Determination Of Lithium In Serum Research Articles

Extraction spectrophotometry using a lithium-ion selective metallacrown: temperature effect on extraction reaction and application to determination of lithium in serum and seawater

A metallacrown-type ionophore, 2,3-pyridinediolate-bridged (3,5-dimethylanisole)ruthenium trinuclear complex, has a high extraction selectivity for Li+, but the extraction reaction is very slow. To solve this problem, the effect of temperature on the rapidity and equilibrium of the extraction of Li+ and Na+ as picrates from water to toluene with the metallacrown was investigated in this study. While the extraction of Li+ requires 6 h of shaking for equilibration at 25 °C, the distribution ratio becomes nearly constant after 4 h and 2 h of shaking at 37 °C and 50 °C, respectively. The extraction equilibrium constants (Kex) and associated thermodynamic parameters determined for Li+ and Na+ indicate that the extraction reactions are exothermic and enthalpy-driven: ΔH° = − 53 kJ/mol, ΔS° = − 0.03 kJ/(mol K) for Li+; ΔH° = − 28 kJ/mol, ΔS° = − 0.03 kJ/(mol K) for Na+. Although the extraction ability for Li+ and selectivity for Li+/Na+ decrease with increasing temperature, the values of Kex and Kex(Li+)/Kex(Na+) are 1.0 × 107 and 1.3 × 104, respectively, even at 50 °C, indicating that both are sufficiently high. In the determination of Li+ by extraction spectrophotometry using this metallacrown, extraction at 50 °C for 2 h was employed to speed up the analysis. The method was applied to seawater and serum samples containing a large amount of coexisting ions such as Na+ and Mg2+, and trace amounts (10−6–10−5 mol/L order) of Li+ in microvolume samples (sub-mL order) could be successfully determined.Graphical abstract

A standard addition method to quantify serum lithium by inductively coupled plasma mass spectrometry.

Therapeutic monitoring of lithium (Li) is important because of its narrow therapeutic range and therapeutic index. Here, the authors present the evaluation of an accurate method for the determination of lithium in serum. Serum samples were diluted with 0.3% ultrapure nitric acid and were spiked with an internal standard germanium (Ge). The Li/Ge ratio was detected in He mode; we utilized standard addition method to quantify lithium in human serum. The new inductively coupled plasma mass spectrometry (ICP-MS) assay was characterized for linearity, specificity, imprecision, trueness, accuracy, and comparison. The correlation coefficients (r) of linearity were all > 0.9999. The specificity proved to be good. The total coefficients of variation (CV) were 1.11% and 0.49% for the two serum samples. The mean bias from target values of standard reference materials (SRM 956d) was -0.71% for Level I, -017% for Level II, and 2.20 for Level III. External Quality Assessment Scheme for Reference Laboratories in Laboratory Medicine (RELA) gave satisfied results for the new method. Comparison with the ion-selective electrode routine method got reasonable results. This high accuracy method is an attractive alternative for lithium measurement and can be used as a candidate reference method to improve quality of serum lithium in China.

Rapid determination of lithium in serum samples by capillary electrophoresis

Lithium salts are still one of the most popular therapeutic approaches to the treatment of bipolar disorders, notwithstanding the introduction of more modern, less toxic drugs. Because of a narrow therapeutic range, lithium serum concentrations must be strictly monitored during the treatment to avoid life-threatening neurotoxicity. For this purpose, methods based on flame photometry or ion-selective electrodes are usually applied. The aim of the present work was to develop and validate a simple method for the determination of lithium in serum based on capillary zone electrophoresis with indirect detection. A validation of the method was carried out, including a comparison with an automated routine method based on ion-selective electrodes.

Superiority of nitric acid for deproteinization in the determination of trace lithium in serum by graphite furnace atomic absorption spectrometry

Physiological level of trace lithium in human serum was determined by graphite furnace atomic absorption spectrometry (GFAAS). 3.5% HNO 3 (v/v) was employed as a protein precipitant for sample treatment and at the same time verified as a very effective chemical modifier to eliminate the interference of chloride. The analytical conditions for lithium determination in serum were investigated and the optimal pyrolysis and atomization temperatures were 800 °C and 2700 °C. The accuracy and precision of the method were tested by determining lithium in a RANDOX HN1530 assayed human multi-sera and a pooled human serum. The result was in good agreement with the target value and CV of the pooled human serum was 4.74% ( n = 10). The characteristic mass, the limit of detection (LOD) of the proposed method were 0.8 pg and 0.01 μmol/L, respectively. Median ± S.E.M. of serum lithium in 220 Chinese people was 0.25 ± 0.02 μmol/L.

Trace Analysis of Lithium with a Water-Soluble Porphyrin

A water-soluble porphyrin (2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin ; H2obtpps4-; H2P4-) was synthesized and developed for the determination and separation of lithium ion in aqueous solution. The octabromo groups lower the basicity of the porphyrin by their electron-withdrawing effect, and enable the porphyrin to react with lithium ion in alkaline aqueous solution to form the lithium complex along with a shift of absorption maxima; λmax (log ∈/mol-1 dm3 cm-1) of the lithium porphyrin are 490.5 nm (5.31) and 734 nm (4.36). Sodium and potassium ions did not react with the porphyrin. The equilibrium constant for the reaction Li+ + HP5- ⇌ [LiP]5- + H+ was found to be 10-8.79 and the conditional formation constant of the [LiP]5- at pH 13 is 104.21. The [LiP]5- can be extracted into chloroform as an ion-pair complex with tetrabutylammonium ion (X+) and the extracted X5LiP dissociates to X4LiP- and X+ in chloroform. The extraction constant for the reaction of [LiP5-]a + 5[X+]a ⇌ [X4LiP-]o + [X-]o was found to be (8.4 ± 0.7) × 1012 mol-4 dm12, where subscripts of a and o denote chemical species in aqueous and organic phases, respectively. The above results were developed for the determination of lithium in serum, sea water and hot spring water samples at a range of 0.07–0.7 mg dm-3 (1 × 10-5 - 1 × 10-4 mol dm-3). The interference of heavy metal ions was masked by N,N'-1,2-ethanediylbis[N-(carboxylmethyl)glycinato]magnesium(II) ([Mg(edta)]2- or H4edta if sample contain magnesium(II) ion.

