ONE-ARM DUMBBELL SCOTT-ZOTTMANN CURLS
Use a seated Scott bench. Have a partner hand you the dumbbell. Using a supinated grip (palms facing ceiling), curl the dumbbell to the point just before tension on the elbow flexors is lost. At this point, pronate your forearm completely, so your palm is facing away from you. When you lower the weight, the biceps brachii will have an ineffective line of pull, thereby shifting the load to the underlying brachialis and the brachioradialis. 

Make sure elbow flexors are fully stretched in the bottom position of the eccentric range before you supinate your wrist to begin the next rep. To enforce this, your forearms should make contact with the padded surface of the Scott bench at the end of the eccentric range. 

PAUSED, STANDING, MID-REVERSE-GRIP EZ BAR CURLS
Grasp an EZ Bar with a shoulder-width, semi-pronated (overhand) grip (the second bend away from the center of the bar). Curl the bar until the tops of your forearms make contact with your biceps. 

Do not swing the bar or flare your elbows to complete the movement. For maximal isolation, support your shoulder blades with a Swiss ball. 

SEATED DUMBBELL ZOTTMANN CURLS
Grasp two dumbbells and sit at the edge of a flat bench, or better yet, one that supports your lower back and allows you to lock your feet into place. 

With arms fully extended downward and dumbbells in the bottom position, palms should face forward. To prevent recruitment of forearm flexors during the concentric phase, curl the dumbbells with palms up and wrists cocked back. At the top (forearms in contact with biceps), pronate your forearms (rotate hands so palms face away from you). At the same time, straighten your wrists. 

From this point, the exercise is identical to the eccentric portion of a reverse dumbbell curl. Keeping wrists in a neutral position with palms facing away, lower the dumbbells in a controlled manner. Keep your elbows glued to your sides throughout. If your elbows flare out, your brachialis muscles are weak in relation to your biceps brachii. Decrease the weight so you can do the exercise correctly. 

SEATED OFFSET-GRIP DUMBBELL CURLS
Sit on a regular bench and hold the dumbbells with an offset grip- that is, an asymmetrical grip in which the thumb side of your hand rests against the inside surface of the dumbbell plate. This grip increases the involvement of the short head of the biceps upon wrist supination. Start with your wrists semi-pronated ( i.e., as if holding a hammer) and curl the weight to about 40 degrees of elbow flexion. Then, supinate your wrists (turn palms up) and complete the curling movement. Your forearms should touch your biceps. 

CLOSE-GRIP BARBELL SCOTT CURLS (PREACHER CURLS)
Use less resistance than you would on standard curls. Set the height of the seat so the tops of your thighs are parallel to the floor. It's best for your lower back if the seat is angled downward. 

Sit on the Scott bench and grasp the barbell using a supinated (palms up) grip, with your little fingers four to six inches apart. Your arms should be outstretched so your triceps are in contact with the padded surface. 

Initiate the movement by bending your elbows. Curl the barbell to the point at which your elbow flexors are just about to lose tension. Then, reverse the movement. Make sure your elbow flexors are fully stretched in the bottom position. Keep your wrists cocked back throughout the full range of motion.

From Musculardevelopment.com