what is the different between dry ashing and wet ashing?

Question

when we must use dry ashing and when we must use wet ashing?

Answer 1

Preparation of hair specimens for trace-metal analyses is
routinelydone by wet- or dry-ashing. Wet-ashing is more
time consuming than dry-ashing and can be dangerous. We
wishedto determine if dry-ashingwas a suitablealternative
to wet-ashingwith HCIO4:HNO3or HNO3alone in preparing
hair for measurement of zinc, copper, iron, and manganese
by atomic absorption spectroscopy. Concentrations of Zn,
Cu, and Mn were not differently affected in hair that was dryor
wet-ashed. Analytical recovery of these elements added to
hair samples ranged from 102 to 108%; day-to-day CVs were<5%. Fe was lost during dry-ashing of hair, and wet-ashing with HNO3 produced results for Fe comparable with those obtained with HCIO4:HNO3.Therefore we recommend dry ashing of hair to be analyzed for Zn, Cu, and Mn, but wetashing with HNO3 for assays of Fe. Addftlonal Keyphras.e: trace elements atomic absorption
spectroscopy . sample preparation variation, source of
neural tube defect Dry- and wet-ashing have been compared as digestion techniques in the analyses of tissues from various sources,including fish and plants . Dry and wet
digestion are routinely used in preparing hair for analyses
of trace elements by various techniques. To our knowledge,
no study as yet has compared the effects of wet- and dryashing on analyses for zinc, copper, manganese, and iron in hair. This is an important consideration in preparing hair
for trace-metal analysis, given previous comparisons of wet and diy-ashing of different tissues that indicated that results
may be tissue dependent . Therefore we wished to
assess whether dry-ashing is as suitable as wet-ashing for
preparing hair samples for determinations of zinc, copper,
manganese, and iron by atomic absorption spectroscopy.

Answer 2

dry ashing wet ashing

Answer 3

Depends on the use.