Search

A high-throughput, sensitive and rapid method was developed for the determination of Zn, Cu and Fe in small volumes (30 μL) of human serum using inductively coupled plasma mass spectrometry (ICP-MS). The sample preparation procedure employed simple 100-fold dilution of the serum samples with 1.0% butanol, 0.5% v/v ammonia, 0.02% v/v Triton X-100 and 0.01% v/v HNO 3. The reliability of the method was evaluated using serum UTAK certified reference material, and the results matched well with the certified values. The method was applied to determine Zn, Cu and Fe in 81 human serum samples from participants in Alzheimer disease (AD) and age-related macular degeneration (AMD) studies. No significant differences were found in Zn and Cu levels between age matched controls, AD and AMD patients. Whilst iron levels appeared marginally higher in the AMD group, compared with the AD group, iron showed larger overall variability than the other two elements. Image 1 • Zn, Cu and Fe were determined in as little as 30μL serum from AD and AMD patients for the first time. • Micro-sampling (30 μL) provided a method readily amenable to automated analysis. • Preparation of serum with Ammonia-Triton X-100-HNO3 provides a stable solution for ICP-MS sample introduction. • Serum UTAK CRM was used for method validation and was more reliable than Seronorm™. • Data from patients with AD/AMD conditions have been compared. [ABSTRACT FROM AUTHOR]

Highlights: [•] Selective and sensitive label for the identification of phosphopeptides. [•] Selective detection of phosphopeptide by LC–ICP-MS after Ga tagging. [•] Experimental and theoretical characterisation of Ga–phosphopeptide complex. [•] Elucidation of energetically favoured structures Ga–phosphopeptide complex. [•] Insight into differential binding of phosphorylated molecules to metals. [Copyright &y& Elsevier]

Abstract: This paper describes methodologies, based on sector field inductively-coupled plasma mass spectrometry (SF-ICP-MS), and their application in the holistic study of the fate of Pt in human cell populations following treatment with cis- or oxaliplatin and combination treatments. Pt–DNA adduct formation data at several time points has been determined in the leukocytes from patients undergoing Pt-based chemotherapy demonstrating significant inter-patient variability and excellent reproducibility of the assay. The sensitivity of the technique enabled quantitation of as little as 0.2 Pt adducts per 106 nucleotides using 10μg of patient DNA. Further, the first ever reported in vivo sub-cellular Pt fractionation data on a patient sample is presented indicating the feasibility of applying the methods presented here in a clinical environment. For in vitro studies, three cell models were used: A549 human lung adenocarcinoma epithelial cells were exposed to 50μM cisplatin for 1h; HCA7 human colorectal cancer cells were treated with either FOLFOX (200μM 5-fluorouracil, 200μM folinic acid and 50μM oxaliplatin) or 50μM oxaliplatin; and HT29 human colorectal cancer cells were treated with 50μM oxaliplatin in combination with 20μM methaneseleninic acid, CH3SeO2H (MSA). The cells were harvested and either the DNA extracted and/or a commercially available kit used to fractionate the treated cells into four sub-cellular compartments. Each of the sub-cellular fractions and extracted DNA were digested separately, evaporated to dryness and reconstituted in 2% nitric acid for analysis by SF-ICP-MS. The sub-cellular Pt distribution for cisplatin treated A549 cells was shown to be as follows: ∼70% localized in the cytosol, ∼17% in the membrane and membrane localized fraction, ∼9% in the nuclear fraction and ∼4% in the cytoskeletal fraction. Both FOLFOX and oxaliplatin treated HCA7 cells showed comparable sub-cellular Pt distributions, and Pt–DNA adduct formation was similar for the oxaliplatin and FOLFOX treatments with adduct yields of 5.6 and 5.5 adducts per 106 nucleotides respectively. It was found that the combination of oxaliplatin with 20μM MSA did not change the distribution of Pt or significantly alter its accumulation in the cytosol of the HT29 cells. Mass balance experiments showed a >99% recovery of the total Pt in the sub-cellular fractions. These experiments are the first to provide such a detailed quantitation of Pt-drug partitioning and they show that the Pt broadly follows the total protein content of the individual compartments with the majority being scavenged in the cytosol compartment. [Copyright &y& Elsevier]

Abstract: A reliable method for the determination of iodine and molybdenum in milk samples, using alkaline digestion with tetramethylammonium hydroxide and hydrogen peroxide, followed by quadrupole ICP-MS analysis, has been developed and tested using certified reference materials. The use of He+O2 (1.0mlmin−1 and 0.6mlmin−1) in the collision-reaction cell of the mass spectrometer to remove 129Xe+ – initially to enable the determination of low levels of 129I – also resulted in the quantitative conversion of Mo+ to MoO2 + which enabled the molybdenum in the milk to be determined at similar mass to the iodine with the use of Sb as a common internal standard. In order to separate and pre-concentrate iodine at sub μgl−1 concentrations, a novel method was developed using a cation-exchange column loaded with Pd2+ and Ca2+ ions to selectively retain iodide followed by elution with a small volume of ammonium thiosulfate. This method showed excellent results for aqueous iodide solutions, although the complex milk digest matrix made the method unsuitable for such samples. An investigation of the iodine species formed during oxidation and extraction of milk sample digests was carried out with a view to controlling the iodine chemistry. [Copyright &y& Elsevier]