Gradients acid

FIGURE 2 Typical chromatograms ofTween-80 in aqueous solutions (0.1-3%,w/w). HPLC method conditions Waters Symmetry columns (5 lm, 4.6xl50mm) were eluted with a mobile phase containing acetonitrile and 0.1% phosphoric acid (gradient program) with UV detection at 220 nm. Injection volume is 20 lL. 

Acenocoumarol and acenocoumarol Whelk-Ol -Hexane-ethanol containing 0.5% acetic acid (gradient) 200... 

FIGURE I A reconstructed extracted ion chromatogram of nicotinic acid and its six metabolites under HILIC conditions. Column Hypersil silica (4.6 X 50 mm) at a flow rate of 4 mL/min. Mobile phase A is water, mobile phase B is acetonitrile, both containing 1% formic acid. Gradient is 0.01-0.25 min 90% B to 65% B 0.25-0.90 min 65% B to 50% B. NA nicotinic acid NAM nicotinamide NUA nicotinuric acid 2-PY l-methyl-2-pyridone-5-carboxamide l-MNAM I-methyl-nicotinamide NAMO nicotinamide-N-oxide 4-PY l-methyl-4-pyridone-5-carboxamide. (Reprinted with permission from Reference 20.)... 

Figure 9. HPLCs of yvater-soluble extracts from peanut cell cultures treated with [ C] PCNB. Extracts were chromatographed on a column of Ct with a water/ acetonitrile/acetic acid gradient similar to that described previously (6).

Figure 6.6 HPLC chromatogram of the extract from Superior potato flesh (a) and of the same extract spiked with standards (b). Identification p.1, chlorogenic acid p.2, chlorogenic acid isomer p.3, caffeic acid p.4, p-coumaric acid p.5, ferulic acid p.6, t-cinnamic acid. Column, Inertsil ODS-3 V (5 p.m, 4.0 X 250 mm) flow rate, l.OmL/min column temperatures, 20°C mobile phase, acetonitrile 0.5% formic acid (gradient mode) detector, UV at 280 nm.

Figure 6.7 LC-MS chromatograms of an extract of Superior potato peel monitored at 280 nm, 340 nm, and TIC. Column Inertsil ODS-3 (3 p,m, 4.0 x 150 mm). Flow rate 0.2 mL/min. Column temperature 30°C. Mobile phase acetonitrile 0.5% formic acid (gradient mode).

BHT, BHA, TBHQ Fats, oils extraction from hexane solution with acetonitrile LiChrosorb RP-18 Acetonitrile/water-phosphoric acid, gradient elution UV 280 nm 139... 

Acetonitrile/water/ phosphoric acid gradient 250 X 4-mm-ID 5-/xm Grom-Sil ODS-O AB Partial Ambient 314 31... 

NThZ, NHMThZ, NMeThZ, and NHMFuThZ in bacon 1. Extraction with CH2C12 2. Cleanup on three cyano-propyl Bond Eluts in series None 250 X 4.6 mm Spheri-sorb ODS 2 (5 /zm) Aceton 0.05 M triethyl-amin/0.15 M phosphoric acid (gradient from 10 90 to 60 40) TEA 35-59 47a... 

Part B 100 900 0.5 (v/v/v) water-acetonitrile-trifluoroacetic acid Gradient... 

ESI and APCI. LC/MS is considerably improved after precolumn oxidation with peroxide to the pentavalent acids (27) and (29). These can be chromatographed on a polymeric PRP-1 column using a standard water-CH3CN-0.2 % formic acid gradient (69). 

Diol (LiChrosorb) 100 X 3.0 5 hexane-isopro- panol-acetic acid gradient Ambient ELSD Moreau et ah, 1996... 

Gently empty the water from both sides of the gradient maker. 4-37. The gradient to be used is a 500 ml, 0-5JV linear formic acid gradient. Place 250 ml water in the stirred side (side connected to the column) of the gradient maker and 250 ml 5M formic acid in the unstirred side. Be sure that the gradient maker is perfectly level. 

