Speciation of low molecular weight Al complexes in serum of CAPD patients.
Speciation of LMW--Al complexes was performed in human serum of six continuous ambulatory peritoneal dialysis (CAPD) patients in order to investigate the individual variability in the percentage and the composition of LMW--Al species. The total concentration of Al in serum ranged from 10 to 120 ng ml(-1). The samples with high total concentration of Al were analysed directly, while those of low total Al concentration were spiked with Al(3+). Spiked and non-spiked samples (100--120 ng ml(-1) of total Al) were microultrafiltered through a membrane filter (cut-off 30,000 Da) to separate Al-transferrin from LMW-Al complexes. On an anion-exchange fast protein liquid chromatography (FPLC) column, 0.2 ml of filtrate was injected. An aqueous -- 4 mol l(-1) NH(4)NO(3) linear gradient elution was applied for 10 min to separate LMW--Al complexes. Fractions of 0.2 ml collected throughout the chromatographic run were diluted 1:1 with water and Al determined 'off line' by electrothermal atomic absorption spectrometry (ETAAS). The characterisation of LMW-Al species eluted under the chromatographic peaks was performed also by electrospray tandem mass spectrometric (ES-MS-MS) analysis. It was found experimentally that the percentage of LMW--Al species in spiked and non-spiked serum ranged from 25 to 50% (in one non-spiked sample 100%). The following LMW--Al species were separated and identified during the chromatographic run: Al-phosphate and a mixture of Al-citrate and ternary Al-citrate--phosphate complexes. It was found experimentally that the distribution of these species varied among particular patients. Similar distribution of LMW--Al species was found in spiked serum of healthy volunteers.
Polak
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TB
Department of Environmental Sciences, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
Milacic
R
R
Mitrovic
B
B
Benedik
M
M
D017607:Aluminum Compounds / Q000097:blood*; D006801:Humans; D008970:Molecular Weight; D010531:Peritoneal Dialysis, Continuous Ambulatory; D010710:Phosphates / Q000097:blood; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013054:Spectrophotometry, Atomic / Q000379:methods
D017607:Aluminum Compounds; D010710:Phosphates; D012996:Solutions; C012714:aluminum phosphate