UK P&I CLUB Carefully to Carry - agmarltd.de

1 UK P&I CLUB. Carefully to Carry SEPTEMBER 2006. The silver nitrate test A solution of silver nitrate in distilled water is regularly used as a simple test for the The carrier detection of seawater contamination of shall properly and Carefully ships' cargoes. Whilst the test is a useful load, handle, preliminary test for saline contamination it stow, Carry , should be considered as indicative only. It keep, care for and discharge has limitations and should not be relied on the goods as definitive proof of saltwater carried.. contamination; more detailed laboratory Hague Rules, analysis will be required to confirm Articles iii, Rule 2. reaction is shown below: This reaction results in the clear test Carefully to Carry solution turning a cloudy white as insoluble Advisory Committee silver chloride is displaced out of the solution.

2 This report was produced by the Carefully to Carry Committee the UK P&I Club's advisory committee on cargo matters. silver nitrate + Sodium chloride (salt) . Sodium nitrate + silver chloride The aim of the Carefully to Carry (clear solution) (contamination) (clear solution) (insoluble Committee is to reduce claims through white precipitate) contemporaneous advice to the Club's Members through the most efficient means available. In order to undertake a spot' test in situ, surveyors will normally Carry a The committee was established in 1961. small dropping/pipette bottle containing acidified silver nitrate solution. A and has produced many articles on few drops of the solution should be dropped onto both the suspected cargoes that cause claims and other cargo contaminated and apparently uncontaminated areas of the subject cargo.

3 Related issues such as hold washing, cargo securing, and ventilation. Alternative samples of the cargo both apparently contaminated and The quality of advice given has uncontaminated should be obtained, placed into sealed plastic sample established Carefully to Carry as a key bags, and removed for later testing. source of guidance for shipowners and ships' officers. In addition, the articles have frequently been the source of It is essential to use distilled water to wash the test samples as the expertise in negotiations over the presence of chloride in some waters may produce anomalous results. settlement of claims and have also been relied on in court hearings. The test solution should also be acidified with nitric acid to prevent the In 2002 all articles were revised and formation of other silver salts.

4 Published in book form as well as on disk. All articles are also available to Members on the Club website. Visit the Carefully to Laboratory identification of water origins Carry section in the Loss Prevention area of the Club website for The source, or origin, of a particular water contamination can be identified more information, or contact the Loss in the laboratory by a number of different testing procedures. The testing Prevention Department. procedures are as follows: Quantitative chloride determination by titration. related to the concentrations. The peak areas of the individual anions ( chloride) are compared to Quantitative determination of anions ( chloride, standard solutions and the concentration in the actual nitrate etc) and cations (sodium, potassium etc) by sample calculated.

5 Examples of a typical anion ion chromatography. chromatogram and standard are shown below. The Quantitative determination of metals, such as determination of the cations ( sodium) is done sodium, magnesium, calcium, potassium and separately using the same instrument but with a strontium, using either inductively coupled plasma different eluent and column system. emission spectroscopy (ICPES) or atomic absorption spectroscopy (AAS). Determination of cations using ICPES or AAS. These two analytical techniques will determine the Test procedures concentrations of various metals/cations, such as sodium, calcium, magnesium, potassium, strontium etc Quantitative chloride determination by titration in an aqueous solution. The two techniques can be Two methods are available, one involving titration described as follows: against standard silver nitrate solution using potassium chromate as an indicator and the other, involving AAS is an analytical technique in which the sample titrating against a standard solution of a soluble to be analysed is converted into an atomic vapour by mercury salt using diphenylcarbazone as an indicator.

6 Spraying the sample or solution of the sample into a The chloride concentration is calculated from (i) the flame. The absorbence at a selected wavelength for volume of standard silver nitrate solution used (ii) the each individual metal/cation is measured and volume of sample taken and (iii) normality/molarity compared to the absorbence measurements of the (strength) of the standard solution used. sample and standard. ICPES is an analytical technique where the sample Determination of anions and cations by ion solution is introduced into an inductively coupled chromatography argon plasma at a temperature of approximately In this instrumental technique a sample ( water) is 8000 C. At this temperature the individual elements introduced via an injection loop into the eluent passing (cations) become thermally excited and emit light at through the system.

7 The sample is then pumped their characteristic wavelengths. This light is through an analytical ion exchange column, which will collected by the spectrometer and amplified to yield separate the various ions ( anions or cations). The an intensity measurement that can be converted to separated ions are then detected using a conductivity an elemental concentration by comparison with detector and the peak areas reported are directly known standards. 5 WS03/1601 Dry cargoes (spot test). Sample Name: WS03/1601 Injection Volume: As noted before, for many dry cargoes such as steel, Vial Number: 5 Injection Volume: ECD_1. Sample Type: unknown Injection Volume: for example, an indication of seawater contamination Control Program: Anions Injection Volume: can be achieved on site by the silver nitrate spot test'.

8 Quantif. Method: Anions_7a Dilution Factor: 1,0000. Recording Time: 8/12/2003 18:55 Injection Volume: 1,0000. The basis of the test is that addition of acidified silver Run Time (min): Injection Volume: 1,0000 nitrate to any solution containing chlorides will produce a white precipitate of insoluble silver chloride. The S. chloride content of most seawaters would be expected 2 - Cl - to be around the 20,000 ppm level. Therefore, the addition of acidified silver nitrate to seawater will produce a dense white precipitate making the solution appear milky'. The test is performed by the attending surveyor by adding a small amount of acidified silver 3 - NO3 - 14,163 4 - SO3 - nitrate to any contaminating water found on the dry cargo. If the resulting solution appears milky' then it is 1 - F - possible that seawater contamination has occurred.

9 Min However, as stated previously, to confirm the presence of seawater further laboratory analysis will be required. No. Ret. Time Peak Name Height Area Rel. Area Amount Type An alternative to the silver nitrate spot test is to take min S S* min % ppm 1 F BMB* swabs of the contaminating water, which should then 2. 3. Cl NO3. BMB*. BMB*. be placed in a suitable airtight container and submitted 4 SO4 BMB* to the laboratory for further analysis. Total: It is important to note that certain other water sources, Production (oilfield) waters have very high sodium such as brackish or river water, will contain chlorides and chloride levels, which are significantly higher and would also produce a milky' solution with the than the levels found in seawater. addition of acidified silver nitrate .

10 Even domestic tap water contains enough chlorides to give a slightly The calcium levels in production waters are milky' solution when tested with acidified silver nitrate . significantly higher than the magnesium levels, which are the reverse for seawater, where the The silver nitrate spot test should be applied to magnesium levels are higher. The calcium/. galvanised goods with caution as it gives a black magnesium ratio is a useful indicator as to whether precipitate due to interference from the zinc present. In the water is seawater or production origin. addition, the silver nitrate spot test can be misleading River waters will vary in cation and anion levels, when applied to certain types of packaging, leather depending on whether it is tidal and the levels will goods etc, which may, themselves, contain chlorides.