Periodic acid, detection determination

Sakamoto [243] determined picomolar levels of cobalt in seawater by flow injection analysis with chemiluminescence detection. In this method flow injection analysis was used to automate the determination of cobalt in seawater by the cobalt-enhanced chemiluminescence oxidation of gallic acid in alkaline hydrogen peroxide. A preconcentration/separation step in the flow injection analysis manifold with an in-line column of immobilised 8-hydroxyquinoline was included to separate the cobalt from alkaline-earth ions. One sample analysis takes 8 min, including the 4-min sample load period. The detection limit is approximately 8 pM. The average standard deviation of replicate analyses at sea of 80 samples was 5%. The method was tested and inter calibrated on samples collected off the California coast. 

System (6) has been described for the simultaneous determination of submicrogram amounts of 17a-deoxy and 17a-hydroxy corticosteroids [145]. Prior to analysis, the corticosteroids were treated with periodic acid in 50% aqueous dioxane, and extracted with dichloromethane. Acylation of the 3- and 17a-hydroxyl groups was carried out using 1 1 butyric anhydride and pyridine. 4- C -cholesterol was added as the tracer, and cholesterol isobutyrate as the internal standard. The column used was glass (8 ft X 5 mm) packed with 1% SE 30 or QF-1 on GasChrom Q (100-120 mesh), and was operated at 250-260°C. Argon (at a flow rate of 30 mL/min) was used as the carrier gas, and detection was by a Sr detector. It was reported that the corticoids could be determined with a precision of approximately 15% down to levels as low as 0.1-0.2 pg. 

The distillate may contain volatile neutral compounds as well as volatile acids and phenols. Add a slight excess of 10-20 per cent, sodium hydroxide solution to this distillate and distil until the liquid passes over clear or has the density of pure water. The presence of a volatile, water-soluble neutral compound is detected by a periodic determination of the density (see Section XI,2) if the density is definitely less than unity, the presence of a neutral compound may be assumed. Keep this solution Si) for Step 4. 

It is used in IC systems when the amperometric process confers selectivity to the determination of the analytes. The operative modes employed in the amperometric techniques for detection in flow systems include those at (1) constant potential, where the current is measured in continuous mode, (2) at pulsed potential with sampling of the current at dehned periods of time (pulsed amperometry, PAD), or (3) at pulsed potential with integration of the current at defined periods of time (integrated pulsed amperometry, IPAD). Amperometric techniques are successfully employed for the determination of carbohydrates, catecholamines, phenols, cyanide, iodide, amines, etc., even if, for optimal detection, it is often required to change the mobile-phase conditions. This is the case of the detection of biogenic amines separated by cation-exchange in acidic eluent and detected by IPAD at the Au electrode after the post-column addition of a pH modiher (NaOH) [262]. 

Detection and determination.—The periodates behave towards reducing agents like the iodates. They are usually but slightly soluble in water and readily soluble in dil. nitric acid. When soln. of sodium periodate are added to barium, strontium, calcium, lead, and silver salts, precipitates of dimesoperiodates are obtained, and the mother liquor has an acid reaction—the silver salt is pale yellow, the others white—silver iodate is also white. The silver precipitate becomes dark red when boiled in water the fresh precipitate is very soluble in ammonia, the dark red... 

---