M. Zafar Iqbal

Simultaneous determination of nitrite and nitrate by normal phase ion-pair liquid chromatography

Normal phase ion-pair high performance liquid chromatography has been used for simultaneous separation of nitrite and nitrate using tetraethylammonium (TEA)(+) as ion-pairing reagent. The concentration effect of (TEA)(+), buffer salt and pH of the eluent on separation is investigated. The UV detector response at various wavelengths has been optimized. The performance of the proposed method is compared with ion chromatography for quantification of the anions in potable water, wastewater and in food samples, such as spinach and lettuce.

Water retention and adhesion of powdered and aqueous polymer-modified mortars

Abstract This paper evaluates and compares the water retention in the fresh state and adhesion or bond strength in the hardened state of powdered and aqueous polymer-modified mortars. The polymer-modified mortars using various powdered and aqueous cement modifiers were prepared with different polymer-cement ratios, and tested for water retention in the fresh state and adhesion in tension in the hardened state. In conclusion, the powdered as well as aqueous polymer-modified mortars show markedly improved water retention and adhesion in tension, which increase with a rise in the polymer-cement ratio regardless of the type of cement modifiers used. The magnitude of improvement in the water retention and adhesion in tension of the powdered and aqueous polymer-modified mortars, however, depends upon the type of cement modifiers used, polymer-cement ratios or both. Moreover, the failure mode distribution of the powdered and aqueous polymer-modified mortars depends on the type of cement modifiers used, polymer-cement ratio, or both.

Three New Steroidal Amines from Sarcococca saligna

Abstract Sarcococca saligna (Buxaceae) has yielded three new steroidal amines. E-salignone (1), Z-salignone (2) and N a-demethylsaracodine (3). The proposed structures of these alkamines are based on spectroscopic studies.

Steroidal alkaloids from Sarcococca saligna

Abstract In addition to epipachysandrine-A and saracocine, two new steroidal alkaloids, sarconidine and sarcorine were isolated from the aerial parts of Sarcococca saligna. Their structures were established as (20S)-20-dimethylamino-3β-methylamino-pregnane-5,16-diene and (20S)-3β-acetylamino-20-dimethylamino-5α-pregnane, respectively, by detailed spectroscopic studies.

Determination of Br, Rb, Cs, Sc and Na in various plant leaves located in an urban park by neutron activation analysis

In order to determine the effect of airborne emission of trace elements, e.g. Br, Rb Cs, Sc and Na on roadside ecosystem, concentrations were determined in different species of plants from an urban park at Lahore. For monitoring purpose attention was paid to the leaves ofSapindus mukorossis, Alstonia scholaris andDiospyros embryopteris. Different varieties of tissues were found to have different concentration of trace elements when compared among themselves. The concentration of trace element deposition was compared with the values reported in literature. Significant pollution was observed.

Determination of Hg, Co, Cr, Zn and Fe in various plant leaves using neutron-activation analysis.

Neutron-activation analysis /NAA/ was used for the estimation of Hg, Co, Cr, Zn and Fe in leaves of various plants namelySapindus mukorossis, Alstonia scholaris andDiospyros embryopteris located in urban areas of Punjab, Pakistan. Different varities of tissues were found to have different concentration of trace elements when compared among themselves. Significant pollution has been observed.

Development of ELISA technique for the analysis of atrazine residues in water

A highly sensitive enzyme immunoassay is described for the detection of atrazine residues in water. Atrazine derivative was conjugated to Bovine Serum Albumin (BSA) to obtain an immunizing antigen and to Horseradish Peroxidase enzyme (POD) to obtain a marker for immunoassay. The formation of these conjugations was confirmed by UV spectroscopy as well as by gel-electrophoresis. Polyclonal antibodies were raised in rabbits by immunization with an atrazine–BSA conjugate containing 29 atrazine residues per BSA molecule. An ELISA on microtitration plates was optimized with peroxidase–atrazine conjugate. The middle of the test (50% B/Bo) was found to be at 90 ng/l, which is well below the maximum concentration permitted by the EC guidelines for drinking water. Detection limits for atrazine of about 1 ng/l could be reached. The assay did not require concentration or cleanup steps for drinking or ground water samples. Validation experiments showed good accuracy and precision. No cross-reactivities were shown by other s-triazines like terbutryn, ametryn, terbuthylazine, des-isopropylatrazine, and de-ethylatrazine except hydroxyatrazine. The latter was present at very low levels that can be calibrated/standardized before analysis or it may be considered as leftover residues of atrazine. Based on these results, it is suggested that this test can be applied to obtain fairly accurate results for atrazine concentration in water samples from different sources.

Neutron activation analysis of Ce, Yb, Se and Cr in the atmosphere of some major urban and industrial areas of Punjab, Pakistan

The determination of Ce, Yb, Se and Cr has been carried out in the atmosphere of Lahore, Faisalabad, Rawalpindi, Islamabad, Wah Cantt and Khanispur (background area) by INAA. Ce and Cr are associated with anthropogenic activities, while Yb is mainly due to soil derived aerosols. Se represents both anthropogenic as well as soil derived aerosols.

Longitudinal distribution of trace elements in the atmosphere of an industrial area from neutron activation analysis

Industrial units play a significant role in atmospheric pollution. Industrial exhausts deteriorate the atmospheric quality causing unhygienic environment for the people working in the vicinity. This work presents a study of the longitudinal distribution of trace elements of the Sheikhupura industrial area. Three kinds of distribution patterns were observed and are discussed in detail. The results are based on the neutron activation analysis of 16 trace elements.

AAS Determination of Lead and Cadmium in Leaves Polluted by Vehicle Exhaust

Abstract The determination of Pb and Cd in three different kinds of biological tissues, namely Sapindus mukorossis, Alstonia scholaris and Diospyros embryopteris collected from a national city park were carried out using atomic absorption spectrophotometry. The various tissues contain different concentrations of Pb and Cd. This phenomenon and changes in concentration with the distance to the sampling sites are discussed and compared with values reported in literature. Significant pollution is mainly due to vehicle exhaust.