt(II)chloride
dissolved in 100 ml of hydrochloric acid and filled up to 1000 ml with
distilled water.
The Hazen-color scale is used to evaluate the colors of nearly
water-clear products. It has narrower gradations in the light yellow
range than the Iodine scale and extends to water-clear color casts.
Note: Samples with Hazen values between 50 and 1000 can be measured
with sufficient accuracy in 10 mm square and 11 mm round
cuvettes/sample cells. Hazen values below 50 are measured in 50 mm
cuvettes/sample cells. Hazen values below 10 are only be measured with
the 50 mm cuvette/sample cell used for calibration, because nearly
water-clear products can easily give faulty measuring results due to
cuvette/sample cell tolerances.
5.5.6 Determine the Gardner color value
The Gardner color value is defined in DIN-ISO 4630.The lighter
Gardner color values (1 to 8) are based on
potassium-chloroplatinate solutions, while the darker ones (9 to 18)
are based on solutions of iron(III)chloride, cobalt(II)chloride and
hydrochloric acid. The LCS III can determine Gardner values at all
cuvette/sample cell path lengths (only values 0 to 4 in 50 mm
cuvettes/sample cells).
The 10 mm and 11 mm cuvettes/sample cells provide sufficient
accuracy.
5.5.7 Determine the Klett color number
The Klett color number is used in the cosmetics industry to evaluate
surfactants and detergents. The Klett color number is
conventionally measured in 4 cm cuvettes/sample cells with a
Summerson photometer, employing a blue filter (no.42).
The measuring range starts at Klett color number 0 and ends at
Klett color number 1000.
The LCS III can measure the Klett color number with all types of
cuvette/sample cell (10,11 and 50 mm), although the 50 mm
cuvette/sample cell gives the highest precision. However, the
measurement result is always calculated for the Klett 4 cm
cuvette/sample cell and blue filter no.42.
5.5.8 Mineral oil color value (ASTM D 1500 and ISO 2049)
The mineral oil color scale is used to evaluate the color of mineral
oil products such as lubricating oils, fuel oil, diesel fuel and paraffin.
The color scale starts at color value 0 for water-white, non-colored
oils and ends at 8 for very dark brown oils. Substances are visually