Tag Archives: oxygenase

Microcrystalline identification does not offer as low an LOD as

Microcrystalline identification does not offer as low an LOD as the colorimetric spot tests, but the growing habits that are observed between reagents and drugs can be very specific [13]. Elie et al. [14] designed a microcrystalline assay oxygenase for BZP using mercury chloride as the reagent. Upon gentle mechanical assistance for nucleation, BZP was found to form distinctive rectangular plates.
BZP is known to produce psychomotor effects similar to amphetamine [15]. Notwithstanding BZP acting on the same receptors as amphetamine, it may not bind to the same oxygenase as those used in amphetamine immunoassays. The response of several piperazines was checked against an enzyme-multiple immunoassay technique (EMIT) and a fluorescence polarisation immunoassay (FPIA) initially designed for amphetamine and methylamphetamine [16]. The FPIA did not detect BZP in a 100,000ngmL spiked urine sample. However the amphetamine EMIT did respond to BZP with cross reactivities of 0.4% and 1.3% at 300 and 12,000ngmL amphetamine equivalents respectively. There are currently no commercially available immunoassays specifically for piperazines [6], however some recent literature has been published to this effect [17]. Also in general with presumptive testing false positives are possible [18] and they are at best semi-quantitative [19].
There can be no doubt as to the general reliability of electrochemical measurements in light of the facts that: globally amperometric quantitation of glucose is relied upon by millions of diabetes patients [20], there is widespread use of fuel-cell breath-alcohol testers by police forces [21] amongst many other medical applications [22]. The major advantages of electrochemical analysis over other techniques can be summarised as:
These benefits could of course be useful in field testing in a forensic context and indeed the relatively new field of “forensic electrochemistry” has found a range of applications in recent years [27] including the voltammetric analysis of gunshot residue using an innovative “lab-on-a-finger” technique [28], and explosives [28]. However the bulk of the published forensic electrochemistry research lies in the area of drug analysis. Some recent highlights from this are presented in Table 2.


Results and discussion

An analytical method has been developed which offers the promise of portability, cheapness, speed, precision and accuracy for the analysis of BZP. Although there are many analytical techniques which have superior LOD parameters, this becomes irrelevant in the analysis of bulk drugs which is the future goal of this research. An LOQ of 20μM is more than sufficient considering the average dose of a tablet is between 50 and 200mg [32]. However if the analysis of body fluids for the presence of BZP using this technique was to be considered it would be important to assess the resolution between the hydroxylated metabolites and the drug itself.


Recently, tellurium (Te) and Te based compounds have attracted great interest due to their outstanding physical and chemical properties. Elemental Te has been widely studied owing to its thermoelectric, nonlinear optical, gas sensing and electrochemical properties. Trigonal Te is a p-type semiconductor of bandgap 0.35eV with a unique helical-chain conformation in its crystal structure. Thermoelectric properties of Te nanowires hybridized with carbon nanotubes show excellent mechanical stability and an electrical conductivity of 50Sm[1]. Nonlinear optical transmission of Te nanowires at 532nm exhibits excited state absorption (β 3.8×10m/W) [2]. NH3 sensing of Te nanowires by hydrazine hydrate assisted hydrothermal route displays high sensitivity, excellent selectivity, short response (5s) and recovery (720s) times at room temperature [3]. Similarly, electrochemistry of Te has been investigated both in acidic and alkaline media. The electrochemical behavior of Te on stainless steel substrate in alkaline solution exhibits two cathodic and an anodic peak assigned to the four electron reduction process of Te (IV) to Te (0), Te (0) to (Te-II) and the oxidation of bulk Te [4]. In the cyclic voltammetric (CV) study in HNO3 solution (pH2.0 and 2.5), an oxidation potential of 0.48V is found in the forward scan. Also, with normal hydrogen electrode (NHE), the reduction potential is −0.8V [5]. The systematic study of current-voltage measurements leads to the fabrication of electrochemical capacitors, also referred to as supercapacitors. Due to its higher charge storage and charge delivery response in comparison with other energy storage devices, supercapacitors achieved importance in modern science and technology.