Agriculture Reference
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determination is useful in food chemistry such as yoghurts, beer, wine, etc.
Improved biosensors for acetaldehyde determination have been developed using a
bienzymatic strategy, based on a mediator-modified carbon film electrode and
co-immobilization of aldehyde dehydrogenase and NADH oxidase. Modification
of the carbon film electrode with poly(neutral red) mediator resulted in a low-cost,
reliable and sensitive NADH detector. Enzyme immobilization was performed
using encapsulation cross-linking with glutaraldehyde or in a sol-gel matrix. The
bienzymatic biosensors were characterized by studying the influence of cofactors,
pH and applied potential. The glutaraldehyde and sol-gel biosensors indicated a
linear response up to 100 and 60 μ M, respectively, with detection limits of 3.3 and
2.6
AmM 1 . The optimized biosensors
denoted good selectivity and good stability and have been tested for application for
the determination of acetaldehyde in natural samples like wine (Ghica et al. 2007 ).
The nutritional significance of folate in the human diet and the forms in which it
may exist in milk have been described in previous studies that formed the basis for
the developments currently presented (Indyk 2010 ). Although supplementation of
foods is currently achieved through the use of synthetic folic acid (pteroylmono-
glutamic acid, PteGlu), the recently available (6S)-5-CH 3 H 4 -PteGlu calcium salt
might become a more appropriate supplement (Houghton et al. 2006 ). National
population strategies regarding the compulsory fortification of selected foods with
folic acid are currently a controversial topic, and it seems unlikely that a common
international policy will be adopted (Lawrence et al. 2009 ; Smith et al. 2008 ). An
optical biosensor assay utilizing folate-binding protein was developed for a quan-
titation of the folate content in milk and milk-based adult and paediatric nutritional
products. Samples extracted in reducing buffer were enzymatically deconjugated
prior to biosensor analysis. The protein-binding assay was configured under inhi-
bition conditions, utilizing a sensor surface functionalised with folic acid, and was
subjected to single laboratory validation. Cross-reactivity of a folate-binding pro-
tein towards the dominant folate vitamers was indicated. The method was compared
with both constituted high-performance liquid chromatographic and microbiolog-
ical methods for a range of products. As a simple, rapid and automated technique,
the method demonstrated to be an accurate and precise alternative to conventional
techniques for application in routine compliance monitoring of milk-based nutri-
tional products (Indyk 2011 ).
Recently, the fate and the occurrence of pharmaceutically active compounds in
the environment has been recognized as one of the prevailing problems in chemistry
and ecological risk assessment, as evidenced by their extensive coverage in the
special issues published on emerging contaminants in soil, water, sludges and
sediments (Barcel
μ
M, and sensitivities were 5.6 and 1.7
μ
o 2003 , 2004 ), and those directly focused on the single subject
of pharmaceuticals (Barcel
o and Petrovic 2007 ). There are several reviews on
analysis (Kim and Carlson 2005 ;D´az-Cruz and Barcelo 2005 ; Gross et al. 2006 )
and environmental risk (Heberer 2002 ; Boxall 2004 ). A recent review of the
scientific literature appearing between 1998 and 2003 denoted that there were
more than 350 papers on pharmaceutical residues (Stolker and Brinkman 2005 ).
Among various pharmaceuticals, antibiotics belonging to the quinolones group,
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