Flow injection methods arsenic

It is seen by examination of Table 1.11(b) that a wide variety of techniques have been employed including spectrophotometry (four determinants), combustion and wet digestion methods and inductively coupled plasma atomic emission spectrometry (three determinants each), atomic absorption spectrometry, potentiometric methods, molecular absorption spectrometry and gas chromatography (two determinants each), and flow-injection analysis and neutron activation analysis (one determinant each). Between them these techniques are capable of determining boron, halogens, total and particulate carbon, nitrogen, phosphorus, sulphur, silicon, selenium, arsenic antimony and bismuth in soils. 

These methods were used to determine arsenic in certified sediments (Table 12.15). Conventional inductively coupled plasma atomic emission spectrometry is satisfactory for all types of samples, but its usefulness was limited to concentrations of arsenic greater than 5pg g-1 dry weight. Better detection limits were achieved using the flow-injection-hydride generation inductively coupled plasma technique in which a coefficient of variation of about 2% for concentrations of lOpg g 1 were achieved. 

Jiminez de Bias et al. [32] have reported a method for the determination of total arsenic in soils based on hydride generation atomic absorption spectrometry and flow injection analysis. The method gave good recoveries and had a detection limit below 1 ig/l for an injection volume of 160 pi... 

The Methylene (and Ethylene) Blue method has been applied in determinations of sulphur in plants [86], biological materials [87], waters [12,88], air [5,12,16,20], hydrocarbons [89], iron alloys [90,91], cobalt and zirconium [91], titanium [92], thallium and its halides [93], arsenic [94], selenium [95], and various reagents (including barium chloride) [14]. Flow-injection analysis has been applied in the determination of sulphur by the Methylene Blue method [96]. 

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