Determination of perfluorooctanoate and perfluorooctanesulfonate in water matrices by inline matrix elimination liquid chromatography with reversed phase separation and suppressed conductivity detection.

This work describes a new method for the determination of perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) in water matrices by suppressed conductivity detection. Separation was achieved by isocratic elution on a reversed-phase column thermostated at 45°C using an aqueous mobile phase containing boric acid and acetonitrile. The PFOA and PFOS content in the water matrix were quantified by a pre-concentration technique. For the concentration range of 1 to 15 ng/mL and 2 to 30 ng/mL, the linear calibration curve for PFOA and PFOS yielded coefficients of determination (R(2)) of 0.9995 and 0.9985, respectively. The relative standard deviations were smaller than 1.5% for PFOA and PFOS. The retention-time precision of four consecutive 12 h injections was smaller than 0.641% and 0.818%, respectively. The presence of common divalent cations, such as calcium, magnesium, and iron in water matrices impairs PFOS recovery. This drawback was overcome by applying inline matrix elimination method. The optimized method was successfully applied for drinking water, ground water, and seawater samples.

Simultaneous determination of arsenite and arsenate in arsenic trioxide injection by dual detection ion chromatography.

This paper describes a rapid method to determine arsenite assay and arsenate impurity in Arsenic Trioxide Injection using a single conductivity detector. The arsenite assay was determined in a non-suppressed conductivity detection mode and arsenate impurity was quantified in a suppressed conductivity detection mode. Dual-conductivity detections were enabled by valve switching and time programming. The method was validated with respect to specificity, linearity, precision, accuracy, stability, and limit of quantification. The limit of detection and quantification for arsenite were 0.855 mg/L and 2.593 mg/L, and 0.044 mg/L and 0.133 mg/L for arsenate, respectively.

Matrix elimination ion chromatography method for trace level azide determination in irbesartan drug.

Ultra-trace analysis of azide in complicated Irbesartan sample matrix is achieved by the in-line sample preparation technique. Sodium azide is the precursor of Irbesartan, which is used as an anti-hypertensive drug. Due to the toxic nature of sodium azide, reliable determination of azide in Irbesartan is necessary. Irbesartan when analyzed for sodium azide, as per the USP 31-NF26 method, gets adsorbed to the analytical column, leading to reduction in column capacity and irreproducible retention time. The retained drug has to be removed with special rinsing solution, followed by re-equilibration with the mobile phase. This process takes at least 3 to 4 h for each sample analysis. The new method developed overcomes the limitations of the USP 31-NF26 method. This method is validated for specificity, linearity, accuracy, precision, sample solution stability, and robustness as per International Conference on Harmonization guidelines. The relationship between peak response and concentration is found to be linear between 5 to 80 ng/mL of sodium azide, with the correlation coefficient (r(2)) of 0.9995. The limits of detection and quantification for sodium azide are 0.532 and 1.61 microg/gm with respect to the sample weight.

Ion chromatographic determination of residual phase transfer catalyst in active pharmaceutical ingredient.

A new ion chromatography method with non-suppressed conductivity detection has been developed for the quantification of residual phase transfer catalyst-tetrabutylammonium bromide (TBAB) in an active pharmaceutical drug, Levetiracetam. Separation conditions are optimized to get a clear separation of TBAB from drug impurities using a Metrosep Cation C2-150 column. Conditions are also optimized to separate tetramethylammonium bromide, tetraethylammonium bromide, and tetrapropylammonium bromide, which are also used as phase transfer catalysts in several syntheses. Method performance was checked for selectivity, linearity, limit of quantification, limit of detection, accuracy, and precision. The method has superior performance with linearity r(2) > or = 0.9999, recovery from 94.7% to 96.5%, precision < or = 0.74%. In-line preconcentration is used to achieve limits of detection and quantification of 39 ng and 118 ng of TBAB, which corresponds to 1.56 and 4.72 microg/g of TBAB with respect to sample weight. The proposed method can be used for routine quality assurance analysis in the pharmaceutical industry.

An improved ion chromatographic method for fast and sensitive determination of N-methylpyrrolidine in cefepime hydrochloride.

