Dynamically modified C18 silica monolithic column for the rapid determinations of lead, cadmium and mercury ions by reversed-phase high-performance liquid chromatography.

In this article, a new reversed-phase high-performance liquid chromatography (RP-HPLC) method for the rapid, selective and sequential separation of toxic heavy metal ions namely, Pb2+, Hg2+, and Cd2+ is reported. For this RP-HPLC method, a C18 silica monolith column (Chromolith RP-18e, 100 × 4.6 mm) has been surface modified using a laboratory-synthesized amphiphilic organic ligand namely, 1,5-dioctanoyl-1,5-diphenylcarbazide (DODPC), which acts an ion-selective receptor, for the separation of the target analytes. The eluted metal ions were subjected to post-column derivatization reaction with 4-(2-pyridylazo) resorcinol (PAR) prior to their detection using a UV-vis detector (at 520 nm). The post-column reagent (PAR; 4.7 × 10-4 M; pH 9.0; 1.5 mL/min) was mixed with the column eluate through an ingeniously designed T-connector. An ultra-fast separation of Pb2+, Cd2+, and Hg2+ ions with a retention time of 1.67, 1.88 and 3.62 min, respectively was achieved, using 0.0526 mmol of DODPC coated C18 monolithic column along with tartaric acid solution (1.0 × 10-2 M; pH 4.0; 1.0 mL/min), as the isocratic eluent (mobile phase). The chromatographic parameters such as linearity, accuracy, recovery, limits of detection and quantification were validated to achieve superior analytical results. The influence of various analytical parameters such as nature of mobile phase and its concentration, solution pH, flow rate, post-column reagent and its concentration were studied and optimized. The studies revealed a lower detection limits of 0.075, 0.090 and 0.120 µg/L, and a quantification limits of 0.225, 0.270 and 0.450 µg/L, for Pb2+, Cd2+ and Hg2+ ions, respectively. A linear signal response in the concentration range of 0.05-50.0 µg/mL, was observed for the target metal ions, with an average r2 value of 0.9994. The method was selective for the target metal ions, with excellent data reliability and reproducibility that accounts for an average recovery value of 99.76%, with a relative standard deviation of ≤1.83%.

Sentinel lymphnode biopsy in early breast cancer using methylene blue dye and radioactive sulphur colloid - a single institution Indian experience.

BACKGROUND: Axillary lymph node dissection is an established procedure in breast cancer staging. However, it is associated with unpleasant side effects. A promising alternative to assess axillary lymph node status in early breast cancer patients is Sentinel Lymph Node Biopsy (SLNB). Isosulfan blue has traditionally been the dye used to identify the Sentinel Lymph Node (SLN). This article is a validation study of SLNB using methylene blue dye and radioactive sulphur colloid in early breast cancer Indian patients. MATERIALS #ENTITYSTARTX00026; METHODS: With written informed consent, 100 patients with cytology or biospy proven carcinoma breast, clinical stage T1/ T2 N0 M0, underwent SLNB using combination of methylene blue dye & radioactive technetium 99m sulphur colloid as a part of validation study from June 2003 to February 2006. After validation study, from March 2006 to February 2007, 35 patients have undergone SLNB followed by complete axillary clearance in only those patients with SLNB being positive for metastases. RESULTS: In all 100 patients of the validation study SLN was identified. Total number of cases with positive axillary nodes was 27, out of which SLN was only positive node for metastases in 69% of cases. The overall sensitivity, specificity, positive predictive valve and negative predictive valve of SLNB 96.2%, 100%, 100% and 98.6% respectively with false negative rate of 3.7%. In subsequent 35 patients who underwent SLNB followed by complete axillary clearance, SLNs was identified in all the cases. CONCLUSIONS: SLNB is effective in early breast cancer patients of Indian population. SLNB using combination of methylene blue dye and radio-active Tc99m sulphur colloid can stage the axilla with high accuracy & low risk of false negativity in early breast cancer patients.