Repeat steps 4-29 to 4-48. This procedure 0-5N linear formic acid gradient) removes the AMP and ADP. 

Figure 4.10 OTA and ZAN LC-MS3 extracted ion chromatograms of a wine spiked with OTA at a concentration of 0.1 ng/mL and internal standard ZAN (lOng/mL). Above signal m/z 239 + 341 of OTA below signal m/z 207 + 189 + 163 of ZAN. Analytical conditions C18 (3 x 250mm 5 pm) column, binary solvent A) H2O/0.1% formic acid/sodium acetate 0.6mM and B) methanol/0.1% formic acid. Gradient program 50% A for 1 min, from 50% to 20% of A in 7 min, isocratic for 4 min, 20-50% A in 3 min, isocratic for 3 min (flow rate 0.5mL/min). SACI vaporizer temperature 400 °C entrance capillary temperature 150 °C SACI surface voltage 50 V surface temperature 110°C nebulizing sheath gas N2 at flow rate 9 L/min curtain gas 2 L/min spray needle voltage set to 0 V. (Adapted from Flamini et al, 2007, RCM) 21, (22), 3737-3742...

Fig. 3-25. Gradient elution of different sugar alcohols and saccharides. - Separator column Ion Pac AS6A eluent (A) water, (B) 0.05 mol/L NaOH + 0.0015 mol/L acetic acid gradient 7% B isocratically for 15 min, then to 100% B in 10 min flow rate 0.8 mL/min detection pulsed ampero-metry on a Au working electrode (post-column addition of NaOH) injection volume 50 pL solute concentrations 15 ppm inositol (1), 40 ppm sorbitol (2), 25 ppm fucose (3), deoxyribose (4), 20 ppm deoxyglucose (5), 25 ppm arabinose (6), rhamnose (7), galactose (8), glucose (9), xylose (10), mannose (11), fructose (12), melibiose (13), isomaltose (14), gentiobiose (15), cellobiose (16), 50 ppm turanose (17), and maltose (18).

Fig. 3-161. Separation of lanthanides via cation exchange processes. — Separator column IonPac CS3 eluent (A) water, (B) 0.4 mol/L a-hydroxyisobutyric acid gradient linear, 14% B to 70% B in 18 min flow rate 1 mL/min detection see Fig. 3-152 injection volume 50 pL solute concentrations 10 ppm each.

Fig. 6-14. Detection of lanthanides by post-column derivatization with Arsena-zol. - Separator column Nucleosil 10 SA eluent 2-methyllactic acid gradient lineai 0.01 mol/L in 30 min to 0.04 mol/ L detection photometry at 600 nm after reaction with Arsenazo I solute concentrations 10 ppm each of the various lanthanides (taken from [28]).

Figure 6.19 Peak identification by LC-MS, LC-MS-MS, LC-UV and LC-NMR [reproduced with permission from J.L. Wolfender, S. Rodriguez and K. Hostett-mann, J. Chromatogr. A, 794, 299 (1998)]. Chromatogram (vertical) sample, extract from Gentiana ottonis column, 15cm x 3.9mm i.d. and precolumn stationary phase, Nova-Pak Cqg, 4p,m mobile phase, 1 ml min water/acetoni-trile with 0.05%trifluoroacetic acid, gradient from 5 to 65% acetonitrile in 50 min detector, UV 254 nm. MS interface, thermospray instrument, quadrupole. UV diode array. NMR D2O instead of H2O stop-flow 500 MHz. Peak 33 is the glucosylflavone swertisin.

Gradient elution is feasible with modem suppressed conductivity detection. Several aliphatic amines were separated as the protonated amine cations in Fig. 7.3 using a sulfuric acid gradient [5]. The increasing acidity served to reduce the effective exchange capacity of the ion exchanger and thereby speed up elution of the larger monoamines and the diamines. 

---