The phrase "collected as a single" is perfectly correct and usable in written English.
You can use it to describe an action that was done together or as a group. For example, "The class had collected as a single unit to listen to the principal's announcement."
Two fragments of bored epidermis from left and right elytra were collected as a single sample in each condition.
Urine was collected as a single morning void.
The average of five cross sections from a given animal was collected as a single value for this animal.
The elution was monitored for absorbance at 214 nm and each absorbance peak was collected as a single fraction.
The fractions were collected as a single fraction and concentrated to 5 mL in a rotary vacuum evaporator at 45°C and then further concentrated to 1 mL under a gentle stream of purified nitrogen gas.
Images were pseudo-colored, overlaid, merged using Photoshop (Adobe), and quantified using Image J. Cells were collected as a single cell suspension by limited trypsin treatment and fixed in 70% ethanol and stored at −20°C overnight.
All fMRI data were collected as follows: single shot gradient echo EPI, TR/TE = 2500/22 ms, 96×96 matrix, 224×224 mm FOV, 36 interleaved transverse slices (aligned to the AC-PC line) 3.5 mm thick with no gap, 1 average, flip angle = 83°.
Plasma samples were collected as described above at a single time point (0.5 h).
This may be somewhat mitigated, as these findings were collected at a single CF clinic over a short time period, where practice patterns were relatively uniform.
As nasal samples were collected at a single point of time in almost all studies included and in most cases at times convenient to the subjects during or after their work shift, no distinction between transient or persistent carriage is possible [ 6].
To avoid fluctuations in gene expression with time of the day [ 55], eyes were collected at a single time period (noon) as previously reported [ 47].
