Coral Powder Research Articles

Determination of Uranium to Calcium and Strontium to Calcium Ratios in Corals by Inductively Coupled Plasma Mass Spectrometry

F. LE CORNEC and T. CORREGE, J. Anal. At. Spectrom., 1997, 12, 969 DOI: 10.1039/A701691C

Determination of Cd, Co, Cu, Fe, Mn, Ni and Zn in coral skeletons by chelation ion chromatography

Cadmium, Co, Cu, Fe, Mn, Ni and Zn incorporated in the aragonitic skeletons of corals ( Porites) were analyzed by chelation ion chromatography (CIC). A 500-mg amount of bleached, oven-dried coral powder was dissolved in 1 ml of 14.4 M HNO 3 and buffered at pH 5.4 ± 0.1 using 50 ml of 2 M ammonium acetate. A 30-g amount of sample was concentrated on-line by pumping the solution through a Dionex MetPac CC-1 chelating concentrator column at a rate of 3 ml/min, and the MetPac was rinsed with 2 M ammonium acetate to elute alkaline earth metals to waste. The transition metals were eluted on a second concentrator column (Dionex TMC-1) using 2 M HNO 3, and the TMC-1 was then converted to a salt form using 0.1 M NH 4NO 3 and switched on-line with the analytical column, the Dionex IonPac CS-5. The metals were then eluted from the separator column using 6 m M pyridine-2,6-dicarboxylic acid-0.4 M NaOH; the pH of this eluent was 4.4. The separated metals were, after they had left the column, complexed by 0.5 m M 4-(2-pyridylazo)resorcinol, and the absorbance was measured in a Dionex ultraviolet-visible detector at 520 nm. The use of two separator columns in series improved the metal separation. This is especially important for Ni and Co because coral samples typically contained an order of magnitude more Zn than Ni or Co. With two columns in series, Ni, Co and Zn were baseline-separated even when a 30-g sample containing 5 ppb Ni, 5 ppb Co and 100 ppb Zn was concentrated. The absolute sensitivity of the instrument was approximately 10 ng Cd. Although Cd was successfully determined in several corals using CIC, most coral samples contain on the order 1 ng/g Cd or less and, thus, the quantitative measurement of Cd in most corals by CIC would require tens of grams of coral powder. Unfortunately, it is not possible to obtain such large quantities of coral material from annual bands. The chelation system may be useful, however, to pre-concentrate coral digests for Cd analyses using more sensitive methods of detection (e.g. graphite furnace atomic absorption spectrometry or inductively coupled plasma mass spectrometry).

Determination of nitrate, phosphate and organically bound phosphorus in coral skeletons by ion chromatography

Nitrate, phosphate and sulphate incorporated in the aragonitic skeletons of corals ( Porites) were analyzed by ion chromatography (IC). All anion analyses were performed using a Dionex 4500i IC system with Dionex columns, conductivity detector and computer interface. The anions were separated on an AS4A separator column behind an AG4 guard column, and the background conductivity of the eluent was suppressed using an AMMSII membrane suppressor. The suppressor was continually regenerated using an anion membrane suppressor regenerant cartridge and H 2SO 4. The eluent used was 1.8 m M Na 2CO 3-1.7 m M NaHCO 3. Bleached, oven-dried coral powder (200 mg) was dissolved in 0.5 ml of 30% HCl (Merck Suprapur) and diluted to 100 ml. Standards were also prepared in HCl, and the linearity was excellent for each anion ( r 2 > 0.999) over the range 20–100 ng/g (ppb) for nitrate, 100–500 ng/g for phosphate and 0.5–12.0 μg/g (ppm) for sulphate. All samples and standards were passed through a chloride-removal cartridge (Dionex OnGuard AG) prior to injection. This cartridge consisted of silver and its sole purpose was to remove Cl − which might otherwise overwhelm the separator column. Using a 250-μl injection loop, the detection limits were approximately 5 ng/g for nitrate and 10 ng/g for phosphate. The analytical procedure variability was 9% for nitrate, 2% for phosphate and 0.5% for sulphate. The concentrations of these species in the corals varied from 0.2 to 18 ppm, 8 to 118 ppm and 560 to 590 ppm, respectively. Coral samples taken from three coral heads at the Grande Rivière Noire Bay (slabs 1Ks, 5Ks, 6Ks) averaged 4.5±0.5 ppm nitrate and 55±1 ppm phosphate, compared with 2.2±0.5 ppm nitrate and 16±1 ppm phosphate for the samples taken further out in the lagoon (slabs 7Ks and 11Ks). Thus, the nitrate and phosphate concentrations clearly distinguish between corals taken from the bay, which are closer to anthropogenic N and P inputs, from samples collected from the lagoon, which are further from such N and P sources. To estimate the possible importance of organically bound phosphorus, samples were also treated with H 2O 2. Following dissolution in HCl, 1 ml of 30% H 2O 2 (Merck Suprapur) was added, and the samples were heated at 50°C for 3 h. The instrument was calibrated using standards prepared in HCl-H 2O 2. The phosphate concentrations measured in the samples dissolved in HCl-H 2O 2 were up to 100% higher than those dissolved in HCl alone, suggesting that organically bound phosphorus contributes significantly to the total phosphorus concentrations of the corals.

Second interlaboratory-comparison project on ESR dating

During the TL- and ESR-Conference in Clemont-Ferrand in 1990 we initiated a second “Intercomparison project on ESR dating” in which 14 ESR groups participated. Each group was provided with two samples of a coral powder, one of which (Sample A) was a fossil coral with a mass spectrometric determined U/Th age. Sample B was a recent coral, irradiated with a definite γ-dose (checked by alanine dosimetry). In both cases the AD had to be determined (for sample A the U-content and age as well). Additionally, the chance of a calibration of γ-sources by alanine dosimeters was offered (GSF). The results show that (i) the γ-source calibration is better than ±5%, (ii) the mean value of the AD from sample A seems to agree with the expected AD but the mean AD value from sample B is overestimated, (iii) systematic errors occur due to the fitting procedure: the AD estimate depends on the maximum γ-dose used for the irradiation curve, (iv) the AD determination including the smallest systematic error gives correct values for sample B but too low values for sample A which may be caused by fading of the signal g = 2.0006.

Relationship between chemotaxis and complement activation by ceramic biomaterials

This paper examines the relationship between complement activation by ceramic biomaterials and chemotaxis. Complement activation was examined by both neutrophil polarization (a technique which has previously been used to examine chemotaxis) and immunoelectrophoresis assays. The results suggest that at increasing serum concentrations of both calcium hydrogen phosphate and coral (calcium carbonate) powder, the quantity of C3 activation increased, as did the quantity of serum-derived chemotactic factors. In the case of tricalcium phosphate powder, the quantity of C3 activation and the neutrophil polarization response to serum were similar for serum levels between 20 and 80 mg/ml. Complement C3 was not activated in serum incubated with calcium hydrogen phosphate powder and serum incubated with this material was not chemotactic for neutrophils.