NOPR Collection:

Sulphonated lignin based screen ink formulations

2008-04-25T04:30:31Z

Title: Sulphonated lignin based screen ink formulations Authors: Mandavgane, S A; Gogte, B B; Subramanian, D Abstract: An attempt is made to develop a screen ink composition, based on lignin obtained from black liquor as a partial replacement for conventional alkyd resin. Lignin has been used as a replacement for alkyd resin to an extent of 35%. Unlike the conventional alkyd resin, efforts were made to prepare a novel alkyd resin with short oil length (20%) using chain stopper. The overall consumption of petroleum solvent in ink is around 16% which is much lesser than conventional ink which utilizes around 40% solvent. The physicochemical and film properties of ink have been studied and compared with commercial sample. The cost of the present product is less than the conventional product. Page(s): 321-324

Relationship of z-tensile strength with in-plane strength properties of paper

2008-04-25T04:30:30Z

Title: Relationship of z-tensile strength with in-plane strength properties of paper Authors: Singh, S P Abstract: Several methods are available for the measurement of strength of paper in the thickness direction. However, the values obtained from these methods are highly correlated with each other and also with the in-plane strength measurements. The relationship between z-direction tensile strength and in-plane tensile index of handsheets made at varying extents of pulp beating, types of strength aids and doses of strength aids has been studied. It has been noticed that the z-direction tensile strength of paper can be expressed in terms of in-plane tensile index by a single relationship whether the tensile index is changed by refining, or by adding strength aids, or by increasing the dose of the strength aid. In practice, an appropriate value of tensile index may be specified to ensure adequate performance of the paper even when it is subjected to stresses in z-direction. Page(s): 317-320

Quantification of an antiviral drug (stavudine) by three procedures based on redox and complex formation using N-bromosuccinimide

2008-04-25T04:30:30Z

Title: Quantification of an antiviral drug (stavudine) by three procedures based on redox and complex formation using N-bromosuccinimide Authors: Basavaiah, K; Rama Krishna, V; Kumar, U R Anil Abstract: Three simple, sensitive and rapid methods are described for the determination of stavudine (STV) in bulk drug and in formulations using N-bromosuccinimide (NBS) as the oxidimetric reagent. In titrimetry, an aqueous solution of STV is titrated directly in HCl medium with NBS using methyl orange as indicator. Spectrophotometric methods involve the addition of a known excess of NBS to STV in HCl medium followed by estimation of the unreacted oxidant by two reaction schemes involving the use of iron(II) and thiocyanate (method A) or tiron (method B). In all the methods, quantification is based on the amount of NBS reacting with STV. Calculations in titrimetry are based on a 1:2 (STV:NBS) reaction stoichiometry and the method is applicable over 1-9 mg range. In spectrophotometric methods, the absorbance is found to decrease linearly with STV concentration. Beer’s law is obeyed over the ranges 0.5-4.0 and 1.5-18 µg mL⁻¹ for method A and method B, respectively. The calculated molar absorptivity values are 6.5×10⁴ and 1.1×10⁴ L mol⁻¹cm⁻¹ for method A and method B, respectively. The limits of detection (LOD) and quantification (LOQ) are also reported for both methods. The RSD values for intra-day and inter-day precision studies were <2.5 and 3.0%, respectively. The procedures were successfully applied for the determination of STV in pharmaceutical formulations with good recovery, good accuracy and precision, and without measurable interference by the excipients. Page(s): 313-316

Indirect complexometric determination of thallium(III) in its alloys and complexes using thiomalic acid as a selective releasing agent

2008-04-24T04:30:33Z

Title: Indirect complexometric determination of thallium(III) in its alloys and complexes using thiomalic acid as a selective releasing agent Authors: Parameshwara, P; Karthikeyan, J; Shetty, A Nityananda; Shetty, Prakash Abstract: A simple and selective complexometric method for the determination of thallium in presence of other metal ions is proposed on the basis of selective masking ability of thiomalic acid towards thallium(III). Thallium present in a given sample solution is first complexed with a known excess of EDTA and the surplus EDTA is titrated with standard lead nitrate solution at pH 5-6, using xylenol orange as the indicator. A 0.6% aqueous solution of thiomalic acid is then added to displace EDTA from the Tl(III)-EDTA complex. The released EDTA is titrated with standard lead nitrate solution. Reproducible and accurate results are obtained for 3-92 mg of Tl(III) with relative error less than ± 0.17% and coefficient of variation not more than 0.36%. The interference of various ions is studied. This method is used for the analysis of thallium in its synthetic alloy mixtures and also in complexes. Page(s): 308-312