Cyano columns

The preseparation utilized a 5 pim cyano column (250 cm X 4.6 mm i.d.) and a 5 p.m silica column (250 cm X 4.6 mm i.d.) in series, followed by GC analysis on an SE-54 column (25 m X 0.2 mm i.d., 0.33 p.m film thickness). The SFC system separated the aviation sample into two peaks, including saturates and single-ring aromatics as the first peak, and two-ring aromatic fractions as the second peak. These fractions were selectively cut and then transferred to the GC unit for further analysis. (Figure 12.20). 

Monomeric HALS have been determined by HPLC [470,663]. Excellent separation was achieved for HALS-type samples (Tinuvin 770 and Chimassorb 944) with NPLC-PDA (230 nm) using an amino column with acetonitrile/water as the mobile phase RPLC using C or cyano columns was not effective [664]. 

High performance liquid chromatography-mass spectrometric methods Nitin et al. [75] developed and validated a sensitive and selective liquid chromatography-tandem mass spectrometric method (LC MS MS) for the simultaneous estimation of bulaquine and its metabolites primaquine in monkey plasma. The mobile phase consisted of acetonitrile ammonium acetate buffer (20 mM, pH 6) (50 50, v/v) at a flow rate of 1 mL/min. The chromatographic separations were achieved on two Spheri cyano columns (5 pm, 30 cm x 4.6 mm), connected in... 

Parkhurst et al. [79] described a high performance liquid chromatographic method for the simultaneous determination of primaquine and its metabolites from plasma and urine samples, utilizing acetonitrile deproteinization, and direct injection onto a cyano column. Levels of 100 ng/mL per 20 pL injection could be quantitated. Preliminary pharmacokinetic analysis is reported for two human subjects after oral doses of 60 90 mg primaquine diphosphate. Two apparent plasma metabolites and two possible urinary metabolites are also reported. 

Multitarget forensic applications of HPLC for other drug classes are also available in the literature. Josefsson et al. [77] applied HPLC-MS-MS to the determination of 19 neuroleptics and their major metabolites in human tissues and body fluids. Optimal separation was achieved using a cyano column within a 9 min gradient run. Detection was curried out in SRM reaching LQDs down to the lower ng/mL level, although more than a 10-fold difference in signal response was observed between analytes. The method was subjected to partial validation only. 

Soup, oyster sauce, RP-HPLC (cyano column), conductometric determination 231... 

When I make a diagram of column polarities versus solvent polarities, I tend to think of the columns as being a continuous series of increasing polarity from Cis to silica C18, phenyl, C8, cyano, C3, diol, amino, and silica (Fig. 5.5). Under that, I have their solvents in opposite order of polarity from hexane under Ci8 to water under silica hexane, benzene, methylene chloride, chloroform, THF, acetonitrile, i-PrOH, MeOH, and water. The cyano column and THF are about equivalent polarity. In setting up a separation system, we cross over nonpolar columns require polar mobile phase and vice versa to achieve a polarity difference. 

How do you make the decision when to choose a reverse-phase instead of a normal-phase column or an intermediate-phase column such as a cyano column Reversed-phase columns are chosen about 70% of the time, so most compounds can be separated by this partition mode. What in the make-up of the compound being separated selects one column over the other ... 

Figure 2 The chromatographic system used for the pharmacokinetic study of the enantiomers of mefloquine (MFQ), where A = system configuration used to direct the column eluent containing MFQ on the silica precolumn after separation from metabolites and other interfering compounds, and B = system configuration used to determine total MFQ concentrations on the achiral cyano column before switching and the enantiomeric composition of MFQ on the naphthylurea CSP after switching. [From Gimenez (38).]...

More recent developments in the TDM of immunosuppressive drags comprise of optimization of LC conditions [21-22]. Hatsis and Volmer [22] evaluated the use of a cyano column (see also [17]) instead of the commonly applied Cjg column, as the... 

Fig. 2 Effect of stationary phase Pressure 25 MPa, temperature 50°C, mobile phase carbon dioxide-ethanol with 0.5% phosphoric acid 90 10, flowrate 1.05 mL/min, stationary phase a) cyano column, b) phenyl column.

Basic solutes such as amines, ethers, esters, and ketones are preferentially retained on amino and diol columns when compared to cyano columns [14,15]. The amino phase is a good alternative to the cyano column for a change in selectivity. When analyzing ketones and aldehydes, the aminopropyl phase should be carefully used due to the possible reactivity of the amino group with these substances. This may lead to the formation of imines and the bonded phase maybe easily oxidized [13],... 

The cyano column may be used in the normal- or re-versed-phase mode and can be regarded as the first column of choice for method development when both modes are under consideration. Typically, it is prepared from mono-, di-, or trifunctional silane. A more... 

Dipolar compounds such as those with chloro, nitro, and nitrile substituents are more strongly retained on cyano columns, compared to amino or diol [14]. Also, cyanopropyl silica can exhibit acidic or basic character, depending on the mobile phase used. It was shown that a complete reversal of elution order was obtained for phenol and anihne when MTBE and chloroform were used as the mobile phases, because phenol eluted first in the MTBE solvent and second in the chloroform solvent [9],... 

If development as outlined meets the initial goal of separating the compounds, it is tempting to assume that method development is complete at this juncture. However, although both the column chemistry and the mobile phase have been selected, further optimization of column length, particle size, and flow rate is warranted (see Section III.E.b). If the separation provides the requisite k range, but does not adequately separate all components, the approach may be repeated using additional column types (phenyl or cyano columns). 

To change selectivity based on the strong solvent, isopropanol may be replaced with methylene chloride, methyl t-butyl ether, or ethyl acetate (separate k optimization is required). However, note should be made of the relatively high UV cutoffs of these solvents when UV detection is to be used. As an alternative to cyano columns, diol columns may be investigated as before. Other stationary phases are also available, but generally provide poorer stability. Triethylamine or acetic acid may be added to the mobile phases to curtail tailing problems. 

Perhaps 90% of all rHPLC separations use a Cig stationary phase. In SFC, there is a much wider choice. The vast majority of SFC separations have been performed on totally porous silica, usually with a bonded organic phase. A full range of achiral stationary phases is available for use in SFC. The most common are silica, cyano, amino, and diol. Several relatively new phases, such as an ethyl pyridine phase, promise to decrease the need for additives in the mobile phase. Almost everything elutes from cyano columns. Diol and bare silica often give the best selectivity for acids and alcohols. Amino is often more retentive but also often yields the best selectivity for amines. Although any of these columns is likely to give a reasonable separation, the use of an automated column selection valve, along with a solvent selection valve, makes it easy to find the one with the best selectivity for a specific application. 

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