Sample digestion

Nagoumey and Madan [20] have considered both AAS and ICP-AES as reliable measurement techniques for the determination of metal components in mixed-metal/phosphite stabiliser systems in PVC. For reasons given elsewhere (Section 8.3.2.4), in this case ICP-AES was considered the technique of choice for most metal stabiliser determinations, while AAS remains a useful method to corroborate the ICP-AES results. For the determination of tin in rigid PVC by means of HG-AAS, the main effort has been to develop a sample digestion procedure [118]. Tin and Ti from a PVC potable... 

Feces Dessication and pulverization of sample digestion with hot acid in Paar bomb ICP/AES 10-50 pg/L >86 Que Hee and Boyle 1988... 

ASTM. 1998d. ASTM E 1726. Standard practice for sample digestion of soils for the determination of lead by atomic spectrometry. American Society for Testing and Materials. 

The content of heavy metals in sediments was determined by sample digestion with 10 ml of the mixture of HCI04, HCI, HN03 and HF at 200°C, followed by Inductively Coupled Plasma Emission Spectrometry (ICP) (ACME, 2003). 

Elemental analysis of sample digests Non-destructive analysis of solid samples... 

Cindy Wagner-Wiebeck sets a Kjeldahl flask in place in a fume hood dedicated to Kjeldahl sample digestion. 

Blood and liver Treatment of HCN released from sample digestion with lead acetate and absorption with NaOH Specific ion electrode (total cyanide) 5 pg/L 100-109 (whole blood, 0.3-130 ppb) Egekeze and Oehme 1979... 

Tomlinson, K.Y. et al. 1998. Refinement of Hafnium (Hf) and Zirconium (Zr) analysis by improvement in the sample digestion procedure. Ontario Geologic... 

Total digestion - 0.125 g of ground sample digested in a mixture of concentrated HF/HNO3/HCIO4 until dry. Residue redissolved in dilute HNO3 then diluted 8x with deionized water. 

Pipette 10 ml of the sample digest (see under Digestion stage ) into the distillation unit, and proceed with addition of sodium hydroxide solution, distillation and titration as above. 

Calculation. Subtract the titre given by the blank from that given by the sample digest. Multiply the difference by 1.4. The result gives the g kg of nitrogen in the sample. (Multiply the difference by 0.14 to get the % N in the sample.) If required, express results for oven-dry soil as in Method 5.2, Calculation (2). 

Example ammonium nitrate - sample weight, 0.05 g. The blank and sample peaks are compared with the standard curve in the normal way. The blank peak value (15 mg N M) is subtracted from the sample peak value (365 mg N 1 ) to give 350 mg N h in the 50 ml of diluted sample digest solution. The weight of N in 0.05 g sample is therefore ... 

Stock standard solution, 2000 pg N mh 200 pg P mM, 1600 pg K mb, (400 pg Ca mb ) - omit the Ca if it is unlikely to be required, so as to avoid the precipitation of calcium sulphate in the diluted standards. This combined standard solution can be used for the autoanaiysis of P and K, and also provides a similar matrix to the sample digests. Each reagent should be dried at 102°C for 1 h and cooled in a desiccator before weighing. Dissolve 1.3745 g potassium chloride, 0.4393 g potassium dihydrogen phosphate, 4.7162 g ammonium sulphate, (and 0.5000 g calcium carbonate), in sulphuric acid (approximately 98% m/m H SO ) and make up to 500 ml with sulphuric acid. 

Sample preparation methods are similar to those used for FAAS and ICP-AES. However, nitric acid is favoured for sample digestion since the other mineral acids contain elements which cause spectroscopic inteferences. 

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