1. Using a small gas flame, soften the middle of a BDH hard glass capillary tube by rotating it slowly over the flame. As soon as the glass softens, withdraw it from the heat, and simultaneously pull the ends apart sharply, but not until the two halves snap.
2. Score the capillary with a diamond pen, and snap it into two. If the pulled portion is too long (>5 cm) or too narrow (<200 |im), score and snap again. The internal diameter of the pipet should be about 300 |im, and the end should be flush with no jagged ends.
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