Gradients capacity

Yamamoto, A., Inoue, Y., Kodama, S., and Matsunaga, A., Capacity gradient anion chromatography with a borate complex as eluent, ]. Chromatogr. A, 850,... 

This chapter provides an overview of essential concepts in HPLC including retention, selectivity, efficiency, and resolution as well as their relationships with key column and mobile phase parameters such as particle size, column length and diameter, mobile phase strength, pH, and flow rate. The significance of several concepts important in pharmaceutical analysis such as peak capacity, gradient time, void volume, and limit of quantitation are discussed. 

Capacity gradients can be achieved in another way in IC by changing the temperature of the macrocycle-based column. Since the reaction of cryptands with metal cations is typically exothermic, raising the temperature reduces the degree of complexation. Based on this concept, gradient separations of anions can be achieved using a 2.2.2 column when the temperature is raised to 80 °C during the separation. [19]... 

Figure 8.1. Gradient separation of carboxylic adds with background correction with a 15 cm x 4.1 mm Hamilton PRP-X300 column of 0.17 mequiv/g exchange capacity. Gradient 1.0 mM sulfuric acid (pH 2.7) for 1.0 min, then a 0-20% acetonitrile linear gradient over 4.0 min. followed by a 5.0 min hold at 20 % acetonitrile. Other conditions were the same as in Fig. 1. Peaks I = oxalic acid, 2 = tartaric acid. 3 = maleic acid, 4 = citric acid, 5 = lactic add, 6 = acetic add, 7 = succinic add, 8 = glutaric acid, 9 = propionic acid, 10 = butyric acid, 11 = valeric add. From Ref. [7] with permission.

FigureS.1 Gradient separation of carboxylic acids with background correction with a 15 cm X 4.1 mm Hamilton PRP-X300 column of 0.17 mequiv g" exchange capacity. Gradient ...

Figure 12 Separation of 14 common anions under isocratic and capacity gradient conditions (a) with 20 mM LiOH as eluent (isocratic) (b) with 20 mM NaOH as eluent (isocratic) (c) with a 20 mM NaOH to 20 mM LiOH gradient. Peaks 1 = F, 2 = CH3C02-, 3 = C1-,4 = N02 , 5 = Br, 6 = N03 , 7 = S042-,8 = C2042-,9 = Cr04-, 10 = r, 11=P043-,...

Capacity gradients can also be carried out on cryptand columns. Cryptands provide a three-dimensional cavity for metal cation entrapment. The basic structure of cryptands is illustrated by the ligand 2.2.2 ... 

Figure 3.90 Separation of inorganic and organic anions on a DVB poiymer (Dionex lonPac NS1) coated with tetradecyl-18-crown-6 utilizing a capacity gradient. Eluent (A)...

Figure 3.93 Comparison of isocratic (a) and capacity gradient (b) separation of standard anions on lonPac Cryptand A1. Coiumn temperature 35 °C eiuents (A) 10 mmoi/L NaOH, (B) 10 mmol/L NaOH, step at 0.1 min to 10 mmol/L LiOH flow rate 0.5 mL/min ...

Figure 3.158 Separation of condensed phosphates with a capacity gradient.

Figure 3.187 Separation of alkanesuifonic and alkanedisulfonic acids in a chromium plating bath utilizing a capacity gradient. Separator column lonPac Cryptand A1 column dimension 150 mm x 3 mm i.d. column temperature 30 °C eluent 25 mmol/L NaOH, switched to 25 mmol/L LiOH after 2.1 min ...

Fig. 3-60. Separation of inorganic and organic anions on a DVB polymer (lonPac NSl. Dionex) coated with tetradecyl-18

Fig. 3-64. Capacity gradient elution of non-polarizable and polarizable anions on lonPac Oyptand Al. Column temperature 35°C eluants (A) 10 mmol/L NaOH, (B) 10 mmol/L NaOH, step at 0.1 min to 10 mmol/L LiOH flow rate 0.5 mL/min detection suppressed conductivity solute concentrations 2 mg/L fluoride (1), 3 mg/L chloride (2), 5 mg/L nitrite (3). 10 mg/L bromide (4), 10 mg/L nitrate (5), 5 mg/L sulfate (6), 5 mg/L thiosul te (7). 5 mg/L orthophosphate (8), 10 mg/L iodide (9), 10 mg/L thiocyanate (10). and 15 mg/L perchlorate (11).

Ysunamoto, A. Kodama, S. Matsimaga, A. Inoue, Y. Aoyama, T. Kumagai, Y. Characteristics of a column suitable for capacity gradient chromatography with a borate eluent. The Analyst, 2001, 126, 465-468. 

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