An alternative ion chromatographic method to the existing USP method for the determination of N-methylpyrrolidine (NMP) in cefepime hydrochloride is developed. The cefepime in solution behaves as a strong cation and gets retained in the analytical column, leading to reduction in column capacity and irreproducible retention time. The retained drug has to be removed with a special rinsing solution, followed by re-equilibration with the mobile phase. This process takes at least 3 to 4 h time for sample analysis. We used a silica-based cation exchange column with poly-butadiene-maleic acid functional group attached with an optimized mobile phase composition. The characteristic feature of this method is the short analysis time with a clear separation of NMP and the cationic drug molecule within a run-time of 30 min. The developed method overcomes the limitations of the USP method. This method describes the matrix elimination by choosing appropriate column and eluent condition. The method is tested for selectivity, linearity, limits of detection and quantification, accuracy, and precision and is suitable for continuous sample analysis.

Rapid, one-pot derivatization and distillation of chlorophenols from solid samples with their on-line enrichment.

A microwave-assisted steam distillation (MASD) sample preparation technique for extracting chlorophenols from solid samples was studied. This open vessel microwave system based study developed as an integrated method since it has incorporated extractive distillation, derivatization and on-line enrichment. Gas chromatography (GC) with electron-capture detection was used for the analysis. The study involved optimization of MASD parameters and on-line enrichments using spiked solid samples. MASD achieved recoveries for spiked soil samples in the range of 94-101% within 20min with a collection of only 20ml distillate facilitating on-line enrichment. Some real samples were analyzed that included soil, wood, leather, textiles, dyes and certified reference materials of soil and wood samples. Limit of detection values of 12ng/g for pentachlorophenol and 194ng/g for monochlorophenol were found. Recoveries of 96.6% in the case of soil certified reference material (CRM) with RSD 2.7% and 80.6% in the case of wood CRM with RSD 3.3% were observed in this study. MASD studied found to produce very clean extracts in comparison to reference techniques.

Focused microwave aqueous extraction of chlorophenols from solid matrices and their analysis by chromatographic techniques.

Open-vessel focused microwave (FMW) extraction with a purely aqueous carbonate solution was used for the extraction of chlorophenols from various solid matrices. After SPE on C18-bonded silica, the analytes were determined as such by LC-UV or, as their acetyl derivatives, by GC-ECD. The FMW aqueous extraction is efficient and rapid and no organic solvents are used. PCP was detected in several solid samples, with recoveries of 101-115% (RSD, 2-4%) relative to Soxhlet extraction. Similar recoveries were obtained for the other chlorophenols for spiked samples.

Analyses of carcinogenic aromatic amines released from harmful azo colorants by Streptomyces SP. SS07.

Extracellular fluid protein (ECFP) of Streptomyces species SS07 has been used to reduce water soluble azo dyes and the carcinogenic amines released have been compared with that from chemical reduction. The effect of temperature, pH and contact time on the recovery of amines using ECFP was studied. The ECFP releases carcinogenic amines at a pH of 9.2 and a temperature of 37 degrees C for a contact period of 24 h. The reduction products were analyzed with HPLC and their structures confirmed by LC-MS and GC-MS. It was observed that both the ECFP and chemical reduction methods released similar type of amine products. In the case of dye samples, compared to chemical reduction, 5-20% increase in the release of carcinogenic amines by ECFP was observed. The percentage of amine products released by chemical reduction was higher for leather garment samples compared to ECFP treatment.

Determination of hexavalent chromium by on-line dialysis ion chromatography in a matrix of strong colourants and trivalent chromium.

Hexavalent chromium detection in the presence of a high load of colourants without any false positive and in-procedure oxidation of Cr(III) is an important area of study. Colourants are a class of interfering substances in many spectroscopic analyses and chromatographic separations and detection. A purification method using an on-line dialysis technique for ion chromatography (IC) has been developed to remove water-soluble anionic dyes and particulate colourants and other substances to facilitate Cr(VI) quantification and the method is discussed. The dialysis was optimized with Cr(VI) standard solutions for quantification. The efficacy of the procedure for the removal of anionic dyes and detection of Cr(VI) was checked with a Cr(VI) spiked synthetic preparation containing a water-soluble dye and trivalent chromium. Soluble Cr(VI) extracted with organic dyes from environmental samples was analyzed. The method has a detection limit of 5 microg/l, recovery rate of 100% and analysis time less than 20 min.

Analysis of arylamine isomers by micellar electrokinetic chromatography.

Analysis of carcinogenic substances is a high-priority area. Carcinogenic arylamines draw the analyst's attention because dyes and pigments are in production and used in large volumes. Identification of carcinogenic isomers of arylamines employing micellar electrokinetic chromatography (MEKC), a mode of capillary electrophoresis was studied as it offers better scope for separation science. Mixed micellar modes of MEKC techniques were employed to achieve acceptable analyses. Success of this analytical method was proved by real-sample analysis, which confirmed that this is a promising technique for the arylamine species.