Determination of lithium in serum and whole blood by graphite furnace atomic absorption spectrometry

A method has been developed for the direct determination of lithium in serum and whole blood by graphite furnace atomic absorption spectrometry using tantalum carbide coated graphite tubes in combination with ammonium nitrate matrix modification. The maximum permissible charring temperature for lithium was raised from 1050 to 1500 °C and the lifetime of the tube was also prolonged for ca. 200 more firings using the tantalum carbide coated graphite tube compared with the conventional pyrolytic graphite coated graphite tube. Matrix interferences from chlorides present in human blood samples were eliminated using the proposed method, which has been used for the determination of lithium in serum and whole blood of normal healthy individuals.

Direct determination of therapeutic concentrations of lithium in serum by flow-injection analysis with atomic absorption spectroscopic detection.

In this flow-injection system for direct determination of lithium in serum by atomic absorption spectroscopy, the 10-microL sample is manually injected into a continuously flowing non-segmented stream of de-ionized water, which is pumped, via a dispersion tube, to the spectrometer's nebulizer. Controlled dispersion of the sample zone, before it is introduced into the nebulizer, produces the required sample dilution. Effects of varying the length of the dispersion tube, the flow rate, and the sample size were studied. Analytical readout is obtained, in the form of transient peaks, 5 s after sample injection. It is necessary to include physiological concentrations of sodium and potassium in the standard because each of these cations enhances the lithium absorbance signal. Analytical recovery (98.5 to 101%) and CV (about 2%) are good, and results compare well with those obtained by aspiration of prediluted samples (n = 121, r = 0.99).

Acetone as solvent in flame-photometric determination of lithium in serum

The effect of some water miscible organic solvents on the flame photometric emission of Li is discussed. A simple procedure is described with acetone as diluting solution giving a ten to twenty fold increase in sensitivity.

The Estimation of Lithium in Serum

Lithium was first used therapeutically for the treatment of gout (Daniels, 1914), but more recently it has been used in the treatment of certain mental disorders (Cade, 1949; Schou et al., 1954; Wharton and Fieve, 1966; Rice, 1956). Among the psychiatric disturbances reported to respond favourably to lithium therapy are manic depressive psychosis, repeated manic attacks, recurrent depression and Parkinsonism. The degree of success attributed to lithium therapy has been the subject of some controversy (Lancet, 1969; Whybrow, 1969; Goodwin et al., 1969) and recently it has been recommended that lithium be used only in those cases of mania which are resistant to phenothiazines and electro-convulsive therapy. Current medical opinion favours more rigorously controlled therapeutic trials and since it is the practice to regulate dosage with reference to serum lithium assays it seemed important to re-examine the technical problem of lithium estimation in serum. Preferably the therapeutic level should be maintained below 1.5 m-equivfl since toxic effects have been observed when the level is between 3.0 and 6.0 m-equiv/l (Amdisen, 1967). The need for accurate estimation was emphasised recently following a fatality in which an elevated serum lithium concentration was thought to be the major contributory cause of death (Hawkins and Dorken, 1969). A number of methods for the determination of lithium in serum have appeared (Barrow, 1960; van der Helm and Andriesse, 1961; Nevius and Lanchantin, 1965; Amdisen, 1967, Blijenberg and Leijnse, 1968; Tompsett, 1968; Little et al., 1968; Lehmann, 1968). Many of these use a 1 in 5 or 1 in 10 dilution with trichloroacetic acid (TCA), a reagent which is known to reduce the sensitivity of the assay. Blijenberg and Leijnse (1968) used 96 % ethanol as diluent, thereby increasing the sensitivity of the method and simultaneously decreasing the blank value. Although Amdisen (1967) using a Beckman D.U. atomic absorption spectrophotometer was able to use as little as 200 11.1 of serum at a 1 in 20 dilution, most methods utilise 1 ml of serum diluted 1 in 5. There is some discrepancy in the literature

Direct determination of lithium in serum by atomic absorption spectroscopy

A direct method for the determination of lithium in serum by atomic absorption spectroscopy is described, employing 0.1 N hydrochloric acid as a diluent. The method is simple and sufficiently reliable for clinical purposes.

The determination of lithium in serum by atomic absorption spectroscopy and flame emission spectroscopy

A comparative investigation for the determination of the serum lithium content is described. The experimental data were obtained by atomic absorption and flame emission spectroscopy. Each method was found to have advantages as well as disadvantages. In developing a routine lithium determination, we found that atomic absorption spectroscopy—which has proved to be a powerful technique in clinical chemistry—is not superior to flame emission spectroscopy.

The determination of lithium in serum during therapy with lithium salts

The determination of lithium in serum during therapy with lithium salts