Optimization of an automated FI-FT-IR procedure for the determination of o-xylene, toluene and ethyl benzene in n-hexane

The development and optimization of an automated flow injection (FI) manifold coupled with a Fourier transform infrared (FT-IR) detector for the determination of toluene, ethyl benzene and o-xylene in an n-hexane matrix is described. FT-IR parameters optimized were resolution and number of co-added scans; FI parameters optimized were type of pump tubing, carrier flow rate and sample volume. ATR and transmission flow cells were compared for the determination of o-xylene, the ATR cell was easier to use and gave better figures of merit, except for sensitivity, for which the transmission cell was twice as good. Multivariate calibration routines were applied to the FI-FT-IR data and the PLS1 algorithm gave relative root mean standard errors of crossvalidation (RRMSECVs) < 7% for all three analytes using mean-centred data and the first derivative for o-xylene

Performance characteristics of a low-cost, field-deployable miniature CCD spectrometer

Miniature spectrometers incorporating array detectors are becoming a viable, low-cost option for field and process deployments. The performance characteristics of one such instrument are reported and compared with those of a conventional benchtop instrument. The parameters investigated were wavelength repeatability, photometric linearity, instrumental noise (photometric precision) and instrumental drift

A submersible battery-powered flow injection (FI) sensor for the determination of nitrate in estuarine and coastal waters

The design, construction and performance of a remotely deployed submersible flow injection-based nutrient (total oxidized nitrogen) sensor are described. The sensor featured a custom-built microcomputer and a solid-state, flow-through spectrophotometric detector, and the derivatization chemistry was based on in-line coppercadmium reduction of nitrate to nitrite, and diazotization with N1NED and sulphanilamide. The limit of detection was 0.0014 mg l-1 NO3-N and the linear range was 0.0014- 0.77 mg l-1 with a 260 μl sample volume and a 20 mm path length flow cell. Results from submersed deployments in the Tamar estuary and North Sea are also reported

ACUTE EFFECT OF TEXTURED INSOLES ON BIOMECHANICS OF MAXIMAL CYCLING

The aim of the study was to investigate whether a within-session intervention of textured insoles worn in participants cycling shoes altered maximal cycling power output and biomechanics. Ten track sprint cyclists performed sprints on an isokinetic ergometer with and without textured insoles. Key biomechanical variables (crank kinetics, joint kinematics and kinetics) characterising sprint cycling were measured. There was a significant reduction in average crank power for the sprints performed with the textured insoles (P = 0.029) potentially associated with the reported discomfort when using the textured insoles. There were no changes in any other biomechanical measures suggesting a textured insoles intervention may have little impact on maximal cycling performance

Analytical Intercomparison Between Flow Injection-Chemiluminescence and Flow Injection-Spectrophotometry for the Determination of Picomolar Concentrations of Iron in Seawater

A lab- and ship-based analytical intercomparison of two flow injection methods for the determination of iron in seawater was conducted, using three different sets of seawater samples collected from the Southern Ocean and South Atlantic. In one exercise, iron was determined in three different size-fractions (\u3c 0.03 &μm, \u3c 0.4 μm, and unfiltered) in an effort to better characterize the operational nature of each analytical technique with respect to filter size. Measured Fe concentrations were in the range 0.19 to 1.19 nM using flow injection with luminol chemiluminescence detection (FI-CL), and 0.07 to 1.54 nM using flow injection with catalytic spectrophotometric detection with N, N-dimethyl-p-phenylenediamine dihydrochloride (FI-DPD). The arithmetic mean for the FI-CL method was higher (by 0.09 nM) than the FI-DPD method for dissolved (\u3c 0.4 μm) Fe, a difference that is comparable to the analytical blanks, which were as high as 0.13 nM ( CL) and 0.09 nM (DPD). There was generally good agreement between the FI-CL determinations for the \u3c 0.03 μm size fraction and the FI-DPD determinations for the \u3c 0.4 μm size fraction in freshly collected samples. Differences in total-dissolvable ( unfiltered) Fe concentrations determined by the two FI methods were more variable, reflecting the added complexity associated with the analysis of partially digested particulate material in these samples. Overall, however, the FI-CL determinations were significantly (P = 0.05) lower than the FI-DPD determinations for the unfiltered samples. Our results suggest that the observed, systematic inter-method differences reflect measurement of different physicochemical fractions of Fe present in seawater, such that colloidal and/or organic iron species are better determined by the FI-CL method than the FI-DPD method. This idea is supported by our observation that inter-method differences were largest for freshly collected acidified seawater, which suggests extended storage (\u3e6 months) of acidified samples as a possible protocol for the determination of dissolved iron in seawater

High temporal resolution field monitoring of phosphate in the River Frome using flow injection with diode array detection

Abstract The design and deployment of an in situ flow injection (FI) monitor for high temporal resolution monitoring of phosphate in the River Frome, Dorset, UK, is described. The monitor incorporates solenoid, self-priming micropumps for propulsion, solenoid-operated switching valves for controlling the fluidics and a miniature CCD spectrometer for full spectrum (200-1000 nm) acquisition and operates in a graphical programming environment. A tangential filtration unit is attached to the sample inlet line to remove suspended particulate matter and prevent blockage of the micropumps and valves. Detection (at 710 nm) is based on molybdenum blue chemistry with tin(II) chloride reduction. The detection limit is 0.67 M PO 4 and the linear range can be adjusted by using different wavelengths for detection. Pump noise is eliminated by subtraction of the signal at a non-absorbing wavelength (447 nm). Data from an intensive (sample every 30 min) field trial on the River Frome performed in October 2000 are presented, and the implications of the data for refining an export coefficient model for phosphorus from the catchment are discussed

A three-season comparison of match performances among selected and unselected elite youth rugby league players

This is an author's accepted manuscript of an article published in Journal of Sports Sciences, 28 February 2014, available online: http:www.tandfonline.com/10.1080/02640414.2014.889838This study compared technical actions, movements, heart rates and perceptual responses of selected and unselected youth rugby league players during matches (under-15 to under-17). The players’ movements and heart rates were assessed using 5 Hz Global Positioning Systems (GPS), while their technical actions were analysed using video analysis. The maturity of each player was predicted before each season for statistical control. There were no differences (P > 0.05) between selected and unselected players in the under-15 or the under-17 age groups for any variables. However, in the under-16 group, the selected players (57.1 ± 11.9 min) played for longer than the unselected players (44.1 ± 12.3 min; P = 0.017; ES = 1.08 ± CI = 0.87), and covered more distance (5,181.0 ± 1063.5 m cf. 3942.6 ± 1,108.6m, respectively; P = 0.012; ES = 1.14 ± CI = 0.88) and high intensity distance (1,808.8 ± 369.3 m cf. 1,380.5 ± 367.7 m, respectively; P = 0.011; ES = 1.16 ± CI = 0.88). Although successful carries per minute was higher in the selected under-15 group, there were no other differences (P > 0.05) in match performance relative to playing minutes between groups. Controlling for maturity, the less mature, unselected players from the under-16 group performed more high-intensity running (P < 0.05). Our findings question the use of match- related measurements in differentiating between selected and unselected players, showing that later maturing players were unselected, even when performing greater high-intensity running during matches