HPLC procedure

On considering the solvent consumption and waste generation, it is clear that NIR measurements reduce drastically the amount of CH CN consumed compared with the HPLC procedure. On the other hand, the sample frequency obtained by the NIR methodology was higher than those obtained by HPLC. 

Scott, K. et al.. Interlaboratory studies of HPLC procedures for the analysis of carotenoids in foods. Food Chem., 57, 85, 1996. 

Multi-residue Method 2 Pesticides Analysed with HPLC Procedures, Submethod 1 N-methylcarbamate Pesticides, in Analytical Methods for Pesticide Residues in Foodstuffs, sixth edition. General Inspectorate for Health Protection, Ministry of Public Health, Welfare and Sport, The Hague, pp. 1-10 (1996). 

Thermospray ionisation sources are usually outfitted with a quadrupole or magnetic sector mass spectrometer (including hybrids or tandem forms). Thermospray operation allows a reversed-phase solvent system, e.g. a 50 50 (v/v) water-methanol or acetonitrile mix containing 0.1 M ammonium acetate. This ensures compatibility with the universal HPLC procedures available in many industrial research laboratories. 

C. J. Milano and L. Bailey. Evaluation of current compendial physiochemical test procedures for pharmaceutical elastomeric closures and development of an improved HPLC procedure. J. Parenter. Sci. Technol., 53, 202 (1999). 

Comparing the two different HPLC procedures, the results of Mengerink et al. (2001) are superior since data on the total polymer samples can be obtained. 

Immunoaffinity procedures have also been developed to selectively extract corticosteroids from different sample matrices. Thus, Seymour et al. demonstrated the higher efficiency of the immunoaffinity methods compared with the conventional extraction procedures using organic solvents [177]. Immunosorbents have also been used for online procedures followed by HLPC-UV [178, 179], HPLC-APCI-MS [179,180], GC-MS [176,181], or capillary electrophoresis [182]. Poly(hydroxyethyl methacrylate) (HEMA) was evaluated as a support material for the anti-dexamethasone antibodies used in IAC. The online IAC-HPLC-MS allowed determination of dexamethasone and flumethasone in equine urine with LODs in the range 3-4 ng mL-1 [180]. The cross-reactivity values obtained in the ELISA and the recoveries of an IAC-HPLC procedure are presented in Table 7. Bagnati et al. developed an immunoaffinity extraction... 

RP-HPLC has been employed for the determination of flavonoids and other phenolic compounds in cranberry juice. The neutral and acidic analytes were preconcentrated octadecyl silica SPE cartridges conditioned with distilled water (neutral analytes) or with 0.01 M HC1 (acidic compounds). Hydrolysis of samples was carried out in aqueous methanol solution acidified with 6 M HC1 at 35°C for 16h. Chromatographic separation was performed in an ODS column (150 X 4.6mm i.d. particle size 5/.an). Solvents A and B were water-acetic acid (97 3, v/v) and methanol, respectively. The gradient started with 0 per cent B (flow rate, 0.9 ml/min), reached 10 per cent B in lQmin (flowrate, 1.0 ml/min) and increased to 70 per cent B in 40min (flowrate, 1.0 ml/min). Analytes were detected at 280 and 360 nm. Some typical chromatograms are presented in Fig. 2.71. The concentrations of flavonoids and phenolic acids are compiled in Table 2.69. It was stated that the SPE-HPLC procedure makes possible the simultaneous determination of phenolic compounds and flavonoids, therefore, it can be employed for the measurement of these classes of analytes in other fruit juices [188],... 

Another RP-HPLC procedure was applied for the study of the distribution and stability of steryl chlorin esters in copepod faecal pellets from diatom grazing. Pigments were sonicated for 15 min with acetone at 0°C and the procedure was repeated until the extract became colourless. The organic phase was evaporated and the fraction containing the free alcohols was separated by TLC (silica stationary and dichloromethane mobile phases) and analysed by gas chromatography. RP-HPLC measurements were performed in an ODS... 

The first objective has been accomplished by the development of an HPLC procedure as reported by Spalik et al. ( 5) and GC/NPD procedures developed by Lemley and Zhong ( ). The second and third objectives are being accomplished by fundamental solution studies and reactive ion exchange experiments conducted in parallel. Lemley and Zhong (7) determined recently the solution kinetics data for base hydrolysis of aldicarb and its oxidative metabolites at ppm concentrations and for acid hydrolysis of aldicarb sulfone. They have since ( ) reported similar results for ppb solutions of aldicarb and its metabolites. In addition, the effect on base hydrolysis of temperature and chlorination was studied and the effect of using actual well water as compared to distilled water was determined. Similar base hydrolysis data for carbofuran, methomyl and oxamyl will be presented in this work. 

Direct injection of blood serum (102) or sample extracts with little or no cleanup (53) is possible, which makes HPLC procedures comparable in speed with other rapid tests With increased use of solid-phase absorption in cleanup, automation of procedures is feasible TLC is also a useful and inexpensive technique and quantitative TLC methods have been described (30,63) The following chapter describes practical application of various procedures in a drug residue monitoring program ... 

Recently, CE has been developed for the analysis of drug substances. It is not employed with great frequency for quality control (owing to inherent sensitivity issues), but on occasion, CE procedures can be employed when HPLC procedures have failed to adequately measure the impurities. CE is particularly useful for the separation of closely related compounds such as the diastereomers and enantiomers of compounds with more than one chiral center. Figure 1.8 illustrates the separation of the diastereomers quinine (QN) and quinidine (QD) and some impurities using CE [17]. 

An improved high pressure liquid chromatographic (HPLC) procedure Tor the PSP toxins is described. The method involves separation of the toxins on a polystyrene divinylbenzene resin colunn (Hamilton, PRP-1) in the reversed phase mode using heptane and hexane sulfonic acids as ion-pairing reagents. Detection of the toxins is by fluorescence following post-column alkaline periodate oxidation. The sensitivity of the HPLC method is better than the standard mouse bioassay by at least a factor of four for each of the individual toxins. 

In this case, enthalpic interactions within the HPLC system exceed the exclusion effects (Eigure 16.3b). The retention volumes of polymer species as a rule exponentially increase with their molar masses. The limitations of the resulting procedures were elucidated in Section 16.3 the retention of (high)polymers is usually so large that these do not elute from the column (Section 16.6). Therefore, the majority of enthalpy controlled HPLC procedures is applicable only to oligomers—up to... 

In conclusion, eluent gradient polymer HPLC represents a useful tool for separation of complex polymer system. It belongs to the important constituents of several two-dimensional polymer HPLC procedures. 

Numerous HPLC systems have been reported for the identification and quantitation of corticosteroids, including cortisone. Several selected systems are presented in the following sections, while other HPLC procedures are summarized in Table 9. 

Khalil and Sheiver have determined procaine in pharmaceuticals by a high speed liquid chromatography method [128], Maurich et al. reported the determination of procaine in ear drops by an HPLC procedure [129]. 

The trends among the parameters studied by the UNCA racemization assay have been borne out when other activation methods are used. By a modification of chiral HPLC procedure below, the assay can be used to study any method of activation (for example, uronium or phosphonium methods), keeping in mind that the activation must be rapid and that epimerization by multiple mechanisms becomes possible. These findings also hold for solid-phase synthesis reactions. 

A Zorbax-CN high performance liquid chromatography (HPLC) column used with hexane as mobile phase produced desirable results. Details of the HPLC procedure will be published elsewhere (5.). Three HPLC subfractions of S1-C2 were made ... 

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