Inorganic nitrites, formation

Inorganic and organic ions can also be introduced into an IMS through the electrospray process, opening up the possibility for the rapid separation of anions and cations in the gas phase rather than the slow processes that are involved using ion chromatography or capillary electrophoresis. In an early application, the anions chloride, nitrite, formate, nitrate, and acetate were all separated by IMS after ESI introduction. 

The banning of calcium chloride during the last decade provided the impetus for the development of alternative materials which accelerated the hydration of cement without the potential for corrosion. A number of inorganic and organic compounds including aluminates, sulfates, formates, thiosulfates, nitrates, silicates, alkali hydroxides, carbonates, nitrites and calcium salts have been evaluated. Commercialization and field experience, however, is limited to only a few of these materials. 

The sensitivity of AN to initiation by heat may be increased or decreased by the presence of certain inorganic impurities. For instance, small amts of Cu increase sensitivity to heat because of the formation of a small amt of copper nitrite, which causes instability (Ref 90). The formation of Cu nitrite also was reported in Mellor, v 7 (Ref 16). Mellor also reports that the presence of Fe, Al or especially Zn in powdered form lowers the temperature required for the decompn of AN. Kast (Ref 31) reported that the presence of KMn04 in powdered form may cause the spontaneous heating of AN. Investigations conducted at Pic Arsn showed that different Cr compds such as the oxide and nitrate catalyze the decompn of AN, and in some cases explosions occurred at temps as low as 200°. Among the inorganic substances which lessen the sensitivity of AN to heat are clay, kiesel-guhr, powdered limestone etc. The same effect was expected of Amm sulfate until the disaster at Oppau in 1921 (Refs 15a 15b) rendered the safety of such a mixt uncertain. Amm sulfate had been used for many years as a desensitizer for AN in fertilizers and it was considered that such mixts could not be... 

Add efficient inhibitors for certain systems since it is believed to assist the formation of a stronger, more stable or more readily repaired passive film. (Miller)24 Phosphates and other inorganic or organic corrosion inhibitors, used in fairly corrosive surroundings, decrease the effects of the SCC. A minimal critical concentration of some oxidizing inhibitors such as nitrites is absolutely necessary to avoid pitting. 

Fig. 3-24. Gradient elution of inorganic and organic anions on IonPac AS5A. - Eluent (A) 0.00075 mol/L NaOH, (B) 0.1 mol/L NaOH gradient 100% A isocratically for 5 min, then linearly to 30% B in 15 min, then linearly to 86% B in 15 min flow rate 1 mL/min detection suppressed conductivity injection volume 50 pL solute concentrations 1.5 ppm fluoride (1), 10 ppm a-hydroxybutyrate (2), acetate (3), glycolate (4), butyrate (5), gluconate (6), a-hydroxyvalerate (7), 5 ppm formate (8), 10 ppm valerate (9), pyruvate (10), monochloroacetate (11), bromate (12), 3 ppm chloride (13), 10 ppm galacturonate (14), 5 ppm nitrite (15), 10 ppm glucoronate (16), dichloroacet-ate (17), trifluoroacetate (18), phosphite (19), selenite (20), bromide (21), nitrate (22), sulfate (23), oxalate (24), selenate (25), a-ketoglutarate (26), fumarate (27), phthalate (28), oxalacetate (29), phosphate (30), arsenate (31), chromate (32), citrate (33), isodtrate (34), eis-aconitate (35), and frons-aconitate (36).

Figure 4.17. Separation of a mixture of inorganic and organic anions by gradient elution ion chromatography with conductivity detection using a micromembrane suppressor. A variable rate gradient from 0.5 mM to about 40 mM sodium hydroxide on an lonPac ASH column was used for the separation. Peak identification 1 = isopropylmethylphosphonate 2 = quinate 3 = fluoride 4 = acetate 5 = propionate 6 = formate 7 = methylsulfonate 8 = pyruvate 9 = chlorite 10 = valerate 11 - monochloroacetate 12 - bromate 13 = chloride 14 = nitrite 15 = trifluoroacetate 16 = bromide 17 = nitrate 18 = chlorate 19 = selenite 20 = carbonate 21 = malonate 22 = maleate 23 = sulfate 24 = oxalate 25 = ketomalonate 26 = tungstate 27 = phthalate 28 = phosphate 29 = chromate 30 = citrate 31 = tricarballylate 32 = isocitrate 33 = cis-aconitate and 34 = trans-aconitate. Each ion is at a concentration between 1 to 10 mg/1. (From ref. [417]. Marcel Dekker).

---