In certain applications, such as acid purification, acidic food or chemical purification or decolorization, or other applications wherein iron may be leached out of the carbon, the use of acid-washed carbons will reduce or eliminate color pickup in the effluent or in the product. The acid soluble iron content is usually specified by the carbon supplier to prevent unacceptable levels of iron leach occurring.

Detection limits, sensitivity, and optimum ranges will vary with the models of atomic absorption spectrophotometers. General instrumental parameters are as follows:

Iron hollow cathode lamp.

Wavelength: 248.3 nm.

Fuel: acetylene (high purity).

Oxidant: air (from compressed air line, laboratory compressor, or a cylinder of compressed airall need to be clean and dry).

Type of flame: oxidizing.

The following lines may also be used:

The method, as written, is intended for carbons having an acid soluble iron content of 0.0030 to 0.050 % For carbons having higher iron contents, larger dilutions or smaller aliquots may be used.

The user should validate that there are no interferences from other metals in the sample matrix.

To prevent erroneous results, the user should ensure that no iron instruments contact any of the sample or the solutions used in this procedure. Only glass, ceramics, or plastic should be allowed to contact the sample or solutions.