you can follow these steps:
1) build a band stop filter to remove power line frequency (select cut-off frequency depending on ur power line frequency i.e 50 or 60 Hz)
2) build a band pass filter
for band pass filter, u can use 2 Hz as low cut-off and higher cut-off depending on ur acquisition frequency. (if u are acquiring signal at a rate of 250 samples/sec, then higher cut-off is 124 Hz)
3) For spectrum analysis, use 'fft' function. with some extra efforts, u can get the exact spectrum. u can even find the psd for power estimation.