230 Leenawaty Limantara et al. / Procedia Chemistry 14 ( 2015 ) 225 – 231
In order to find out the distribution of the feasibility of in vivo measurement among ten selected leafy vegetables,
compared to their in vitro data, the data plot between total
peak area of chlorophylls (HPLC) and SPAD value was
generated (Fig. 3a). The best-fit regression was obtained as linear cor
relation with goodness of fit (R
) > 0.7,
revealing the presence of moderate relation between SPAD value and total peak area of HPLC for chlorophyll a and
b. In green vegetables, chlorophyll degradation will occu
r along with leaf senescence after harvest
. Therefore,
chlorophyll meter can be employed for rapid detection of vegetable quality and freshness. Several limiting factors
are the thickness, morphology of leaf surface, as well as homogeneity of the distribution of chlorophyll in leaves.
F
ig. 3. Data plots of SPAD values versus total peak area of chlorophyll a and b obtained from HPLC measurement (a), and
nitrogen meter versus SPAD values (b). The equation of the linear reg
ression line and its coefficient of determination
(R
2
-value) is given in the figure. Abbreviations were defined in Table 1.
In addition, appreciable linear fit (R
2
= 0.98) was found in the positive correlation among in vivo measurement
(Fig. 3b). This finding is comparable with the result of Johan et al.
6
and Qihua et al.
5
, in which a strong linear
relationship was observed between SPAD and nitrogen meter values. This is acceptable since the development of
nitrogen meter is technically based on the chlorophyll meter (SPAD-502)
6
. However, beside the influence of leaf
thickness, the SPAD-502 may be more reliable at very low values, since the lowest SPAD value of Kbs was not
recorde
d by nitrogen meter.
4. Conclusion
Investigation on chlorophyll content of ten species green leafy vegetables which are common in daily diet of
local co
mmunity in Malang, East Java, Indonesia, was carried out. Overall, in vivo (chlorophyll meter and nitrogen
m
eter) and in vitro (HPLC) measurements could provide similar preference of vegetables having significantly high
con
tent of chlorophyll than the lower ones. The positive relation between in vivo SPAD values and total peak area
of
chlorophyll a and b which was measured in vitro by means of HPLC can be explained as 74 % of the variation in
a lin
ear relationship. Furthermore, the SPAD and nitrogen values among all samples showed strong relationship of
98 % b
ased on the similarity of working principle of the devices. The appropriate in vivo detection of photosynthetic
pigm
ents on green leafy vegetables is worthwhile for the prediction of freshness and nutritional quality. Several
limiting factors, such as leaf thickness, size, and non-uniform distribution of chlorophyll, can be overcome by the
develo
pment of calibration curve of standard for each species as well as the improvement of measuring capacity of
the instrumentation.
Acknowledgements
This project was supported by the National Innovation System research grant (RT-2015-0270) provided by the
In
donesian Ministry of Research, Technology, and Higher Education.
3,10
2