Controlling pesticide and other residues in herbs and spices 49
and/or time-resolved fluorescence, field-based instruments, immunochemical assays,
biosensors, and other techniques. Direct sample introduction for gas chromatography/
tandem mass spectrometry (DSI/GC/MS-MS) is a novel approach for the analysis of
multiple pesticides in a variety of herbal food matrices. This approach has the potential
to make a major impact in the analysis of many types of pesticides and other semi-
volatile chemicals in a variety of matrices in food.
Tandem Quadrupole LC and GC/MS/MS is another new MRM system being used
for multiple pesticide residues. This method involves a less selective extraction and
cleanup, and is particularly applicable to complex food matrices of spices like ginger,
garlic, and herbs, where the selectivity is sufficient to allow generic sample cleanup,
apart from providing a good sensitivity up to 10 pg on column for most pesticide
residues. A UPLC (ultra performance liquid chromatography) method is also available
now where the cycle time can be halved, and improved efficiency coupled with high
sample throughput could be realised through a combination of new technologies that
offer enhanced chromatographic resolution and short analysis time. In addition, it
can group MRM functions into time windows enabling the incorporation of confirmatory
MRM traces, and switch rapidly between MRM channels and between positive and
negative ionisation modes. The newly developed travelling wave (T-wave) technology
can prevent cross-talk even at very short cycle times. The T-wave is produced by
application of a transient d.c. voltage with opposite phase to alternate plates thus
creating a square wave which travels along the length of the collision cell.
2.4 Control of pesticide residues in herbs and spices
Monitoring usage of chemicals and their residue levels in raw materials and finished
products sets up strategies for controlling them at farm level. There are different
ways of usage control at farm level that, grouped together, are termed as farm
management systems. These are basically tools to achieve supply of quality agro-
products through sustainable programs of agriculture and farmer development. These
systems ensure quality at source through superior seed varieties, modern and sustainable
agricultural practices, and provide consistent raw material quality to improve process
efficiencies. There are many options open to herb and spice processors under these
systems, like corporate farming through own land/leased land, and contract farming
with large/institutional bodies and small/medium/large farmers. The rural farmers
and small-scale entrepreneurs lack both reliable and cost-efficient inputs such as
extension advice, mechanisation services, seeds, fertilisers and credit, and guaranteed
and profitable markets for their output. Well-organised contract farming provides
such linkages apart from providing the investors with the opportunity to guarantee a
reliable source of supply, from the perspectives of both quantity and quality.
Contracting of crops has existed from time immemorial. In ancient Greece, the
practice, known as hektemoroi or ‘sixth partner’ was widespread, in which specified
shares of particular crops were contracted for paying tithes, rents and debts. Such
sharecropping was also practised in China during the first century. In the USA, by
end of the nineteenth century, sharecropping agreements had been drawn that allowed
for a specific share to be deducted for rent payment to the landowner. In the first
decades of the twentieth century, formal farmer-corporate agreements were established
in colonies controlled by European powers.