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12:3 Acid Digestions of Organic Samples

Nitric and Perchloric Acid Diges3ons: see www.ivstandards.com and go to Tech Center/Reliable Measurements/part 12 for a detailed proc.

• Organic matrices should always be pre-treated with nitric acid (see excep9ons above). • Perchloric acid should never be used alone. • Perchloric acid diges9ons should never be allowed to go to dryness. • Hot perchloric acid should never be added to an organic matrix. • Sample sizes should never exceed 1 gram (dry weight for biologicals). • Perchloric acid fumes should not be allowed to ‘go free' unless a perchloric acid hood is used. • Unknown organic matrices should be analyzed by molecular spectroscopy to determine primary structure before aGemp9ng the use of either nitric or perchloric acid

13:1 Sample Prepara:on by Fusion

Fusions are considered to be more of a 'last resort' by trace analysts because:

• They are expensive and o0en not available (high purity fluxes). • They yield high solids solu:ons that can salt out in the nebulizer.

• Large dilu:ons of the sample are a necessity. • They o0en require expensive equipment. • Spectral interferences from the flux and/or crucible construc:on material must be considered. • Contamina:on of the sample with the crucible construc:on element and impuri:es must be considered. • They are labor intensive