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Analysis of hydrogen peroxide from samples collected from CTD bottles and the ships non-toxic underway supply during cruise AMT16

Originator's Protocol for Data Acquisition and Analysis

This data originates from analyses on samples collected from the noon (trace metal clean) CTD cast and from the ships non-toxic underway supply between 20 May 2005 and 29 May 2005. CTD Water samples were collected taken using Go-Flow bottles and collected in 250 ml, dark glass bottles then analysed within 1 hour. Surface samples were generally analysed within 10 minutes of collection. Surface underway samples were collected over two 24 hour periods into clean containers. All the hydrogen peroxide measurements were made on unfiltered samples.

Hydrogen peroxide was analysed in the range 0 - 180 nM using a flow injection analytical system (see Price et al., 1998). A peristaltic pump (Gilson Minipulse 2) was used to transport a Luminol reagent along with cobalt nitrate (catalyst) and the sample to a Thorn EMI photomultiplier tube (PMT) operating at a potential of 1.2 kV. The chemiluminescent emission (Lmax=440 nm) results from the oxidation of the Luminol which is directly proportional to the hydrogen peroixde concentration. The signals from the PMT were recorded on a char recorder at 0.2 or 0.5 V Full Scale Deflection (FSD). The Luminol, cobalt nitrate hexahydrate and hydrogen peroxide (30%) used were analytical grade.

References Cited

Price, D., Mantoura, R.F.C., Worsfold, P.J. 1998. Shipboard determination of hydrogen peroxide in the western Mediterranean sea using flow injection with chemiluminescence detection. Analytica Chimica Acta 377(2-3), 145-155.

Instrumentation Description

Not applicable for this data set.

BODC Data Processing Procedures

Data were submitted in two Excel spreadsheets (AMT16_perox.xls and AMT16_perox_rec.xls) and archived under BODC's accession number PML050167. The former spreadsheet contained the data (CTD and underway) and was linked to the other file (containing the metadata) using the depth and CTD number. Sample metadata (CTD cast, bottle number and depth) were checked against information held in the database and the central navigation log.

There were no discrepancies for the underway data. There were several discrepancies in the depth-rosette bottle number combinations between the Sea-Bird CTD log sheets and the originators data file. Samples were loaded against bottles fired at the depths that matched the originators depths. The discrepancies we due to typos in the rosette position or bottles being fired out of sequence and the firing number being provided instead of the rosette position in the data originator's file.

The average and standard deviation of the samples with repeat measurements were loaded. Underway samples were loaded with a depth of 5 m according to the cruise report.

The data originator provided hydrogen peroxide concentration data in nanomoles per litre. These units were consistent with the BODC parameter code units, so no conversion was applied.

The data were reformatted and loaded in BODC's samples database under Oracle Relational Database Management System. Data were marked up with BODC parameter codes and loaded into the database.

A parameter mapping table is provided below;

Data Quality Report

BODC was not advised of any specific quality issues with the data. No values were flagged by BODC.

Problem Report

Not relevant to this data set.