Macrocycleversus podant-type neutral ionophore in potentiometric detection of mucolytic agents following separation by various HPLC modes

Abstract

SummaryPotentiometrTc detection of lipophTlic drugs such as clenbuterol, ambroxol and bromhexine in standard bore cyano and narrow bore hybrid, reversed phase HPLC systems was developed to enable specific determination of these mucolytic agents in some marketed oral formula tions. The macrocycle and podant type, neutral ionophores, respectively: hexaks(2,3,64ri O octyl) ~ cyclodextrin (CDX) and N,N,N',N'4etracyclohexyl oxybis(o phenyleneoxy)diaceta mide flOPA), were used to construct PVC based, liquid membrane electrodes. In addic aqu eous-acetonTtrile, mobTle phases both Tonophores Tmproved the sensitTvTty of these electrodes for mucolytic agents when compared to single-wavelength UV detedTon -as well as wTth the ionophore-free based electrode. In the case of bromhexTne, TndTcating highest ITpophilTdty (IogP6.40), detection limits of 2.6 x ]0 lo and 1.4 x ]0 l~ (injected concentration) were achieved with a signal-to-noTse (S/N) ratio of 3 wTth the TOPA-modified, liquid membrane electrode in the varTous RP-HPLC systems. The results of procedures validated for sTmultaneous potentiometrTc determination of clenbuterol and ambroxol Tn tablets marketed in di[ferent countries are also presented.

Unique potentiometric detection systems for HPLC determination of some steroids in human urine

“…Based on the results of potentiometric detection with the MPI_Comp electrode developed here the analyzed male urine sample contains 46.3 lM DHEAS, and 3.17 lM ADS, while the analyzed female urine sample contains 29.4 lM DHEAS and 6.92 lM ADS. The satisfactory RSD of the intra-and interday assays for these average values (n = 6) of both analytes were obtained, i.e., below 6 and 18%, respectively, which is comparable with repeatability and reproducibility observed previously for the determination of mucolytic drugs by HPLC with potentiometric detection [18,34]. The obtained calibration curves of the MPI_Comp electrode (see Fig.…”

“…The applied flow rate was 1 mL/min. A Shimadzu UV -Vis detector (SPD-10Avp/10AVvp) (260 nm), and "wall-jet" type potentiometric flow cell constructed in the laboratory [34] were used in series. The jet-to-electrode distance was 100 lm.…”

“…In addition, this column stationary phase shows a distinct selectivity for polar organic compounds as well as for molecules containing p-electron systems (Online Application Database, Macherey Nagel GmbH, http:// www.mn-net.com/Default.aspx?alias = www.mn-net.com/ apps (accessed April 10, 2008)). This column was used in our study as the separation efficiency of GP derivatized 17-KS was quite acceptable in applied isocratic elution condition and in here used highly acidic mobile phase (pH 2.63) both of which are preferred with respect to optimized short time response (a2.0 s) of developed potentiometric detector (sensor) for cationic substances [18,34,37,38]. The high values of selectivity factor a and resolution R s achieved on this column for the structurally simi- LOD (DHEA): the difference is significant at the 0.05 level between the MM_CW and the other tested electrodes.…”

Hydrophobicity‐aided potentiometric detection of catecholamines, beta‐agonists, and beta‐blockers in a mixed‐solvent capillary electrophoresis system

“…The results of a detailed study on the lifetimes, robustness, and reliability of the PVC-based membrane CWE electrode in acetonitrile/dilute acid conditions were described in our earlier reports [30,50]. Similarly, we observed that the activity of the TCPB-based CWE electrode used here was reduced to 75% of its initial level (measured as peak area of bufuralol) after continuous use in applied CE conditions during three weeks.…”

“…As the diameter of copper wire was reduced here by a factor of 2.5, this improvement in the detection limit of dopamine is probably related to the use of acetonitrile in BGE and its lower pH*. The effect of acetonitrile as a component of the acidic mobile phase on the greatly increased response of the PVC-based CWE under nano-HPLC conditions has already been described [50]. The LOD observed here for dopamine was also improved in comparison with the millimolar LOD reported by Kappes et al [18] in CE with a 90 lm platinum wire PVC-based CWE and a content of the non-specific cation exchanger TCPB increased to 3.4%, o-nitrophenyl octyl ether (NPOE) as the low-hydrophobicity (log P = 5.9 [31]) and high resistance (e r = 23.9 [31]) plasticiser, and tartaric acid as BGE component.…”