S.N. Alvi

Monitoring the effluents of the trichloroacetic acid process by high-performance liquid chromatography

Abstract A simple and rapid high-performance liquid chromatographic method for the simultaneous determination of small amounts of nitric acid and trichloroacetic acid in process effluents was developed. Acidic components of the effluents were separated on a reversed-phase C 18 column using 0.15 M ammonium sulphate as mobile phase and determined quantitatively by UV absorption at 210 nm. The detection limits for nitric acid and trichloroacetic acid were 1.4 and 10 μg/l, respectively.

Studies on photoisomerization of 4,4′-diaminostilbene-2,2′-disulphonic acid for quality assurance by high-performance liquid chromatography☆

Abstract Studies on the photoisomerization of 4,4′-diaminostilbene-2,2′-disulphonic acid (DAST) were carried out using controlled light at 350 nm to follow the E to Z isomerization and to develop a simple and rapid stability-indicating assay using high-performance liquid chromatography. Photoisomers and process impurities, viz ., 4,4′-diaminodibenzyl-2,2′-disulphonic acid and 4,4′-dinitrostilbene-2,2′-disulphonic acid, were separated using a reversed-phase C 18 column, an eluent containing aqueous ammonium sulphate and 2-propanol and a variable-wavelength UV spectrophotometric detector at 245 and 338 nm. The method was used for quality assurance and validated using several lots of industrial samples. The mean recovery of DAST from authentic samples was 99.75 ± 1.17%.

Monitoring the products of acetylation, sulphonation and condensation of 2,4-diaminobenzenesulphonic acid by high-performance liquid chromatography

Abstract A simple and rapid high-performance liquid chromatographic method was developed for the separation and determination of 2,4-diaminobenzenesulphonic acid (DASA) in acetylation, sulphonation and condensation products. The separation was achieved on a reversed-phased μBondapak C 18 column using 0.15 M ammonium sulphate—acetonitrile (80:20, v/v) as the eluent. The method was used not only for quality assurance but also for process development of 2,4-DASA and was validated using several industrial samples. The mean recovery of DASA from authentic samples was 99.86 ± 1.54% and the limit of detection was 5·10 −9 g.

Separation and determination of E and Z-isomers of Tamoxifen by ion-pair high-performance liquid chromatography

Abstract A simple and rapid high performance liquid chromatographic method for separation and determination of E and Z-Tamoxifens using μ-Bondapak C18 column with aqueous tetrabutyl ammonium hydrogen sulphate (pH 4.0) containing acetonitrile as mobile solvent has been developed. The separation between E and Z-Tamoxifens has been found to be good with resolution and separation factors of 2.85 and 1.27, respectively. The effect of light on stability of Z-Tamoxifen and its conversion to E-isomer has also been studied.

High-performance liquid chromatographic separation and determination of small amounts of 2-naphthaleneacetic acid in 1-naphthaleneacetic acid☆

Abstract A simple and rapid high-performance liquid chromatographic method was developed for the separation and determination of small amounts of 2-naphthaleneacetic acid in 1-naphthaleneacetic acid. The separation was achieved on a reversed- phased μBondapak CN column using 0.15 M ammonium sulphate-2-propanol (97.5:2.5 v/v) as the eluent. Reaction mixtures collected during the course of condensation of naphthalene with monochloroacetic acid were analysed by the proposed method and the yields of 1-naphthaleneacetic acid were monitored. The limit of detection of 2-naphthaleneacetic acid in a large excess of 1-naphthaleneacetic acid was 3 · 10−9 g.

Quality assurance of petrol by high-performance size-exclusion chromatography

A simple and rapid size-exclusion chromatographic method for the determination of either kerosine or diesel adulteration of petrol has been developed, based on the differences found in the average relative molecular masses of hydrocarbons present in petrol, kerosine and diesel. It is effective for detecting either kerosine or diesel adulteration of petrol down to a level of 1%. The method is ideal for serving as an ‘in-field method’ of analysis for monitoring the quality of petrol by using a portable gel-permeation chromatograph at delivery stations.

Gas chromatographic-mass spectrometric separation, identification and determination of C6-C12 cyclic imides in thermally treated epoxy and alkyd resins to locate hot spots inside large electricity generators

A simple and rapid GC-MS method for separation, identification and quantitative determination of long-chain cyclic imides in the 300 degrees C thermally treated epoxy and alkyd resins has been developed. The method provides a positive means of identifying C6-C12 cyclic imide derivatives by GC-MS and enables the specific area of overheating to be identified, thereby averting catastrophic failures of power generators in service.