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Abstract: Simple voltammetric determination of thiodiglycolic acid (TDGA) offers the possibility to follow individual deviations in metabolism of thiocompounds and one-carbon (1c) and two-carbon (2c) units, which take part in endogenous synthesis of creatine (CR). In three groups of young men the levels of TDGA in urine were followed after application of CR given as food supplement in 5g daily doses. In the first group (7 men) it was found that the level of TDGA increased independently of the day time of application of CR. In the second group (9 men) the level of TDGA increased within an interval of 3–8.5h after CR application and then dropped during 2h to the normal level (20mgL−1). In the third group (11 men), in 4 days’ study the effects of CR were compared in alternation to vitamin B12. Vitamin B12 was given in the evening of the 1st and 3rd day and CR in the morning of the 3rd and 4th day. CR increased the excretion of TDGA in all men, while B12 only in four men independently of CR application. [Copyright &y& Elsevier]

Abstract: The voltammetric behavior of leucovorin (LV), as an important and stable reduced metabolite of folic acid, has been investigated on polished (p-AgSAE) and mercury meniscus modified (m-AgSAE) silver solid amalgam electrodes in this paper. LV, after its reverse electrochemical oxidation, can be reduced in two reduction steps in an acidic medium on both electrodes used. The first reduction peak (E p =−400mV) can be used for determination of LV. Differential Pulse Voltammetry (DPV) was applied for monitoring voltammetric behavior of LV on both working electrodes. Elimination voltammetry with linear scan was applied for elucidation of the reaction mechanisms. The limits of detection were calculated as 2.2×10−8 molL−1 (t acc =60s) for m-AgSAE and 5.0×10−8 molL−1 (t acc =100s) for p-AgSAE. The proposed method was applied for LV determination in the pharmaceutical preparation which has been commonly used during methotrexate therapy. [Copyright &y& Elsevier]

Abstract: Voltammetric behavior of folic acid and folates has been investigated using direct current voltammetry, differential pulse voltammetry and adsorptive stripping differential pulse voltammetry at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE). The optimum conditions have been found for their determination in a 1:9 mixture of methanol and aqueous acetate buffer, with the limit of detection about 0.5nmolL−1. RSD at this concentration level amounted to less than 4%. Practical applicability of the newly developed method was verified by analysis of three vitamin preparations and of two multivitamin juices. [Copyright &y& Elsevier]