Application Note

Fast and automated turbidity measurement ofprotein formulations
Introduction

on the sample cell.
The lowest turbidiThe visual inspection
ty measurement ofstation can provide
the three positions
up to 45-fold
was recorded. A
savings of operator
freeslate jr. with thetime for turbidity
VIS was used formeasurements ofautomated turbidity
drug products.
measurements. The
samples and standards were loaded
onto the freeslate jr. The system was programmed
to perform calibration and measure the samples.
The freeslate jr. then transferred each standard
and sample vial into the VIS where the turbidity
was measured in a specified region of the vial. The
freeslate jr. then rotated the vial 90° and a second
turbidity measurement performed and the readings
averaged. Five replicates were measured for eachsample. For direct comparison with the Hach procedure, the lowest turbidity value from the five replicate measurement was reported as the final result.

Protein formulation is no easy task. Developing asafe, effec­tive and stable formulation can require
screening a wide array of formulations with a variety of analytical techniques, requiring significant
hands-on time. Turbidity measurement is a simple,
method routinely used to evaluate protein stability throughout formulation development. Whileturbidimeters are easy and accurate, they requiresignifi­cant hands-on time. Each sample must be
manually transferred to a sample cell that must be
cleaned and polished prior to analysis. This manual
method is not ideal for efficiently screening large
numbers of protein formu­lations. A better option isthe visual inspection station (VIS) from UnchainedLabs.
The VIS automatically measures turbidity, counts
visible particles and assesses color of formulation
samples. With this system, hundreds of turbidity
measurements can be performed per day withminimal hands-on time. The VIS can be integrated
with other analytics such as pH and viscosity on thefreeslate jr. or into a customized larger workflow ona freeslate system configured for biologics formulation. In this application note, we compare the automated VIS to a standard turbidimeter, the HachLange 2100 AN, using five mAb drug formulations
currently in development.

Results
Turbidity results for the five mAb formulations aresummarized in Figure 1. Turbidity results from theVIS were slightly higher but still comparable to theHach Lange 2100 AN turbidimeter. The replicate
measurements for the VIS demonstrate that data
generated by the instrument are precise (Table 1).

Materials and methods

While the two systems provide comparable results,
the required hands-on time to run the systems
are very different. After a short manual setup, allmeasurements with the VIS were unattended. The
VIS requires a short system setup, about 15-20
minutes, that was performed only once for eachManual turbidity measurements were performedon the Hach Lange 2100 AN turbidimeter peruser guide instructions. Each sample was analyzed at three different vial positions to minimize
the interference of scratches and imperfections
1

FAST AND AUTOMATED TURBIDITY MEASUREMENT OF PROTEIN FORMULATIONS

sequence. Typical sample sequences can range from
1–260 vials. Turbidity analysis with the VIS requires
approximately two minutes per sample which
includes both vial transfer and measurement. The
Hach Lange 2100 AN turbidimeter measurements
require about 3.5 minutes per sample. Table 2compares the hands-on time per sample for bothmethods. Table 3 compares total analysis timemAb
formulation

Turbidity(NTU)

Averageturbidity(NTU)

RSD
turbidity(%)

of both methods. Using the Hach Lange 2100 AN
turbidimeter to measure the turbidities of 260
samples would require approximately 15 hours ofmanual operation. In contrast, one scientist using
Unchained Labs' instru­ment can measure turbiditiesof up to 260 samples with only a 20 minute setup
providing a 45-fold savings of operator time forturbidity measurements of drug products.

Minimumturbidityresult(NTU)

Turbidity comparison
459.4540A9.99

10.0

5

Nephelometric turbidity units (NTU)

9.71
9.4

10.64
10.12
15.71
16.21
B

17.59

16.6

4

15.7

16.79
16.78
17.48

C

18.15

Unchained labs visual inspection station

34.8

35
30
26.1
25

21.7

20

17.4

15.7
15
10

14.4

12.4
7.4

9.4

50

18.15

40.0

Hach lange 2100 An turbidimeter

ABc

DemAb formulation

17.9

3

17.4

26.7

2

26.1

Figure 1: A comparison of the turbidity results of five mAb
formulations using the Hach Lange 2100 AN turbidimeter andUnchained Labs' VIS.

17.35
18.50
26.79
26.47
D27.44

Hands-on time persample measurement

26.76
26.08
40.02
40.52
E

40.39

40.9

2

40.0

40.97
42.53

HachUnchainedLabs

Transfer sample tocuvette

0.5 min

N/A

Polish cuvette

1 min

N/A

Read cuvette

2 min

N/A

Total time

3.5 min0 min

Table 2: Comparison of hands-on time for Hach and Unchained Labs'turbidity instruments. After a brief setup time, turbidity analysis on theVIS is completely automated.

Table 1: Turbidity results of five mAb formulations measured
using the VIS.

2FAST AND AUTOMATED TURBIDITY MEASUREMENT OF PROTEIN FORMULATIONSHachUnchained Labs

Required

Required hands-ontime

Required hands-ontime

Automated
analysis time

Setup time

20 min20 minN/ATime per sample

3.5 min

0 min

2 min

Number of samples

260

260

260

Total time

15 hrs

0.3 hrs

8.7 hrs

Hands-on time per sample
measurement

Table 3: Comparison of total analysis time for Hach and Unchained Labs' turbidity instruments. To automatically analyze
260 formulations with the VIS requires a 20 minute setup, and the entire analysis is complete in approximately nine hours.

Conclusion
This turbidity study demonstrates that the VISfrom Unchained Labs generates comparable
turbidity results faster and more easily thantraditional, manual methods. When combined withthe ability to automatically count visible particles
and assess color changes in a formulation, theVIS allows a single scientist to quickly screen

a large number of formulations with minimal
manual intervention. Automating manual assays
such as turbidity measurement, visible particle
counting, pH measurement and viscosity canhave a significant impact on lab productivity andaccelerate formulation development.

Unchained Labs
6940 Koll Center Pkwy, Suite 200
Pleasanton, CA 94566
Phone: 1.925.587.9800
Toll-free: 1.800.815.6384
Email: info@unchainedlabs.com© 2016 Unchained Labs. All rights reserved. UnchainedLabs is a registered trademark. All other brands or
product names mentioned are trademarks owned bytheir respective organizations.

Rev B3