(surface plasmon resonance) which method are helpful for reduce negative curve?

1X tbs w/ sample
(1X TBS buffer : 90% DW+10% 10X TBS)

<1>
sample 100ul(diluted at DW until 1000X)
DW 800ul
10X TBS 100ul

it's my co-worker's opinion. he said "sample in DW, then when you dilute in 1X TBS buffer, it's final conc. will 0.9X. negative curve occurs by conc. mismatch, and we need to 1X TBS, so this method will reduce negative curve by buffer mismatch. "

<2>
sample 100ul(1000X stock was serially diluted at 10X TBS, triple)
1X TBS 900ul(90% DW+10% 10X TBS)

it's my counter opinion. "Diluted sample is 1000X stock. then, we don't have to calculate complexly, Serial dilution in 1X TBS three times. "

I am harassing by negative curve by buffer conc. mismatch...
chip is Biotin-SAM, I using streptavidin.